RESEARCH IN HIGH ENERGY PHYSICS - Department …rpr/2010/hepmaster10nobud.pdf1.0.1 Introduction The...

Technical Progress Report

and

FY2010-2012 Funding Request

for

DOE Grant DE-FG02-04ER41291

to

The U.S. Department of Energyfrom

The University of Hawaii

Honolulu, Hawaii 96822

Title of Project:

RESEARCH IN HIGH ENERGY PHYSICS

December 1, 2009 to November 30, 2012

Single Point of Contact

Thomas E. Browder

Email: [email protected]

Address: 2505 Correa Road

Honolulu, HI 96822

Phone: 808-956-2936

Principal InvestigatorsT.E. Browder P. Gorham

F.A. Harris J.G. Learned

S. Parker X. Tata

G.S. Varner

Contents

1 Preface 1

1.0.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.0.2 Some highlights from the past year . . . . . . . . . . . . . . . . . . . . . . . . 2

2 Accelerator-Based Experiments: KA120101 & KA110101 3

2.1 The Belle and Belle II Experiments, KA120101 . . . . . . . . . . . . . . . . . . . . . 3

2.1.1 Introduction and Current Status . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.1.2 Belle II at SuperKEKB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2.1.3 Physics Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2.1.4 Analyses of B Decay Modes with Charmonium . . . . . . . . . . . . . . . . . 7

2.1.5 Inclusive Analysis of Rare B Decays . . . . . . . . . . . . . . . . . . . . . . . 7

2.1.6 Time-Dependent Analysis of CP-Violating Asymmetries . . . . . . . . . . . . 8

2.1.7 Υ(1S) running and search for the light Higgs . . . . . . . . . . . . . . . . . . 10

2.1.8 Time of Flight System: calibration and monitoring . . . . . . . . . . . . . . . 10

2.1.9 High Luminosity Belle-II Detector Instrumentation . . . . . . . . . . . . . . . 11

2.1.9.1 Photodetector Read-Out Monolithic, Precision Timing (PROMPT) 11

2.1.9.2 Imaging Time-Of-Propagation (iTOP) . . . . . . . . . . . . . . . . . 11

2.1.9.3 Pixel Vertex Detector Upgrade at Belle II . . . . . . . . . . . . . . . 11

2.1.9.4 Continuous Acquisition Pixel [CAP] Development . . . . . . . . . . 12

2.1.10 UH-Belle Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.1.11 Invited talks by T. E. Browder, G. Varner, J. Li, etc. . . . . . . . . . . . . . . 14

2.1.12 Recent Belle papers with large Hawaii contributions, Belle-II R+D papersand Super B Factory Reviews . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2.1.13 Recent Belle publications, in reverse order of submission . . . . . . . . . . . . 15

2.2 The BES Experiment, KA120101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.2.1.1 Charmed particle physics with BES-III . . . . . . . . . . . . . . . . 18

2.2.1.1.1 BES-III and D0-D0 mixing . . . . . . . . . . . . . . . . . . 18

2.2.1.1.2 BES-III measurement of fDs . . . . . . . . . . . . . . . . . 18

2.2.1.1.3 BES-III and the XY Z mesons . . . . . . . . . . . . . . . . 18

2.2.1.2 Other physics at BES-III . . . . . . . . . . . . . . . . . . . . . . . . 19

2.2.2 Hawaii Participation in BES . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2.2.3 Recent Physics Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2.2.4 BEPCII/BES-III Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

2.2.5 BES-III TOF Monitoring System . . . . . . . . . . . . . . . . . . . . . . . . . 21

2.2.6 Precision beam energy measurement at BEPCII . . . . . . . . . . . . . . . . 21

2.2.7 Computing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.2.8 Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

2.2.9 UH-BES Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

2.3 3D Silicon Sensors, KA110101 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.3.2 Proposed uses in ATLAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.3.3 Fabrication Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.3.4 ATLAS groups working on 3D sensors . . . . . . . . . . . . . . . . . . . . . . 28

2.3.5 Keys to the technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

2.3.6 Some initial results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

2.3.6.1 Electrode Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.3.7 Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

3 Non-Accelerator Experiments: KA130101 37

3.1 KamLAND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.1.1 Status of KamLAND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

3.1.2 Hawaii Role in KamLAND . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

3.1.3 Future Plans for KamLAND . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

3.2 Super-Kamiokande . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

3.2.1 SuperK Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

3.2.2 Hawaii Participation in SuperK . . . . . . . . . . . . . . . . . . . . . . . . . . 40

3.2.3 Physics Results from SuperK . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

3.2.4 Future Plans with SuperK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

3.3 Hanohano studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

3.3.1 Introduction to Hanohano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

3.3.2 Hawaii Role in Hanohano . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Hawaii FY10 DOE Proposal

3.3.3 Results of Hanohano Studies . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

3.3.4 Large Liquid Scintillation Detector Long-Baseline Neutrino Experiment . . . 44

3.3.5 Future Plans for Hanohano . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.4 Other Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.5 Invited Talks, 2008-2009 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

3.6 Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

3.6.1 Recent KamLAND Publications . . . . . . . . . . . . . . . . . . . . . . . . . 47

3.6.2 Recent SuperK & K2K Publications . . . . . . . . . . . . . . . . . . . . . . . 47

3.6.3 Recent Hanohano Publications . . . . . . . . . . . . . . . . . . . . . . . . . . 48

4 Radio Detection of High Energy Particles: KA130101 51

4.0.4 ANITA-2 2008-2009 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

4.0.5 ExaVolt Antenna: A Next Generation Long-duration Balloon-based NeutrinoObservatory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

4.0.6 AMBER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

4.0.6.1 AMBER progress in 2008-2009 . . . . . . . . . . . . . . . . . . . . . 59

5 Detector Research and Development: KA150302 65

5.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.2 Fine Spatial Resolution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

5.3 High Precision Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

5.4 Precision 3D Silicon Space-Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66

5.5 Large Format Photodetectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.6 Tera-ton Detector instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.7 Beamline Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

5.8 Other Efforts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

5.9 Invited talks by G. S. Varner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

5.10 Recent Dectector R&D papers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

6 Theoretical Physics: KA140101 71

6.1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

6.2 Particle Physics, Cosmology, and the LHC(Jason Kumar) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

6.2.1 Dark Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

6.2.2 CP-Violation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

6.2.3 Inflation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

6.2.4 Dynamical Supersymmetry-Breaking . . . . . . . . . . . . . . . . . . . . . . . 74

6.2.5 Future Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

6.3 Neutrino Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

6.4 Heavy Quark and Flavor Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

6.5 Supersymmetry Phenomenology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

6.5.1 Simulation of supersymmetry at colliders . . . . . . . . . . . . . . . . . . . . 79

6.5.2 Dark Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

6.5.3 Heavy quarks as a probe of supersymmetry . . . . . . . . . . . . . . . . . . . 80

6.5.4 Flavour and CP violation in supersymmetric models . . . . . . . . . . . . . . 81

6.5.5 A U(1)′ solution to the SUSY μ − bμ and proton decay problems . . . . . . . 81

6.5.6 SUSY at the LHC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

6.5.7 Dark Matter at linear colliders and LHC-ILC interplay . . . . . . . . . . . . . 82

6.5.8 Future Plans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

6.6 Talks and other activities of Theory Group since last review . . . . . . . . . . . . . . 83

6.7 Publications of the Theory Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

7 Budget Explanations & Forms 88

8 Appendix-Current FY09 Budget 90


Chapter 1

Preface

High Energy Physics at the University of Hawaii:FY 2009 Progress Report & FY2010-FY2012 Funding Request

Abstract

The high energy physics research program at the University of Hawaii is engaged in experimentsstudying neutrinos, flavor physics, hadron spectroscopy, high-energy neutrino astrophysics and de-veloping new types of instrumentation. Theoretical physics research is phenomenologically orientedand studies experimental consequences of existing and proposed new theories.

1.0.1 Introduction

The Hawaii high energy physics group consists of three University-supported theoretical faculty(Kumar, Pakvasa and Tata) and eight University-supported experimental faculty: Browder, Harris,Gorham, Learned, Matsuno, Olsen, Peters and Varner.∗ Olsen retired in July 2009 and continuesworking on BES-III and Belle as an emeritus faculty; the University is currently recruiting hisreplacement. Full-time research scientists Jones and Parker are primarily supported by DOE fundsalong with eight Research Associates, and nine graduate students. In addition, there are fiveaffiliate faculty: Domback (experimental particle physics), Dye and Morse (cosmic rays), Ohnuma(accelerator physics) and Simmons (theory).

The group has permanent laboratory facilities in Watanabe Hall, Krauss Hall and the PhysicalSciences Building on the UH Manoa Campus. Much of the laboratory equipment was purchasedwith university funds. We have an excellent engineering support staff: Ibaraki & Zi for computingand networking, Rosen for mechanical and optical systems, and Kennedy for electronics. An assort-ment of largely university-provided computers, workstations and 44-node and 30-node PC farmsare connected by Ethernet and linked to the mainland via the university’s fiber-optic T1 lines. Weare the major user of the physics department’s machine shop, which has two full-time, university-supported machinists. We maintain close contact with our department’s free electron laser groupand with astronomers, astrophysicists and cosmologists at the UH Institute for Astronomy.

We benefit from our proximity to world-class experimental facilities in Asia, such as the Super-K & KamLAND underground neutrino detectors and the KEKB/Belle B-factory in Japan, andthe new BEPC-II/BES-III facility in Beijing, China. Our experimental work is collaborative andwe have important impact on these activities: Gorham is the innovator, PI and spokesperson ofANITA; Browder replaced Olsen as co-spokesperson of Belle; Harris has been co-spokesperson ofBES since 1998.

∗Learned, Matsuno and Peters have 11-month University positions and receive no salary support from the DOEgrant.


CHAPTER 1. PREFACE

The theoretical research has close overlap with the experimental program and concentrates onphenomenological analyses of quarks, neutrinos, tests of the standard model, and search strategiesfor new physics.

1.0.2 Some highlights from the past year

Ultra-high energy cosmic rays: The Hawaii-led ANITA payload completed its second Antarcticlong-duration balloon flight, with 31 days aloft. The payload performed flawlessly and initialestimates of the sensitivity indicate it will improve by a factor of 3-5 over the first flight. ANITAretains its pre-eminence as the world’s most sensitive ultra-high energy cosmic-ray neutrinoexperiment.

First operation of BEPCII/BES-III: The new Beijing τ -charm threshold facility turned on inJuly 2008 and currently operates with a luminosity that exceeds 3 × 1032cm−2s−1. This is thehighest ever achieved in the charm-tau threshold region and 30% of the ultimate design value.BES-III is now accumulating high quality data at the J/ψ and ψ′ resonances.

Theory highlights: Pakvasa’s early and comprehensive analysis of the implications of D0 − D0

mixing is receiving considerable attention now that mixing signals are being experimentallyobserved. Implications of Kumar’s suggestion of light non-WIMP dark matter have receivednotice in Nature and New Scientist. Tata is incorporating his recently completed comprehensiveanalysis of the flavor structure of super-particle interactions into the ISAJET code.

Tightened constraints on neutrino oscillations from KamLAND:KamLAND continues to tighten the constraints on neutrino oscillations with further clarifi-cation of oscillating cycles and smaller error on Δm2

12, and prepares for another more sensitiveround of measurements.

Belle II Detector and SuperKEKB Design: Five million dollars in initial funding for theBelle-II detector and 27 million dollars for the SuperKEKB accelerator has been allocatedby the Japanese government. Browder is an interim co-spokesperson of the new internationalBelle II detector collaboration.

Electronics for Belle II: Varner leads an international team that is developing a ”unified read-out” system for the Belle-II detector upgrade. This high-speed/precision fiber-optic-based read-out system is based on Varner’s LABRADOR “oscilloscope on a chip” concept.

3-D pixels for LHC & SLHC: The Parker-invented 3-D, active-edge silicon pixel technology isbeing incorporated in both near-term and future LHC experiments.

Nobel Dreams: Olsen and Pakvasa were invited to attend the 2008 Nobel ceremonies as guestsof Makoto Kobayashi: Olsen as a representative of the Belle group and Pakvasa because of hisseminal paper with H. Sugawara that first pointed out the relevance of the Kobayashi-Maskawasix-quark model for CP violation.

2 Hawaii FY10 DOE Proposal

Chapter 2

Accelerator-Based Experiments:KA120101 & KA110101

2.1 The Belle and Belle II Ex-periments, KA120101

Drs. T.E. Browder, G.S. Varner, H. Hoedl-moser, M.D. Jones, J. Li, S.L. Olsen, M.W. Pe-ters, C-P Shen, and Mr. K. Nishimura, Mr. J.Rorie, Mr. L. Ruckman and Mr. H. Sahoo

(Browder and Varner are the co-principal in-vestigators of this task)

2.1.1 Introduction and Current Status

The Belle physics highlights in 2009 include ameasurement of an intriguing forward-backwardasymmetry in B → K∗�+�− that may deviatefrom the SM expectation, confirmation of Belle’soriginal evidence for B → τν and observationof several new unexpected particles above charmpair threshold. In addition, Belle has publisheda series of results on new decay modes of theBs meson and unusual properties of the Υ(5S)resonance.

In January 2007 after a long struggle, crabcavities, a new accelerator technology, were in-stalled in KEKB. These superconducting radio-frequency cavities rotate the incoming bunchesso that in the KEKB crossing angle geometry thebunches collide head-on at the interaction point.

The detailed commissioning of these novel de-vices at KEKB started in February 2007. Fora long period of time, the performance was inpoor agreement with simulation and the im-provements in tune-shift and luminosity weremodest. Recently, a breakthrough was achievedby controlling the behaviour of off-energy beamparticles with special skew sextupole magnets.

On May 6, 2009, KEKB broke the world luminos-ity record and achieved a luminosity of 2 × 1034

/cm2/sec using its crab cavities. This new recordis a factor of two higher than the original designluminosity of KEKB. While this record luminos-ity was occurring, background conditions weregood and the Belle experiment was able to recorddata smoothly.

Belle has integrated 925 fb−1 at the time thisreport was submitted. Most of the data wererecorded on the Υ(4S) and used to study thephysics of B mesons. However, Belle has alsotaken special runs at other center of mass en-ergies and is currently running at the Υ(5S).More than 50 fb−1 of data has now been recordedon the Υ(5S) resonance in order to study Bs

mesons. Belle plans to eventually record adataset of 100 fb−1 on the Υ(5S).

A part of this dataset (∼ 23fb−1) has alreadybeen used to make the first observation of thepenguin Bs decay Bs → φγ, as well as the obser-vation of an anomalous two order of magnitudeenhancement in the production rate of Υ(1S)ππand Υ(2S)ππ. Varner was an internal referee forthe Bs → φγ paper. Jin Li and Browder havereported the first signals for the CP eigenstatemode Bs → J/ψη from this subset (shown atMoriond 2009, Fig. 2.1). Although hadron col-liders produce large quantities of Bs mesons, thetopics described above require good detection ofphotons and π0 mesons and hence cannot be ac-cessed easily at hadron machines. Work is inprogress on the CP eigenstate Bs → J/ψη

′. Li

and Browder plan to further extend the sample ofCP eigenstates and will study the sensitivity fortime-dependent Bs measurements in this sample.


CHAPTER 2. ACCELERATOR-BASED EXPERIMENTS: KA120101 & KA110101

E (GeV)Δ-0.2 -0.1 0 0.1 0.2 0.3 0.4

Eve

nts

/(16

MeV

)

0

1

2

3

4

5

6

7

)2 (GeV/cbcM5.26 5.28 5.3 5.32 5.34 5.36 5.38 5.4 5.42 5.44

Eve

nts

/(4

MeV

)

0

1

2

3

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5

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8

Figure 2.1: The first observation of the Bs CPeigenstate mode Bs → J/ψη with η → γγ orη → π+π−π0, (a) ΔE distribution; (b) Beam-constrained mass distribution, which is domi-nated by B∗

s B∗s production. The small contri-

bution to the left of the signal is due to BsB∗s

production.

A special 3 fb−1 run with a modified triggerconfiguration was also taken on the Υ(3S) in2006 to search for dark matter from the Υ(1S).The experimental signature was Υ(3S) →Υ(1S)π+π− with the Υ(1S) decaying to invisibleparticles. In the last two weeks of June 2008, a 5fb−1 run was taken on the Υ(1S) resonance. Thisis now the world’s largest data sample on theΥ(1S) (∼ 5 times larger than the CLEO datasetand at an energy below the range where PEP-II could operate). At the end of 2008, a sampleof 7 fb−1 was taken on the Υ(2S) resonance. Alarger sample will be recorded in the fall of 2009.An additional 14 fb−1 will be recorded on the

Υ(2S) resonance. This will make the Belle 2Ssample the largest sample on this resonance (ap-proximately 50% larger than the correspondingBaBar sample). The 1S and 2S data sampleswill be used to study strong interaction physicsand search for a non-SM light Higgs (now beingstudied by Jamal Rorie and Varner).

At KEK there has been an intense series ofworkshops and activities focused on the prepa-ration of an accelerator and detector upgrade forthe KEK super B factory. The new machine isdesigned to integrate 50 ab−1 and have a peakluminosity of 8 × 1035/cm2/sec. The upgradeddetector will be called Belle II.

2.1.2 Belle II at SuperKEKB

The KEK Super B factory is the highlight ofthe KEK roadmap (5-year plan) adopted by theKEK laboratory directorate. Belle and KEKBwill shut down sometime around the beginningof 2010. This will be followed by a three yearperiod of accelerator and detector construction.Funding and full approval are now under discus-sion at the MEXT, which is the Japanese sciencefunding agency.

The Super-B factory will require significantupgrades of the KEKB accelerator as well verysignificant improvements to the Belle detectorto handle much higher data rates and, also, the20 to 50-fold increases in machine-related back-grounds that are expected; these will present oc-cupancy challenges for the vertex detection andparticle id systems.

Particle identification in the original Belle de-tector was based on aerogel Cherenkov detectorsreadout by fine mesh phototubes in the activevolume of the detector and time of flight (TOF)scintillators. The aerogel Cerenkov devices pro-vided kaon/pion separation in the momentumrange up to 4 GeV while the TOF was used toseparate pions and kaons in the momentum upto 1.5 GeV. The information from the TOF andaerogel was combined with dE/dx measurementsfrom the central drift chamber (CDC) to aug-ment particle id. The University of Hawaii groupassembled the TOF counters and then was re-


2.1. THE BELLE AND BELLE II EXPERIMENTS, KA120101

End Cap PID:

Aerogel RICH

-800 CDC position in Z +1600

CU

RR

EN

T

F

UTU

RE

Figure 2.2: A two-dimensional CAD drawing showing a top view of the Belle-II detector on theupper half and the original Belle detector on the lower part. This CAD drawing was prepared byHawaii engineer Marc Rosen. Note that the original TOF and aerogel systems in Belle have beenreplaced by a quartz bar Cherenkov detector in Belle II.

sponsible for the reconstruction and calibrationthroughout the entire Belle run. Varner devel-oped the trigger electronics as well as the timestretcher circuit for the TOF readout.

For Belle II, particle identification will insteadbe based on internally reflected Cherenkov lightin quartz bars. This technique, originally devel-oped by B. Ratcliff et al. for the BaBar DIRCdetector, must be modified to be consistent withthe space constraints of the Belle structure aswell as the constraints of the Super KEKB back-ground environment.

Hawaii’s past contributions to the machine de-tector interface region and design of the interac-

tion region as well as Varner’s current activitiesin high-speed readout electronics, his proposalfor an imaging TOP (Time of Propagation)-style Cherenkov particle identification device(see Fig. 2.3) and his experience in develop-ing prototype pixel detectors guarantee that theHawaii group will have a significant impact onthe upgraded machine and detector hardware.Browder will continue in his organizational rolefor the Belle-II detector collaboration. Rosenwill design the support structure for the bar-rel particle identification system as well provideCAD and FEA (see Fig. 2.4) for overall detectorsubsystem integration. A new assistant profes-sor currently being recruited to replace Olsen is

Hawaii FY10 DOE Proposal 5


FEA: Barrel Model with Circular Bulkheads

Barrel Deflection due to Gravity ~395kg Barrel Deflection with full Quartz ~1,230kg

Deflection ~80um Deflection ~300um

Figure 2.4: Finite element analysis of a proposed support structure for the iTOP particle identifi-cation detector in Belle II by engineer Rosen.

expected to join in this Belle II effort.

The ultimate luminosity for the KEK Super-B design is 8 × 1035/cm2/sec. This will allowthe integration of a 50 ab−1 data sample thatis needed to cover the full range of new physicssearches and possibilities. Browder has long beena leading proponent of the super-B factory pathat KEK where it is viewed as a natural follow-up to the very successful KEKB/Belle program.His activities in his area include the organizationof the Belle II collaboration structure, meetingsand workshops as well as the preparation of re-view articles on the physics of the super-B facto-ries [5], [6]. The Hawaii group (Browder, Varnerand a new assistant professor) will play a high-profile role in the Belle II experiment at the KEKSuper B factory facility, similar to the role of theHawaii group during the last decade at Belle.

Hawaii was one the founding members of theBelle collaboration. We have played a criticalrole in many aspects of the experiment. Olsenwas one of the original co-spokespersons whileBrowder served for many years as analysis co-ordinator. Browder is currently serving his 2nd

term as a co-spokesperson and Varner is the in-stitutional board representative.

In addition to analyzing Belle data and ex-tracting physics, we are responsible for moni-toring and calibration of the Belle TOF system(Jones); this is described in detail below. In ad-dition, we measure the number of B-meson pairsand KEKB beam energy calibration (Nishimura)and developed high speed electronics for recentupgrades to the Belle DAQ and TOF systems(Varner and Rorie) that were required to keepup with KEKB’s ever increasing luminosity. Weare now concentrating on the final round of R&Dfor Belle II at the KEK super-B factory. Con-struction of the Belle II barrel PID and electron-ics (“oscilloscope on chips”) for several detectorsubsystems will be the future focus of the groupand will be the subject of a supplemental pro-posal.

The work on the Super B factory includes thedevelopment of a novel particle identification de-vice called the i-TOP (Varner, Browder, Rosen,Nishimura, Ruckman et al.), a pixel vertex de-tector upgrade (Varner, Hoedlmoser et al.), and



iTOP PID CONCEPT

QUARTZ RADIATOR

EXPANSION VOLUME

PHOTO DETECTORMECHANICAL BARREL ENCLOSURE

READ-OUT ELECTRONICS

Figure 2.3: The concept of the iTOP parti-cle identification detector in Belle II. Cherenkovlight is produced in the quartz bar and is trans-mitted by total internal reflection to a standoffblock. The image and arrival times are recordedby pixelated photon detectors.

high speed SVD readout devices (Varner, Li, Sa-hoo et al.). Varner is the leader of the Belle/BelleII hardware work.

2.1.3 Physics Publications

New publications since last year are listedin Section 2.1.13. Browder founded the Bellepublication council (PC). Hawaii faculty mem-bers scrutinize all Belle papers and are active inrewriting many if not all of them.

2.1.4 Analyses of B Decay Modes withCharmonium

The b → ccs transition is a strong decay chan-nel for b quarks. Consequently about 15% ofall B meson decay final states contain a cc pair.These frequently combine to form a final-statecharmonium (or charmonium-like) meson state.

Olsen and his collaborators showed that the kine-matic constraints of B decay allow one to ex-perimentally isolate new charmonium-like reso-nances, some of which are candidates for exoticstates (4-quark states or hybrid charmonium).

The detailed analysis of B decay modes withcharmonium in the large Belle data sample hasyielded many surprises. Olsen discovered theX(3872) particle in B → K(J/ψπ+π−) and theY (3940) in B → K(ωJ/ψ). This catalyzed agreat deal of experimental activity and theoret-ical interest. The discovery of the X(3872) wasthe first in a series of observations of new andunexpected charmonium-like states.

Recently, Olsen found a resonant structure inthe (ψ

′π+) system in the decay B → Kψ

′π+.

This year he participated in a sophisticatedDalitz plot reanalysis of this Z(4430) resonancethat confirmed the original result. Belle has alsorecently reported two new charged charmonium-like states (observed as enhancements in χc1π

+

mass).

Former graduate student Hulya Guler exam-ined the B → (Kππ)J/ψ and (Kππ)ψ′ decaymodes in detail to determine the resonant prop-erties of the kaonic system. Clear evidence isfound for the K1(1270), K1(1400) as well ashigher mass kaonic states. Olsen supervised herthesis research. She is now finishing a journalpublication at her new postdoctoral position inCanada.

2.1.5 Inclusive Analysis of Rare B Decays

Kurtis Nishimura and Browder are examiningthe inclusive decay B → ηXs. This decay hasnever been observed and would complement theresults on the anomalous inclusive process B →η′Xs by former student Kirika Uchida as well

as measurements of B → η′Xs by BaBar and

CLEO. Comparison of the rates and Xs massdistributions would help determine whether theη′anomaly (a special two-gluon coupling of the

η′) or new physics plays a role.

After extensive MC studies, during the fall of2008 we unblinded a 35% subset of the full datasample. This subset will be used to check the



robustness of the analysis procedure and verifyMC expectations for background. Results fromthe 35% subset are shown in Fig. 2.5. A signalfrom B → K∗η is clearly visible along with ahigher mass excess, whose nature is under study.

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2.1.6 Time-Dependent Analysis of CP-Violating Asymmetries

Himansu Sahoo and Browder have analyzedthe time-dependent CP asymmetry in B →ψ

′KS , which is shown in Fig. 2.6. Using the

Belle data sample of 657 × 106 BB pairs, theyobtained the world’s most precise measurementof the effective value of sin 2φ1 (a.k.a sin(2β)) inthis mode, sin(2φ1) = 0.72±0.09±0.03. The re-sult was published in Phys. Rev. D Rapid Com-munications. The analysis [4] will be extendedto other b → ccs modes such as B → χc1KS todetermine whether the effective value of sin(2φ1)is the same for all modes. Some new physics sce-narios predict small differences between b → ccs

modes; these might be visible with high statis-tics. Sahoo will also analyse time-dependentasymmetries in B → ψ(2S)KS and B → J/ψKS

for the final measurements with the full Belledata sample.

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dependent CP asymmetry for B → ψ′KS , which

has the characteristic sin(Δmt) modulation ex-pected in the SM.

Jin Li and Browder have examined the de-cay mode B → KSπ+π−γ to determine whetherit can be used for time-dependent CP viola-tion analysis. Clear signals are visible in thebeam-constrained mass distribution as shown inFig. 2.7. The B → KSρ0γ component may beused to detect the presence of right-handed cur-rents due to new physics. At present the onlymode that has been used to search for this typeof new physics is B → K∗0γ. This mode mustbe reconstructed as KSπ0γ and the KS vertexmust be measured inside the silicon vertex de-tector system. In contrast, the mode used by Lihas a prompt two charged pion vertex that canbe detected efficiently.

To use this mode for CP violation, the frac-tion of KSργ in the B → KSπ+π−γ final statemust be known. The flavor specific state B →K∗+π−γ will dilute any potential CP asymme-try.

As shown in Fig. 2.7, the final state in the



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vertexing in the silicon detector.

ρ mass region is dominated by B → KSρ0γ.Li finds that the time-dependent CP violatingparameter SKSργ = 0.11 ± 0.33(stat)+0.05

−0.09(syst),consistent with no right-handed weak currents.

A second class of modes can also be used tosearch for right-handed weak currents withoutKS vertexing. The most promising example isB → φKSγ in which the time dependent CPasymmetry is measured from the charged kaonsin the φ → K+K− decay. MC studies by Sahooand Browder of this mode as well as B → ωKSγ

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are in progress. Typical distributions are shownin Fig. 2.9. MC studies are nearly complete andthe unblinded data will be examined soon.

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2.1.7 Υ(1S) running and search for the lightHiggs

Jamal Rorie and Varner played an importantrole in planning and carrying out the dedicatedΥ(1S) and Υ(2S) runs. Rorie was in close dailycontact with the KEKB machine group, partic-ipated in the energy scan to locate the Υ(1S)peak and reported regularly at the KEKB dailyaccelerator meetings. He and Varner will nowuse this 1S data sample to search for light non-standard model Higgs. This search is motivatedby the possibility that there is a Higgs, H, near100 GeV that eluded previous LEP limits. TheH decays predominantly to pairs of lighter Hig-gses, a0a0, where the a0 then goes to τ+τ−. AtBelle, we search for Υ(1S) → γa0, a0 → τ+τ−.The search is sensitive to light Higgs, a0’s, withmasses below 10 GeV. The Υ(1S) dataset mayalso be used to confirm the existence of the ηb

particle recently found by BaBar. In the Υ(2S)and Υ(1S) data samples, one expects to observemonochromatic photon lines from the Υ(nS) →γηb radiative transitions.

2.1.8 Time of Flight System: calibrationand monitoring

Jones continues to have a major role in main-taining the calibration of the TOF (time of flight)system and monitoring the data quality. Mostof the quality checks use dimuon events, whichare also used to determine calibration parame-ters. This monitoring is necessary to find subtleproblems with individual counters (e.g. short-term variations in PMT gain or timing) or withinsingle runs that are not apparent in the onlinemonitoring. Such problems are infrequent andtypically involve only a few PMTs but requireadjustments in calibrations; PMTs with suddentime shifts require special treatment. After nineyears of data taking, one of 64 TSC PMTs iscompletely dead. One of 256 TOF PMTs died atthe start of 2007 and another died in Fall 2007.These required a modification to the calibrationcode to allow calibration of the other PMT onthis counter. One TOF PMT has a very lowgain and thus poor time resolution (about 1200ps), and four others have resolutions worse than

250 ps.

Figure 2.10: TOF total time resolution versuscalendar year. The resolution is for all TOFcounters combined and is based upon calibrationusing dimuon events. The different symbols de-note major changes that might affect TOF per-formance. New TOF preamps were installed inSummer 2003, a 128 MHz clock was used startingin Fall 2005, and there was an increase in highvoltages and lower thresholds starting in 2006.

TOF monitoring continues to find occasionalproblems with the time stretcher electronics.The time stretchers for such PMTs were re-placed as soon as possible after the problemswere found. There are also a few PMTs withunstable gain which require special handling incalibration.

Figure 2.10 shows the TOF time resolutionsfrom calibrations using dimuon events as a func-tion of calendar time. The resolution degradedat a rate of 2 ps per year until new TOF preampswere installed in late 2003. Since then, the degra-dation has been slower and was not affected bythe change to the new 128 MHz clock in Fall2005. The gradual degradation is due in part tothe observed reduction in the attenuation lengthof the TOF scintillators. The sudden short-termdegradations in early 2004 and early 2007 weredue to poor tracking parameters and were cor-rected.

Finally, we also monitor the dimuon andBhabha cross sections to check TOF perfor-mance. This monitoring continues to revealoccasional problems with the data processing.



Some of these problems are fixed by reprocess-ing; in one case, problems were found in repro-cessed data that were not present in the originalprocessing.

2.1.9 High Luminosity Belle-II Detector In-strumentation

The Belle II detector will use a new Cherenkovlight based particle indentification detector to re-place the existing threshold aerogel and time offlight detectors. This detector will require pre-cise timing and waveform sampling to achieve itsreolution goals. To exploit fully the potential ofan upgraded B-factory a thin, exquisite resolu-tion pixel vertex detector is needed.

2.1.9.1 Photodetector Read-Out Monolithic, Pre-cision Timing (PROMPT) Recently Varnerwith Ruckman and Wong developed a read-out system for future single-photon, high-precision timing devices as part of a DOE ADRaward [2]. This is based upon an evolution of theLABRADOR ASIC, designated BLAB1 [5], to aconfiguration matched to the trigger latencies ex-pected in a Super B-factory environment. A testof this readout was performed with the focusingDIRC prototype detector at SLAC (T-492) [10],as illustrated in Fig. 2.11.

2.1.9.2 Imaging Time-Of-Propagation (iTOP)We are designing a particle identification de-tector upgrade for Belle II. While the per-formance of the focusing DIRC prototype hasbeen outstanding, the expansion volume require-ments do not match the space available withinthe Belle II detector. Therefore Varner andBrowder with Rosen, Ruckman and Nishimurahave been simulating and evaluating a compactquartz Cherenkov device that provides both ex-cellent photon timing and modest imaging res-olution – thus designated the imaging Time-Of-Propagation (iTOP) detector.

An example of a GEANT4 simulation of aniTOP counter is shown in Fig. 2.12. It shouldbe noted that in addition to pixelated photondetectors, timing resolution at or below the 40 pslevel (with jitter in the T0 signal below 25 ps) is

required for acceptable high momentum particleidentification performance.

In order to optimize the design and character-ize the performance of the prototype, a cosmicmuon detector, with precision tracking is underconstruction as shown in Fig. 2.13.

2.1.9.3 Pixel Vertex Detector Upgrade at BelleII To handle the occupancy at Super KEKB, amore finely segmented vertex detector is needed;the current occupancy in the innermost siliconstrip detector is approaching 10%. In the fu-ture larger statistics are necessary to extend thereach of current analyses to the SM limits formany rare decay modes. Even at an upgradedB-factory these modes may require access to newobservables. Drastically improved vertex recon-struction can distinguish secondary and tertiaryvertices, thereby providing background suppres-sion without the statistical penalty of requiringfull opposite B meson reconstruction. In order toachieve these goals for vertexing performance ina Super-B environment [12] a thin device withfine spatial resolution is needed. The baselinetechnology for Belle II will be the DEPFET pix-els originally developed for the ILC by a largeinternational consortium of research universities

Figure 2.12: A GEANT4 simulation of an iTOPcounter in Belle II by Nishimura. Internal reflec-tion of some photons as well as partial Cerenkovrings in the standoff region are visible.



0.2%/degree C(can correct)

6GSa/s

Focusing DIRC(End Station A)

Figure 2.11: The T-492 (focusing DIRC) experiment at SLAC End Station A. A schematic of theHawaii electronics is inset left, background is the readout rack assembly attached to the focusingDIRC prototype, with readout PCs at right. Inset right are from top-to-bottom: BLAB1 ASIC, asample waveform, and the 16-channel, 6 Giga-sample/second CAMAC digitizer card (a 16-channel“digital signal oscilloscope” on a CAMAC card).

and institutes led by MPI Munich. DEPFETpixels can be modified for the super B factoryenvironment and should be adequate to handlethe occupancy demands up to 1× 1035/cm2/sec.However, a more robust pxiel detector solutionis needed for the full SuperKEKB design lumi-nosity.

2.1.9.4 Continuous Acquisition Pixel [CAP] De-velopment For the last few years the Hawaiigroup has continued to evolve the ContinuousAcquisition Pixel (CAP) architecture, a vari-ant of the CMOS Monolithic Active Pixel Sen-sor (MAPS). Excellent results were reported forthe first generation of basic device [13], andpipelined storage was subsequently explored ina CAP2 device [14]. Based on this success, a“full-sized” CAP3 prototype was fabricated andtested [15]. Important lessons were learned fromthis and three techniques have subsequently ex-plored in CAP4 and CAP6 designed by Martinand Cooney, guided by Varner and evaluated bymembers of our international collaboration [16].Detailed testing was performed by Hoedlmoser,Cooney, Li and Sahoo.

Concurrent with these MAPS studies, it isrealized that one of the major problems withthe standard MAPS architecture is the limitedsignal produced in the epitaxial layer. To ad-dress this issue, Varner, Hoedlmoser and stu-dents have been exploring a Silicon On Insu-lator (SOI) process being developed jointly byKEK and OKI Semiconductor [16]. CAP5 hasbeen implemented in this process and testing isin progress.

Hoedlmoser has proposed a new type of pixeldetector with binary hexagonal readout to ad-dress the readout speed issue, reduce reconstruc-tion ambiguities and reduce the pixel data size.He has given talks on this very original idea atvarious hardware conferences and published aNIM paper (H. Hoedlmoser et al., NIM A 599,152 (2009)). If this hexagonal pixel readout canbe realized (for example in a SOI or AMS pro-cess), this could be a major breakthrough.

2.1.10 UH-Belle Personnel

Peters is now an interim associate dean of Nat-ural Sciences in the university but continues hisBelle paper refereeing work and consults on TOF



Figure 2.13: (a) Diagram of a cosmic ray teststand under construction at the University ofHawaii. Using an array of drift tubes to localizea muon track, and internally reflected Cherenkovlight in a quartz bar, the innovative iTOP par-ticle identification detector concept for Belle IIat SuperKEKB can be verified. (b) Photo of thetest stand at the University of Hawaii

calibration issues. Olsen has retired but will con-tinue to participate in Belle as a Seoul NationalUniversity faculty member and emeritus profes-sor at Hawaii. A faculty search is underway foran assistant professor to replace Olsen.

Varner is the Hawaii representative on both the

Belle and Belle II institutional boards and one ofthe Belle II group leaders in particle identifica-tion and high speed electronics. He has proposeda new barrel region particle identification detec-tor for Belle II (the i-TOP, which is an acronoymfor imaging TOP). Varner will be a major par-ticipant in the particle ID “shootout” in 2009 atwhich final choices about the particle id technolo-gies will be made. Browder is co-spokespersonfor Belle and the US representative on the in-ternational steering committee for the KEK Su-per B factory collabration as well as an interimspokesperson for the Belle II detector.

To exploit fully the giant data samples accu-mulated by Belle (by 2010 nearly 1 ab−1) andthe wide range of physics and discovery poten-tial that are available we will need to maintainthe current strength of analysis and activity. Toparticipate at an adequate level in both the datataking and analysis requires frequent travel toKEK by Browder in his role as spokespersonand by Varner for Super KEKB hardware devel-opment as well as by the Hawaii/Belle faculty,postdocs and students.

Mechanical engineering support provided byMarc Rosen will be needed for both the designand construction of the particle identificationsystem as well as for integration of detector sub-systems; in addition to designing the iTOP/TOPstructure, Rosen is currently maintaining a CADfile of the entire Belle II detector. Since tech-nology choices will be made soon, support willbe urgently needed for construction of the newBelle II detector. The electronics that Varnerand his team are developing for high luminosity(i.e. including the “oscilloscope on a chip” forthe readout of the TOP/iTOP particle identifi-cation detector and the readout of other detectorsubsystems) have many applications in Belle II.

Belle II construction at SuperKEKB will bethe subject of another supplemental proposal.We also note that last year the University ofHawaii allocated 55K in “seed money” for BelleII hardware development.



2.1.11 Invited talks by T. E. Browder, G.Varner, J. Li, etc.

1. Browder will give the plenary talk on CP vio-lation at the DPF Meeting in Detroit, Michi-gan in July 2009.

2. Browder reviewed Hints for New Physics inheavy flavor decays at the Hints for NewPhysics conference at KEK in March 2009.

3. Browder reviewed Belle results at the AspenWinter Physics 2009 Conference in February2009.

4. Browder gave a talk on Belle results in D Me-son and Baryon Spectroscopy at the Interna-tional Conference on High Energy Physics inPhiladelphia in July 2008.

5. Varner gave a talk on Searches for NewPhysics at SuperKEKB at SUSY09, June2009 in Boston, Massachusetts.

6. Varner gave a talk on a 500 channel BLABreadout for the fast focusing-DIRC prototypeat the TIPP09 conference, March 2009, inTsukuba, Japan.

7. Varner gave a talk on picosecond timing elec-tronics for Super B factory particle ID detec-tors at the 6th Pico-second Timing Workshop,Oct. 2008, in Lyon, France.

8. Li Jin reviewed results on Bs hadronic decaysat the FPCP (Flavor Physics and CP Viola-tion) conference in May 2009.

9. Li Jin gave a talk on Belle results on radiativepenguin b → sγ type decays at the Interna-tional Conference on High Energy Physics inPhiladelphia in July 2008.

10. Nishimura gave a talk on the iTOP parti-cle identification counter for Belle II at theTIPP09 conference, March 2009, in Tsukuba,Japan.

11. Ruckman gave a talk on iTOP readout elec-tronics at the TIPP09 conference, March2009, in Tsukuba, Japan.

12. Hoedlmoser gave a talk about pixel detectorswith time- encoded binary readout at a meet-ing on Monolithic and vertically integratedpixel detectors at CERN/Geneva in Novem-ber 2008.

13. Hoedlmoser gave a talk about pixel detec-tors with time-encoded binary readout at theLinear Collider Workshop November, 2008 inChicago.


Bibliography

2.1.12 Recent Belle papers with largeHawaii contributions, Belle-II R+D papersand Super B Factory Reviews

[1] Observation of the φ(1680) and the Y (2175) ine+e− → φπ+π−, I. Adachi et al. (Belle Collab.),BELLE-CONF-0865, arXiv: 0808.0006, submit-ted to Phys. Rev. D.

[2] Time-dependent CP Asymmetries in B0 →K0

Sργ Decays, J. Li et al. (Belle Collab.), arXiv:0806.1980, submitted to Phys. Rev. Lett.

[3] Observation of a resonance-like structure in theπ±ψ(2S) mass distribution in exclusive B →Kπψ(2S) decays, S. K.Choi, S. L. Olsen et.al (Belle Collab.), Phys. Rev. Lett. 100, 142001(2008), arXiv: 0708.2604.

[4] Measurements of time-dependent CP violationin B0 → ψ(2S)KS decays, H. Sahoo, T.E. Brow-der et. al (Belle Collab.), Phys. Rev. D. R77,091103 (2008), arXiv: 0708.1790.

[5] New Physics at a Super Flavor Factory, T. E.Browder, T. Gershon, D. Pirjol, A. Soni and J.Zupan, arXiv:0802.3201, to appear in Reviewsof Modern Physics.

[6] On the Physics Case of a Super Flavor Factory,T. E. Browder, M. Ciuchini, T. Gershon, M.Hazumi, T. Hurth, Y. Okada and A. Stocchi,arXiv:0710.3799, published as JHEP 0802:110,2008.

[7] H. Hoedlmoser, G. Varner and M. Cooney,“Hexagonal Pixel Detector With Time EncodedBinary Readout,” Nucl. Instrum. Meth. A 599,152 (2009).

[8] L. L. Ruckman and G. S. Varner, “Sub-10psMonolithic and Low-power Photodetector Read-out,” Nucl. Instrum. Meth. A 602, 438 (2009)[arXiv:0805.2225 [physics.ins-det]].

[9] T. Tsuboyama et al., “R&D Of A Pixel Sen-sor Based On 0.15-Mu-M Fully Depleted SoiTechnology,” Nucl. Instrum. Meth. A 582, 861(2007).

[10] J. Benitez et al., “Status of the Fast FocusingDIRC (fDIRC),” Nucl. Instrum. Meth. A 595,104 (2008).

[11] G. Varner et al., “The Large Analog BandwidthRecorder And Digitizer with Ordered Readout(LABRADOR) ASIC,”Nucl. Instr. Meth. A583(2007) 447.

[12] H. Aihara et al. (Belle SVD Group), “Status andUpgrade Plans of the Belle Silicon Vertex Detec-tor”, Nucl. Instr. Meth. A582 (2007) 709.

[13] G. Varner et al., Nucl. Instr. Meth. A541 (2005)166-171.

[14] M. Barbero, G. Varner et al., IEEE Trans. Nucl.Sci. 52 no 4, August 2005.

[15] G. Varner et al., “Development of the Contin-uous Acquisition Pixel (CAP) sensor for highluminosity lepton colliders,” Nucl. Instr. Meth.A565 (2006) 126-131.

[16] T. Tsuboyama et al. (SOI Pixel Detector Col-laboration), “ R& D of a pixel sensor based on0.15μm fully depleted SOI technology,”Nucl. In-str. Meth. A582 (2007) 861.

[17] G.S. Varner, L.L. Ruckman, J. Schwiening andJ. Vavra, “Compact, low-power and precisiontiming photodetector readout,”Proc. of Science,PD07:026 (2008).

[18] G.S. Varner, L.L. Ruckman and A. Wong,“The first version Buffered Large Analog Band-width (BLAB1) ASIC”, Nucl. Instr. Meth. A591(2008) 534.

2.1.13 Recent Belle publications, in reverseorder of submission

1. Dalitz analysis of B → Kπψ′

decays andthe Z(4430)+, R. Mizuk et al. (TheBelle collaboration), submitted to PRD(RC)(Belle preprint 2009-9, KEK Preprint 2009-2,arXiv:0905.2869[hep-ex]).


BIBLIOGRAPHY

2. Measurement of Charmless Hadronic b → s Pen-guin Decays in the π+π−K+π− Final State andObservation of B0 → ρ0K+π−, S.-H. Kyeong, Y.-J Kwon et al. (The Belle collaboration), submit-ted to PRL (arXiv:0905.0763[hep-ex]).

3. Measurement of the Differential Branching Frac-tion and Forward-Backword Asymmetry forB → K(∗)�+�−, J.-T. Wei, P. Chang et al.(The Belle collaboration), submitted to PRL(Belle preprint 2009-7, KEK Preprint 2008-56,arXiv:0904.0770[hep-ex]).

4. Observation of the doubly Cabibbo-suppresseddecay D+

s → K+K+π−, B.R.Ko, E. Won etal. (The Belle collaboration), submitted to PRL(Belle preprint 2009-6, KEK Preprint 2008-54,arXiv:0903.5126[hep-ex]).

5. Measurement of B → D(∗)s Kπ branching

fractions, J. Wiechczynski, T. Lesiak et al.(The Belle collaboration), submitted to PRD(arXiv:0903.4946[hep-ex].

6. Search for the X(1812) in B± → K±ωφ, C. Liu,Z.P. Zhang et al. (The Belle collaboration), toappear in PRD (RC) (Belle preprint 2009-5), KEKPreprint 2008-53, arXiv:0902.4757[hep-ex].

7. Improved measurement of the polarization andtime-dependent CP violation in the decay B0 →D∗+D∗−, K. Vervink, T. Aushev, O. Schneider etal. (The Belle collaboration), submitted to PRL(Belle preprint 2008-31, KEK Preprint 2008-45,arXiv:0901.4057[hep-ex])

8. High-statistics study of neutral-pion pair pro-duction in two-photon collisions, S. Uehara, Y.Watanabe, H. Nakazawa et al. (The Belle col-laboration), published in PRD 79, 052009 (2009)(Belle preprint 2009-4, KEK Preprint 2008-50,arXiv:0903.3697[hep-ex]).

9. Measurement of the e+e− → J/ψcc cross sectionat

√s = 10.6GeV , P. Pakhlov et al. (The Belle

collaboration), published in PRD(RC) 79, 072004(2009) (Belle preprint 2009-3, KEK Preprint 2008-49, arXiv:0901.2775[hep-ex]).

10. Measurement of the branching fraction for the de-cay Υ(4S) → Υ(1S)π+π−, A. Sokolov, M. Shap-kin et al. (The Belle collaboration), published inPRD(RC) 79, 051103 (2009), (Belle preprint 2009-2, KEK Preprint 2008-48, arXiv:0901.1431[hep-ex]).

11. Observation of B0 → ΛΛK0 and B0 → ΛΛK∗0

at Belle, Y.-W. Chang, M.-Z. Wang et al.

(The Belle collaboration), to appear in PRD(Belle preprint 2008-30, KEK Preprint 2008-41,arXiv:0811.3826[hep-ex]).

12. Time-dependent Dalitz Plot Measurement of CPParameters in B0 → Ksπ

+π− Decays, J. Dalsenoet al. (The Belle collaboration), publishd in PRD79, 072004 (2009), (Belle preprint 2008-29, KEKPreprint 2008-39, arXiv:0811.3665[hep-ex]).

13. Precise measurement of hadronic tau-decays withan η meson, K. Inami et al. (The Belle col-laboration), published in PLB 672, 209 (2009)(Belle preprint 2008-28, KEK Preprint 2008-38,arXiv:0811.0088[hep-ex]).

14. Search for Lepton-Flavor-Violating tau Decaysinto a Lepton and an f0(980) Meson, Y. Miyazakiet al. (The Belle collaboration), published PLB672, 317 (2009) (Belle preprint 2008-27, KEKPreprint 2008-37, arXiv:0810.3519[hep-ex]).

15. Measurement of the Decay B0s → D−

s π+ andEvidence for B0

s → D+/−s K−/+ in e+e− An-

nihilation at√

s = 10.87 GeV, R. Louvot, J.Wicht, O. Schneider et al. (The Belle collab-oration), published in PRL 102, 021801 (2008),(Belle preprint 2008-24, KEK Preprint 2008-27,arXiv:0809.2526[hep-ex]).

16. Evidence for B0 → χc1π0 at Belle, R. Ku-

mar, J.B. Singh et al. (The Belle collabora-tion), published in PRD(RC) 78, 091104 (2008),(Belle preprint 2008-26, KEK Preprint 2008-32,arXiv:0809.1778[hep-ex]).

17. Study of Ω0c and Ω∗0

c Baryons at Belle, E.Solovieva, R. Chistov et al. (The Belle col-laboration), published in PLB 672, 1 (2008)(Belle preprint 2008-25, KEK Preprint 2008-30,arXiv:0808.3677v2[hep-ex]).

18. Study of intermediate two-body decays in B0 →Σc(2455)0pπ+, H.-O. Kim, H. Kichimi et al. (TheBelle collaboration), published in PLB 669, 287(2008) (Belle preprint 2008-23, KEK Preprint2008-23, arXiv:0808.3650[hep-ex]).

19. Measurement of B0 → π+π−π+π− Decays andSearch for B0 → ρ0ρ0, C. -C. Chiang et al.(The Belle collaboration), published in PRD(RC)78, 111102 (2008), (Belle preprint 2008-22, KEKPreprint 2008-22, arXiv:0808.2576[hep-ex]).

20. Observation of a near-threshold enhancement inthe e+e− → Λ+

c Λ−c cross section using initial-state

radiation, G. Pakhlova et al. (The Belle collab-oration), published in PRL 101, 172001 (2008)


(Belle preprint 2008-21, KEK Preprint 2008-19,arXiv:0807.4458[hep-ex]).

21. Evidence for Neutral B Meson Decays to ωK∗0,P. Goldenzweig et al. (The Belle collaboration),published in PRL 101, 231801 (2008).


CHAPTER 2. ACCELERATOR-BASED EXPERIMENTS

2.2 The BES Experiment,KA120101

Drs. F.A. Harris, Q. Liu, S.L. Olsen,C.P. Shen, and G. Varner

(Harris is principal investigator for this task)

2.2.1 Introduction

After ten years of planning, designing, con-struction and assembly, the BEPCII collider andBES-III detector had its first data run in March2009. In just one month over 100 M events werecollected at the ψ(2S) resonance, a data sam-ple that is seven times larger than the BESIIψ(2S) sample that took over a year to collect,and four times larger than the CLEOc samplethat took several months to accumulate. Afteronly six months of commissioning, the BEPCIIcollider has reached 30% of its design luminos-ity. Figure 2.14 shows two different ψ(2S) →π+π−J/ψ, J/ψ → l+l− events recorded duringthe ψ(2S) run.

The new, two-ring BEPCII collider’s designluminosity is 1 ×1033cm−2s−1, 100 times thatof BEPCII and 15 times the highest luminosityachieved at CESRc. BES-III is a new state-of-the-art detector, with a helium-based drift cham-ber, a TOF system with sub-100 ps time resolu-tion, a CsI(Tl) crystal calorimeter, and an RPCmuon detector that uses the flux-return iron ofa new 1 Tesla superconducting magnet. Moredetail on BEPCII and BES-III can be found inRef. [1].

2.2.1.1 Charmed particle physics with BES-IIIThe start-up of the BEPCII/BES-III facility co-incides with a dramatic revival of interest incharm physics. This has been driven by recentaccumulation of evidence for an unexpectedlylarge rate for D0-D0 mixing from the B-factoryexperiments [2], an apparent (∼ 2.6σ) discrep-ancy between the world averaged measured valueof fDs = 261 ± 7 MeV and the precision latticeQCD value from the HPQCD-HISQ collabora-tion of fDs = 241 ± 3 MeV [3], and the obser-vation of a number of charmonium-like states,

the so-called XY Z mesons, that do not fit intothe traditional cc scheme of the quark partonmodel [4]. We discuss these three items briefly.

2.2.1.1.1 BES-III and D0-D0 mixing Experi-mentally, B factory experiments typically mea-sure x′ and y′, which are linear combinations ofthe D0-D0 mixing parameters x = ΔM/Γ andy = ΔΓ/2Γ. In order to extract x, which is theparameter that is sensitive to new physics, onehas to know the value of a process-dependentstrong phase δ. While BES-III probably cannotcompete with B-factory measurements of x′ andy′, it is ideally suited for making precision mea-surements of the strong phases δ via quantumcorrelations between neutral D-meson pairs pro-duced in ψ(3770) → D0D0 decays. For exam-ple, a simulation shows that the BES-III mea-surement of the strong phase difference betweenthe D0 → K−π+ and D0 → K−π+ amplitudeswill have a precision of Δ cos δ = ±0.04 [5]. Ofcourse the ultimate quantum correlation goal isCP -conservation, and BES-III will be an orderof magnitude more sensitive to CP violation inthe charm system than any previous experiment.Moreover, strong phase measurements for three-body D0 meson decays will be crucial input toprecision B-factory determinations of the CP vi-olation angle φ3 (γ) [6].

2.2.1.1.2 BES-III measurement of fDs Thecurrent world-average experimental value for fDs

is based primarily on the terminated BaBar &CLEOc experiments, and Belle, which will soonshutdown for a few years while it is being up-graded. The experimental error on fDs is morethan twice the claimed theoretical precision. Thenext major improvement will come from BES-III, where simulations indicate that a single mea-surement precision of ≤ ±3 MeV will be possi-ble [5]. If the central value of the current worldaverage experimental value persists, this wouldcorrespond to a ∼ 7σ signal for new physics.

2.2.1.1.3 BES-III and the XY Z mesons Aninteresting recent development is evidence forcounterparts of the Y (4260) in the b-quark [7]and s-quark [8] systems. The BES-III exper-iment can address interesting issues related to


2.2. THE BES EXPERIMENT, KA120101

Figure 2.14: On-line event displays from data taking run at the ψ(2S) resonance. The event on theleft is a ψ(2S) → π+π−J/ψ, J/ψ → μ+μ−, while the one on the right is ψ(2S) → π+π−J/ψ, J/ψ →e+e−.

both the c-quark and s-quark versions of thesestates.

2.2.1.2 Other physics at BES-III In additionto charm physics, BES-III will make measure-ments of fundamental Standard Model quanti-ties such as the R value for e+e− → hadronsand the mass of the τ lepton with substantiallyimproved precision. These quantities are impor-tant inputs to precision tests of the SM. BESIIreduced the R measurement errors in the charmthreshold region from the 15% to the 6% level.Recent special BESII runs at a few energy pointsdemonstrate that BES-III will be able to furtherreduce errors to the ∼ 2% level (33). The experi-mental precision on low-energy R value measure-ments translates to more precise SM predictionsfor the Higgs mass, and these will be especiallyinteresting if and when the Higgs mass is directlymeasured at the Tevatron and/or LHC collider.

BES-III will also expand upon the extensiveBESII program of light hadron spectroscopy.Here important mysteries such as the apparentsuper-abundance of light scalar mesons and thenature of the X(1835) and Y (2175) exotic mesoncandidates will be addressed.

2.2.2 Hawaii Participation in BES

Hawaii joined the BES collaboration in 1993and since then has had a strong impact on theBES program. We contributed substantially tothe construction of tracking chambers and elec-tronics for BESII and participated in some of the

most interesting analyses. Harris and former UHstudent Kong were deeply involved in the BESIIR value measurements, which was BESII’s sig-nature — and most highly cited — result [9].Olsen and former student Paluselli found a sub-threshold pp mass peak in J/ψ → γpp decaysthat has attracted considerable attention and isthe subject of the BESII’s second most highlycited paper [10].

Harris has been co-spokesman of BESII since1998 and is currently co-spokesman for BES-III for which the US participation now includesthree CLEOc groups: Rochester, Carnegie-Mellon, and Minnesota. Hawaii’s main hardwareresponsibility in BES-III was a laser/fiber-opticmonitoring system for the TOF counters. Cur-rently, Hawaii is collaborating with groups fromIHEP and the Budker Institute at Novosibirskon the implementation of a back-scattered lasersystem to measure precisely the energies of theelectron and positron beams at BEPCII for high-precision mass measurements for the τ -leptonand D mesons.

2.2.3 Recent Physics Results

BES publications during the past three yearsare listed in Section 2.2.9. Olsen was involvedin the analyses and paper preparation for 23(Search for invisible decays of the J/ψ) and 26(Observation of Y (2175) in J/ψ → ηφf0(980));Harris was similarly involved in paper 18 (Deter-mination of the ψ(3770), ψ(4040), ψ(4160) andψ(4415) resonance parameters) and was the cor-



responding author of 30 (BES-III time of flightmonitoring system). Hawaii members partici-pate in almost all BES analyses through the ref-eree process and in paper rewriting.

2.2.4 BEPCII/BES-III Status

In May, BEPCII operated at a luminosity at3× 1032 cm−2 s−1, a world record in this energyregion. Machine operation is stable, and refillingis very rapid. There is also a fairly clear path tohigher luminosity. Currently, a major limitingfactor is the onset of longitudinal beam instabil-ities during high current operation. These canbe controlled by the incorporation of longitudi-nal feedback in each ring. Longitudinal kickerplates have been provided by SLAC and will beinstalled into both rings this summer; the associ-ated electronics systems are already on hand atIHEP. We are confident that the luminosity willcontinue to improve and reach the design valuein due time.

Another concern at present are beam associ-ated backgrounds in the inner layers of the driftchamber; these limit the useful beam currentsto below 600 mA (compared to the design val-ues of 1A). These backgrounds are diminishing(and the maximum tolerable beam currents areincreasing) slowly with time as the vacuum sys-tem is scrubbed by the beam. It has also beenobserved that they can be reduced by small dis-placements of the beam from the nominal colli-sion point, but further studies are needed.

The first BES-III physics run was at the ψ(2S).The cross section is large (∼ 700 nb) so ahuge data set could be accumulated quickly andmany ψ(2S) decay channels are ideally suitedfor calibrating the detector. Thus, the en-ergy scale of the CsI(Tl) calorimeter has al-ready been calibrated to the 0.5% level usinge+e− → e+e−γ, e+e− → γγ, π0 → γγ, andψ(2S) → γχc1,2,3, which are about 30% of allψ(2S) decays. ψ(2S) → ππJ/ψ transitions,about 50% of all ψ(2S) decays, are ideal sourcesof tagged low energy pions for studying trackingin the MDC and π0 reconstruction in the CsI(Tl)calorimeter. Studies of a 10 M event ψ(2S) data

sample obtained during a fall 2008 commission-ing run and preliminary studies of the recentlyaccumulated 100 M ψ(2S) sample have demon-strated that the BES-III detector is already op-erating very near design specifications. For p =1.84 GeV/c Bhabha tracks, the rms momentumand spatial resolutions of the drift chamber are15 MeV/c and 143 μm, respectively; the en-ergy resolution of the barrel CsI(Tl) calorime-ter is σE/E = 2.4%, and the time of flight res-olution of the barrel TOF is better than 90 ps.Hawaii post-doc Liu is studying the performanceof BES-III using muons from ψ(2S) → μ+μ−

and ψ(2S) → π+π−J/ψ, J/ψ → μ+μ− events.Figure 2.15 shows the particle identification per-formance of the TOF system versus momentum.Work is ongoing to refine calibration constantsand software to further improve the detector per-formance.

Figure 2.15: Scatterplot of β versus momentumdetermined from the barrel TOF counters.

In addition to calibration, the 100 M ψ(2S)events are being used for interesting physics anal-yses. The first of these are studies of ηc, hc

and χc decays. As an example of the qual-ity of this data sample, Fig. 2.16 compares (a)J/ψ → γπ0π0 from BESII [11] and (b) prelimi-nary ψ(2S) → γπ0π0 from a subset of the newBES-III data. The general features of the spectraare remarkably similar but the structures in (b)are much more distinct. Former Hawaii post-docGuo analyzed J/ψ → γπ+π−, and Harris was areferee for J/ψ → γπ0π0 for BESII.

Figure 2.17 shows the distribution of massesrecoiling from the π0 in inclusive ψ(2S) → π0X



(a) (b)

Figure 2.16: (a) J/ψ → π0π0 from BESII, and (b) preliminary ψ(2S) → π0π0 from BES-III .

decays for (a) CLEOc [12] and (b) a subset ofthe BES-III sample. Distinct peaks are evidentat the hc mass corresponding to to ψ(2S) →π0hc, hc → γηc, ηc → anything. Searches for hc

decays to channels other than γηc are in progress.

In Hawaii, we are studying ηc production fromψ(2S) and, soon, in J/ψ decays. Liu is ana-lyzing ψ(2S) → γηc, ηc → K∗Kπ and KKππ(see Fig. 2.18), and Shen is analyzing ψ(2S) →γηc, ηc → ηππ. CLEOc found intriguing lineshape discrepancies in both the ψ′ → γηc andJ/ψ → γηc channels that we plan to investi-gate [13].

2.2.5 BES-III TOF Monitoring System

The TOF monitoring system distributes lightpulses from a laser-diode through an array of op-tical fibers with carefully controlled relative tran-sit times to each of the TOF scintillators, therebyproviding a simple and robust means for moni-toring the TOF system performance.

Hawaii provided similar systems for BESII andBelle. A major improvement over earlier sys-tems is the use of a PicoQuant 440 nm laserdiode (LD), which has a longer lifetime and ismuch simpler to use and maintain than the previ-ously used nitrogen plasma lasers. Pulses of lightfrom the laser diode are injected into one of twospecially designed optical fiber bundles, one foreach end of the BES-III detector, and the light isdelivered by the individual optical fibers to theTOF counters. The laser pulsing and the bundlebeing illuminated are under computer control.

Central to this system is the optics box, whichhouses the laser diode head, two compact Hama-matsu R7400U series reference photomultipliers(PMTs), and optical components that couple the1.5 mm × 3.5 mm elliptical laser beam to the 256fibers at the input end of the fiber bundles withnearly uniform illumination.

The system, which is described in detail inRef. [14], was installed into the BES-III detectorin spring 2008 as part the TOF system. Hawaiipost-doc Liu supervised the installation at IHEPand provided the online and offline software forthe TOF monitoring system.

Figure 2.19 shows the mean and sigma ofthe time differences with a reference PMT forall barrel PMTs for a sequence of 10,000 laserpulses. The system works according to specifica-tions and is being used to test the TOF PMTsand electronics and check the performance ofeach PMT against historical values saved in adatabase. Figure 2.20 shows the average pulseheight and sigma for one PMT versus run fromFeb. 26, 2008 until April 26, 2009. For each setof magnetic field and high voltage conditions, theresponse of the TOF system is found to be verystable.

2.2.6 Precision beam energy measurementat BEPCII

We are collaborating with groups from theBudker Institute of Nuclear Physics (BINP) andIHEP on the first upgrade of the BEPCII/BES-III complex: a system to determine the beam



(a)

(b)

Figure 2.17: Distributions of mass recoiling from the π0 for (a) CLEOc [12] and (b) a subset ofthe BES-III sample.

Figure 2.18: (a) K∗Kπ mass distributions for ψ(2S) → γηC , ηC → K∗Kπ candidate events. Theshaded areas are the K∗ sideband background events. A clear ηC signal with good signal to noiseis evident.

Figure 2.19: Time difference (top) mean and(bottom) sigma in ps between TOF counter andreference counter versus Barrel PMT number.Projections for all PMTs are shown on the right.

energies with high precision using back-scattered

Compton photons from both of the circulatingbeams in BEPCII. This method has been demon-strated at BESSY-I, BESSY-II, VEPP-4M, andVEPP-3 storage rings at Novosibirsk.

A precise knowledge of the energy of each beamis crucial for many interesting and fundamen-tal measurements, especially the measurement ofthe τ mass, mτ , a fundamental parameter of theStandard Model. While the e and μ masses areknown with precisions of δm/m of ∼ 10−8, the τprecision is only ∼ 10−4 [18]. A precise mτ mea-surement tests lepton universality, and BES-IIIprovides an opportunity to improve the precisionof mτ and to help provide the most stringent testof lepton universality.

Until recently, the precision of the mτ

world average value was dominated by the1996 BES threshold scan measurement, mτ =1776.96+0.18+0.25

−0.21−0.17 MeV/c2 [15]. Recently the



Figure 2.20: Mean pulse height and sigma forone PMT for the TOF monitoring system versusrun from Feb. 26, 2008 until April 26. Variousmagnetic field and high voltage conditions areindicated.

KEDR collaboration performed a threshold scanat the VEPP-4M collider [16], and the Belle col-laboration has used the kinematics of hadronictau decays to obtain the τ mass value withcompetitive precision [17]. The current world-average value for mτ is 1776.90 ± 0.20 MeV/c2

[18]. An important feature of the KEDR mea-surement was the Compton back-scattered lasersystem for beam energy monitoring.

For the mτ measurement, statistics is not anissue: at BES-III , one week of data taking timewill lead to a statistical uncertainty of less than17 keV/c2. The critical issue are the system-atic errors, and among these the most importantsource of uncertainty is is that of the beam en-ergy.

To measure the beam energy, laser light is in-jected into BEPCII and made to collide head-on with a beam; the energies of the backscat-tered photons are precisely measured with a highpurity Germanium detector (HPGe) with excel-lent energy resolution. The maximal energy ofthe scattered photons is determined from theabrupt Compton edge in the energy spectrum.For a monochromatic laser beam of 0.12 eV pho-

tons, the energies of the scattered photons arein the 1 – 10 MeV range, an energy region thatcan be accurately calibrated using radioactive γ-sources.

The accuracy of the method has been testedby comparing it with the resonant depolariza-tion technique∗ in experiments at the VEPP-4Mcollider [19, 20]. These tests show that the twomethods agree at the level of Δε = 40 keV, orΔε/ε ≈ 2 · 10−5. A detailed description of thistechnique is provided in Ref. [21].

2.2.7 Computing

While IHEP has assembled an extremely pow-erful online and offline computing system, it isdifficult to access interactively via the network.The University of Hawaii recently provided uswith 32 rack-mounted Dell Xeon 3.2 Ghz, 64 bitdual processors to which we added an 18 Tbytedisk array system. The latest BES software re-lease (BOSS 6.4.4) is installed on the system anda copy of all of the reconstructed ψ(2S) data hasbeen transferred from IHEP. This system, whichis maintained by Hawaii post-doc Shen, providesus with computing resources that are adequatefor the current data set. Additional disk spacewill be required in the future when the muchlarger J/ψ data set is available.

2.2.8 Plans

BES-III will run this spring or summer at theJ/ψ peak in order to test machine operation atlower energy and to accumulate a huge, multi-hundred-million-event J/ψ data sample. In ad-dition to being by far the largest sample of J/ψevents ever to be accumulated, these will be thefirst events of this type to be detected in a mod-ern high resolution detector. In the fall, BEPCIIwill run at the ψ(3770) peak. This will providethe different physics groups data sets with whichto test software and detector performance. Theeventual goal is to have long, multi-year runsin the open-charm energy range to accumulatethe large samples of tagged D and Ds mesons

∗Resonant depolarization beam energy measurementsare very precise but are only applicable for a few discretebeam energy values.



required for the charmed physics program, ourhighest physics priority.

Hawaii will continue to be responsible for mon-itoring the TOF performance using the lasermonitor. The Hawaii Belle team has found thatthis is an essential ingredient for maintaininghigh performance of the TOF system. Hawaiiwill also participate in the installation of theback scattered Compton photon beam energymeasurement system with the eventual goal ofmeasuring the τ mass to high precision.

We are currently investigating the possibilitiesfor utilizing initial state radiation events in theD and Ds data samples to measure low energycross sections for e+e− → hadrons. These mea-surements are important for interpreting resultsfrom the g−2 experiment and for indirect deter-minations of the Higgs mass.

2.2.9 UH-BES Personnel

Post-docs Liu and Shen joined our group inJuly 2007. Liu remained at IHEP to supervisethe installation of the TOF monitoring systemuntil Feb. 2008. Olsen spent his sabbatical leaveat IHEP from June 2007 until Aug. 2008 andhelped with the early detector commissioning.Harris will spend a sabbatical leave at IHEP fromSept. 2009 - June 2010. Each Hawaii author isexpected to take about ten BES-III shifts eachyear. Olsen retired from Hawaii in summer 2009,but will continue on the BES experiment as aSeoul National University faculty member andan emeritus professor at Hawaii.


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BES Publications from 2006 - 2009

1. M. Ablikim et al. (BES Collab.), “Measurementof the branching fractions for J/ψ → γπ0, γη, andγη

′,” Physical Review D 73, 052008 (2006)

2. M. Ablikim et al. (BES Collab.), “Search for ηc

decays into ππ and KK,” European Physics Jour-nal C45, 337 (2006)

3. M. Ablikim et al. (BES Collab.), “Measurementsof J/ψ decays into ωπ0, ωη, and ωη

′,” Physical

Review D 73, 052007 (2006)

4. M. Ablikim et al. (BES Collab.), “Observationof a near-threshold enhancement in the ωφ massspectrum from the doubly OZI suppressed decayJ/ψ → γωφ,” Physical Review Letters 96, 162002(2006)

5. M. Ablikim et al. (BES Collab.), “Measurementof χcJ decays to 2(π+π−)pp final states,”PhysicalReview D 73, 052006 (2006)

6. M. Ablikim et al. (BES Collab.), “Partial waveanalyses of J/ψ → γπ+π− and γπ0π0,” PhysicsLetters B 642, 441 (2006)

7. M. Ablikim et al. (BES Collab.), “Search for therare decays J/ψ → D−

s e+νe, J/ψ → D−e+νe,and J/ψ → D0e+e−,” Physics Letters B 639, 418(2006)



8. M. Ablikim et al. (BES Collab.), “Pseudoscalarproduction at ωω threshold in J/ψ → γωω,”Phys-ical Review D 73, 112007 (2006)

9. M. Ablikim et al. (BES Collab.), “First observa-tion of ψ(2S) → pnπ− + c.c.,” Physical Review D74, 012004 (2006)

10. M. Ablikim et al. (BES Collab.), “Observationof a broad 1−− resonant structure around 1.5-GeV/c2 in the K+K− mass spectrum in J/ψ →K+K−π0,” Physical Review Letters 97, 142002(2006)

11. M. Ablikim et al. (BES Collab.), “Search forinvisible decays of η and η

′in the processes J/ψ →

φη and φη′,” Physical Review Letters 97, 202002

(2006)

12. M. Ablikim et al. (BES Collab.), “Measurementsof ψ(2S) decays into γKKπ and γηπ+π−,” Phys-ical Review D 74, 072001 (2006)

13. M. Ablikim et al. (BES Collab.), “Measurementof χcJ → K+K−K+K−,” Physics Letters B 642,197 (2006)

14. M. Ablikim et al. (BES Collab.),“Improved mea-surement of ψ(2S) decays into τ+τ−,” PhysicalReview D 74, 112003 (2006)

15. M. Ablikim et al. (BES Collab.), “Production ofσ in ψ(2S) → π+π−J/ψ,” Physics Letters B 645,19 (2007)

16. M. Ablikim et al. (BES Collab.), “Measurementsof ψ(2S) decays to octet baryon antibaryon pairs,”Physics Letters B 648, 149 (2007)

17. M. Ablikim et al. (BES Collab.), “Measurementof ψ(2S) radiative decays,” Physical Review Let-ters 99, 011802 (2007)

18. M. Ablikim et al. (BES Collab.), “Determinationof the ψ(3770), ψ(4040), ψ(4160) and ψ(4415) res-onance parameters,” Physics Letters B 660, 315(2008)

19. M. Ablikim et al. (BES Collab.), “Measurementsof J/ψ and ψ(2S) decays into ΛΛπ0 and ΛΛη,”Physical Review D 76, 092003 (2007)

20. M. Ablikim et al. (BES Collab.), “Search for theRare Decays J/ψ → D−

S π+, J/ψ → D−π+, andJ/ψ → D

0K

0,”Physics Letters B 663, 297 (2008)

22. M. Ablikim et al. (BES Collab.), “Search for theC-parity violating process J/ψ → γγ via ψ(2S) →π+π−J/ψ,” Physical Review D 76, 117101 (2007)

23. M. Ablikim et al. (BES Collab.), “Search for theInvisible Decay of J/ψ in ψ(2S) → π+π−J/ψ,”Physical Review Letters 100, 192001 (2008)

24. M. Ablikim et al. (BES Collab.), “First observa-tion of J/ψ and ψ(2S) decaying to nK0

SΛ + c.c,”Physics Letters B 659, 789 (2008)

25. M. Ablikim et al. (BES Collab.), “Study of J/ψdecaying into ωpp,” , European Physics JournalC53, 15 (2008)

26. M. Ablikim et al. (BES Collab.), “Observationof Y (2175) in J/ψ → ηφf0(980),”Physical ReviewLetters 100, 102003 (2008)

27. M. Ablikim et al. (BES Collab.), “Measure-ments of J/ψ decays into ωKKπ, φKKπ, andηK0

SK±π∓,” Physical Review D 77, 032005(2008)

28. M. Ablikim et al. (BES Collab.), “Search for thedecays J/ψ → γρφ and J/ψ → γρω,” PhysicalReview D 77, 012001 (2008)

29. M. Ablikim et al. (BES Collab.), “Partial waveanalysis of J/ψ → γφφ,” Physics Letters B 662,330 (2008)

30. F. A. Harris et al., “BES3 time of flight monitor-ing system,” Nuclear Instruments and Methods A593, 255 (2008)

31. M. Ablikim et al. (BES Collab.), “First mea-surements of J/ψ decays into Σ+Σ

−and Ξ0Ξ

0,”

Physical Review D 78, 092005 (2008)

32. M. Ablikim et al. (BES Collab.), “Measure-ment of branching fractions for J/ψ → ppη andJ/ψ → ppη

′”, accepted by Phys. Lett. B,

arXiv:0902.3501 (2009).

33. M. Ablikim et al. (BES Collab.), “R value mea-surements for e+e− annihilation at 2.60, 3.07,and 3.65 GeV”, submitted to Phys. Lett. B,arXiv:0903.0900 (2009).


2.3. 3D SILICON SENSORS, KA110101

2.3 3D Silicon Sensors,KA110101

S. I. Parker

2.3.1 Introduction

3D silicon sensors use standard PIN diodes,but with the electrodes forming a three-dimensional array penetrating part or all the waythrough the silicon, rather than being confined tothe surfaces, as was the case prior to their devel-opment. Their electrodes that can have manydifferent shapes, can be placed close together,and can form the physical edges. Such “activeedges”, long tracks and short collection distancescan give them:

1. low full-depletion bias voltages

2. negligible border dead areas

3. extreme radiation hardness,

4. extreme speed, and

5. With both electrode types reaching both sur-faces, metal lines can join one type to form astrip detector for a fast trigger.

Figure 2.21: Schematic diagram of a 3D active-edge sensor.

Figure 2.21 shows a schematic diagram of sucha sensor using cylindrical electrodes. Trench or

wall electrodes will be better for high-speed ap-plications. With a suitable RC network fabri-cated on one surface, strip signals from the biaselectrodes could even be read out by a separatepart of the pixel ASIC.

The reference section has a full list of our 3Dpublications [1-22]. However, it does not includepapers from other groups working independentlyon 3D technology such as those in Trento orBarcelona.

2.3.2 Proposed uses in ATLAS

3D sensors have a number of applications, in-cluding several in high energy physics and othersin photon science. This proposal however willconcentrate on those proposed for the ATLASexperiment at the Large Hadron Collider:

1. Because of their radiation hardness and activeedges, the FP420 (forward proton at ± 420 m)collaboration has chosen 3D as their baselineposition sensor. Detector systems have beenproposed to both ATLAS and CMS. ATLASalready had a group working on detectors tobe located at ± 220 m, and for the purposesof ATLAS, the two groups have merged.

2. Events at 220 m, close enough to be used fora trigger, would use the dual readout featurementioned in point 5 above [18].

3. The present ATLAS inner pixel layer (calledthe “B layer” due to its importance in identi-fying B mesons) is not expected to last untilthe planned inner detector replacement priorto the start of the Super LHC (sLHC). Asmaller beam pipe with an additional layerof pixel detectors that can be inserted insidethe present detector, the Insertable B Layeris planned. 3D’s radiation hardness and ac-tive edges, with little extra scattering mate-rial, make it a possible choice.

4. Finally, 3D sensors designed for extreme ra-diation hardness might be used for the in-ner pixel layers of the sLHC detector. Dualreadout in the z direction could help untanglenearby events.



2.3.3 Fabrication Sites

Four labs are currently fabricating sensors us-ing 3D technology:

1. Stanford Nanofabrication Facility, Stanford,CA, where all initial devices were made.

Some years ago some devices were made usinga laser to make each electrode hole at the Uni-versity of Glasgow. The three labs in Europecurrently making 3D silicon sensors are:

2. Institut de Fisica d’Altes Energies, Barcelona,Spain,

3. ITC-irst, Microsystems Division, Trento,Italy, and

4. SINTEF, Oslo, Norway, a combined researchinstitute and detector company.

We are working closely with SINTEF, whichhas even better deep reactive-ion etchers formaking electrode holes than those at Stanford,but does not yet have the capability to depositthe thick layers of polycrystalline silicon neededto fill the electrode holes. We have been ableto produce all types of devices that have beendesired, have added checking and cleaning stepsto improve the yield, and are still working onadditional steps. Barcelona and Trento are fab-ricating sensors with electrodes going most, butnot all of the way through the substrate, withn+ and p+ electrodes etched from opposite faces.They are also part of ATLAS, and we expect itis likely we will all eventually work together onATLAS sensors.

2.3.4 ATLAS groups working on 3D sensors

The results given here come from thework of many physicists and engineers. Inaddition to those working on 3D at the abovelabs, ones from twelve institutions are now work-ing on the design, fabrication, and/or testing of3D sensors for potential use in ATLAS. They are:

1. Barcelona, IFAE, CNM

2. University of Bergen

3. University of Bonn

4. CERN (Heinz Pernegger)

5. Czech Technical University, Praha

6. Freiburg University

7. Glasgow University

8. Institute of Physics - Academy of Sciences,Praha

9. Manchester University

10. University of Genova and I.N.F.N.

11. University of Oslo, (Steinar Stapnes)

12. SLAC

13. LBL chips

Giovanni Darbo of the University of Genova isboth working on 3D sensors and is also in chargeof the group working on the Insertable B Layer.In addition, one physicist from Purdue (which isa member of CMS) is also part of our extended3D group.

2.3.5 Keys to the technology

1. Plasma etchers can now make deep, near-vertical holes and trenches by alternating adirected stream of etchant ions with ones thatprotect the side walls from being etched dur-ing the next cycle by etchant ions that hit theside walls before or after they hit the bottom.

2. At a properly chosen temperature and pres-sure silane and dopant gasses such as diboraneor phosphine will bounce off the walls manytimes before they stick, mostly entering andleaving the electrode holes. When they stick,it can be anywhere, so they form a conformal,doped polycrystalline electrode as the hydro-gen or other molecules leave.

3. Heating drives the dopants into the singlecrystal silicon, forming p-n junctions andohmic contacts there.



4. Active edges are made from trench electrodesfollowed by a lithographically defined plasmadicing etch. An oxide-bonded support wafer,which also improves the yields of the earliersteps, is necessary for active edges, and isetched off after the dicing steps. More detailsare given in Table 1 of [3].

Figure 2.22: Signal from a pulsed red LED fortwo pixel sizes as a function of bias voltage.

2.3.6 Some initial results

Low depletion voltages. Figure 2.22 [3],shows the signal made by penetrating, near-infrared light as a function of bias voltage.The signal plateaus at voltages an order ofmagnitude lower than those of standard sil-icon detectors. A similar reduction factor isseen after irradiation.

Active-edge. Measurements were made us-ing both x-rays and charged particles. De-tails are given in [10, 13, 16] and [21]. Sincethe built-in electric fields are in the directionthat expels the charge carriers from the elec-trodes, there is no certain minimum size fordead regions. Limits from the experimentaldata are set by knowledge of the x-ray micro-beam sizes and charged-particle beam tele-scope accuracies.

Figure 2.23 shows one set of results from a120 GeV CERN muon beam [21]. Both AT-LAS and CMS sensors, made without activeedges, have a dead border of 1.1 mm due tothe space for an array of guard rings neces-

Figure 2.23: Counts in a 3D sensor per beam-telescope projected hit as a function of projectedy position. The plateau value of less than 1 is dueto a trigger timing inefficiency discussed in [21].The observed width is (3.203 ± 0.004) mm whilethe expection (drawn) is 3.195 mm. Lower edgeσ = (4.3 ± 4.1)μm; upper edge: σ = (9.7 ± 3.0)μm; 10% - 90% interval (25.0 ±8)μm

sary, after irradiation, to withstand high de-pletion voltages. In addition the bulging edgefield lines must be kept away from edge micro-cracks and chips.

Radiation Hardness. It was always ex-pected that 3D sensors would be radiationhard because of their full-thickness trackscombined with short collection distances andhigh average electric fields for any given biasvoltage. Even the first sensors, not designedfor radiation hardness with collection paths50% longer than modern devices worked wellafter an irradiation of 1015 55-MeV protons /cm2 even at room temperature [5].

This is equivalent to 1.8×1015 MeV neutrons/ cm2(≡ n/cm2), a level beyond the originaldesign specifications of the multi-guard-ring,radiation-hard ATLAS pixel sensors that needa much times higher bias voltage. The nextresults from the Czech Technical Universitygroup with the analysis led by Cinzia Da Via,used cyclotron-generated neutrons at levelsclose to 1016n/cm2 [17, 22].



3d Signal Signal Full Noise

type Efficiency Charge Depletion (electrons)

(electrons) Voltage (non-irradiated)

2E 36% 6048 130 200

3E 51% 8568 112 275

4E 66% 11088 94 290

Table 2.1: Electrical parameters of 2E, 3E and 4E sensors irradiated to 8.8 ×1015neqcm−2(1.73 × 1016

protons cm−2).

0

20

40

60

80

100

0 5 1015 1 1016 1.5 1016

4E

3E

2E

Sign

al e

ffici

ency

[%]

Fluence [n/cm2]

0 9.8 1015 1.96 1016 2.94 1016Fluence [p/cm2]

C. Da Via'/ July 07

Figure 2.24: Signal Efficiency versus n/cm2 (bot-tom legend) and 24 Gev/c proton fluence/cm2

(top legend).

Figure 2.24 shows the signal efficiencies (the sig-nal from an irradiated sensor / the signal beforeirradiation) for 2, 3, and 4 electrodes per pixel.The upper end of the scale, 1.5 × 1016n/cm2,corresponds to ∼ 10 years of operation at theexpected SLHC fluence at 4 cm radius.

Tables 2.1 and 2 show the comparative perfor-mance of 2, 3, and 4 electrode per pixel sensors.2E ones, with their low capacitance, are best atlow irradiation levels, while 4E ones, with theirshort collection distances and low depletion volt-ages are best at high irradiation levels.

Figure 2.25 shows the total signal from 3D,standard planar, and epi (single-crystal silicondeposited on a substrate) sensors, the latter ex-pected by some ATLAS members to be radiationhard. The fitted lines are of the form 1/(1+ kϕ)where k depends on the maximum collection dis-tance and the carrier velocities and ϕ is the totalirradiation fluence. 3D sensor charge detectionclearly is better at all radiation levels than thatof the other sensors. However, in most cases sig-nal to noise will be the important quantity and4-electrodes per pixel sensors (4E), while best athigh irradiation levels, are not as good as 2E onesat low levels due to their higher capacitance ascan be seen from Table 2.

These results are from normalized infrared il-lumination. Irradiated sensors have been placedin a high-energy beam and data from that run isnow being analyzed.

The next major task will be to

• change back to irradiation by protons to addoxide damage with the sensor under realisticbias voltages (oxide damage, for example, isbias-dependent)

• bump-bond the sensor to a readout chip andthen examine the performance in a test beam.

2.3.6.1 Electrode Efficiency Calculations inthe initial paper [1] indicated the electrodescould be efficient despite the low fields and shortrecombination lifetimes in polycrystalline silicon,but it was still something of a surprise to see thecomplete absence of a low-side tail in the lines



SensorIrradiation(n / cm2) 2 3 4

0 84 61 583.5 x 1015 56 47 498.8 x 1015 30 31 38

Electrodes per50 m X 400 m pixel

Most Probable Signal / Noise

Table 2. Most probable signal to noise ratio for 2E, 3E, and 4E sensors.

Figure 2.25: Signal fluence for 2, 3, and 4E 3D, epi, and planar sensors.

in the pulse-height distributions from a 241Amsource, indicating all x-rays gave either full- orzero-size pulses. (See Figures 2.26 and 2.27 of[4].) More detail came from a run by J. Morse atESRF (see Figure 2.26). The pulse height inde-pendence of the efficiency in Figure 2.26 and onemeasured with a micro-beam at the LBL ALSwhich, with the beam profile unfolded, showedcompletely flat bottoms 5 and 11 μm wide forN and P electrodes, are not what would be ex-pected from a short lifetime in polycrystallinesilicon.

Efficiency was also measured in the secondbeam test with 100 GeV pions in the CERNH8 beam line [20]. Data were taken with 2, 3,and 4 electrodes per pixel 3D sensors at sev-eral bias voltages and beam incidence angles,primarily to verify satisfactory performance of3D sensors within the ATLAS data acquisitionsystem. Measurements also showed accurate

tracking, signal-to-noise ratios for un-irradiatedsensors, and active-edge sensitivity. The pulseheight distributions are shown in Figure 2.27.With 90 ± 10 incidence angle (and less than 2mr angle spread), there is a low-pulse height tailfrom electrode traversals, which reduces the effi-ciency to 95.9±0.1%. When the sensors are tiltedat 150, part of every track is in single crystal sil-icon and the efficiency rises to 99.9±0.1 %. Thereduced efficiency inside the electrodes might bedue to the original unavailability of non-oxygencontaining dopant gasses, resulting in possiblethin layers of SiO2 that could block the collec-tion of charge carriers. Diborane and phosphineare now available and will be tried in a comingfabrication run.

2.3.7 Speed

The first two generations, (1) surface barrierand (2) planar-technology silicon tracking detec-



Perpendicular Beam Sensor tilted by 15°.

Figure 2.27: Pulse height spectra for a 3D sensor with an FEI3 readout chip at 900 and 750 to thebeam.

43

Figure 2.28: 3D wall-electrode sensor (left). Output end of 3D active-edge hex sensor (right).

tors had large elements, high capacitances, lowQ/C input voltages, and slow amplifiers withseveral - μs wide output pulses for adequate sig-nal to noise ratios [23]. This time dropped bytwo orders of magnitude with the third genera-tion: planar, micro-strip detectors and the devel-opment of the first VLSI readout chip that had20 ns rise times [24, 25]. The use of a fast cur-rent amplifier further increased speeds with risetimes of 4 ns and pulse widths of 30 ns [26].

A fourth step is available now using 3D sen-sors. An example is shown in Figures 8,9,and 10. Electrons from an un-collimated 90Srsource traversing the hexagonal-cell 3D sensorof Fig. 2.28 (right), amplified by a 0.13 μm-technology current amplifier [27] and read outby a 16 sample / ns oscilloscope produced a setof 99 traces, 67 of which had pulses only in the

triggering (red) channel and not in the two neigh-boring (green and blue) ones. The first and lastpulses are shown in Fig. 2.29. The output risetime is 1.6 ns, close to the 1.5 ns from a 0.8ns-rise time pulse generator. At these speeds,the tail from the hole collection time is visible.The red arrows are 30 ns long, the width of 3rdgeneration pulses. The fast, smooth rise resultsfrom the collection of perpendicular tracks, deltarays and all, as a unit, with a drift distanceless than the sensor thickness. Twenty hexagonswere ganged into each of the 16 channels, in-creasing the noise, which will be the main limiton resolution time. An (almost) noise-free pulseshape was determined by adding the 6 largestpulses (all larger than the pulses of Fig. 2.29)and scaling the sum to the Landau distributionof all 67 pulses (shown in Fig. 2.30). The pre-



linescan through p+ electrode column and across active edge

line scan

0 20 40 600

50

100

ADC

cou

nts

Energy (keV)

1.73keV

ID 3

rd h

arm

onic

15V bias

100 200 3000

3000

6000

Win

dow

cou

nt in

tegr

al to

24.

9keV

posit ion (microns)

thresh6.5keV thresh10keV thresh15keV

electrode pitch 150 m

2 30 2 35 24 0 2 45 2 50 25 5 26 0 2 65 2 700

3 00 0

6 00 0

15 m

p+ electrode

edge response over ~10 m

Figure 2.26: 20 keV (1.73 keV FWHM), narrowbeam x-ray scan across a p+ electrode showing adecreased efficiency, but nearly identical countsfor thresholds of 5, 10, and 15 keV

-10

-8

-6

-4

-2

0

2

-30 -20 -10 0 10 20 30

Sr - 90 20V, event 01

trigger channeladjacent channeladjacent channel

puls

e he

ight

(mV)

time (ns)

30 ns 30 ns

Uncollimated 90Sr betas, 20 C, hex sensor (20V bias) to 0.13 m current amplifier, self-triggers, events 1 and 99 of 99

-10

-8

-6

-4

-2

0

2

-30 -20 -10 0 10 20 30

Sr - 90, 20V, event 99

puls

e he

ight

(mV)

time (ns)

Figure 2.29: Beta pulses from the hex sensor am-plified by a 0.13 μm technology current amplifier.

pulse traces produced 3×67 noise samples, whichwere sequentially added to each scaled pulse, andthe times of the 201 50% points were determined.The bottom part of Fig. 2.30 shows the rms scat-ter for each scaled pulse.

Improving time resolution

0

100

200

300

2 4 6 8 10 12 14 16dt

(ps)

pulse height (mV)

0

5

10

15

20

25number vs. pulse height

Cou

nts

Figure 2.30: Pulse heights (top plot) and timeerror distribution from combined signal pulseshape added to multiple noise segments (bottomplot). The median and average dt values are 139and 134 ps for the bottom plot.

Several steps can improve the time resolutionwell beyond the 134 - 139 ps of Fig. 2.30.

• Decrease the sensor capacitance per amplifierchannel, or modify the amplifier design.

• Reduce temperatures: +200 to −280 C in-creases drift velocities by factors of 1.3 to 1.5,depending on the electric field value, and willalso increase circuit speed.

• Since the noise is Gaussian to at least, andprobably more than 3 orders of magnitude,increase the number of layers. For at leastsome applications, the needed silicon area isnot large, and 9 layers, which would improvetiming by a factor of 3, could reasonably beused.

• Record the pulse with one of the fast wave-form recorders now under development, and



Figure 2.31: 200 10-keV (left) and 200 30-keV (right) delta rays. The arrows are 1 μm (left) and5 μm (right) long. Backscattered tracks are in red.

fit the output with a time-shifted expectedpulse shape. This will be less sensitive thana constant-fraction discriminator to noise-induced time shifts.

• Trench (or “wall”) electrodes could be usedto provide pulse shapes that, with theirnearly uniform Ramo weighting fields, are al-most independent of lateral track position fortracks away from channel borders. The sig-nal start is delayed only by the few picosec-onds taken for the electromagnetic signal gen-erated by the electron - hole separation toreach the electrodes. The drift velocity is alsonearly independent of position for high-purity,un-irradiated silicon. After high-irradiation,both the breakdown voltage and the drift ve-locity increase but now have a space-chargeinduced position dependence. Fig. 2.28(left)shows a small, test wall-electrode sensor - toosmall for data collection with the source, butlarger ones are planned as part of the nextStanford fabrication run.

As speed increases, one needs to check thatdelta ray tracks, even though they move withthe track, do not distort the received pulse. Themean number of delta rays of kinetic energygreater than T in a track in the 170 μm sensorsof Fig. 2.28 is 3.03 keV / T, so the probabilityfor energies greater than the 10 and 30 keV are30% and 10%. Figure 2.31, calculated with theprogram Casino, shows the ranges for both ofthese are small compared with the sensor thick-ness, and already a 30 keV delta ray will addenough energy, compared to the most probableenergy loss of about 50 keV, to be obvious.

One possible use, if ≈ 10ps resolution can bereached, is to supplement the Cerenkov timingsystem used to determine the z-vertex locationfor protons detected at ±420m, since a siliconsystem has greater radiation hardness and farless confusion from double hits.

Other work There are other tasks underwaybeyond those listed in Section 2 that are not de-tailed in this report, for example the design andfabrication (by C. Kenney and J. Hasi) of (1)sensors for testing FEI4 chips and (2) a thermal-mechanical test chip that generates heat in a waysimilar to the ATLAS FEI3 and FEI4 pixel read-out chips.

Conclusions, Schedules 3D sensors havebeen shown to be fast with negligible-dead-area borders and are extremely radiation hard.Pending scheduled proton irradiations up to1016/cm2, they should be adequate for 10 yearsat the inner radii of the sLHC.

The times for ATLAS decisions on the 220 -420 m proposal and the Insertable B Layer tech-nology are not yet set, and without that no spe-cific milestones can be specified. The programof sensor production, with improved fabricationmethods and new devices such as dual readoutand trench-electrode sensors will continue as willirradiation with charged particle beams and bi-ased sensors. Beam test runs will have magneticfields and already-irradiated detectors. ManyATLAS institutions are working cooperativelyon aspects of 3D technology, and decisions onwho does what are made as we go.


Bibliography

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[8] “Radiation hard silicon detectors lead the way”,C. Da Via, CERN Courier, Vol. 43, Jan. 2003,pp 23 - 26.

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[13] C. J. Kenney, J. D. Segal, E. Westbrook, Sher-wood. Parker, J. Hasi, C. Da Via, S. Watts, J.Morse, ”Active-edge planar radiation sensors”,Nucl. Instr. and Meth, A565, (2006), pp. 272-277.

[14] Sherwood Parker, C. J. Kenney, D. Gnani, A. C.Thompson, E. Mandelli, G. Meddeler, J. Hasi, J.Morse, E. M. Westbrook, ”3DX: an X-ray pixelarray detector with active edges”, IEEE Trans.Nucl. Sci., 53, issue 3, part 3, (2006), pp. 1676-1688.

[15] J. Uher, C. Frojdh, J. Jakubek, C. Kenney, Z.Kohout, V. Linhart, S. Parker, S. Petersson, S.Pospisil, G. Thungstrom, ”Characterization of3D thermal neutron semiconductor detectors”,Nucl. Instr. Meth, A576 (2007) 32-37.

[16] C.J. Kenney, J. Hasi, Sherwood Parker, A.C.Thompson, E. Westbrook, ”Use of active-edgesilicon detectors as X-ray beam monitors”, Nucl.Instr. and Meth. A 582 (2007) pp. 178-181.

[17] C. Da Via, J. Hasi, C. Kenney, V. Linhart,S. Parker, T. Slavicek, S.J. Watts, P. Bem,T. Horazdovsk, S. Pospisil, ”Radiation hardnessproperties of full-3D active edge silicon sensors”,Nucl. Instr. Meth, A587 (2008) 243-249.

[18] Cinzia Da Via, Sherwood Parker, Mario Deile,Thor-Erik Hansen, Jasmine Hasi, ChristopherKenney, Angela Kok, Stephen Watts, ”DualReadout - Strip / Pixel Systems”, Nucl. Instr.Meth A594 (2008) 7.


Chapter 2. ACCELERATOR-BASED EXPERIMENTS

[19] Sherwood Parker, Cinzia Da Via, Mario Deile,Thor-Erik Hansen, Jasmine Hasi, ChristopherKenney, Angela Kok, Stephen Watts, DualReadout, ”3D Direct / Induced-Signals PixelSystems”, Nucl. Instr. Meth A594 (2008) 332.

[20] M. Mathes, M. Cristinziani, C. Da Via’, M.Garcia-Sciveres, K. Einsweiler, J. Hasi, C. Ken-ney, S. I. Parker, L. Reuen, M. Ruspa, J.Velthuis, S. Watts, N. Wermes, ”Test BeamCharacterizations of 3-D Silicon Pixel Detec-tors”, IEEE Trans. Nucl. Sci., 53 (2008) 3731.

[21] Cinzia Da Via’, Mario Deile, Jasmine Hasi,Christopher Kenney, Angela Kok, SherwoodParker, Stephen Watts, et al., “3D Active EdgeSilicon Detector Tests with 120 GeV Muons”,IEEE Trans. Nucl. Sci. 56 (2009) 505.

[22] C. Da Via, E. Bolle, K. Einsweiler, M. Garcia-Sciveres, J. Hasi, C. Kenney, V. Linhart, Sher-wood Parker, S. Pospisil, O. Rohne, T. Slav-icek, S. Watts, N. Wermes, ”3D Active EdgeSilicon Sensors with Different Electrode Config-urations: Radiation Hardness and Noise Perfor-mance”, submitted for publication to Nucl. Instr.Meth, A.

[23] K. Borrer et al., ”Construction and performanceof a 1m2 silicon detector in UA2”, Nucl. Instr.Meth A253 (1987) 548-557.

[24] J. Walker, S. I. Parker, B. Hyams, S. Shapiro,”Development of high density readout for sili-con strip detectors”, Nucl. Instr. and Meth. 226(1984) 200-203.

[25] G. Anzivino, R. Horisberger, L. Hubbeling, B.Hyams, S. I. Parker, A. Breakstone, A. Litke,J. Walker, N. Bingefors, ”First results from asilicon-strip detector with VLSI readout”, Nucl.Instr. and Meth. A243 (1986) 153-158.

[26] Sonnenblick et al., ”Electrostatic simulations forthe design of silicon strip detectors and front-end electronics”, Nucl. Instr. and Meth. A 310(1991) 189.

[27] P. Jarron et al., ”A transimpedance amplifier us-ing a novel current mode feedback loop”, Nucl.Instr. and Meth. A 377 (1996) 435 describes a0.25μm technology current amplifier similar tothe faster 0.13μm one, designed by M. Despeisse,that was used here.


Chapter 3

Non-Accelerator Experiments:KA130101

3.1 KamLAND

Drs. Mikhail Batygov, John Learned,Shigenobu Matsuno, and Sandip Pakvasa, Ms.Stephanie Smith

(Learned is the principal investigator of thistask)

KamLAND is a 1 kiloton liquid scintillationdetector located in a mine tunnel at the Uni-versity of Tokyo’s Kamioka Laboratory under-ground complex in Western Japan. It has pro-duced dramatic observations of electron anti-neutrino oscillations during their flight from nu-clear power reactors located typically 180 km dis-tant in Japan. Results confirm electron neutrinooscillations consistent with solar neutrino obser-vations. The observation of neutrinos from Ura-nium and Thorium decays throughout the earthinitiated a new field of geoneutrinos.

KamLAND is entering a new era, with repro-cessed scintillator permitting a new round of so-lar neutrino observations, plus planning for in-troduction of material to carry out double β de-cay studies. Meanwhile, of course, the watchfor a galactic supernova continues. Moreover wehave begun studies of the utility of a large liq-uid Cherenkov detector for use in a long baselineneutrino facility, such as may come into existencewith a beam from Fermilab to DUSEL. The J-PARC beam now starting operation will providea test sample of this type of data.

3.1.1 Status of KamLAND

The KamLAND detector has been operat-ing now for seven years [3]. The early results

yielded evidence for oscillations of electron anti-neutrinos, which are consistent with inferencesfor electron neutrinos from solar neutrino ex-periments [8]. Moreover as the resolution im-proved due to increasing statistics, we were ableto definitively resolve oscillations [1], as illus-trated in Fig. 3.1, ruling out alternative modelsand finally nailing the case for electron neutrino(and anti-neutrino) oscillations and not simplyneutrino disappearance. As illustrated in Figure3.2, KamLAND has now measured the ‘solar’mass squared difference Δm2 =

(7.58+0.21

−0.20

)×

10−5 eV 2, to an amazing level of 2.8%. The‘solar’ mixing angle is less well determined, attan2(θ) = 0.56+0.14

−0.09, but combining with solarexperimental results (mainly SNO), appears tobe definitely less than maximal mixing (unlikethe muon neutrinos).

Kamland’s reference [1] also includes an up-dated value for geoneutrinos, but in terse fash-ion (due to page limits), and for which a longerpaper will be forthcoming. We received a greatdeal of notice for the first observation of neu-trinos from radioactive decays throughout theearth, leading to a cover article in Nature [6].The new data extraction (quoted by Learnedat NU08 in Christchurch, NZ in 5/08) yields73 ± 27 antineutrino events in the range from0.9 to 3.6 MeV, which are attributable to naturalterrestrial Uranium and Thorium decay chain in-duced events. The errors are large because signif-icant backgrounds due to Japanese reactors andsome internal detector backgrounds must be sub-tracted. The expected number of events is 69.7,based upon a simple (Bulk Silicate Earth) modeland dominated by crustal radioactivity from theJapan region (and not from the Earth’s man-


CHAPTER 3. NON-ACCELERATOR EXPERIMENTS: KA130101

tle which is what the geologists most want tounderstand: see later discussion for Hanohano).It is very hard to pin down errors in geologi-cal models, but they are said to be about 20%,and maybe larger, even though the agreement isbetter than it should be (note, the model wasproposed before KamLAND data was taken).We also set a new limit upon natural reactors,such as those proposed by several authors forthe Earth’s core or core-mantle boundary, andthis is 6.2 TW at an Earth radius range, at 90%C.L. This begins to seriously squeeze the Hern-don Earth centered geo-reactor model, whichpredicted up to 10 TW. (Note for comparisonthat the total of all manmade reactors is about1 TW.)

Some other null results have been published,having to do with no anomalous sources of anti-neutrinos from the sun or from the sum of allold supernovae (or anything else), and the non-disappearance of neutrons [2]. A longer paper isin preparation (for PRD) that will contain de-tails of the analysis procedures, and such, whichhave not yet been submitted to an archival jour-nal.

The detector has been in the process of redis-tillation of the liquid scintillator for the last twoyears, in order to lower backgrounds for the nextphase in solar Be line measurement. The distilla-tion will have the added benefit of lowering back-grounds for the low energy end of the event spec-trum, where the geoneutrino signal resides, andwill improve oscillation measurements further aswell. New electronics have been installed (madeby the Tohoku group); this deadtimeless elec-tronics will permit better elimination of back-grounds. The future of KamLAND is discussedbelow.

3.1.2 Hawaii Role in KamLAND

Aside from being regular collaborators, takingshifts, serving on publication committees, host-ing collaboration meetings (next one in HawaiiSeptember 2009), and the like, we have special-ized in analysis of the geoneutrino data. JelenaMaricic’s thesis [4] was the first calculation ofsteady unidentified reactor-like backgrounds as

-110 1

-410

KamLAND95% C.L.99% C.L.99.73% C.L.best fit

Solar95% C.L.99% C.L.99.73% C.L.best fit

10 20 30 40

σ1 σ2 σ3 σ4 σ5 σ6

5

10

15

20

σ1σ2

σ3

σ4

12θ2tan 2χΔ

)2 (

eV212

mΔ2 χΔ

Figure 3.2: Oscillation parameters resultingfrom five years of KamLAND data. Note im-proved and surprisingly precise constraints onmass-squared differences.

could arise from a natural reactor in the earth’score (this has now become part of the regular re-actor data reduction). Batygov, who joined thegroup in January, 2007 has been making signifi-cant contributions to the Tohoku based analysis.His fitters now give the best energy and posi-tion resolution and have been widely adopted.His method of universal maximum likelihood fit-ting, including all systematic parameters, hasimproved the oscillations results. The UH groupalso participates in plans for improved detectorperformance, such as for directional measure-ments and advanced detectors. We plan to re-main collaborators in KamLAND for a few moreyears. Our participation has synergy with theSuperK involvement, and overlaps with the To-hoku involvement in the plans for Hanohano (seebelow). And of course, we are all waiting to thenext supernova neutrino wave to arrive.

3.1.3 Future Plans for KamLAND

Since the initiation of the experiment it hasbeen the stated plan to evolve from the reac-tor measurements, which are relatively easy sinceone has the distinctive double-hit inverse beta-decay signature, to the more difficult solar neu-


3.1. KAMLAND

(km/MeV)eν/E0L

20 30 40 50 60 70 80 90 100Su

rviv

al P

roba

bilit

y0

0.2

0.4

0.6

0.8

1

eνData - BG - Geo Expectation based on osci. parameters

determined by KamLAND

Figure 3.1: L/E distribution in KamLAND, illustrating the ratio of events seen to those ex-pected with no-oscillations. The blue curve illustrates the oscillations as fitted in a simple threeflavor model. Most importantly one sees the first several reappearance peaks, indicating definiteoscillations and ruling out many alternative models (with decay, etc.).

trino measurements, in particular of the 7Be line,and possibly the pep and CNO neutrinos. Theseare terribly difficult measurements, since one hasonly the handle of energy deposition in the de-tector, and no directionality in a scintillation de-tector. The recently activated (2007) and muchsmaller Borexino instrument in Italy is well onthe way to doing this, but was built with muchmore strict radio-purity standards from the be-ginning since their prime goal was measurementof solar neutrinos. KamLAND has been workingtowards this with various improvements, mostparticularly the re-distillation of the scintillatorfrom the inner 1000 ton detector volume. Var-ious difficulties have been overcome and it ap-pears that great progress is in the offing, asreported during the Collaboration Meeting ofMarch 2009, with redistillation continuing for afew months this year (2009).

The most dramatic proposal for a changeof direction in KamLAND has been to enterthe neutrino-less double beta decay competi-tion. Other completed and running experimentshave employed only several kg of active iso-topes. Planned sensitivity for the effective neu-trino mass in year 2009 is < m >= 0.2− 0.7 eV .The spread in < m > comes from several dif-ferent experimental results and choice of ma-trix elements. Among the next-generation ofapproved and funded experiments, the possible

KamLAND rivals are CUORE and SuperNEMO,which are going to use double β isotope massesbetween 140 and 200 kg. These experiments maybegin operation in 2011-2013 if R&D and con-struction schedules are met. The EXO200 sen-sitivity is lower compared to these two experi-ments due to a higher expected background forthe measurement without the Ba++ ion tagging.The SNO+ group also announced plans to starta double β experiment with Nd in 2010 but plansare not yet firm.

Examination of various possibilities for addingdouble β decay nuclei to KamLAND point to-wards 136Xe as the best choice. Ultimately tomake this work will require some upgrades inlight output and perhaps photomultipliers. How-ever, during the solar neutrino phase of Kam-LAND, R&D for a medium size zero neutrinodouble beta decay experiment employing 200 kgof enriched 136Xe can be completed. That in-cludes insertion of a small balloon (1.5m radius)into the existing detector, manufacturing, con-struction of the Xenon loading/extraction sys-tem, etc. Depending on results of the mediumsize experiment a larger Xenon experiment maystart few years later. That may allow initialprobing of the neutrino effective mass regioncorresponding to inverted hierarchy faster thanCUORE, SuperNEMO or other double β decayexperiments. One may wonder why KamLAND



should enter this world-wide race for the observa-tion of double beta decay, but the collaborationargues that the goal is so important and yet dif-ficult that many techniques should be pursued,and modification of the existing KamLAND isone of the more interesting and cost effective av-enues. That said, one that can proceed whilestill continuing with other observations (reactorneutrinos, solar neutrinos, geoneutrinos, super-nova neutrinos, and observation of a sample ofJ-PARC events).

3.2 Super-Kamiokande

Drs. John Learned and Shigenobu Matsuno,Mr. Michinari Sakai

(Learned is the principal investigator of thistask.)

The Super-Kamiokande detector is a 50 kilotonwater Cherenkov detector, with 11,146 twentyinch photomultiplier tubes surrounding a 22.5kiloton fiducial volume ultra pure water region(plus 1,885 eight inch PMTs, many from the IMBexperiment, in the veto region). While initiallyfunded to search for nucleon decay (as it has, torecord-level limits, without success), the SuperKteam reported the first definitive measurementsof neutrino oscillations in 1998. Other measure-ments have included directional (Boron) solarneutrino observations, playing a key role withSNO in solving the “solar neutrino problem” (asdue to MSW oscillations). The detector has alsoused with detection of a beam of muon neutrinosfrom KEK, and will operate with a new high in-tensity beam from a new accelerator at J-PARCin Tokai (T2K) starting this year (2009). Manyother studies continue, including the addition ofGadolinium to permit neutron detection.

3.2.1 SuperK Introduction

The Super-Kamiokande experiment continuesto operate, in renewed and slightly improvedconfiguration, with upgrades in place and moreon the horizon, with T2K running just start-ing (4/09). This instrument continues to be

the world’s premier low to moderate energy (4MeV to TeV) neutrino detector and nucleon de-cay search instrument, and will be so for the nextdecade. SuperK opened the era of neutrino os-cillations and mass in 1997, and a decade laterSuperK still owns most of the best results onmuon neutrino oscillations, as well as significantcontributions to solar neutrino studies. All themost significant limits on the search for nucleondecay in various possible modes now come fromSuperK, as is easily seen in the Particle DataGroup compilation (http://pdglive.lbl.gov). Pa-pers have been published on a surprisingly largerange of topics (observation of solar electronneutrinos, observation of atmospheric neutri-nos over a range of six orders of magnitudein energy, muon neutrino oscillations, relic su-pernova neutrino searches, indirect searches forWIMPs, measurements of cosmic ray propertiesand isotropy, high energy astrophysical neutri-nos point source searches, tau lepton appearance,nucleon decay, properties of weak interactions,searches for various exotic particles, and correla-tions with astrophysical phenomena), resultingin at least 68 publications in journals, more than42 PhD theses, and hundreds of conference talks.The experiment is generally heralded as one ofthe most fruitful (and we note, cost effective) inthe history of particle physics. Many beginningphysics textbooks now have pictures of this in-strument, for example. There is a general expec-tation that a Nobel Prize will be given for thediscovery of muon neutrino oscillations (follow-ing on the Prize given project initiator MasatoshiKoshiba’s prize citing solar neutrinos and super-nova 1987A).

3.2.2 Hawaii Participation in SuperK

Hawaii was one the founding members of theSuperK collaboration, after long (co-founding)participation in the first large underground de-tector, the IMB experiment. (Indeed one of ourformer students Steve Dye, who is now Professorat Hawaii Pacific University and Adjunct Profes-sor at UH made the first arrangements for con-solidation of the old IMB and Kamioka groups).The detector is in SK-IV operating mode now,


3.2. SUPER-KAMIOKANDE

with all the PMTs that were destroyed in theaccident of 2001 replaced, the detector operat-ing stably for about two years and with upgradedelectronics and software. We have played a crit-ical role in many aspects of the experiment, in-cluding the first PhD on muon neutrino oscilla-tions. Matsuno and Learned continue as collabo-rators, with some responsibilities in the calibra-tion area and continuing activity in muon andhigh energy neutrino data analysis. Sakai is juststarting as a grad student.

3.2.3 Physics Results from SuperK

New publications since last year plus other im-portant publications, are listed in Section 3.6.2.We have published updated nucleon decay re-sults, which push the most stringent limits(e+πo) to near 1034 yrs (along with the μπo

mode), reported the first study of neutron tag-ging with a water Cherenkov detector, and donereconstruction of proton tracks with a waterCherenkov detector. We are in the slow accu-mulation phase now, improving data fitting al-gorithms, getting better statistics in all areas,awaiting a galactic supernova, working towardsmore remote operations, and have been prepar-ing for T2K, now starting.

One special area of recent Hawaii activity, ini-tially carried out by Learned and then broughtto publication by Guillian, was the analysis ofdown-going cosmic ray muon directional isotropy[18], finally published last year. It turns out thatthere is a surprising (slight though significant)variation in the 10 TeV primary cosmic ray fluxarrival directions (10−3 level). We first mappedthis out with the IMB experiment (in Gary Mc-Grath’s 1993 UH thesis), but we did not takeit seriously as the effect is quite subtle. Thereis similar evidence found in the MILAGRO andthe Tibet EAS array results. Most peculiarly theexcess region is not in 180 degree opposition toa deficit region. And, with limited resolution,the sizes of the regions of excess and deficit ap-pear to be different and more peaked than a sim-ple dipole. From the Compton-Getting (Dopplereffect on a steeply falling spectrum by a mov-ing observer) effect we would expect a dipole

asymmetry, which is not what we observe. Infact we do not know (nobody knows) what di-rection and velocity to expect for the Compton-Getting effect, since it is not obvious what is theproper rest frame for the cosmic ray flux ! Thus,we have discovered an unexpected and not eas-ily explained cosmic ray anisotropy. Whetherthis effect turns out to be of great significanceor due to some peculiarities of the local galac-tic magnetic field remains undetermined. Giventhe recent peculiarities with cosmic gamma andelectron/positron ray observations, we speculatethat it could be related, but this is an area ofmuch current confusion and speculation (partic-ularly since some suggest that the source of suchflux could be WIMP annihilation or even decay).

3.2.4 Future Plans with SuperK

The SuperK Collaboration plans to operatefor about a decade into the future. The nextfew years will see data taking starting with thenew accelerator at Tokai this year, and the T2Kexperiment (follow-on to K2K) running for sev-eral years (and perhaps longer if accelerator up-grades are forthcoming). This experiment willhave a good opportunity to make the first obser-vation of the θ13 mixing angle, starting in late2009 and proceeding beyond 2015. We will notgo into details of those plans here, as they aremuch discussed elsewhere (see much detail athttp://jnusrv01.kek.jp/public/t2k/) and we arenot engaged in constructing the near-acceleratordetector.

Beyond operations as now configured, there arecontinuing studies (mostly pushed by UCI andUC Davis, as well as ICRR) for Gadolinium dop-ing of the water, to permit neutron detection. Ifthis takes place (and there is significant reluc-tance by the ICRR group to take this risky step)SuperK may become the world’s most sensitiveelectron anti-neutrino detector (at least above 4MeV). Unfortunately, it has been learned thatthe GdCl3, and several other chemicals with Gd,all result in deterioration of water optical trans-missivity due to corrosion of the stainless steel(employed in the PMT support structure in Su-perK). It may be that a fiducial volume enclosing



transparent bag or acrylic layer over the PMTswill be needed. Learned has proposed instal-lation of Gd doped columns (transparent hosesabout 8 inches in diameter) from the top accessports, which would constitute neutron detectors(as with the Helium detectors in SNO). Probablyany modification to SuperK will be on hold untilsignificant T2K running is complete, however.

Of course we continue to analyze the data forimpulsive events, such as could come from aGamma Ray Burst or a Supernova. In addition,the search for nucleon decay will move slowlyahead. There remains more data to be analyzedthan we have graduate students, so SuperK willcontinue to be fertile training ground for particlephysicists. We see continuing UH participationat a low level in SuperK for some years. This ismade easier since we are also involved in Kam-LAND and can (and do) link trips. Also withtime, there are more opportunities for remoteshift taking as the detector becomes more sta-ble and remotely operable.

3.3 Hanohano studies

Drs. Mikhail Batygov, Stephen Dye, JohnLearned, Shigenobu Matsuno, Sandip Pakvasa,Gary Varner, and Mr. Marc Rosen, Ms.Stephanie Smith and Mr. Michinari Sakai, plusseveral undergraduates.

Hanohano (Hawaii Anti-Neutrino Observa-tory) is the name for a new (as yet unreviewed)project aimed at studying electron-antineutrinosin the deep ocean for particle physics, geophysics,and demonstration of portable remote nuclear re-actor monitoring. It is in the stage of R&D andproject formation.

3.3.1 Introduction to Hanohano

The Hanohano Project as now conceived bya team of physicists and geologists is a follow-on to KamLAND, and has dual science goals ofneutrino particle property studies and the studyof geoneutrinos [33], plus it serves as a demon-stration platform for remote monitoring of nu-clear reactors. Recently, Spring 2009, it was re-alized that Hanohano can also accomplish sig-

nificant long-baseline work; we have identifieda means of analyzing interactions in the 1 GeVrange (and which may be competitive or at leastcomplementary to large Water Cherenkov detec-tors in this energy range). The detector will bea > 10, 000 m3 tank of liquid scintillator viewedby photomultiplier tubes, designed to be sunkin the deep (> 3 km) ocean, and recovered andtransported for studies at various locations.

The notion of measuring geoneutrinos asprobes of the energy source of the Earth hasgarnered a good deal of interest in the geologycommunity [35]. It is indeed transformative sci-ence to measure the energy sources that driveall of plate tectonics and much of the dynamicsof geology. Geologists have had no way to di-rectly measure where the Uranium and Thoriumare located, whose decays chains are thought todominate the Earth’s heat budget.

Along with purely scientific neutrino physicsstudies (more about that below), the project hasattracted a great deal of notice as an initial stepin the building of large portable anti-neutrinodetectors to monitor nuclear reactors. There ismuch concern in the defense community aboutnuclear proliferation in the oncoming era of oildepletion, and most probably great expansionin the number and distribution of nuclear powerreactors worldwide. Close-in neutrino monitor-ing (tens of meters) at cooperative facilities ispractical and has been developed by groups atLLNL and Sandia, and elsewhere (France, Rus-sia). Long range monitoring will require detec-tors akin to the KamLAND detector, which mon-itors an ensemble of reactors at an average dis-tance of 180 km in Japan. For serious worldmonitoring, detectors on the megaton scale aregoing to be needed. This has been recognized byU.S. authorities, as well as in other concernedstates such as France. Several recent workshopshave been carried out, specifically focused uponremote monitoring: in December 2007 in Parisand at the University of Maryland in January2008 and in Hawaii in March 2009, the lattertwo sponsored by the DIA and with limited at-tendance).


3.3. HANOHANO STUDIES

Physics community interest in Hanohano isgrowing, as indicated by a stack of requests forseminars and colloquia about this project, whichis not even formally proposed as yet. In thelast year talks have been given at U. Wash-ington, JASON in La Jolla CA, UCSB(KITP),UC Davis, LBL, LLNL, ANL, Philadelphia Pa,Austin Texas, Taipei Taiwan, Christchurch N.Z.,Paris, Athens Greece, Rome Italy, Cornell, andWichita State (some physics, some geology, someboth). The project is beginning to reach a widesection of the geology and physics communities,as well as the anti-nuclear-proliferation commu-nity, and attracts much interest.

3.3.2 Hawaii Role in Hanohano

This project was initiated by Dye, Learned,Matsuno, Pakvasa and Varner at UH. We havehad four relevant workshops in Hawaii, financedby DTRA, UH and DIA. The science crew nowinvolves informally both physicists and geologistsfrom a growing number of institutions (U. Al-abama, UCB, CalTech, UCD, Drexel, Fermilab,Kansas, LLNL, U. Md., Stanford, U. Texas, To-hoku U. in Sendai, U. Munich, U. Wash., Wi-chita State, Yale, and others totaling 22 institu-tions), though a formal collaboration agreementhas not yet been signed.

We have carried out an initial design study inHawaii with funds from a local source (CEROS).Engineering studies by a local (but internation-ally well known) firm, Makai Ocean Engineering,has established baseline constraints and costs,concluded there are no technical show-stoppers,and have identified issues for further engineering[41]. Initial ocean tests have been conducted. AtUH we have done some laboratory work (enoughto be confident of no show stoppers with the scin-tillator under pressure), and are now engaged inmore careful parametric studies 3.3. We havealso carried out physics studies including firstand second generation computer analyses of theparticle physics, the results of which have beenpresented at physics conferences and several pa-pers in press.

We are also engaged in a study with the Na-tional Geospatial Agency, which has undertaken

Figure 3.3: Pressure cell in temperature con-trolled volume for optical studies of liquid scin-tillaton materials.

a project (our initial suggestion) to attempt toimage the inverse beta reaction. The NGAteam is looking at optics and sensor technology,while we at UH are generating the events (usingGEANT, which has had to be updated for thesepurposes). There is complementary work goingon at Tohoku as well.

For purposes of this renewal proposal, wenote that Hanohano is not an officially approvedproject yet, as it has not been formally reviewed,nor has a formal project proposal been submit-ted. At this stage we are conducting detectorR&D, much of which has overlap with Kam-LAND, DUSEL and other projects. See par-ticularly the photodetector work described inthe Detector Development section (led by Prof.Varner).

3.3.3 Results of Hanohano Studies

The surprising result of investigation of the po-tential neutrino studies employing a land-based



nuclear power reactor complex as the neutrinosource, is that a 10 kiloton detector 50-60 kmoffshore from a reactor complex can within oneyear make competitive measurements of the θ13

angle down to values similar to the reach of Dou-ble Chooz, and with a long run down to valuesnear to those achievable with Daya Bay [39, 42].While it seems likely that Hanohano will not beas fast on the draw as these other experiments,they do have formidable obstacles to overcome,and the Hanohano method is less sensitive tobackgrounds and delicate calibrations. Also, be-ing a significantly different approach to measur-ing θ13 (and θ12), it provides a cross check and analternative route to untangling the PMNS ma-trix. Moreover, we have discovered that thismethod can be used to discern the mass hi-erarchy, and in a way different from that inlong baseline experiments: we directly determinethe mass order of Δm13 and Δm23(without de-pending upon matter effects). The initial re-sults employed a Fourier transform method, nowreplicated by a group in China (Zhan et al.,arXiv:0807.3203[hep-ex]), but it was difficult toincorporate systematic errors in this approach.We have now completed a study [42], employinga full maximum likelihood technique and analy-sis software derived from the tested KamLANDsoftware, which demonstrates the earlier asser-tions. Interestingly this study indicates thatthere is not one single optimum distance forall neutrino physics studies, but various favoreddistances depending upon which parameter onewishes to measure. The study also demonstratesthe robustness of this approach to independencefrom systematic errors. It also emphasizes theimportance of energy resolution, particularly ifθ13 is very small, for the neutrino mass hierarchymeasurement, and hence our keen interest in op-timizing scintillator and photodetector choices.

Note also, that while the near-reactor experi-ments have essentially only one physics measure-ment, which may be null if θ13 should be zero (orvery small), the Hanohano experiment can stilldo useful particle physics in measuring an accu-rate value of θ12 to a few percent, along with allthe ancillary particle searches, and astrophysics

(the latter which can also be done with Kam-LAND, but much better with 20x fiducial vol-ume in Hanohano). And all this is aside fromthe transformative science to be done in measur-ing geoneutrinos [40].

3.3.4 Large Liquid Scintillation DetectorLong-Baseline Neutrino Experiment

In Spring 2009 we realized that large liquidscintillation detectors such as Hanohano (10 kilo-ton), LENA (proposed 50 kilotons in Europe),and possibly a new large detector at DUSEL.could have significant capability as detectors ofneutrinos in the 1 GeV energy range [43]. In thepast we had written of this capability in favor ofwater Cherenkov detectors, which as SuperK hasso well demonstrated do very well with resolu-tion and particle identification (muon-like versuselectron-like) in this energy region. The simplereason for dismissing liquid scintillators was thatthe scintillator is nearly isotropic in its response,and hence one assumed the higher energy eventswould just be registered as in a nice calorime-ter. For example, KamLAND has a responseof about 250 photoelectrons/MeV (PE/MeV) ofdeposited energy, so a one GeV event producesmore than 100 PE in each photomultiplier tube.The realization was that the timing of the firstPE in such bright events will always be close tothe ”Fermat surface”. For example, for a singlestraight muon track there will be a band that hasthe same timing as for Cherenkov radiation. For-ward and backward from the Cherenkov ring willbe spherical radiation (in timing). We have em-ployed a Monte Carlo program to demonstratethat one can locate the track this way, as well asdiscern the difference between an electron and amuon for (quasi-elastic events, which dominatein this region).

First indications are that the energy, angle andparticle identification may rival or exceed a waterCherenkov detector of the same size. Hence onemay wish to consider the employment of a liq-uid scintillation detector for applications wherewe have been thinking about a water Cherenkovdetector, most particularly in a long baselineneutrino experiment employing a beam from an


3.4. OTHER PHYSICS

accelerator such as at Fermilab-DUSEL or atCERN-LENA, or even J-PARC-Hanohano. Theas yet unanswered question is whether the liquidscintillator can do better (or as well) at πo rejec-tion, which needs a more serious Monte Carlostudy. If the liquid scintillator detector is asgood, the advantage would be that all the lowenergy physics (below about 4.5 MeV, includinggeoneutrinos) becomes simultaneously accessiblewith the higher energy studies.

3.3.5 Future Plans for Hanohano

Our UH HEP efforts will continue in studyingthe physics potential of the Hanohano detectorconcept, along with laboratory investigations ofscintillators and photo-detectors, studies of pos-sible means to make low energy neutrino direc-tion measurements, and studies of the applica-tion of Hanohano to long-baseline experimentswith an accelerator beam, and collaboration or-ganization.

Various collaborators are submitting propos-als to study differing aspects of the science andtechnology. One important area being exploredis the ability for directional discrimination. Weknow this is extremely difficult, but have someideas to explore, for which the payoff in neu-trino detectors could be wide reaching. Otherthan that we plan to carry on further simula-tion work in concert with our work for Kam-LAND, and in relation to possible experimentsat DUSEL. We also, with help from UH support,have been moving ahead with both laboratorystudies of scintillator properties under pressure(500 atmospheres) and deep ocean temperature(few degrees C), and with construction of a smalldemonstration detector. We have acquired manycomponents, from the CEROS funds, from UHfunds and from collaborators (particularly Wi-chita State). We expect support from UH forship time for deployment of a one ton demon-stration instrument. We anticipate being able tomake an ocean demonstration run in early 2010with this device.

In the longer run, while we are exploring av-enues for substantial bootstrap funding, we will

have to request project review, which we can an-ticipate doing in about one year.

3.4 Other Physics

The UH HEP Group continues to be support-ive of several other related projects, though atlow levels. We advise our colleagues in Europeinvolved in the KM3 efforts to build a cubickilometer underwater detector of the DUMANDstyle. We give some administrative and consulta-tive support to the U. Tokyo ICRR group build-ing the ASHRA Project (optical UHE cosmic rayand neutrino detector) on the Big Island. Weprovide help with State of Hawaii bureaucracy,and advice. Discussions continue on new meth-ods for dark matter detection and future liquidargon detectors.

Learned also continues to write some specu-lative papers, along with Sandip Pakvasa, RolfKudritski (Director of the Institute for Astron-omy at UH), and Tony Zee of UCSB: two pa-pers have been submitted for publication, aboutnew ways to seek signal from extra-terrestrialadvanced civilizations, both schemes employingneutrinos (see more in Theory section). Learnedcontinues working on a new cosmology model in-volving mirror matter and a possibly new solu-tion to the dark energy problem, along with gen-eral relativist Sabine Hossenfelder of the Perime-ter Institute in Canada and astrophysicist NickKaiser of the UH IfA.

We continue to explore far future defense ap-plications of nuclear reactor and weapons testingmonitoring with huge electron anti-neutrino de-tectors.

3.5 Invited Talks, 2008-2009

1. Learned gave a LLNL Colloquium about mo-bile neutrino detectors for mixing, masses, ge-ology and reactor snooping, August 2008 inLivermore, CA.

2. Learned gave a talk in the KITP program onboundary layers in the earth, 24 July 2008,Santa Barbara, CA; and also gave a talk on



geoneutrinos: Hanohano, a new deep oceanproject to measure the mantle U/Th content.

3. Learned gave a KITP Colloquium talk on mo-bile neutrino detectors for mixing, masses,geology and reactor snooping, June 2008 inSanta Barbara, CA.

4. Learned gave a talk on new directions inneutrino research: mobile detectors for ge-ology, mixing and mass hierarchy, and anti-proliferation, American Geophysical Union,May 2008 in Baltimore.

5. Learned gave a talk on particle astrophysicsseminar New Directions in Neutrino Re-search, June 2008 at the University of Wash-ington, Seattle.

6. Learned gave a talk on Detection of Geoneu-trinos at the Neutrino 2008 conference, May2008 in Christchurch, New Zealand.

7. Learned gave an Introductory Talk on Neu-trino Monitoring at the AAW, January 2008in U. Maryland, College Park, MD.

8. Learned gave a talk on the age of neutrinophysics, April 2009 at Wichita State Univ &Cornell University.

9. Learned gave a talk on Prospects for LiquidScintillation Detectors Employing GeV Neu-trinos: the Fermat Surface, March 2009 at UCBerkeley.

10. Learned gave talks on Liquid Scintillation De-tectors for High Energy Neutrinos; and NewIdeas in Long Range Reactor Monitoring withNeutrinos at the Neutrino Monitoring Work-shop, March 2009 in Honolulu, HI.

11. Learned gave public lecture on ET: So whereis he? Science Cafe, Hawaii Academy of Sci-ences, February 2009.


Bibliography

3.6 Publications

3.6.1 Recent KamLAND Publications

[1] KamLAND Collaboration, (S. Abe, etal.), “Precision Measurement of Neu-trino Oscillation Parameters with Kam-LAND”, Phys.Rev.Lett.100, 221803 (2008),(http://arxiv.org/pdf/0801.4589v3)

[2] KamLAND Collaboration, (T. Araki, et al.),“Search for the invisible decay of neutronswith KamLAND”, Phys.Rev.Lett.96:101802(2006)(hep-ex/0512059)

[3] J. Maricic and J. G. Learned, “The KamlandAnti-Neutrino Oscillation Experiment,” Con-temp. Phys.46, 1 (2005).

[4] J. Maricic [KAMLAND Collaboration], “Exper-imental status of geo-reactor search with Kam-LAND detector,”Proceedings Neutrino Sciences2005: Neutrino Geophysics, Honolulu, Hawaii,14-16 Dec 2005, S. Dye, ed., Springer (2007).

[5] KamLAND Collaboration, (T. Araki, etal.), “Measurement of neutrino oscillationwith KamLAND: Evidence of spectral dis-tortion”, Phys.Rev.Lett.94:081801 (2005)(hep-ex/0406035).

[6] KamLAND Collaboration, (T. Araki, et al.),“Experimental investigation of geologically pro-duced antineutrinos with KamLAND”, Nature436:499-503 (2005) (cover article).

[7] KamLAND Collaboration (K. Eguchi etal.), “A high sensitivity search for νe’sfrom the sun and other sources at Kam-LAND” Phys.Rev.Lett.92:071301 (2004)(hep-ex/0310047)

[8] KamLAND Collaboration (K. Eguchi etal.), “First results from KamLAND: Evi-dence for reactor anti-neutrino disappear-ance”, Phys.Rev.Lett.90:021802 (2003)(hep-ex/0212021).

3.6.2 Recent SuperK & K2K Publications

[9] SuperKamiokande Collaboration, “Kinematicreconstruction of atmospheric neutrino eventsin a large water Cherenkov detector with pro-ton identification”, submitted to Phys Rev D.[arXiv:0901.1645]

[10] SuperKamiokande Collaboration, “First Studyof Neutron Tagging with a Water Cherenkov De-tector”, submitted to NIM A. [arXiv:0811.0735]

[11] E. Thrane, et al. [Super-Kamiokande Collabora-tion], “Search for Neutrinos from GRB 080319Bat Super-Kamiokande”, Ap.J.697, 730 (2009);[arXiv:0903.0624].

[12] H. Nishino, S. Clark, et al. SuperKamiokandeCollaboration, “Search for proton decay via p →e+π0 and p → μ+π0 in a Large Water CherenkovDetector ”, Phys.Rev.Lett. 102, 141801, (2009)[arXiv:0903.0676]

[13] J.P. Cravens, et al., SuperKamiokande Collabo-ration, “Solar neutrino measurements in Super-Kamiokande-II”, Phys.Rev. D78, 032002 (2008)[arXiv:0803.4312).

[14] K. Abe, et al., SuperKamiokande Collab-oration, “Search for Matter-Dependent At-mospheric Neutrino Oscillations in Super-Kamiokande”, Phys.Rev. D77, 052001 (2008)[arXiv:0801.0776].

[15] S. Desai, et al., SuperKamiokande Col-laboration, “Study of TeV Neutrinoswith Upward Showering Muons in Super-Kamiokande”, Astropart. Phys. 29, 42 (2008),[arXiv:0711.0053v1).

[16] M. Ikeda, A. Takeda, Y. Fukuda, M.R. Va-gins, et al., [Super-Kamokande Collaboration],“Search for Supernova Neutrino Bursts at Super-Kamiokande”, Astrophys.J. 669,519-524,(2007)[arXiv:0706.2283]

[17] K. Abe et al., Super-Kamokande Collabora-tion, “High energy neutrino astronomy us-ing upward-going muons in Super-Kamiokande-I”, Astrophys. J.652, 198 (2006)[arXiv:astro-ph/0606413].


BIBLIOGRAPHY

[18] G. Guillian et al. Super-Kamiokande Collabo-ration, “Observation of the anisotropy of 10-TeV primary cosmic ray nuclei flux with theSuper-Kamiokande-I detector”, Phys. Rev. D75, 062003 (2007)[arXiv:astro-ph/0508468].

[19] Y. Takenaga et al. Super-Kamiokande Col-laboration, “Search for neutral Q-balls inSuper-Kamiokande II”, Phys. Lett. B 647, 18(2007)[arXiv:hep-ex/0608057].

[20] M.E.C. Swanson et al. Super-Kamiokande Col-laboration,“Search for diffuse astrophysical neu-trino flux using ultra-high energy upward-goingmuons in Super-Kamiokande I”, Astrophys.J.652, 206 (2006)[arXiv:astro-ph/0606126].

[21] K. Abe et al. Super-Kamiokande Collabora-tion, “A measurement of atmospheric neutrinoflux consistent with tau neutrino appearance”,Phys. Rev. Lett.97, 171801 (2006)[arXiv:hep-ex/0607059].

[22] J. Hosaka et al. Super-Kamiokande Collabora-tion, “Three flavor neutrino oscillation analysisof atmospheric neutrinos in Super-Kamiokande”,Phys. Rev. D 74, 032002 (2006)[arXiv:hep-ex/0604011].

[23] J. Hosaka et al. Super-Kamkiokande Collabora-tion, “Solar neutrino measurements in Super-Kamiokande-I”, Phys. Rev. D 73, 112001(2006)[arXiv:hep-ex/0508053].

[24] A. T. Habig Super-Kamiokande Collabora-tion, “High-energy neutrino astronomy withthe super-Kamiokande detector,” [arXiv:astro-ph/0507051].

[25] K. Kobayashi et al. Super-Kamiokande Collab-oration, “Search for nucleon decay via modes fa-vored by supersymmetric grand unification mod-els in Super-Kamiokande-I,” Phys. Rev. D 72,052007 (2005) [arXiv:hep-ex/0502026].

[26] Y. Ashie et al. Super-Kamiokande Collabora-tion, “A measurement of atmospheric neutrinooscillation parameters by Super-Kamiokande I,”Phys. Rev. D 71, 112005 (2005) [arXiv:hep-ex/0501064].

[27] A. Rodriguez, et al., K2K Collaboration, “Mea-surement of single charged pion production inthe charged-current interactions of neutrinosin a 1.3 GeV wide band beam” ,Phys.Rev.D78,032003,(2008), [arXiv:0805.0186v2].

[28] S. Mine, et al., K2K Collaboration, “Ex-perimental study of the atmospheric neutrinobackgrounds for proton decay to positronand neutral pion searches in water Cherenkovdetectors”, Phys.Rev. D77, 032003 (2008),[arXiv:0801.0182].

[29] M. H. Ahn et al. [K2K Collaboration], “Mea-surement of neutrino oscillation by the K2Kexperiment,” Phys. Rev. D 74, 072003 (2006)[arXiv:hep-ex/0606032].

[30] S. Yamamoto et al. [K2K Collaboration], “Animproved search for νµ → νe oscillation ina long-baseline accelerator experiment,” Phys.Rev. Lett. 96, 181801 (2006) [arXiv:hep-ex/0603004].

[31] R. Gran et al. [K2K Collaboration], “Measure-ment of the quasi-elastic axial vector mass inneutrino oxygen interactions,”Phys. Rev. D 74,052002 (2006) [arXiv:hep-ex/0603034].

[32] M. Hasegawa et al. [K2K Collaboration],“Searchfor coherent charged pion production in neu-trino carbon interactions,” Phys. Rev. Lett. 95,252301 (2005) [arXiv:hep-ex/0506008].

3.6.3 Recent Hanohano Publications

[33] John G. Learned, Stephen T. Dye, Sandip Pak-vasa, “Hanohano: A Deep Ocean Anti-neutrinodetector for unique neutrino physics and geo-physics studies”, Proceedings of the 13th In-ternational Workshop on Neutrino Telescopes,Venice, February 2007, 36pp.

[34] S. T. Dye, “Science Potential of a Deep OceanAntineutrino Observatory”, Nuc. Phys. B, 168,144 (2007).

[35] W.F. McDonough, “Mapping the Earth’s En-gine”, Science 317, 1177 (2007).

[36] Stephen T. Dye, ed., “Neutrino Geo-physics: Proceedings of Neutrino Sciences2005”, Springer 2007, ISBN 0387707662,9780387707662, 368 pages.

[37] M.S. Batygov, “Prospects of precision neutrinooscillation studies with Hanohano”, J. Phys.120, 052027 (2008).

[38] J. G. Learned, S. T. Dye and S. Pakvasa, “Neu-trino geophysics conference introduction”, Pre-pared for Neutrino Sciences 2005: Neutrino Geo-physics, Honolulu, Hawaii, 14-16 Dec 2005.


3.6. PUBLICATIONS

[39] J. Learned, S. T. Dye, S. Pakvasa and R. C. Svo-boda, “Determination of neutrino mass hierar-chy and θ13 with a remote detector of reactorantineutrinos”,[arXiv:hep-ex/0612022v1].

[40] S. Dye, ed., “Neutrino Geophysics: Proceed-ings of Neutrino Sciences 2005”, refereed articles,Earth Moon and Planets99, 1-4, 2006, Springer2007.

[41] “A Deep Ocean Anti-Neutrino Detector NearHawaii - Hanohano, Final Report”, prepared byMakai Ocean Engineering and Department ofPhysics and Astronomy, University of Hawaii,for the The National Center of Excellence for Re-search in Ocean Sciences (CEROS), (21 Novem-ber 2006, 48pp).

[42] Mikhail Batygov, Stephen Dye, John Learned,Sandip Pakvasa, “Prospects of neutrino oscilla-tion measurements in the detection of reactorantineutrinos with a large underwater detector”,in preparation for Phys. Rev. D, August 2008.

[43] John G. Learned, ”High Energy NeutrinoPhysics with Liquid Scintillation Detectors”,arXiv:0902.4009 (hep-ex) Feb. 2009.


BIBLIOGRAPHY


Chapter 4

Radio Detection of High EnergyParticles: KA130101

Faculty: P. Gorham, J. Learned, R. Morse, S.Matsuno, G. Varner; Postdoctoral Fellow P.Allison; Staff: J. Kennedy; Students: C. Miki,A. Romero-Wolf, L. Ruckman

(Gorham is the principal investigator of thistask)

The highest energy particles in the universe–1020 eV cosmic ray particles, and their as-yet undiscovered cosmogenic 1017−20+

eV part-ner neutrinos–are the focus of the Hawaii Ra-dio Detection subgroup of the High EnergyPhysics Group. Our group has fostered a world-renowned expertise in radio methods of parti-cle detection. We believe these methods presentsome of the most promising techniques for bothdiscovery and detailed characterization of theseultra-energetic particles. We anticipate that anyinvestment in understanding these exotic andrare particles will surely provide unexpected ben-efits to mainstream high energy physics, as weprobe both strong and weak interaction physicsat 100-1000 TeV center-of-momentum energies.Measurements of any sort that constrain theultra-high energy behavior in the neutrino sec-tor are of compelling interest both in high energyphysics and particle astrophysics.

Neutrinos are in fact the only viable astrophys-ical messenger above PeV energies, as Fig. 4.1shows. Here the allowed regions of surviving en-ergy of known particle messengers that can prop-agate on cosmic scales–photons, protons, andneutrinos–are plotted as a function of cosmicpropagation distance. Colored bands near thebottom of the plot indicate the distance rangefor various source populations. For photons,

absorption against the infrared and 3K cosmicmicrowave background radiation (CMBR) limitstheir usefulness as messengers above 100 TeV orso, and at PeV energies photons are absorbedeven on sub-galactic scales. Protons and othercharged hadron primaries, while not absorbedat PetaVolt to ExaVolt energies, develop prop-agation trajectories that are severely distortedby galactic magnetic fields. At higher energies,10-100 EeV, proton primaries begin to suffer ab-sorption by the Δ-resonance on the CMBR (thewell-known GZK process [1, 2]), and althoughtheir gyroradius in intergalactic magnetic fieldsis becoming large enough to make them useful forastronomy, their propagation distance becomeslimited to of order 100 Mpc, only a tiny fractionof the universe. In contrast to these messengers,the universe is completely transparent to neutri-nos at all epochs. In addition, the prominent roleof ultra-high energy neutrinos as secondaries inthe GZK process leads to a “guaranteed” flux ofin the energy range 1017.5−20 eV [3], and thesecosmogenic neutrinos carry unique informationabout the origin and propagation of the highestenergy particles in the universe [4].

When a high energy particle such as a neutrinoshowers in any dielectric medium , Cherenkov ra-diation from the charged secondaries is a natu-ral consequence. For primary particles with lab-frame energies of order 100 TeV or more, coher-ent radio Cherenkov emission dominates over allother forms of secondary electromagnetic radia-tion. Most dielectric media are also highly trans-parent to radio waves below ∼ 1 GHz, far moreso than for optical transmission, and as a re-sult radio detection methods become completelydominant for such interactions. These ideas


CHAPTER 4. RADIO DETECTION OF HIGH ENERGY PARTICLES: KA130101

of universe99.999999%

adia

bat

ic li

mit

cosmology (GRBs, Hi−z QSO’s, reionization)

of universe99%

AGN & QSOs to z=1

Nearby clusters

local group

galaxy

Figure 4.1: Highest observable astronomicalmessenger energy vs. cosmic distance. Photonsand protons are ineffective messengers at ultra-high energies, while neutrinos are unattenuatedat all distances.

trace their roots back to the early 1960’s in theprescient papers of the Armenian-born Russianphysicist Gurgen Askaryan [5]. Askaryan’s re-alization that showers in dielectric media wouldproduce strong radio impulses once the showerenergy exceeded PeV energies was seen as in-teresting at the time, but beyond an initialflurry of effort it was largely forgotten since thecosmic rays could be detected more easily byother methods, and neutrinos of these energiesseemed improbable in any case. In recent yearshowever, the case for UHE neutrinos associatedwith the ultra-high energy cosmic rays (UHECR)has become irrefutable, and the extreme rar-ity of the interactions, requiring enormous tar-get masses to achieve even modest event rates,have demanded the development of new meth-ods. Askaryan’s idea has now come to the fore-front of promising approaches both for expand-ing the reach of current UHECR detectors, andfor making the first detections of the cosmogenicneutrino flux.

The UH radio detection group has been atthe forefront of this research since 2001, whenGorham joined the faculty shortly after co-authoring, with David Saltzberg at UCLA, alandmark paper first confirming Askaryan’s hy-pothesis in experiments in silica sand at theStanford Linear Accelerator Center. Since thattime, our group has led the NASA-sponsoredANITA-lite, ANITA-1, and ANITA-2 experi-ments, for which Gorham was the initiator andNASA Principal Investigator, which have thebest limits for cosmogenic neutrino fluxes, andhave achieved unprecedented sensitivity in thefield. The radio detection group has also pi-oneered further tests of the Askaryan effect intwo additional SLAC beamtests, further demon-strating the validity of the methods in other nat-ural dielectrics: rock-salt and ice [7]. Gorham’sachievements in leading the group were recog-nized by DOE with a coveted Outstanding Ju-nior Investigator Award in 2002.

In the following sections we highlight work onANITA-2, whose flight was just completed; de-scribe briefly a proposed NASA follow-up mis-sion, the ExaVolt Antenna, which shows promiseto extend the ANITA approach much higher sen-sitivities;and we conclude with a detailed de-scription of our progress on the Air shower Mi-crowave Bremsstrahlung Radiometer (AMBER)prototype development, which is a radio augmen-tation to the Auger Observatory.

4.0.4 ANITA-2 2008-2009

The Antarctic Impulsive Transient Antenna(ANITA) experiment, a long-duration balloonpayload designed to detect UHE neutrinos viatheir interactions with the Antarctic ice sheet,was first proposed by Gorham prior to his ar-rival at Hawaii in 2001, while part of the seniorscientific research staff at NASA’s Jet PropulsionLaboratory.

ANITA was selected by NASA for funding in2002, shortly after Gorham won a DOE Out-standing Junior Investigator Award–and partlyas a result of that OJI award, thus beginning along a fruitful synergy between DOE and NASAsupport for UHE neutrino detection at UH. In


2003-2004, a prototype flight, called ANITA-lite,was completed, validating the approach [8]. In2006-2007, ANITA-1 flew in Antarctica for 35days, establishing the most stringent limits todate on the UHE neutrino flux, limits that sig-nificantly exceed those of much more costly ex-periments in ANITA’s energy range, as shown inFig 4.2, a result that is currently in final reviewfor publication in Phys. Rev. Letters [9].

Figure 4.2: ANITA-1 limits based on no surviv-ing candidates for 18 days of livetime. Other lim-its are from AMANDA [16], RICE [17], ANITA-lite [8], Auger [18], HiRes [20], FORTE [19]. TheBZ (GZK) neutrino model range is determinedby a variety of models [21, 11, 23, 25, 26, 27, 29].

In 2007 ANITA was selected again by NASAfor a 2nd flight with a significantly improved pay-load. Augmentations included a 40% reductionin system thermal noise, an improved triggeringsystem that lowered the effective trigger thresh-old by 30-40%, an additional 8 deployable hornantennas that increased the collecting area of thepayload by 20%, and an adaptive control systemto respond to anthropogenic noise. The payloadwas launched from Williams Field on the RossIce Shelf on Dec. 20, 2008, and completed itsmission on Jan. 19, 2009 with just over 31 daysaloft. The exposure over deep ice was excep-

Figure 4.3: View of the ANITA-2 payload inlaunch configuration, with photovoltaics at thetop and bottom, and antenna clusters between.The side of each square antenna mouth is about0.9 m, and the payload stands about 8 m tall.The retracted drop-down antenna array is justvisible below the lower PV panels.

tional for this mission, and initial analysis of thedata shows it to be of excellent quality.

Fig. 4.3 shows the ANITA-2 payload just out-side its Antarctic hangar shortly before launch,with Gorham and two UH grad students C. Mikiand B. Hill for scale. The two upper rings of8 antennas each form a single 16 antenna clus-ter with fields-of-view spaced 22.5◦ in azimuth,and matched by 16 antennas in the lower ring atthe same spacing. Antennas are sensitive over a200-1200 MHz band, matching a region of ex-cellent transmissivity of Antarctica ice. Eachantenna has a response wide enough to acceptsignals from its nearest neighbor’s fields-of-view



Figure 4.4: ANITA-2 at float altitude of about120,000 ft, with fully inflated balloon.

as well, and thus 4-7 antennas will detect ev-ery incoming plane-wave signal, enabling pulse-phase interferometry with baselines varying fromabout 1 m in azimuth to 3.5 m in elevation. Com-bined with waveform timing that achieves about25-30 picseconds precision, the angular resolu-tion of ANITA-2 is about 0.3◦ by 0.8◦ in ele-vation and azimuth. The drop-down antennas(retracted in this view) are spaced every 45◦ inazimuth providing additional angular and wave-form constraints, as well as improved triggering.

The ANITA-2 payload at float altitude isshown in Fig. ??. By performing high-precisiongeo-location of any impulse that occurs anywherewithin is 1.5 M km2 field-of-regard from the 110-120kft altitude, and then correlating it againstknown anthropogenic activity, ANITA-2 will beable to identify any remaining events of unknownorigin. A neutrino flux will appear as a set ofevents isolated in time and space from any knownsources, correlated to the deep ice. Data anal-ysis is underway currently, using data-blindingmethods, and the initial unblinding is plannedfor the late fall of this year. Our estimates in-

dicate that we have improved our sensitivity bya factor of 3 over the ANITA-1 flight, taking usinto the heart of the GZK neutrino flux predic-tions. To date, no physics-related backgroundshave been detected, and once all anthropogenicevents are accounted for, ANITA-2 may see thefirst glimpse of the cosmogenic UHE neutrinoflux.

4.0.5 ExaVolt Antenna: A Next Genera-tion Long-duration Balloon-based Neu-trino Observatory

The ExaVolt Antenna (EeVA) experiment iscurrently under consideration as a NASA Long-Duration Balloon payload. It has drawn greatbenefit–as is certainly the case for ANITA–froma high degree of synergy in Gorham’s radio detec-tion activities as supported by DOE. Thus we de-scribe this proposed effort in broad strokes sinceit was conceptually engendered in part throughDOE HEP support for our group.

ANITA currently represents the state-of-theart for detection of UHE neutrinos, although todate no positive detections have been reported.Even if ANITA-2 provides a first glimpse of thecosmogenic neutrino fluxes, the result will be inthe range of a handful of events, and current fluxmodels have enough uncertainty that some couldcertainly evade detection even by ANITA-2. Toensure detection or to provide solid statistics incharacterizing any weakly detected flux, a next-generation instrument must push at least an or-der of magnitude higher in acceptance.

ANITA’s quad-ridged horn antennas (seen inFig. ??) determine the trigger sensitivity. Theseantennas had an effective average directivitygain of 10 log10(G) � 7 dBi (dB relative toan isotropic antenna) for impulse-triggering pur-poses, and this gain was roughly constant overANITA’s frequency range of 0.2-1.2 GHz. An-tenna effective area Aeff in terms of directiv-ity gain G and frequency ν is given by Aeff =Gc2/(4πν2), where c is the speed of light. Thusan antenna with constant gain vs. frequency hasa collecting area which decreases as the squareof increasing frequency. Since ANITA required a


Science ComputerControl & Telemetry

RF trigger system

Digitizer, data archivePhotovoltaics

SIP PV arraySIP

Flight Train

optical fiber bundle

29Mcft, 112 m diameterOuter Balloon

RF−over−optical−fiber

(toroidal)~5m high

feed arrayinner balloon

Inner balloon suspension/tethers

"Topknot:" PVs, power distribution, metrology

power cables,tethers

inner balloon

diameter~50−60m

Reflective toroid~10 m high

Figure 4.5: Sketch of the primary subsystems forEeVA.

broad-band frequency content to trigger, the ef-fective center-frequency at which to evaluate theaverage gain is about 400 MHz, and the impliedeffective area is 0.22 m2 per antenna. In form-ing a trigger, the signals from 4 antennas thatcan view an incoming plane wave are used in athreshold-crossing square-law discriminator, butare not combined coherently, so the improvementin combinatorics goes as the square root of thenumber of combined antennas, and the net ef-fective area for ANITA, in determining the radiosensitivity, is of order 0.5 m2.

This effective area sets the scale of the currentstate of the art for a balloon-based neutrino de-tector. For EeVA our goal is to increase the effec-tive area of the antenna by a factor of 100, yield-ing a neutrino energy threshold which is lowerby a factor of order 10 compared to ANITA.

Figure 4.6: Flight 591NT ULDB at float altitudeduring the 2009 flight, showing the “pumpkin”shape of the fully-inflated super-pressure balloonwhich would be used for EeVA.

The implied design-goal gain Ggoal, using again400 MHz as the reference frequency, is

Ggoal = 26.9 dBi (4.1)

above an isotropic antenna. An estimate of theequivalent circular aperture dish diameter D re-quired to achieve this gain can be made by theapproximation

D =

√λ2G

π

which indicates a diameter of D = 9.3 m for thiscase. If an LDB payload can achieve a similarfield-of-view as ANITA, with this large increasein collecting area, it would potentially increasethe neutrino detection rate by as much as a fac-tor of 100, depending on the underlying GZKneutrino spectrum. It is this large potential sci-entific payoff that motivates the EeVA concept.

Flying such a large aperture on a suspendedballoon payload is currently impractical. There



Y

f = 600 MHz maxgain = 22.27 dBi vgain = -18.53 dBi

Y


Y


Y


Y


Y


−1dB

−3dB−10dB

22.7 dBi

−10dB

−3dB−1dB

−1dB

−3dB−10dB

22.7 dBi

−10dB

−3dB

−10dB−3dB

−3dB

−10dB

−1dB

−1dB

−1dB

27.84 dBi

27.84 dBi27.84 dBi

27.84 dBi600 MHz

500 MHz

700 MHz

200 MHz

400 MHz

300 MHz

Figure 4.8: Elevation gain polar plots for four frequencies and the largest off-axis elevation angle(about -13 degrees) expected to be observed with EeVA. The gain peaks at about 27.8 dBi, exceedingthe design goal of 26.9 dBi as shown in equation 4.1.

is however one portion of the balloon craft sys-tem which could support this very large aper-ture: the balloon itself, if it could be arrangedto include a reflective surface and feed systemthat would provide the necessary optics. Ge-ometrically a balloon free surface already pro-vides the first-order shape of a powered optic,as is evident from a recent photograph taken ofa NASA 2008-2009 ultra-long-duration balloon(ULDB) at its full inflation near 40 km altitudeshown in Fig. 4.6. EeVA is the first attempt toutilize such optics to provide a coherent focusingsystem, based on the principles of a prime-focustoroidal reflector system.

Fig. 4.7 shows the basic optics for EeVA: anouter toroidal reflective section (using standard“radar tape”) on a ULDB focuses incoming planewaves onto a smaller tethered inner balloon with

a printed-antenna feed array. The optics have infact been simulated with a full Numerical Elec-tromagnetics Code (NEC2) simulation which in-cluded an accurate model of the free surface ofthe balloon, including the lobes and tendons ofa realistic balloon surface. Some of the resultsof this analysis are shown in Fig. 4.6 where thedirectivity gain is shown in polar plots for dif-ferent frequencies. While the surface distortionposes some difficulties at the higher frequencies,these studies indicate that the design goals canbe met over the frequency range 200-500 MHz atleast. It may be possible to extend the responseto higher frequencies with a more careful sys-tem design, but we have currently restricted ourstudies to the results obtained here, including theaberration distortions shown. However, despitethese apparent shortcomings, the enormous col-lecting aperture of EeVA more than compensates


Table 4.1: Expected numbers of events from a full range of GZK neutrino models for a 50-day EeVA flightcompared to ANITA, which had a net 17 days of livetime in its first flight.

BZ neutrino models Events, Events, ratio,

ANITA,17d EeVA,50d EeVA/ANITA

Mixed UHECR composition [18] 0.014 5.0 36

Minimal, no evolution [11, 21, 26] 0.12-0.38 9.2-38 77-100

Ωm = 0.3, ΩΛ = 0.7, Standard model [11] 0.4 29 73

Waxman-Bahcall E−2 flux (minimal) [12] 0.27 6.5 41

GRB UHECR-sources [28] 0.56 66 118

Strong source z-evolution [11, 26, 23] 1.0 44 44

Maximal, saturate all bounds [23, 26] 8.5-10 180-220 21-22

for the reduced quality of the antenna figure.

A full Monte-Carlo simulation based on theseinitial results, summarized in Table 4.1, is verypromising: EeVA has the sensitivity in a 50 dayflight–the same duration as the recent NASAULDB flight completed earlier this year– to ob-serve between 30-60 events from a wide rangeof standard GZK neutrino models, and has ad-equate reach to constrain even the most pes-simistic models which are currently inaccessibleto experiments such as ANITA and IceCube.

The challenges of developing and deployingnew technology such as EeVA are significant,but the science potential is compelling. Whilethe development of the outer reflector balloon iswell-within the reach of current technology, therequirements both for construction, launch, anddeployment of the inner balloon which supportsthe critical feed-antenna structure is beyond cur-rent state-of-the-art. While recognizing the diffi-culties, NASA’s Columbia Scientific Balloon Fa-cility and Balloon Program Office have expressedtheir support for the pending EeVA proposal.

We emphasize again that DOE support for ra-dio detection research and development throughGorham’s task has been crucial in enabling andmaintaining the expertise for developing con-cepts such as EeVA. While NASA provides the“heavy lifting” for project funds for such activi-ties, these efforts could not have matured to thestage where they could be proposed to NASA

without DOE’s continuing base of support.

4.0.6 AMBER

There has been significant interest in the par-ticle astrophysics community in the possible useof radio detection methods to extend the reach ofUHECR observatories or provide complementarymeasurements which might assist in the cross-calibration of these systems. Toward this goalwe have developed the Air Shower MicrowaveBremsstrahlung Radiometer (AMBER) experi-ment, to complement current Nitrogen Fluores-cence detection methods by identifying and char-acterizing a microwave analog to this very suc-cessful approach, which is hampered by its 6-10%overall operational duty cycle. We have com-pleted two promising beam tests, and developeda testbed prototype detector. A complete de-scription of the basis and experimental resultsthe led to the AMBER DOE support can befound in reference [30].

In 2007 AMBER was selected by both DOE(for Hawaii) and NSF (for Ohio State Univer-sity, our partner institution) to install a proto-type system as an augmentation to the AugerObservatory for UHECR, and we are making ex-cellent progress in achieving that goal, with ex-pectations of our first deployment later this sum-mer.

AMBER’s goal is to detect partially-coherentbroadband microwave radiation that arises via



X

Y

X Y

~10m highreflectiveregion

feed array, ~3−5m wide

ballooninner

outer balloon

29 Mcft ‘pumpkin’diameter 112m

focal plane

incoming

waveplane

below horizontal−6 to −13 degrees

Figure 4.7: A schematic view of the basic opti-cal path for EeVA. Neutrino impulses arrive fromangles ranging between about 6-13◦ from belowthe horizontal (the horizon is at −6◦ from analtitude of 120,000ft). The toroidal reflector fo-cuses an incident plane-wave over about 15 m ofwidth; in this case a 10 m high reflective regionis utilized. The toroidal reflector focuses on aninner balloon surface which is used to supporta printed-antenna patch array that provides thefeed-antennas for receiving the signals. Thesefeed antennas form a continuous array thus re-ceiving impulses from 2π in azimuth from the icebelow.

the same energetics that produce Nitrogen Fluo-rescence: the ionization of air around the core ofa passing high energy extensive air shower. Asthe ionized electrons in this shower wake cooloff, they excite nitrogen molecules, which flu-oresce optically, but also emit their own colli-sional continuum radiation at cm wavelengths

Figure 4.9: AMBER feed array showing the 16pixels defined by the individual feedhorns. Thecentral feeds accept dual linear polarization andboth C-band and K-band frequencies for a totalof 4 independent channels each, and the outer 12horns accept 45 degree linear polarization in C-band only. The total number of array channelsis thus 28.

at what appears to be an eminently detectablelevel if our accelerator tests are correct. Theunique aspect of AMBER is that this emissiondoes not arise from relativistic processes suchas Cherenkov or geo-synchrotron emission, andis thus not beamed, but isotropically emittedfrom the shower ionization, in very close anal-ogy to the optical nitrogen fluorescence emis-sion that has been so successfully exploited bycurrent UHECR detectors. If AMBER estab-lishes the viability of the detection of molecu-lar bremsstrahlung emission, it would enable the


1

3

4

2

Feed #:

52 deg.

78 deg

AMBER central feedbeam taper

Figure 4.10: Plot of calibration data taken in UHanechoic chamber confirming the feedhorn arraybeam pattern, here for the central 4 feedhorns.The data are fit by a Gaussian taper. The in-cluded angle subtended by the dish is about 72◦,and this matches well the -10dB taper level of thecentral feeds, indicating that the array responsehas not seriously degraded the single-feedhornresponse, and that the off-axis distortions (eg.,coma) are minimal.

possibility that “microwave fluorescence” mea-surements could be made with ∼ 100% duty cy-cle, in contrast to the 10% duty cycle of cur-rent optical fluorescence detectors, due to theneed to operate on very clear moonless nights.Microwave molecular bremsstrahlung detectionis largely insensitive to solar effects, and canoperate effectively even during rain, and thuspresents great potential as a long-term aug-mentation to UHECR observatories such as theAuger Observatory.

Our accepted proposal detailed plans to deployseveral 3m satellite-television off-axis parabolicdish reflectors to one of the Auger Observa-tory Fluorescence detection sites. Each reflec-tor would have a feed array capable of distin-

ADC

crat

e co

ntro

lco

mpu

ter 100 Ms/s

8 GbyteDDR mem.ring buffer12 bit

Xilinx FPGA (cntrl/comms)

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JEDIbaseband downconversionlog−amplifier

x28

boar

d (t

imin

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f.)G

PS

inte

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e

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ilinx

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GA

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(1 of 1)(1 of 1)(1 of 4)

Data archive,Auger Obs.

interface LAN/WAN

65 dB

15V DC

C−band & K−bandemission from

EAS

1 of 28

Air shower Microwave Bremstrahlung Radiometer

Data−flow Schematic

compact PCI backplane

Xilinx FPGA

DDR2 memory

ADC section

AMBER−DAQ

board

(dual FPGAs,dual DDR2,dual 4 chADC sections)

x28

Figure 4.11: Schematic of the AMBER signalflow.

guishing coarsely sampled microwave emissiontracks across a 10 − 15◦ diameter field-of-viewthat would overlap with both the fluorescenceand surface detector array’s aperture. The con-tinuous microwave intensity from all of the feed-horn array pixels would be then continuouslysampled into a large ring-buffer. When a trig-ger is received from either the surface array orthe fluorescence detector, the ring-buffer is ad-dressed around the time of the trigger and theappropriate window of samples is read out into adisk archive. In this way we planned to validatethat AMBER can actually detect events alreadytagged by the Auger Observatory, and to char-acterize the detection efficiency.

4.0.6.1 AMBER progress in 2008-2009 Devel-opment of our feedhorn array and baseband sig-nal converter (used to pre-filter the microwavesignals for analog-to-digital conversion) beganin early 2008, and the 28-channel feedhorn ar-ray for our initial prototype was completed andpassed initial tests early this year. The feed-horn array and its stand, photographed dur-ing its calibration sequence in the UH anechoicchamber, is shown in Fig. 4.9. The central fourfeeds are dual-linear-polarization, dual frequency



-90

-85

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-55

31 32 33 34 35 36

RF

pow

er (

dBm

)

Time from GPS PPS (us)

channel 0channel 0, 16 sample running avg

channel 3channel 3, 16 sample running avg

Figure 4.12: Full-signal-path traces of AMBER test data for two different channels on an 8-channelAMBER-DAQ board. The top trace is offset by +10 dB from its absolute level. The absolutereference level is calibrated to first order, and represents the thermal noise power from a 320 Ksystem temperature into the ∼ 800 MHz bandwidth of the low-noise amplifier block downconvertersused for the AMBER signal path. A 400 ns wide injected pulse consisting of excess thermal is shownin both channels, with arrows marking the time of injection, along with boxcar-smoothed curves foreach channel. The excess noise over this timescale is representative of the type of signals AMBERwill trigger on, and it is evident that even at instantaneous SNR of order 1, as in the case of theweaker pulse shown, we can still detect signals with good efficiency using matched filter methods.

feedhorns, with response from 3.4-4.2 GHz (C-band), and 10-11 GHz (K-band). Since the emis-sion is expected to be unpolarized, the dual-polarization feeds can be run in coincidence be-tween the polarizations, since the thermal noiseis statistically independent in each. Surroundingthe four central feeds are a ring of 12 standard C-band gain horns, angled at 45◦ and thus sensitiveto both vertical and horizontal polarization.

We have now calibrated the beam response ofthe feed array in the UH HEPG anechoic an-tenna test chamber; an example of the results forthe central 4-feed cluster is shown in Fig. 4.10.The beam shape appears to match well with theexpected Gaussian taper, and there is no evi-dence that the array clustering of the feeds hasproduced distortion in any of the response. We

have separately also completed a physical opticssimulation of the focal plane array off-axis aber-rations. We find that the coma effects are onlymodest for the current array, and we estimateonly a 10-20% reduction in feed efficiency com-pared to the on-axis case.

The signal path for AMBER data acquisitionis shown in Fig. 4.11. Microwave emission is col-lected by a 2.8 m offset parabolic dish and fo-cused on the feed array. Each of the 28 channels(20 C-band + 8 K-band) is amplified by about65 dB and downconverted to the 950-1750 MHzband using standard low-noise satellite TV blockdownconverters. These bipolar RF signals arethen fed into the JEDI board, which is centeredaround an Analog Devices AD8318 8 GHz Log-arithmic Detector/Amplifier. This device pro-


vides a 50 MHz bandwidth unipolar voltage pro-portional to the logarithm of the RF power, witha response time of order 10 ns. The JEDI boardsare housed in a weathertight box attached to thebase of the feed array, as shown in the inset inthe figure.

The signals are then led to the AMBER-DAQ board, which combines the functions of a100 Msample/sec, 12-bit Analog-to-Digital Con-verter (ADC) with an 8 Gbyte buffer fully-addressable memory, and on-board control logicusing a Xilinx Field Programmable Gate Array(FPGA). The AMBER-DAQ handles 7 of the 28JEDI signals, and it’s eighth channel is used todigitize a GPS clock reference signal for fiducialtiming. The AMBER-DAQ board can store upto 6.7 seconds worth of data, which is more thanadequate for the known latency of the Auger sur-face detector trigger, which can take as long as5 seconds to be determined.

Once a trigger is established from Auger’s trig-ger distribution system, the precise GPS timeof the trigger is given to the crate control com-puter which hosts the 4 AMBER-DAQ boardsin a compact-PCI crate. The computer then de-termines the address space of a memory windowaround that event and the AMBER-DAQ boardsare momentarily paused while that event data isread out and stored. Separately, a local triggerboard within the same crate flags events of in-terest based only on the microwave signal infor-mation, which may allow us to identify signals ofinterest independent of the Auger trigger, oncewe have established the signal levels.

AMBER’s entire signal chain has been com-pleted and is now undergoing lab testing to ver-ify FPGA firmware. An example of a test-signal is shown in Fig. 4.12. Here we have usedthe excellent precision of the AD8318 calibratedresponse to reference the signals back to truekTΔν thermal noise levels, to about 1 dB pre-cision. An excess thermal noise pulse of order400 ns is injected onto the baseline thermal noisebackground, at two different signal levels in twodifferent AMBER-DAQ channels. The channelwith the weaker pulse is offset by +10dB from its

absolute level for clarity. AMBER-DAQ signif-icantly oversamples the expected signal pulses,which are typically of duration comparable tothose shown; this is done to match current Augersampling rates, although in practice we will opti-mally filter the data to produce much smoothersignals for analysis, as is also done with Augerfluorescence data.

As of this writing we are performing final sub-system tests and calibration prior to a full sys-tem integration which we anticipate will be com-plete by the end of June. We then plan for aboutone month of system burn-in in Hawaii using ourroof-top AMBER installation. Following that wewill begin deployment to the Auger Observatoryin late summer of the first two AMBER dishes,followed by two more early next year.

In summary, if the AMBER approach is con-firmed by coincident detections at Auger, andthe energy threshold for UHECR event detec-tion is favorable, we anticipate proposing a largerscale deployment, providing enough coincidentaperture to roughly match that of one of the ex-isting Auger fluorescence telescopes, for a timeframe early in the next decade.

Invited Presentations, 2008-2009

1. P. Gorham, “Radio Cherenkov Seaches forCosmogenic Ultra-high Energy Neutrinos andANITA Results,” invited plenary presenta-tion, Neutrino 2008, Christchurch, NZ, April2008.

2. R. Morse, “IceRay–an IceCube Centered Ra-dio GZK Array,” International AstroparticlePhysics Symposium, Golden, CO, May 8,2008.

3. Varner gave an HEP seminar at the Univer-sity of Chicago on Radio Detection of UltraHigh Energy neutrinos, September 2008.

4. Varner gave an HEP seminar at UniversityCollege London on Ultra High Energy CosmicRay detection via Molecular Bremstrahlungemission, October 2008.



5. Varner gave a Particle Astrophysics plenarysession talk on Radio Detection of Ultra HighEnergy neutrinos at the TIPP09 Conferencein Tsukuba, Japan, March 2009.

2008-2009 Radio Detection Bibliography

Journal Publications.

1. Observations of Microwave Continuum Emis-sion from Air Shower Plasmas, P. W.Gorham, N. G. Lehtinen, G. S. Varner, J. J.Beatty, A. Connolly, P. Chen, M. E. Conde,W. Gai, C. Hast, C. L. Hebert, C. Miki, R.Konecny, J. Kowalski, J. Ng, J. G. Power,K. Reil, D. Saltzberg, B. T. Stokes, D. Walz,2008, Phys. Rev. D 78, 032007.

2. In situ radioglaciological measurements nearTaylor Dome, Antarctica and implicationsfor UHE neutrino astronomy, D.Besson,J.Jenkins, S.Matsuno, J.Nam, M.Smith,S.W.Barwick, J.J.Beatty, W.R.Binns,C.Chen, P.Chen, J.M.Clem, A.Connolly,P.F.Dowkontt, M.A.DuVernois, R.C.Field,D.Goldstein, P.W.Gorham, A.Goodhue,C.Hast, C.L.Hebert, S.Hoover, M.H.Israel,J.Kowalski, J.G.Learned, K.M.Liewer,J.T.Link, E.Lusczek, B.Mercurio, C.Miki,P.Miocinovic, C.J.Naudet, J.Ng, R.Nichol,K.Palladino, K.Reil, A.Romero-Wolf,M.Rosen, L.Ruckman, D.Saltzberg, D.Seckel,G.S.Varner, D.Walz, F.Wu Astropart. Phys.29: 130-157, 2008.

3. The Antarctic Impulsive Transient AntennaUltra-high Energy Neutrino Detector Design,Performance, and Sensitivity for 2006-2007Balloon Flight, ANITA collaboration: P.Gorham, P. Allison, S. Barwick, J. Beatty,D. Besson, W. Binns, C. Chen, P. Chen, J.Clem, A. Connolly, P. Dowkontt, M. DuVer-nois, R. Field, D. Goldstein, A. Goodhue,C. Hast, C. Hebert, S. Hoover, M. Israel, J.Kowalski, J. Learned, K. Liewer, J. Link, E.Lusczek, S. Matsuno, B. Mercurio, C. Miki,P. Miocinovic, J. Nam, C. Naudet, R. Nichol,K. Palladino, K. Reil, A. Romero-Wolf, M.Rosen, L. Ruckman, D. Saltzberg, D. Seckel,

G. Varner, D. Walz, Y. Wang, F. Wu, As-tropart. Phys. 2009 (in press).

4. New Limits on the Ultra-high Energy CosmicNeutrino Flux from the ANITA Experiment,ANITA collaboration: P. Gorham, P. Allison,S. Barwick, J. Beatty, D. Besson, W. Binns,C. Chen, P. Chen, J. Clem, A. Connolly, P.Dowkontt, M. DuVernois, R. Field, D. Gold-stein, A. Goodhue, C. Hast, C. Hebert, S.Hoover, M. Israel, J. Kowalski, J. Learned,K. Liewer, J. Link, E. Lusczek, S. Matsuno,B. Mercurio, C. Miki, P. Miocinovic, J. Nam,C. Naudet, R. Nichol, K. Palladino, K. Reil,A. Romero-Wolf, M. Rosen, L. Ruckman, D.Saltzberg, D. Seckel, G. Varner, D. Walz, Y.Wang, F. Wu, Phys. Rev. Lett. 2009 (in finalreview).

Conference & other publications, 2008-2009.

1. IceRay: An IceCube-centeredRadio-Cherenkov GZK Neutrino Detector, P.Allison, J. Beatty, P. Chen, A. Connolly, M.DuVernois, P. Gorham, F. Halzen, K. Han-son, K. Hoffman, A. Karle, J. L. Kelley, H.Landsman, J. Learned, C. Miki, R. Morse, R.Nichol, C. Rott, L. Ruckman, D. Seckel, G.Varner, D. Williams, Proceedings of ARENA2008, to be published in Nucl. Inst. andMeth. A.


Bibliography

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[2] G. T. Zatsepin, V. A. Kuzmin, JETP Lett.f 4, 78 (1966) [Pisma Zh. Eksp. Teor. Fiz. 4,114, (1966)].

[3] V. S. Beresinsky, G. T. Zatsepin, Phys. Lett.B 28, 423 (1969).

[4] D. Seckel, T. Stanev, Phys. Rev. Lett. 95,141101, (2005).

[5] G. A. Askaryan, JETP 14, 441, (1962);JETP 21, 658, (1965).

[6] “Observation of the Askaryan effect: Co-herent microwave Cherenkov emission fromcharge asymmetry in high-energy particlecascades” Saltzberg D, Gorham P, Walz D,et al. PHYSICAL REVIEW LETTERS 86(13), 2802-2805 (2001); 92 citations cur-rently.

[7] ANITA Collaboration: P. W. Gorham, etal., Phys. Rev. Lett. 99 , 171101, (2007).

[8] ANITA Collaboration: S. W. Barwick et al.,Phys. Rev. Lett. 96, 171101, (2006).

[9] ANITA Collaboration: P. W. Gorham,et al., Phys. Rev. D, submitted 2008;arxiv:0812.1920.

[10] S. Barwick, D. Besson, P. Gorham, D.Saltzberg, J. Glaciol. 51, 231, (2005).

[11] R. Engel, D. Seckel, T. Stanev, Phys. Rev.D 64, 093010, (2001).

[12] E. Waxman, J. Bahcall, Phys. Rev. D 59,023002, (1999).

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[18] Pierre Auger Collaboration, Phys. Rev.Lett. 100, 211101, (2008).

[19] N. Lehtinen, P. Gorham, A. Jacobson, R.Roussel-Dupre, Phys. Rev. D 69, 013008,(2004).

[20] HiRes Collaboration: R. U. Abbassi et al.,ApJ 684, 790 (2008).

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[22] R. Gandhi, Nucl. Phys. Proc. Suppl. 91,(2000) 453, (2000).

[23] O. E. Kalashev, V. A. Kuzmin,D. V. Semikoz, G. Sigl, Phys. Rev. D66, 063004 (2002).

[24] L. A. Anchordoqui, J. L. Feng, H. Goldberg,A. D. Shapere, Phys. Rev. D 66, 103002,(2002).

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BIBLIOGRAPHY

[29] V. Barger, P. Huber, D. Marfatia,Phys.Lett. B 642, 333, (2006).

[30] Observations of Microwave ContinuumEmission from Air Shower Plasmas, P. W.Gorham, N. G. Lehtinen, G. S. Varner,J. J. Beatty, A. Connolly, P. Chen, M. E.Conde, W. Gai, C. Hast, C. L. Hebert, C.Miki, R. Konecny, J. Kowalski, J. Ng, J. G.Power, K. Reil, D. Saltzberg, B. T. Stokes,D. Walz, 2008, Phys. Rev. D 78, 032007.


Chapter 5

Detector Research and Development:KA150302

Drs. H. Hoedlmoser, J. Li and G. Varner andMessers M. Cooney, J. Kennedy, M. Rosen, andL. Ruckman

(Varner is the principal investigator of thistask)

5.1 Overview

Future discoveries at the energy and inten-sity frontiers will require large, finely segmenteddetector volumes. Addressing the cost, speed,bandwidth, radiation hardness, power and form-factor demands is essential to realizing the sci-entific objectives of these budget-limited experi-ments. We present recent progress and activitiesin these areas as well as prospects for future de-velopments.

5.2 Fine Spatial Resolution

Development efforts toward a CMOS-basedfast sampling device for an upgraded B-factorydetector are described in Section 2.1. Whilemuch of that effort is targeted toward the par-ticular vertexing needs of a detector operatingat 10 GeV center-of-mass energy and very highhit rates, much of the architecture is more gen-eral. Aspects of the studied continuous, space-time encoded sampling are directly applicableto a future vertex detector requiring very low-occupancies, such as that of an ILC vertex detec-tor. This last year Hoedlmoser with Varner andCooney completed a detailed design study [1] foran enhanced version of space-time encoding ofhits that extends the simple technique studied inearlier Continuous Acquisition Pixel (CAP) pro-totypes. Fig. 5.1 illustrates this basic scheme.

Figure 5.1: An improved space-time encoding forcontinuous readout. Using correlations betweenmultiple readout pathways, unique hit positionsare determined for a given trigger time, signifi-cantly reducing background hit occupancy.

Fig. 5.2 illustrates a Monte Carlo of the abovearray, where actual hits are embedded in a back-ground of out of time hits. During continu-ous readout, without using space-time encod-ing, there are hit-correlation ambiguities in ei-ther space or time. Coincidencing the multiplepaths, at a time constrained to the bunch colli-sion timing, significantly reduces accidental hits.Further reduction is obtained by making the pe-riphery transfers more parallel, that is the Trans-fer Multiplicity (TM). Increasing the number ofthese lines reduces the transit time of hits off-chip, as well as providing unique output lines,within groups of the TM modularity.

In general one should expect to reduce thenumber of such fake hits, and this general trend


CHAPTER 5. DETECTOR RESEARCH AND DEVELOPMENT: KA150302

Figure 5.2: Monte Carlo simulation used to eval-uate the efficacy of Transfer line Multiplicity(TM) in reducing background hits.

is seen for quite high background conditions asplotted in Fig. 5.3. Several different silicon pro-totype implementations of this architecture areunder study, and 2 prototype devices are in fab-rication, with the results to be reported later.

Figure 5.3: Reduction in the average number ofhit candidates as a function of Transfer line Mul-tiplicity (TM).

5.3 High Precision Timing

In the last few years Varner with Ruckmanand Wong developed a readout system for fu-ture single-photon, high-precision timing devicesas part of a DOE ADR award [2, 3]. Thisis based upon a deeper sample-depth evolutionof the LABRADOR ASIC [4], designated theBuffered LABRADOR (BLAB) [5]. A test ofthis readout was performed with the focusingDIRC prototype detector at SLAC (T-492) intest beam. Based upon the success of those few-

channel tests, a second ADR has supported thedeployment of a full complement of 450 channelson the f-DIRC prototype, and the results of thosesystem-level tests will be reported later.

In parallel with demonstrating the perfor-mance of a large readout array, careful study ofthe attainable performance for these devices onthe test bench has continued. Using MCP-PMTsignals, a time difference was measured for sig-nals recorded with two BLAB ASICs to be about6.4ps [6] as plotted in Fig. 5.4.

BLAB1Entries 10000Mean 0.0007588RMS 0.006737

/ ndf 2χ 177.4 / 36Constant 16.9± 1303 Mean 0.0000615± 0.0004431 Sigma 0.000049± 0.006009

time (ns)-0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0.05 0.00

200

400

600

800

1000

1200

1400 BLAB1Entries 10000Mean 0.0007588RMS 0.006737

/ ndf 2χ 177.4 / 36Constant 16.9± 1303 Mean 0.0000615± 0.0004431 Sigma 0.000049± 0.006009

Two CH Timing

Figure 5.4: Measured PMT pulse time differencebetween a pair of PMT signals recorded with apair of BLAB1 ASICs.

Our ongoing program will continue to studythe limits of timing resolution that can be real-ized with Switched Capacitor Array sampling ininexpensive CMOS processes. Scaling to systemswith many thousands of channels, while main-taining excellent timing performance, will alsobe an important direction for this research.

5.4 Precision 3D Sili-

con Space-Time

Excellent spatial resolution has been demon-strated for so-called 3D silicon detectors, origi-nally pioneered Parker and Kenney. Fabricationof electrodes through the sensor bulk permits thedepletion of the detector with only a few volts ofdetector bias. Possible applications of this areusing timing to improve the spatial resolution


5.7. BEAMLINE DIAGNOSTICS

for such a detector. Turning the concept around,we intend to study the use of such a detector asan intermediate “timing layer”. Time differencesbetween signals on the collection electrodes areused to interpolate the spatial impact position,while the mean time can be used to provide atime zero for the particle identification system,independent of the bunch collision time. To re-alize such a silicon timing detector, integrationof fast electronics discussed above with 3D tech-nology is proposed. Studies of such a hybrid de-tector is envisioned to be the subject of a futureADR proposal.

5.5 Large Format Photode-

tectors

Future large scale, low-energy neutrino de-tectors require a fundamental advancement inphotodetection technology. From its beginningHawaii has been a member of the Argonne-Chicago centered effort to develop low-cost, highperformance single-photon detectors with high-performance integrated time and charge read-out. Planned readout strategies are being guidedby lessons learned from the waveform samplingASIC development efforts reported above andwill be an important direction of future work.

5.6 Tera-ton Detector instru-

mentation

In order to achieve a canonical 1000km3-srneeded for observing a statistically significantnumber of GZK neutrino events, an array of ra-dio stations instrumenting a radio transparenttarget volume has been proposed. The data log-ging and triggering issues for such an extendedarray have been studied in the context of a SaltDome Shower Array concept [7]. Similarly, anice surface array prototype station has been con-structed, primarily by Ruckman, based upon ex-perience integrating our radio sampling instru-mentation within the IceCube infrastructure [8].Experience with operation of these prototypeswill guide the design of future low-cost, high re-liability radio detection stations.

5.7 Beamline Diagnostics

Utilizing fast sampling instru-mentation, Varner has been working with beam-line diagnostics experts at KEKB and CESR-TAto develop an x-ray monitor [9] to permit turn-by-turn precision bunch imaging, a valuable toolfor diagnosing instabilities in very low-emittancelepton storage rings, such as a Super B-factorynano-beam option or future ILC low-emittancedamping ring.

A first integrated prototype x-ray sensor andSampler for Transients of the Uniformly Redun-dant Mask (STURM) readout was tested in anx-ray beamline at the KEK Photon Factory inMarch 2009. A photo of the test set-up is seenFig. 5.5, where an InGaAs array records x-raypulses that are separated by about 2ns.

STURMReadoutBoard

DAQ computerLaptop via USB2

InGaAs linear Array in Rad“hutch”

Precision timing delay “trombone”

Figure 5.5: Photograph of the cramped quartersof the KEK Photon Factory beamline where theSTURM prototype was used to record x-ray sig-nals observed by an InGaAs array (inset at righttop).

Fig. 5.6 demonstrates the ability to capture the∼250ps risetime of the x-ray pulse observed withthe InGaAs linear-array detector. For each trig-gered readout, 8 samples are recorded, separatedby 100ps. To allow a fine scan, an RF trom-bone delay was used to offset the signal in 5pssteps. Event-to-event fluctuations in the signalamplitude required some averaging and result inthe scatter observed. Nevertheless, the risetime


CHAPTER 5. DETECTOR RESEARCH AND DEVELOPMENT: KA150302

(starting at 800ps) is clearly seen and matchesthat recorded with a 10GHz analog bandwidthdigital oscilloscope.

Figure 5.6: Cumulative recorded results for 8samples, separated by 100ps, stitched togetherwith 5ps offset steps.

In the next stages, a group of these 8-channelSTURM ASICs will be used to instrument 32 or64 elements of a linear array, which will enablehigh-speed imaging.

5.8 Other Efforts

A number of smaller projects are ongoing thatrepresent upgrades to existing major projects orprototype initiatives.

• HanoHano – PMT high voltage base,FPGA-based trigger and digitizer [10], andfiber-optic data collection system. First gen-eration system developed with visiting engi-neering students from Finland and overseenby Kennedy.

• Polarized Gamma Observatory – Varnerwith Cooney have developed two generationsof pipelined readout, upon which the pro-duction PoGO-lite balloon payload flight [11]electronics is based.

• Astro-E Prototype – Varner with Cooneyhave fabricated an SOI prototype [12] of a sil-icon pixel tracker for next generation x-ray(multiple Compton scattering) telescope.

5.9 Invited talks by G. S.Varner

1. “Ultra Fast Analog and Timing CMOS Dig-itizers,” Real-Time 2009 Conference keynotetalk, Beijing, China, May 12, 2009.

2. “Sub 10-ps timing with the BLAB ASIC,”6th Workshop on Pico-second Timing, Lyon,France, Oct. 11, 2008.

3. “Radio Detection of Cosmic Ray Air Showersvia Atmospheric Microwave Bremsstrahlung,”Institute for Cosmic Ray Research, Kashiwa,Japan, July 20, 2008.

4. “Radio Detection of Ultra High Energy Neu-trinos,” Institute for High Energy Physics,Beijing, China, July 18, 2007.

5. “ASICs for Particle andAstroparticle Physics,” SLAC Advanced In-strumentation Seminar, Stanford Linear Ac-celerator Center, Palo Alto, California, July11, 2007.

6. “Compact, low-power and (deadtimeless)high timing precision photodetector readout,”Photo-Detector 2007 International Confer-ence, Kobe, Japan, June 30, 2007.


Bibliography

5.10 Recent Dectector R&D

papers

[1] H. Hoedlmoser, G. Varner and M. Cooney,“Hexagonal pixel detector with time en-coded binary readout,” Nucl. Instr. Meth.A599 (2009) 152.

[2] G.S. Varner, L.L. Ruckman, J. Schwieningand J. Vavra, “Compact, low-power and pre-cision timing photodetector readout,” Proc.of Science, PD07:026 (2008).

[3] J. Benitez, D.W.G.S. Leith, G. Mazaheri,B.N. Ratcliff, J. Schwiening, J. Vavra, G.S.Varner and L.L. Ruckman, “Status of theFast Focusing DIRC,” Nucl. Instr. Meth.A595 (2008) 104.

[4] G. Varner et al., “The Large Analog Band-width Recorder And Digitizer with OrderedReadout (LABRADOR) ASIC,”Nucl. Instr.Meth. A583 (2007) 447.

[5] L. Ruckman, G. Varner and A. Wong, “Thefirst version Buffered Large Analog Band-width (BLAB1) ASIC for high luminositycollider and extensive radio neutrino detec-tors,” Nucl. Instr. Meth. A591 (2008) 534.

[6] L.L. Ruckman and G.S. Varner, “Sub-10psMonolithic and Low-power PhotodetectorReadout,” Nucl. Instr. Meth. A602 (2009)438.

[7] G. Varner et al. “Giga-bit Ethernet Instru-mentation for SalSA Electronics Readout(GEISER)”, Nucl. Instr. Meth. A554 (2005)166.

[8] H. Landsman et al. (IceCube Collaboration)and L. Ruckman and G. Varner, “AURA- A radio frequency extension to IceCube,”Nucl. Instr. Meth. A554 (2005) 166.

[9] J.W. Flanagan, H. Fukuma, S. Hiramatsu,H. Ikeda, T. Mitsuhashi, J. Urakawa, G.SVarner, J.P. Alexander and M. Palmer,“X-ray Monitor based on Coded-aperatureImaging for KEKB Upgrade and ILC Damp-ing ring,” Proc. European Particle Accel-erator Conference (EPAC08), Genoa, Italy(2008) TUOCM02.

[10] G. Varner, “The Modern FPGA as Discrim.,TDC and ADC”, J. Instr. 1 (2006) P07001.

[11] H. Arimoto et al. (PoGO Collaboration),“Performance assessment study of theballoon-bourne astronomical soft gamma-ray polarimeter PoGOLite, Physica E 40(2007) 438.

[12] E. Martin, G. Varner, M. Barbero, J.Kennedy, H. Tajima and Y. Arai, “HardX-ray SOI Sensor Prototype,” Proceedingsof the 2nd Conference on PhD Research inMicroelectronics and Electronics (PRIME),pp. 417-420, Otranto (Lecce) Italy, June 12-15, 2006.


BIBLIOGRAPHY


Chapter 6

Theoretical Physics: KA140101

Drs. R. Srikanth Hundi, J. Kumar, R. Nev-zorov, S. Pakvasa, W. Simmons, X. Tata, andMessrs. S. Biswas, and R. Kadala

(Tata is the principal investigator of this task.)

6.1 Overview

The theory group currently consists of facultymembers, Kumar, Pakvasa, and Tata, an af-filiate faculty member Simmons, post-doctoralresearchers Hundi and Nevzorov, and graduatestudents, Biswas and Kadala.

The research of the theory group is largely phe-nomenological in character. The main theme isto identify new physics that addresses interestingquestions in particle physics and cosmology thatare beyond the scope of the Standard Model, andthen to identify strategies to confront the Stan-dard Model and these new physics extensions viaexperimental tests at high-energy and/or high-luminosity colliders as well as at non-acceleratorexperimental facilities. Kumar, who has justjoined our group, has done significant work instring theory, but his recent interests have beenvery phenomenological and include dark matter,observational implications of inflationary cos-mology, CP violation in gauge boson interac-tions at the LHC and dynamical SUSY break-ing. Pakvasa’s activities center around neutrinophysics & astro-physics, as well as flavor physics,including mixing, CP violation and rare decaysof heavy-flavor systems. Tata mainly works onthe search for new physics with emphasis uponweak scale supersymmetry, both at high-energycolliders and via dark matter searches. The dif-ferent research directions have considerable over-lap as well as a common goal. This results inhealthy interactions among the theorists and ex-

perimentalists in Hawaii.

Kumar replaced Melnikov who went to JohnsHopkins at the start of this academic year. Hehas a broad range of interests spanning cosmol-ogy and LHC physics. His novel suggestion (withJ. Feng) on WIMPless dark matter received no-tice in Nature and in New Scientist. He is in-teracting vigorously with other members of theHEP group. Tata’s student Box graduated lastFall, and is currently a post-doc at the Universityof Oklahoma. Roman Nevzorov (Glasgow), whohas worked on a variety of topics spanning su-persymmetry, Higgs physics and aspects of cos-mology will join the Theory group in October,2009 as a post-doc. He is already an experiencedresearcher (with over 50 publications), and withhis broad range of interests, we expect that hewill collaborate with all members of the group.

Theory group students and postdocs are alsoinvolved in a variety of projects. Hundi, Pak-vasa and Tata have proposed a new SUSY sce-nario that addresses the proton decay and the μand bμ problems of SUSY models, and also ac-commodates the broad features of all neutrinodata. Hundi is also working on a project withcollaborators in Japan, to investigate whetherexperiments at an e+e− linear collider may, inwell-motivated theoretical models, be able to de-termine the spin of a weakly interacting darkmatter particle. Kadala teaches at a local com-munity college and does not require DOE sup-port. He completed an investigation on heavyflavor tagging for SUSY searches at the LHC,and is working with Hundi and Tata on develop-ing new strategies to extract information aboutneutralino properties from a study of dileptonsat the LHC. Box and Tata completed an ex-tensive study that will enable a general analysisof flavour violation in supersymmetric processes.


CHAPTER 6. THEORETICAL PHYSICS: KA140101

Biswas continues as a Hawaii student resident atJohns Hopkins and is working with Melnikov onprecision calculations of b-quark decays. A highpriority is to recruit a student to work with Ku-mar.

Tata will spend the 2009 AY doing researchat the University of Wisconsin in Madison. Heshares many common research interests with sci-entists at the Phenomenology Institute at theUniversity of Wisconsin, and with researchersat the IceCube Center involved in dark mat-ter searches. This, coupled with the fact thatthe experimental group at Wisconsin is involvedin both ATLAS and CMS experiments, shouldmake Tata’s stay a winning proposition for allsides. During the year, he expects that LHCand dark matter physics will be his main focus.It is anticipated that other theorists with relatedinterests will also visit UW in this period.

A list of the group’s scientific publications andconference talks during the last three years ap-pears separately.

6.2 Particle Physics, Cosmol-ogy, and the LHC(Jason Kumar)

We are entering a very exciting time for high-energy physics. Over the past few decades, therehas been a growing realization within the high-energy physics community that our basic pictureof fundamental physics, the Standard Model, isinadequate.

One shortcoming of the Standard Model is thehierarchy problem. Experimental evidence indi-cates that the Higgs boson should have a massof order the electroweak scale, but the quantumcorrections to this mass are much larger (of orderthe Planck scale). This implies a very fine-tunedcancelation between the pieces contributing tothe Higgs boson mass (to 1 part in 1016), whichseems very unnatural.

Furthermore, astronomical data from a widevariety of sources collectively indicates that mostof the matter in the universe consists of a newtype of “dark matter.” This matter cannot arise

within the Standard Model, and implies the ex-istence of new particles and symmetries. More-over, a variety of problems with traditional cos-mology (such as horizon and monopole prob-lems) have been found to have robust solutionswithin the paradigm of inflation. However, allmodels of inflation require the existence of atleast one scalar field, and in most models con-sidered this field must come from outside theStandard Model. The observation of neutrinooscillations as well as the baryon asymmetry allindicate the existence of new physics beyond theStandard Model.

A wide variety of theoretical ideas have pro-vided increasingly sophisticated models to ex-plain these mysterious aspects of high-energyphysics and cosmology. At the same time, awide variety of new experiments either are tak-ing or will soon begin to take data. These in-clude direct dark matter detection experimentslike DAMA, CDMS and XENON, neutrino ex-periments like Super-Kamiokande, astronomicaldevices like PAMELA, ATIC and Fermi, and,above all, the Large Hadron Collider. Kumar’sresearch is focussed on connecting this broad webof theoretical ideas to observational predictions,which can be tested at the new experiments.

6.2.1 Dark Matter

Observational evidence indicates that ∼ 80%of the matter in universe is dark matter, a type ofnon-baryonic matter which only interacts weaklywith the Standard Model. It is not known ifthese particles arise entirely within the minimalsupersymmetric Standard Model framework, oras part of a new hidden “dark sector.” A va-riety of experiments have thus been developedto detect dark matter, either directly or indi-rectly. Kumar has been involved in developingnew models for dark matter particles, and in un-derstanding how these models can explain theresults of current experiments and also be testedwith future data.

One of the most theoretically appealing ideasfor dark matter is weakly interacting massiveparticles (WIMPs). This appeal derives from


6.2. PARTICLE PHYSICS, COSMOLOGY, AND THE LHC(JASON KUMAR)

the“WIMP miracle,” the fact that a stable parti-cle with weak interactions and mass at the weakscale would have a thermal relic density whichis approximately the same as that of dark mat-ter. Moreover, gravity-mediated SUSY-breakingmodels provide a natural candidate WIMP.

Recently, Kumar and Jonathan Feng (Univer-sity of California, Irvine) have shown that this“WIMP miracle” is in fact a more general phe-nomenon that can be realized in a much broaderclass of models that exhibit gauge-mediated su-persymmetry breaking (GMSB). In these mod-els, the WIMPless dark matter particle arises ina hidden sector can have a wide range of masses( ∼ 10MeV−10TeV). Nevertheless, the“WIMPmiracle” implies that these particles have approx-imately the correct relic density. This allows oneto now consider candidate dark matter particleswith a much wider range of masses then usu-ally considered for WIMPs, while still retain-ing the theoretical motivations which underlyWIMP models. Moreover, although GMSB hasstrong theoretical motivation (such as an elegantexplanation for the small magnitude of flavor-changing neutral currents), the downside to thisscenario has been the difficulty in finding a gooddark matter candidate; WIMPless dark matteralleviates this difficulty.

WIMPless models have implications for detec-tion searches at a wide range of mass scales.Of particular interest are the implications forthe signal seen at the DAMA/LIBRA experi-ment. This experiment has seen 8.2σ evidencefor an annual modulation in nuclear recoil events,which could be explained by elastic scatteringof dark matter particles. This result has ledto much experimental and theoretical contro-versy. A good choice for a candidate dark mat-ter particle that could explain the DAMA re-sult without conflicting with other experimentswould be a light dark matter particle (m ∼2−10GeV) with a large nucleon scattering cross-section (σSI ∼ 10−38−41 cm2). It is rather diffi-cult to find WIMPs with these properties. ButKumar, along with Feng and Louis E. Strigari(UC Irvine) showed that a model of WIMPlessdark matter can easily give a candidate which

could explain the DAMA result. This model hasvery distinctive signatures at the LHC, and givesa robust prediction for γ-ray production fromdark matter annihilation which could potentiallybe observed with the Fermi LAT.

However, given the controversy surround-ing the dark matter interpretation of theDAMA/LIBRA result, it is important to cross-check this result at different experiments. Forthis task, Super-Kamiokande can play a uniquerole. Super-K can detect neutrinos which arisefrom dark matter annihilation at the core of thesun. Although it probes dark matter indirectlyin a manner very different from DAMA, its re-sults can be compared to DAMA in a largelymodel-independent way. In addition, Super-Khas a relatively low energy threshold, making itsensitive to light dark matter candidates whichcould explain the DAMA signal. Kumar, alongwith Feng, Strigari and John Learned, stud-ied the possibility of light dark matter detec-tion at Super-K and found that there were goodprospects for testing the DAMA/LIBRA result.

6.2.2 CP-Violation

There has been longstanding interest in theCP-violation, partly because measurements ofCP-violating processes can provide indications ofbeyond-the-Standard-Model physics, and partlybecause CP-violation is required for baryogene-sis. Although CP-violation has been well-studiedin the quark sector by experiments such as Belleand BaBar, less emphasis has been placed onstudies of CP-violation in the vector boson sec-tor. Since the LHC is expected to begin tak-ing data within the next year, it is importantto study the best avenues for detecting CP-violation in this sector. Kumar has begun astudy of this question, along with Arvind Rajara-man (University of California, Irvine) and JamesWells (University of Michigan) .

These authors studied CP-violation in theWWZ vertex, and the prospects for measuringsuch CP-violation at the LHC through the pro-cess pp → W ∗ → WZ → lllν. They found thatvery good prospects for observing CP-violationin this process lay in studying asymmetries in



the phase-space of the three outgoing leptons.As an example, they considered the dimension 6CP-violating operator which generates a WWZcoupling,

λZ

2M2W

W−ρμW+μ

νενραβZαβ.

They found that with 100 fb−1 of data, the LHCshould be sensitive to λZ at the level λZ

<∼ 0.002,bettering LEP2 by close to a factor of 100.

6.2.3 Inflation

Inflation is perhaps the most well-studiedparadigm for early cosmology. On the one hand,there is great interest in trying to find new in-flationary models which require less fine-tuning.On the other hand, observational cosmologyhas entered a precision era, with measured ob-servables such as the spectral index and non-Gaussianity constraining theoretical models. Assuch, there is also interest in finding new mod-els which can make distinguishing predictionsthat can be tested at the Wilkinson MicrowaveAnisotropy Probe (WMAP) and Planck.

Kumar and his collaborators (Bhaskar Duttaand Louis Leblond, of Texas A&M University)had proposed a model of inflation that arose in aclass of string constructions known as intersect-ing brane models. They found a robust, largeclass of models in which D-term inflation couldarise, and found that the extra gauge symmetrieswhich are inherent to these string constructionsameliorated the fine-tuning typically required ininflation models.

More recently, these authors studied a partic-ular example of this class of models in whichnon-Gaussianities in the curvature spectrum aregenerated. This model utilizes the large numberof scalar fields which are also inherent to thesestring constructions to produce non-Gaussiancurvature fluctuations.

The latest data from WMAP already testsnon-Gaussianity in the CMB. This issue willlikely be settled by the Planck satellite, whichwill probe non-Gaussianity with much higher

precision than WMAP. These models thus havea timely connection to observational cosmology.

6.2.4 Dynamical Supersymmetry-Breaking

Supersymmetry is the most well-studiedframework for explaining the hierarchy problem.However, a necessary piece of this solution is thatsupersymmetry must be broken at some smallscale, and the effects of supersymmetry-breakingmust be communicated to the Standard Modelvia interactions. There are several different waysin which SUSY-breaking can be mediated to theStandard Model, and the correct choice not onlyhas theoretical implications (such as implicationsfor the existence of dark matter candidates), butalso distinct signatures that can be observed atthe LHC.

String theory provides a natural avenue forstudying these issues. From the point of view ofeffective field theory, dynamical SUSY-breakingrequires the generation of a small number whichdetermines the SUSY-breaking scale; as a puta-tive microscopic theory, string models can ex-plain why the relevant coefficients are small.Moreover, as a theory that includes the quan-tum gravity and gauge theory, as well as mod-uli, string theory can simultaneously encompassall of the interactions which can mediate SUSY-breaking.

Kumar has studied this problem from the pointof view of string theory. Earlier he showed that,when “Fayet-Iliopoulos” terms (more precisely,those field-dependent terms that play the role ofFayet-Illiopoulos terms in the low energy limit)were turned on, intersecting brane models typ-ically exhibited broken supersymmetry in theopen-string sector with an exponentially smallSUSY-breaking scale.

More recently, Kumar has studied mechanismsfor mediating SUSY-breaking to the MSSM sec-tor in this intersecting brane model context.He found that in this class of models, gauge-mediation very naturally arises as the dominantmechanism for communicating SUSY-breakingto the Standard Model. Gravitational interac-tions, though subdominant, are non-negligible;


6.2. PARTICLE PHYSICS, COSMOLOGY, AND THE LHC(JASON KUMAR)

for scalar masses ∼ TeV, one finds m3/2>∼

10GeV.

6.2.5 Future Plans

The projects described above are ongoing, andin the short-term Kumar plans to continue thesestudies. He is continuing investigation of darkmatter models and signals. One immediate fo-cus is on dark matter detection prospects at theLHC.

WIMPless dark matter can couple to the Stan-dard Model via an exotic quark. Such an ex-otic quark is permitted by current experimentalbounds, but would have very striking effects atthe LHC. Signatures for this model would in-clude events with two b-jets, an enhanced Higgsproduction cross-section, and possibly long-livedcharged particles. Kumar is currently involved ina detailed analysis of detection prospects, alongwith Feng, Johan Alwall (SLAC), Shufang Su(University of Arizona) and Fumihiro Takayama(Cornell University). This detection pathway isespecially interesting, because the exotic quarksare produced by QCD processes, and then de-cay to dark matter. There can thus be gooddetection possibilities at the LHC even if thedark matter couples very weakly to the StandardModel, in which case other direct and indirectsearch strategies become problematic.

They are also analyzing the de-tection prospects for more general dark mattermodels through single b-jet signals. This analy-sis is relevant to WIMPless models, but also tomore general models, such as neutralino WIMPmodels of dark matter.

Kumar is also pursuing, with Learned and UHgraduate student Stefanie Smith, a study of darkmatter detection strategies and prospects for liq-uid scintillator neutrino experiments, such as theproposed Hanohano experiment. In these exper-iments, a νμ (produced from dark matter annihi-lation) interacts with the material in the detectorto produce a muon, which is observed throughthe photons produced as it moves through thedetector. Learned has recently argued that, fromthe arrival times of photons at the various pho-

tomultiplier tubes, it is possible to obtain infor-mation on the direction of the produced muon.This data, accompanied by the high-resolutionenergy measurement of a liquid scintillator ap-paratus, can be used to place tighter bounds ondark matter annihilation in the core of the sun.

Another more long-term project which Kumaris pursuing with Feng is a study of concrete hid-den sectors which can yield realistic WIMPlessdark matter. If dark matter particles interactwith each other or with the Standard Modelthrough new forces and couplings, then new con-straints on these hidden sector forces can arisefrom the details of cosmological evolution. Heis studying the features of hidden sectors whichare consistent with current constraints, and whatthese features could imply for future measure-ments.

He is also continuing studies of CP-violationat the LHC using phase-space asymmetries, withRajaraman and Wells. The immediate focus ison a broader and more detailed study of CP-violation in WWZ and hZZ interactions at theLHC. Particular emphasis is being placed onunderstanding the absorptive phases that couldarise as a Standard Model background to CP-violating new physics. These results will havebroader application to other asymmetric mea-surements of CP-violation.

Kumar’s continuing work on inflationary mod-els is focussed on possible loop corrections toboth the 2-point function and to non-Gaussiansignatures. This work is in collaboration withDutta, Leblond and Rajaraman. There has beena great deal of interested in quantum and non-linear corrections to inflationary observables fortwo reasons. First of all, it is possible that, insome models, these corrections will become sig-nificant and can be detected in the running ofthe spectral index or non-Gaussianity. Secondly,these corrections seem to exhibit divergences atlong distance scales, and the problem of under-standing the physical significance of these diver-gences has drawn much recent interest. A cur-rent project of Kumar is to understand in de-tail the effect of resumming higher-loop diver-



gent contributions to obtain physical observablesof the CMB, including those sensitive to non-Gaussianity.

Continuing work on dynamical supersymmetrybreaking in string theory is focussed on the con-nection between moduli-stabilization and SUSY-breaking.

Over the longer term, Kumar intends to fo-cus on new models which can explain the resultsof the many new experiments which are comingonline and which can be tested with future data.It is anticipated that string theory intuition andmotivation will guide many of these models.

6.3 Neutrino Physics

The properties of neutrinos, such as theirmasses, mixings, magnetic moments, etc. are ex-tremely important in several ways. These arefundamental parameters, they play an impor-tant role in astrophysics and cosmology, and theytell us about what may be beyond the Stan-dard Model (SM). Apart from direct laboratorymeasurements of masses from β decay end-pointmeasurements, the other technique for obtaininginformation on neutrino properties is the studyof neutrino propagation and flavor conversionover long distances via neutrino mixing and os-cillations. It continues to be an aim of the Hawaiitheory group (and especially Pakvasa) to devisemeans to deduce neutrinos properties from var-ious neutrino experiments, to propose new ex-periments, and to construct models for neutrinomasses and mixings.

In 1999, Pakvasa withdrew from the Borex-ino collaboration (of which he was a founding-member) because he was able to attend onlya very few group meetings and did not feel hewas participating adequately in the collabora-tion. He has since joined the KamLAND collab-oration, as part of the UH group. The wisdom ofthis choice is borne out by the spectacular resultsof KamLAND described elsewhere in the pro-posal. The most recent results from KamLAND,just published, exhibit in the L/E distributionof reactor neutrino events, a spectacular signa-ture of oscillations via two full cycles. This is

the most convincing proof of neutrinos oscillat-ing as yet and is the most precise measurementof the solar Δm2 (Phys. Rev. Lett. 100, 221805(2008)).

Pakvasa’s participation in the Hanohano col-laboration and the Hanohano proposal are de-scribed elsewhere in this proposal.

It is well known that high energy neutrinosfrom astrophysical sources such as AGNs (ac-tive galactic nuclei) and GRBs (Gamma RayBursters) are produced in beam dumps whenprotons collide with matter and produce pions.The neutrinos that come from π → μ decays havea characteristic flavor mix of νe/νμ/ντ ≈ 1/2/0.For large L/E and the known values of Δm2, theneutrino oscillations average out and the largemixings will make the flavor into νe/νμ/ντ ≈1/1/1. This is a canonical result known for along time (first discussed in the paper by Learnedand Pakvasa: Astropart. Phys. 3, 267 (1995)).Deviations from this universal flavor mix wouldbe very interesting, since these would serve as aprobe of a variety of new phenomena. In a seriesof papers, Pakvasa and collaborators developedscenarios that can be tested in deviations of theneutrino flavor mix from the canonical 1/1/1. Athorough detailed review of this whole subjectwas given by Pakvasa in “Neutrino Flavor Go-niometry by High Energy Astrophysical Beams,”arXiv:0803.1701 [hep-ph].

There have been a number of proposals tomeasure a variety of neutrino properties (e.g.the small deviations from Tri-Bi-Maximal mixingmatrix or CP violation phase etc.) by measur-ing the small deviations from the universal 1/1/1flavor mix. However, this depends not only onextremely accurate determination of the flavormixes in the neutrino fluxes, but also on the as-sumption of simplified forms for the initial fluxessuch as 1/2/0 mix naively expected in the piondecay production model. In general, this is toosimple and naive. When one does a more care-ful study, the initial mixes are more complex,as shown especially by P. Lipari and collabora-tors. A detailed critical review of the whole sub-ject was carried out by Pakvasa, Rodejohann and


6.4. HEAVY QUARK AND FLAVOR PHYSICS

Weiler, (JHEP 0802, 005(2008)).

A persistent puzzle in neutrino physics is howto accommodate the evidence for νμ → νe os-cillations at the accelerator experiment LSND.As this result requires a different Δm2 than theatmospheric and solar neutrino oscillations, atleast a fourth sterile neutrino – one that doesnot contribute to the width of the Z boson – isrequired to fit all the data for neutrino oscilla-tions. There are, however, stringent limits onoscillations into sterile states from solar, atmo-spheric, accelerator and reactor experiments thatexclude simplest models accommodating sterileneutrinos. Pas, Pakvasa and Weiler (Phys. Rev.D 73, 033004 (2006)) constructed a scenario inwhich sterile neutrinos take short cuts in a extradimension, that fits all neutrino data in a con-sistent framework. Such short cuts, which havebeen discussed earlier for gravitons as a solutionto the cosmological horizon problem, arise nat-urally in extra dimensional models of neutrinomass generation, where self-gravity bends thebrane or the extra dimension is warped asym-metrically. The short cuts effectively decreasethe path length of sterile neutrinos through theextra-dimensional bulk, thereby inducing a newresonance in active-sterile neutrino oscillations.

When the neutrino energy is well below orwell above the resonance, active-sterile oscilla-tions are suppressed. This allows for a good fitto the LSND data and the stringent bounds fromCDHS and Bugey are easily evaded. The predic-tion for the on-going Mini-Boone experiment atFermilab was especially interesting. For a reso-nance energy of around 30 MeV, which gives anexcellent fit to the LSND data, the predictionwas that Mini-Boone should observe no effect,This was spectacularly confirmed when Mini-Boone announced their results in April 2008.But in addition, Mini-Boone found a resonance-like anomaly at low energies in the range of 300-475 MeV. Whether the PPW model can accountfor this as well and still be consistent with allthe neutrino oscillation data is under investiga-tion. A detailed paper with a complete and si-multaneous fit to all neutrino data is now underpreparation (V. Barger, P. Huber, J. Learned, D.

Marfatia, H. Pas, S. Pakvasa and T. Weiler).

Pakvasa, with Rodejohann and Weiler initi-ated a study and analysis of the deviations ofthe neutrino mixing matrix from the simple andempirically successful form of tri-bi-maximal ma-trix. The initial analysis was to simple write aunitary parameterization of the deviations whichwas named “triminimal”. This enabled writingin a very simple form many expressions for sur-vival/conversion probabilities in a compact form,especially when expanded to second order in thesmall parameters. (Phys. Rev. Letters, 100,111801 (2008)). There are continuing efforts tofind physical significance and theoretical under-standing of this form of the matrix. Future plansinvolve a study of models for neutrino mass ma-trix, with further possibilities of a unified de-scription of the fermion masses and mixings,both quarks and leptons. This is of course veryambitious and many attempts exist and it is avery active area of investigation. However, Pak-vasa is encouraged by the fact that many ideason which he had worked on in the period 1979-1984, such as discrete non-Abelian family sym-metries for the fermion mass matrix are makingtheir appearance once more once more e.g. thepermutation symmetry S4 and its subgroups.

6.4 Heavy Quark and Flavor

Physics

There are several aspects to the study of quarkflavor physics. One is to devise tests of the Stan-dard Model and/or deduce its parameters (suchas KM angles and phase); another is to devisetests of various proposals for new physics beyondthe standard model, and yet another is to specu-late about the origin of masses and mixings (i.e.model building).

CP violation and mixing in the D0−D0 systemare of great interest as probes of new physics.In the SM, the short distance contribution toΔmD is known to be extremely small, of or-der 10−17 GeV. At one time, it was thoughtthat there could be long distance enhancementby several orders of magnitudes. Now, thereis some rethinking about this. The CP vio-



lating phase is also expected to be very small.Specifically, the phase φ in mixing which is givenby tan−1(ImM12/ReM12) is approximately 10−3

when ReM12 is taken from the current measure-ments of xD (in the Standard Model).

Pakvasa (in collaboration with T. Browder, N.Deshpande, N. Sinha and R. Sinha) published apaper on a proposal of a new method for an ac-curate determination of the mixing parametersin the D0− D0 system. They showed that a pre-cision measurement of all the mixing parametersis possible for an arbitrary CP violating phase,by combining observables from a time dependentstudy of D decays to doubly Cabibbo suppressedmode with information from a decay into a CPeigenstate. Examples are D0 → K∗0π0 decaywhere the K∗0 is reconstructed in both K+π−

and KSπ0 modes. The decay modes to CP eigen-state K+K− together with D → K+π− can beused to extract all the mixing parameters: x,y and the CP violating phase φ (N. Sinha, R.Sinha, T. Browder, N. Deshpande and S. Pak-vasa, Phys. Rev. Lett. 99, 26002 (2007))

The long standing project of a review of Dmixing was finished with the impetus of the newexperimental results from Belle and BaBar onboth x = ΔM/Γ and y = ΔΓ/2Γ (Implicationsof D0−D0 Mixing for New Physics, E. Golowich,J. Hewett, S. Pakvasa and A. Petrov, Phys. Rev.D 76, 095009 (2007)). In this paper, the new re-sults for mixing are reviewed in the light of bothSM and possible new physics contributions. Theexperimental results for both x and y are in theO(10−2) range. The SM short distance estimatesare several orders of magnitude below this. How-ever, long distance contributions, which are dif-ficult to estimate, can reach 0 (10−3) level andperhaps even 0(10−2). Although it is plausiblethat y, which depends only on contributions fromon-shell intermediate states, can easily reach val-ues as large as the observed (∼ 1%); the SMestimates for x from off-shell contributions arevery model-dependent and remain in doubt. Itis not clear that even the relative sign of x/y canbe obtained correctly in these SM long distanceestimates. Hence, it is natural to consider con-tributions from beyond SM physics to D0 − D0

mixing. Many new physics scenarios for physicsbeyond SM can contribute to ΔMD (and x) andthus can be severely constrained in their param-eter space. It was found in this work that of the21 new physics models studied, only four wereunconstrained by the new D mixing results. Al-though it is possible that the bulk of the observedmass mixing and comes from new physics, with-out further observables it is impossible to eitherestablish that or identify the specific new physicsthat is responsible. One possibility is the studyof rare D decay modes such as D0 → μ+μ−.Each new physics scenario which can account forthe observed mixing (value of x) makes a spe-cific and distinct prediction for a branching ratiosuch as for D0 → μ+μ−. Pakvasa and collabo-rators pursued this in some detail. They foundthe following. In certain models of new physics,the same combination of couplings appears inthe amplitudes of both D0 − D

0 mixing and arare decay mode such as D0 → μ+μ−. If thenew physics dominates and is responsible for theobserved mixing, then a very simple and directcorrelation exists between the two magnitudes;in fact the rate for D0 → �+�− is completelyfixed by the observed mixing. An observation ofD0 → μ+μ− in excess of the minuscule rate ex-pected in the Standard Model would identify thespecific New Physics contributing to the mixing.Thus this decay mode can act as a diagnostic.

Another possible diagnostic is the phase φ inD0− D0 mixing. This is given approximately byφ = tan−1(ImM12/ReM12). With the ReM12

fixed by the observed value of x, an SM estimateyields φ ≈ 10−3 or about 0.060. If x is due to newphysics, φ can reach values as high as 450. Thecurrent bound is about |φ| < 250 at 90% C.L. Ameasurement of φ can confirm new physics originof mixing in the D system as well as pinpointthe specific mechanism at work. Different newphysics scenarios predict different values for thephase and a measurement of the phase can alsodiscriminate between New Physics models.

Direct CP violation in rate asymmetries is an-other useful probe of new physics. In SM directCP violation is expected only in singly CKMsuppressed modes such as D → KK, ρπ etc.


6.5. SUPERSYMMETRY PHENOMENOLOGY

and Cabibbo at a level of about 10−3. Newphysics can lead to CP -violating asymmetriesin Cabibbo-allowed and Double-Cabibbo sup-pressed modes at similar levels.

All the above is part of the plans for futureand is under active investigation by Golowich,Hewett, Pakvasa and Petrov.

6.5 SupersymmetryPhenomenology

The elucidation of the mechanism of elec-troweak symmetry breaking is the main rea-son for the construction of high energy collid-ers. Within the Standard Model (SM) frame-work, the scalar Higgs boson is the anticipatedrelic of spontaneous symmetry breaking. As iswell known, the instability of elementary scalarmasses to radiative corrections leads to the so-called fine-tuning problem; i.e. the parametersof the theory have to be adjusted to an uncannyprecision unless either (i) electroweak symmetrybreaking interactions become strong at the TeVscale so that perturbative arguments are inappli-cable, or (ii) there are new perturbative degreesof freedom, not present in the SM, that mustmanifest themselves in high energy collisions atthe TeV scale. In either case, new phenomena,not described by the SM, are expected whenthe TeV energy scale is explored at supercol-liders such as the Large Hadron Collider (LHC)at CERN, and, perhaps, at 0.5-1 TeV electron-positron international linear collider (ILC) beingconsidered at various places in the world. Possi-bilities include a strongly interacting symmetry-breaking sector (strong WLWL scattering), com-posite quarks, leptons and leptoquarks, compos-ite “Higgs bosons”, supersymmetry, extra spatialdimensions, or something even more surprising.

The imminent commencement of the LargeHadron Collider, is an exciting time for Tatawho, together with his collaborators, has devel-oped a program of study of the experimental im-plications of weak scale supersymmetry, which heregards as the most promising extension of theStandard Model. The codes that they have de-veloped, as well as the strategies that they have

suggested, have been extensively used by the DØand CDF Collaborations at the Tevatron in theirsearch for supersymmetric particles, as well asby various groups studying projections at theCERN LHC, or a future linear electron-positroncollider such as the ILC. Their work has involvedthe development of techniques for the discoveryof supersymmetry at colliders and dark mattersearch facilities, and also on how one might goabout elucidating any new physics that mightbe discovered. A long term goal of the HawaiiSUSY effort is to study the extent to which itwill be possible to use data from both the LHCas well as from DM search experiments to elu-cidate the mechanism by which superpartners ofSM particles obtain SUSY-breaking masses andcouplings.

In a series of papers over the last three orfour years, Tata and his collaborators have beenexamining robust implications of the measuredrelic density of cold dark matter (CDM) for theLHC and dark matter searches, assuming onlythat a stable neutralino forms a significant com-ponent of the CDM. He has been examining thedata from Pamela and ATIC, and eagerly awaitsthe data from the Fermi LAT: over the range ofenergies where there is an apparent signal in theATIC data, the instrument is not well-calibratedso, given the stakes, an independent confirma-tion of this signal is essential. Last year, Tataand Box completed a lengthy program describedbelow that will enable general analyses of flavourviolation in the production and decays of spar-ticles. Baer, Box and Tata are currently work-ing on incorporating it into the event generatorISAJET.

6.5.1 Simulation of supersymmetry at col-liders

H. Baer (Oklahoma), F. Paige (Brookhaven),S. Protopopescu (Brookhaven) and Tata havedeveloped, and are maintaining, the ISAJETprogram to simulate production of sparticles andSUSY Higgs bosons at pp, pp and also e+e− col-liders, with longitudinal beam polarization andinitial state radiation effects included. ISAJET



has many popular models hard-wired for easysimulation, and has been used by the CDF andDØ collaborations as well as for simulations atthe LHC and the ILC.

ISAJET is continually evolving. Aside fromthe inclusion of new promising models as theyappear, ISAJET now includes the tool kit“Isatools” that allows the user to evaluatephenomenologically relevant quantities such asB(b → sγ), B(Bs → �+�−), gμ − 2, ΩZ1

h2 andσ(Z1p/n) directly. Tata’s former student Box,now at Oklahoma, has constructed a programthat solves the two-loop renormalization groupequations of the minimal supersymmetric Stan-dard Model, including all flavour-violating massand coupling parameters, and including an im-proved treatment of SUSY thresholds. The codealso allows all parameters to be complex num-bers. In collaboration with Baer, they are work-ing on incorporating this code into ISAJET. Weexpect that this will be a useful tool for studiesof flavour violation in the decays of supersym-metric particles as well as for phenomenologicalstudies of new sources of CP violation in SUSYmodels.

6.5.2 Dark Matter

Baer and Tata, in collaboration with others,have been examining the implications of theprecisely determined CDM density, for SUSYmodels, under the assumption that neutrali-nos form the bulk of the DM. Except whensparticles are very light (MSUSY

<∼ 100 −200 GeV), and frequently in tension with othermeasurements, the neutralino density tends tobe larger than its measured value, implyinga need for a mechanism for efficient annihila-tion of neutralinos, with resulting implicationsfor SUSY searches (usually inferred within themSUGRA framework). To examine the robust-ness of these conclusions, Tata and collabora-tors constructed many one-parameter-extensionsof mSUGRA (where they relax the underlyinguniversality assumption) and showed that expec-tations for SUSY searches at colliders, as well asfor direct and indirect detection of DM, are in-

deed model-dependent, and showed that theseexperiments may probe how superpartners ac-quire their masses.

Specifically, they have allowed non-universalityof Higgs and matter scalar masses, or alterna-tively, allowed one of the three gaugino mass pa-rameters to deviate from its usually assumed uni-fied value. Non-universal Higgs mass (NUHM)models allow resonant annihilation of neutrali-nos via the A/H bosons for all values of matterscalar and gaugino masses, and likewise also al-low mixed higgsino dark matter solutions com-patible with the measured CDM density. Modelswith non-universal gaugino mass parameters alsoallow viable solutions via resonant Higgs annihi-lation, and other solutions with mixed wino DM,mixed higgsino DM, or via bino-wino coannihi-lation.

Baer, A. Mustafayev (Kansas), E. Park (Bonn)and Tata compiled and extended these analy-ses to include prospects for direct and indirectsearches of DM in a study published in JHEP.They showed that the mechanism that enhancesneutralino annihilation in the early universe fre-quently also enhances the DM detection rate inmany experiments, though not always to observ-able levels. Generally speaking, mixed-higgsinoDM detection tends to give the most promis-ing signals. Especially exciting is that directDM detection with noble liquid detectors suchas XENON will soon have the sensitivity to de-tect the signal in a wide variety of models withmixed higgsino DM, since the nucleon-neutralinocross section asymptotes to about 10−8 pb, forvery heavy neutralinos. In an invited article for aspecial issue of the New J. Phys., Baer and Tataupdated these results and also discussed the in-teresting possibility that axions and or axinoscould be the bulk of DM in SUSY SO(10) mod-els. Tata and Baer also completed an invited re-view on dark matter and the LHC for a generalphysics audience.

6.5.3 Heavy quarks as a probe of supersym-metry

In the mSUGRA model’s relic-density-favoredfocus point/hyperbolic branch region, |μ| is small


6.5. SUPERSYMMETRY PHENOMENOLOGY

and the lightest neutralino contains a signifi-cant higgsino component, and so couples pref-erentially to the third generation. As a re-sult, cascade decays of gluinos are expected tobe rich in b-jets. As shown by Tata, P. Mer-cadante (Sao Paulo) and J. K. Mizukoshi (SaoPaulo) b-tagging extends the reach of LHC ex-periments by up to 15% from current projections.Student Kadala joined Mercadante, Mizukoshiand Tata in the examination of several promis-ing models consistent with WMAP data whereb-tagging could potentially increase the LHCreach. They found that b-tagging generally in-creases the reach when the E/T signals comemainly from gluinos, but in models where squarkproduction also makes a significant contribution,requiring a tagged b-jet may even reduce thereach. They also showed that while top-taggingmay serve as a useful diagnostic, it will not leadto an increased reach because the top-taggingefficiency is too low. Finally, they found thattagging c-jets by soft muons inside a jet is notuseful for enhancing the SUSY signal because ofthe contamination from b-quarks. Their resultshave appeared in the European Physical JournalC.

6.5.4 Flavour and CP violation in super-symmetric models

The presence of numerous scalars in super-symmetry automatically introduces many newsources of flavour violation connected withsfermion mass matrices and trilinear scalar cou-plings. There are also a large number of potentialCP -violating parameters. Tata’s former studentBox, who has just moved to Oklahoma, has writ-ten a code to solve the two-loop renormalizationgroup equations (RGEs) of the MSSM that in-cludes all flavour violating masses and couplings,for arbitrary boundary conditions at the highscale. This code also allows the user to set var-ious parameters to assume complex values. Theidea is to provide a tool that will allow a detailedexamination of various possible flavour struc-tures and CP -violating parameters and exploretheir phenomenological implications using eventgenerators. In two long papers that have been

published in Physical Review D, Box and Tataderive and solve the RGEs for the dimension-less and dimensionful couplings of the MSSM.They show that when SUSY-breaking thresh-old effects are incorporated, gaugino couplingscouplings evolve differently from gauge couplings(and, in fact, become flavour-violating matrices).Likewise, higgsino coupling matrices evolve dif-ferently from the corresponding Higgs Yukawacouplings. In the second paper that appearedearlier this year, they analyse the evolution ofthe sfermion mass matrices and A-parameters.They also point out that, like the dimensionlesscouplings discussed in the first paper, the su-persymmetric higgsino mass parameter μ evolvesdifferently from its bosonic cousin in the scalarsector, and discuss how this may impact on theelectroweak symmetry breaking conditions (be-yond tree level). As an illustration of the effectsthey consider, they show (1) that the gauginomass parameters in split SUSY models may differfrom naive expectations by 10-20%, and (2) therate for the loop decay t1 → cZ1 is smaller thanthat obtained via the single step approximation(still widely used in the literature) by more thanan order of magnitude, so that projections forstop decay patterns may be strongly affected.

6.5.5 A U(1)′ solution to the SUSY µ − bμ

and proton decay problems

Hundi, Pakvasa and Tata, have constructed asupergravity-based model where SUSY breakingin the hidden sector at the intermediate scalegives masses to SM superpartners. They requirethat the model: (1) invokes only anomaly-freelocal symmetries (since gravitational dynamicsrespects only gauge symmetries); (2) is completein that all VEVs are obtained from a superpo-tential Kahler function and a gauge kinetic func-tion; and (3) the SUSY μ and bμ and the pro-ton decay problems are solved. The small ra-tio (∼ 10−8) between the SUSY-breaking andPlanck scales is put in by hand, as in all su-pergravity models, and the cosmological con-stant is fine-tuned. The novel feature is thatthe SUSY-breaking scale also fixes the massscale in the active neutrino sector and can ac-



commodate the observed mixing pattern. Froma phenomenological perspective, the resultingframework is similar to the MSSM with bilinearR-parity violation where the would-be-lightest-supersymmetric-particle decays with a lifetimeof ∼ 10−12 − 10−8 s. Theoretical consistencyof the scenario also requires new coloured weak-isosinglet scalars or fermions, with either conven-tional or exotic charges, and masses in the TeVto multi-TeV range, that should be readily de-tectable if they are within the kinematic reachof a hadron collider. Predictions for low energyquantities such as B(b → sγ), B(b → s��) andgμ − 2 are as in the MSSM with the same corre-sponding parameters. Finally, the dark mattercannot be the weakly interacting neutralino.

6.5.6 SUSY at the LHC

Tata has long explored strategies to identifynew physics signals at the LHC, and further, todevise ways for elucidating what this new physicsmight be. For the most part, he has focussed onSUSY as the new physics, and suggested waysby which experimental data may be used to re-construct weak scale parameters, and so zero inon the underlying model. In this vein, Kadala,Hundi and Tata are studying the dilepton massdistribution from neutralino decay with an eyeto what this tells us about the neutralino sector.Their early investigation shows that this distri-bution peaks closer to the end point of the dilep-ton spectrum if the parent and daughter neu-tralinos have the same signs for their eigenval-ues, and peaks substantially inward in the othercase, confirming an earlier observation by Kitanoand Nomura for the case of higgsino-like neu-tralinos. They are currently examining whetherit is possible to tell gaugino-like neutralinos fromhiggsino-like neutralinos and also whether thereis other information about neutralinos that maybe gleaned from the LHC data.

In collaboration with Baer, V. Barger (Wis-consin) and A. Lessa (Oklahoma) Tata is re-assessing the SUSY reach of the LHC, with amuch more detailed SM background calculationthan used previously. Specifically, they are us-ing AlpGen that includes exact matrix elements

for additional radiation (rather than a partonshower approximation), and including poten-tially important background subprocesses suchas ttZ, bbZ, tttt, ttbb and bbbb processes thathave not been included in their previous studies.Aside from examining how these backgrounds af-fect the reach, they also examine the prospectsfor early SUSY discovery (without using E/T ) inthe trimuon, the SS dimuon and OS dimuon plusjet channels. Their preliminary finding is thatthe last channel gives the best “early reach” forSUSY. Finally, they are examining how much theLHC reach will be degraded if the LHC energy isnever increased from its current starting energyof 10 TeV to its design value of 14 TeV. Thisstudy is in progress.

6.5.7 Dark Matter at linear colliders andLHC-ILC interplay

Post-doc Hundi is part of a collaboration ofabout ten Japanese scientists from KEK, To-hoku U., Sokkendai, Toyama and Tokyo thatis exploring prospects for studying and distin-guishing DM in three very different models atlinear electron-positron colliders. These models:Dark Scalar Doublet Higgs Model (DSDHM), theMSSM with a conserved R-parity, and the Lit-tle Higgs model with T-parity (LHT), all includean exact discrete Z2 symmetry that renders theDM particle stable. The DM particle in the DS-DHM has spin-0, in the MSSM, spin-1

2 and inthe LHT spin-1. It is thus natural to expect thatexperiments at the International Linear Collider(ILC) will be able to distinguish these scenariosby studying pair production and subsequent de-cays of charged heavy partners associated withthe DM sector. In the DSDHM this chargedpartner is a charged scalar field, in the MSSMit is the chargino, and in the LHT, a heavy W -gauge boson.

They have completed an analytic analysis ofangular distributions for pair production of theseheavy charged particles in the three differentmodels, from which it seems that these modelscan be distinguished at the ILC, allowing them toconclude that these experiments will provide in-formation about the spin of the DM particle. De-


6.6. TALKS AND OTHER ACTIVITIES OF THEORY GROUP SINCE LAST REVIEW

tailed Monte Carlo simulations are in progress.Hundi reported on this work at the linear collidermeeting at the University of Illinois, Chicago andM. Asano presented a talk on this work at theTILC09 conference in Tsukuba, Japan last April.

Tata was a member of the Working Group onthe Physics Interplay of the LHC and the ILC.Along with Baer, S. Belyaev (now at Southamp-ton) and T. Krupovnickas (Brookhaven), heshowed that, with specialized analyses, experi-ments at linear colliders should be able to probeportions of the WMAP-favoured HB/FP regionof the mSUGRA model where there will be noobservable signals at the LHC because squarksas well as gluinos are too heavy. Without linearcolliders, DM searches offer the only hope for asignal in this region. The report of this Work-ing Group has appeared as an issue of PhysicsReports.

6.5.8 Future Plans

Tata will continue to complete the variouson-going projects mentioned above, includingthe major upgrade of ISAJET to enable stud-ies of flavour and CP physics of sparticles. Heexpects that they will be able to use this tostudy prospects for detecting flavour violation insparticle decays at linear electron-positron col-liders, especially if some squarks are kinemat-ically accessible. The intermediate and longerterm future depends on what LHC experiments,and on-going experiments for direct (CDMS,XENON,...) and also indirect (Pamela, ATIC,Fermi LAT....) dark matter searches find. Earlydata from Pamela and ATIC are suggestive, butare, in his view, in dire need of confirmation. Inhis view, it is also imperative that the positronflux from pulsars need to be better understood.Tata has been awaiting this era for two decadesand, if SUSY is indeed discovered, he and hiscollaborators will finally have the opportunity touse the tools and strategies they have developedover the years to use data as a guide for un-derstanding how sparticles acquire masses, andwhat the DM is. If something other than SUSYis discovered, Tata has the experience to adapt.

6.6 Talks and other activitiesof Theory Group since last

review

Kumar presented talks at the Strings & GaugesTheories Workshop (MCTP, Sept. 2008) and atCook’s Branch workshop (Texas, March 2009).He is an invited speaker at the 3rd InternationalWorkshop on the Interconnection Between Parti-cle Physics and Cosmology (Norman, Oklahoma,May 2009) and at SUSY09 (Boston, June 2009).

Pakvasa presented an invited talk on D0 −D0

mixing and new physics at the Oberwoelz QCDworkshop in September 2008. During his sabbat-ical leave in Spring 2009, Pakvasa gave a seriesof talks at many places. He gave several pub-lic lectures on ’Neutrinos: yesterday, today andtomorrow” and colloquia on “From Parity Vio-lation to Nobel 2008”, on “Hanohano: A deepocean anti-neutrino observatory”along with sem-inars on his recent work. He was the 2009 Ram-nathan Professor at Physical Research Labora-tory, Ahmedabad, and visited the Tata Instituteof Fundamental Research, Mumbai; M. S. Uni-versity of Baroda, Baroda; JamiaMilia Ismalia,New Delhi; Inter University Centre for Astron-omy and Astrophysics, Pune; University of Mi-lan, Milan; Institute of Mathematical Sciences,Chennai; Indian Institute of Science, Bangalore.He also presented an invited talk on Hanohano atthe Goa meeting on Aspects of Neutrinos, April8-15, 2009.

Tata presented a plenary talk at COSMO 08,Madison (August, 2008), an invited talk at theWorkshop on Low Energy Precision EW Physicsin the LHC Era, Seattle (September, 2008), atthe VII Latin American Symposium on HighEnergy Physics, Bariloche, Argentina (January,2009), at the Cooks Branch Workshop orga-nized by the Mitchell Institute, Houston (March,2009), and a seminar at the University of Min-nesota, Minneapolis (April, 2009). He has alsobeen invited to present talks at the 3rd Interna-tional Workshop on the Interconnection BetweenParticle Physics and Cosmology in Norman, Ok-lahoma, and at SUSY 09 (Boston, June 2009).



6.7 Publications of the The-ory Group

We list publications since the last external re-view, including papers which were listed as sub-mitted for publication but which have since beenpublished. Kumar’s publications from when hewas not in Hawaii are also separately listed.

Publications in refereed journals

1. J. L. Feng, J. Kumar, J. Learned andL. E. Strigari, “Testing the Dark Matter Inter-pretation of the DAMA/LIBRA Result withSuper-Kamiokande,” JCAP 01, 032 (2009).

2. J. Kumar,“A Toy Model for Gauge-Mediationin Intersecting Brane Models,” Phys. Rev. D79, 066007 (2009)

3. R.S. Hundi, S. Pakvasa and X.Tata, Ad-dressing the μ − bμ and proton life-time problems and active neutrino massesin a U(1)′-extended supergravity model,arXiv:0903.1631 (2009), submitted to Phys.Rev. D.

4. H. Baer, E. Park and X. Tata, Collider, di-rect and indirect detection of supersymmetricdark matter, arXiv:0903.0555, New J. Phys.(in press).

5. A. Box and X. Tata, Threshold and flavoreffects in the renormalization group equa-tions of the MSSM II: Dimensionful couplings,Phys. Rev. D 79, 035004 (2009).

6. H. Baer, A. Mustafayev, E. Park and X. Tata,Collider signals and neutralino dark matterdetection in relic-density-consistent modelswithout universality, J. High Energy. Phys.0805, 058 (2008).

7. R. Kadala, P. Mercadante, J. Mizukoshi andX. Tata, Heavy flavor tagging and the super-symmetry reach of the CERN Large HadronCollider, Eur. Phys. J. C 56, 511 (2008).

8. A. Box and X. Tata, Threshold and flavor ef-fects in the renormalization group equationsof the MSSM: Dimensionless couplings, Phys.Rev. D 77, 055007 (2008).

9. C. Kao, D. Dicus, R. Malhotra, Y. Wang,Discovering the Higgs bosons of minimal su-persymmetry with tau leptons and a bottomquark, Phys. Rev. D77, 095002 (2008).

10. H. Baer, A. Box, E. Park and X. Tata, Im-plications of compressed supersymmetry forcollider and dark matter searches, J. High En-ergy Phys. 0708, 060 (2007).

11. H. Baer, A. Mustafayev, H. Summy andX. Tata, Mixed higgsino dark matter froma large SU(2) gaugino mass, J. High EnergyPhys. 0710, 088 (2007).

12. P. Mercadante, J. K. Mizukoshi and X. Tata,Extending SUSY reach at the CERN LargeHadron Collider using b-tagging, Braz. J.Phys. 37, 549 (2007).

13. H. Baer, E. Park, X. Tata and T. Wang, Col-lider and dark matter phenomenology of mod-els with mirage unification, J. High EnergyPhys. 0706, 033 (2007).

14. H. Baer, A. Mustafayev, E. Park and X. Tata,Target dark matter detection rates in mod-els with a well-tempered neutralino, J. Cosm.and Astrophys. 01, 017 (2007).

15. H. Baer, A. Mustafayev, S. Profumo andX. Tata, Probing supersymmetry beyond thereach of LEP2 at the Fermilab Tevatron: Low|M3| dark matter models, Phys. Rev. D 75,035004 (2007).

16. H. Baer, E. Park, X. Tata and T. Wang, Mea-suring modular weights in mirage unificationmodels at the LHC and ILC, Phys. Lett. B641, 447 (2006).

17. H. Baer, A. Mustafayev, E. Park, S. Profumoand X. Tata, Mixed higgsino dark matter frona reduced SU(3) gaugino mass: Consequencesfor dark matter and collider searches, J. HighEnergy Phys. 0604, 041 (2006).

18. H. Baer, E. Park, X. Tata and T. Wang,Collider and dark matter searches in mod-els with mixed modulus-anomaly mediatedSUSY breaking, J. High Energy Physics0608, 041 (2006).


6.7. PUBLICATIONS OF THE THEORY GROUP

19. A. G. Akeroyd, X. Tata et al., Physics Inter-play of the LHC and the ILC, Phys. Rep.426, 47 (2006).

20. E. Golowich, S. Pakvasa and A. Petrov, NewPhysics contributions to the lifetime differ-ences in D0−D

0 mixing, Phys. Rev. Lett.98,181801 (2007).

21. J. Learned, S. Dye, S. Pakvasa and R. Svo-boda, Determination of neutrino mass hier-archy and θ13 with a remote detector of eac-tor antineutrinos, Phys. Rev. D 78, 071302(2008).

22. E. Golowich, J. Hewett, S. Pakvasa and A.Petrov, Implications of D0 − D

0 mixing fornew physics, Phys. Rev. D 76, 095009(2007).

23. S. Pakvasa, W. Rodejohann and T. Weiler,Triminimal Parametrisation of the neutrinomixing matrix, Phys. Rev. Lett. 100, 111801(2009).

24. S. Pakvasa, W. Rodejohann and T. Weiler,Flavor ratios of astrophysical neutrinos: im-plications of precision measurements, J. HighEnergy Phys. 0802, 005 (2008).

25. X-G. He and S. Pakvasa, Unparticle inducedbaryon number violating decay, Phys. Lett.B 662, 259 (2008).

26. S. Abe et al. (Kamland Collaboration), Preci-sion Measurements of neutrino oscillation pa-rameters with Kam LAND, Phys. Rev. Lett.100, 221803 (2008).

27. N. Sinha et al. Method for determining D0 −D

0 mixing parameters, Phys. Rev. Lett. 99,262002 (2007).

28. L. S. Kisslinger and S. Pakvasa, SN1987APulsar velocity from modified URCA processand Landau levels, arXiv:0802.1689.

29. J. Learned, S. Pakvasa and A. Zee, Galacticneutrino Communication, Phys. Lett. B 671,15 (2009).

30. J. Learned, R-P. Kudritzki, S. Pakvasa andA. Zee, The Cepheid Galactic Internet, Phys.Rev. Lett. (in press).

31. M. Batygov et al., Prospects of neutrino os-cillation measurements in the detection of re-actor antineutrinos with a medium baselineexperiment, arXiv:0810.2590, Phys. Rev. D(in press).

32. E. Golowich, J. Hewett, S. Pakvasa andA.Petrov, Relating D0−D

0 mixing and D0 →�+�− with new physics, arXiv:0903.2830,Phys. Rev. D (in press).

33. A. Lazopoulos, K. Melnikov, T. McElmurryand F. Petriello, Next-to-leading order QCDa corrections to ttZ production at the LHC,Phys. Lett. B 666, 62 (2008).

34. K. Melnikov, O(α2s) corrections to semilep-

tonic decays of b → c�ν�, Phys. Lett. B 666,336 (2008).

35. W. T. Giele, Z. Kunszt, K. Melnikov, Fullone-loop amplitudes from tree amplitudes,JHEP 0804 049 (2008).

36. A. Lazopoulos, K. Melnikov and F. Petriello,NLO QCD corrections to the production ofttZ in gluon fusion, Phys. Rev. D 77, 034021(2008).

37. T. Becher and K. Melnikov, Two-loop QEDcorrections to Bhabha scattering, JHEP0706, 084 (2007).

38. A. Lazopoulos, K. Melnikov and F. Petriello,QCD corrections to tri-boson production,Phys. Rev. D 76, 014001 (2007).

39. S. Biswas, K. Melnikov, The rotation of themagnetic field does not impact vacuum bire-fringence, Phys. Rev. D 75, 053003 (2007).

40. K. Melnikov and F. Petriello, Electroweakgauge boson production at hadron collidersthrough O(α2

s), Phys. Rev. D74, 114017(2006).

41. S. Alekhin, K. Melnikov and F. Petriello,Fixed target Drell-Yan data and NNLO QCDfits of parton distribution functions, Phys.Rev. D 74, 054033 (2006).



42. K. Melnikov, On the QCD corrections toVainshtein’s theorem for VVA correlator,Phys. Lett. B 639, 294-298, (2006).

43. G. Davatz, F. Stockli, C. Anastasiou, G. Dis-sertori, M. Dittmar, K. Melnikov andF. Petriello, Combining Monte Carlo gener-ators with next-to-next-to-leading order ca-clulations: event reweighting for Higgs bosonproduction at the LHC, J. High Energy Phys.0607, 037 (2006).

44. K. Melnikov and F. Petriello, The W bosonproduction cross-section at the LHC throughO(α2

s), Phys. Rev. Lett. 96, 231803 (2006).

45. R.K. Ellis, W.T. Giele, Z. Kunszt, K. Mel-nikov, Masses, fermions and generalized D-dimensional unitarity, arXiv:0806.3467.

Kumar’s publications prior to arrival in Hawaii

1. J. L. Feng, J. Kumar and L. E. Strigari, Ex-plaining the DAMA Signal with WIMPlessDark Matter, Phys. Lett. B 670, 37 (2008)[arXiv:0806.3746 [hep-ph]].

2. B. Dutta, L. Leblond and J. Kumar, TachyonMediated Non-Gaussianity, Phys. Rev. D 78,083522 (2008).

3. J. L. Feng and J. Kumar, The Wimpless Mir-acle: Dark-Matter Particles Without Weak-Scale Masses Or Weak Interactions, Phys.Rev. Lett. 101, 231301 (2008).

4. J. Kumar, A. Rajaraman and J. D. Wells,Probing CP-violation at colliders through in-terference effects in diboson production anddecay, Phys. Rev. D 78, 035014 (2008).

5. J. Kumar, Dynamical SUSY Breaking in In-tersecting Brane Models, Phys. Rev. D 77,046010 (2008).

6. J. Kumar, A. Rajaraman and J. D. Wells,Probing the Green-Schwarz Mechanism at theLarge Hadron Collider, Phys. Rev. D 77,066011 (2008)

7. B. Dutta, J. Kumar and L. Leblond, An Infla-tionary Scenario in Intersecting Brane Mod-els, JHEP 0707, 045 (2007)

8. B. Dutta and J. Kumar, Hidden sector baryo-genesis, Phys. Lett. B 643, 284 (2006).

9. J. Kumar and J. D. Wells, LHC andILC probes of hidden-sector gauge bosons,[arXiv:hep-ph/0606183].

Text Books and Monographs

1. H. Baer and X. Tata, Weak Scale Supersym-metry, Cambridge University Press (2006).

2. K. Melnikov and A. Vainshtein, Theory of themuon anomalous magnetic moment, SpringerTracts in Modern Physics, vol. 216 (2006).

Conference Publications

1. J. Kumar, “From DAMA/LIBRA To Super-Kamiokande,” arXiv:0903.1700 [hep-ph], Pro-ceedings of the Seventh International Heidel-berg Conference on Dark Matter in Astro andParticle Physics.

2. J. Kumar, Intersecting Brane Models andCosmology, e-Print: arXiv:0710.2141 [hep-th], SUSY07 Conf. Proceedings.

3. H. Baer and X. Tata, Dark matter and theLHC, Invited article to appear in a spe-cial volume commemorating the diamond ju-bilee of the Indian National Science Academy,A. Datta, B. Mukhopadhyaya and A. Ray-achaudhuri, Editors (Springer).

4. S. Pakvasa, D0−D0 mixing and new physics,

Proc. Workshop on High Energy Physics Phe-nomenology, Jan. 2008, Pramana, 22, 205(2009).

5. S. Pakvasa, Neutrino Flavor Goniometry byHigh Energy Astrophysical Beams, Poc. ofthe International Symposium on Cosmologyand Particle Astrophysics 2007, Taipei, Tai-wan, Mod. Phys. Lett. A 23, 1313 (2008).


6.7. PUBLICATIONS OF THE THEORY GROUP

6. S. Pakvasa, Non-standard neutrino oscilla-tions revisited, Proc. 12th InternationalWorkshop on Neutrino Telescopes, Venice,Ed. M. Baldo-Ceolin, Venice 2007, NeutrinoTelescopes, p. 477.

7. S. Pakvasa et al., Hanohano, A deep ocean an-tineutrino observatory, in Proc. ICHEP 2008,Philadelphia, Aug. 2008.

8. S. Pakvasa, Neutrino Properties from HighEnergy Astrophysical Neutrinos, “Challengesin Particle Astrophysics,” Proc. of Sixth Re-contres de Vietnam, Hawaii, Aug. 6-12, 2006,ed. J. Dumarchez and J. Tran Thanh Van,The Gioi Publishers (2006), p. 167.

9. S. Pakvasa, Neutrino Physics and Geophysicswith a Deep Ocean Antineutrino Observa-tory, Proc. of International Symposium onCosmology and Particle Astrophysics (CosPA2006), Taipei, Taiwan, 15-17 Nov. 2006, Mod.Phys. Lett. A22, 1887 (2007).


Curriculum Vitae

November 12, 2008

Thomas E. BrowderProfessor

Physics Department

Born: October 14, 1962Citizenship: American.Present Address: University of Hawaii at Manoa, Honolulu, HI, 96822Phone number: (808)-956-2936E-mail: [email protected]

Education:University of California (Santa Barbara) - PhD. Physics (1988)University of Chicago - B.S. Physics (1982)

Positions Held:Professor, University of Hawaii (August 2003-present)Co-spokesperson, Belle experiment (2004-present)Associate Professor, University of Hawaii (August 1999-August 2003).Analysis Coordinator, BELLE experiment (August 1998-2004).Assistant Professor, University of Hawaii (January 1994-August 1999).Analysis Coordinator, CLEO experiment (August 1993-August 1994).Research Associate, Cornell University (September 1989 - December 1993).Research Associate, SLAC (September 1988 to September 1989).Research Associate, UCSB (1998)

Awards and Honors:• Fellow of the American Physical Society 2004 Particles & Fields• Natural Sciences Faculty Performance Award 2000 University of Hawaii• Monbusho Fellowship 2000 KEK Laboratory, Japan• Monbusho Fellowship 1998 KEK Laboratory, Japan• Regents Scholar 1982 University of California• Bachelor of Science with Honors 1982 University of Chicago• Phi Beta Kappa 1981 University of Chicago

Thesis:• A Study of D0 − D0 Mixing.

PhD, University of California at Santa Barbara, 1988.

Teaching experience:Supervision of Graduate Students at Hawaii (B. Casey, F. Fang, Y. Li,S. Swain, Y.H.Zheng, N. Kent, K. Uchida, H. Sahoo, K. Nishimura)Topics in High Energy Physics (Physics 711)General Physics (Physics 151, 170, 272, 274L), Theoretical Mechanics (310, 311)

Recent Publications with Major Contributions

• T.E. Browder, T. Gershon, D. Pirjol, A. Soni and J. ZupanNew Physics at a Super Flavor Factory To appear in Reviews of Modern Physics

• T.E. Browder, M. Cuichini, T. Gershon, M. Hazumi, T. Hurth, Y. Okada and M.StocchiOn the Physics Case for a Super Flavor Factory JHEP 0802: 110 (2008)

• T.E. Browder,Why a Super B Factory is needed, Nucl. Phys. Proc. Suppl. 163: 198 (2007)

• T.E. Browder,Two Topics in Rare B Decays, Nucl. Phys. Proc. Suppl. 117: 198 (2007)

• T.E. Browder and A. Soni,Search for New Physics at a Super B Factory, hep-ph/04010192, Pramana 63, 1171(2004)

• T.E. Browder, I. Klebanov and D. Marlow,Prospects for Pentaquark Production at Meson Factories, hep-ph/0401115, Phys. Lett.B. 587, 62 (2004)

• T.E. Browder and R. Faccini,Establishment of CP Violation in the B Meson System Annual Review of Nuclear andParticle Science, Vol 53, (2003).

Publications with the Belle Detector:

• H. Sahoo, T. E. Browder et al. (Belle collaboration),Measurement of time-dependent CP violation in B0 → ψ(2S)KS decays Phys Rev D77, 091103 (2008)

• J. Li et al. (Belle collaboration),Time dependent CP asymmetries B → KSρ0γ Phys. Rev. Lett. 98, 211803 (2007).

• M. Staric et al (Belle collaboration),Evidence for D0 − D0 mixing, Phys. Rev. Lett. 98, 211803 (2007).

• F. Fang, T.E. Browder et al. (Belle collaboration),Search for the hc meson in B+ → hcK

+, hep-ph/0605007, Phys Rev D 74, 012007

(2006)

• S. Swain, T.E. Browder et al., Measurement of Branching Fractions Ratios and CPasymmetries in B± → DCP K±. Phys. Rev. D 68, 051101 (2003)

• Y-H. Zheng, T.E. Browder et al., Measurement of the B0 − B0 Mixing Rate withB0(B0) → D∗∓π+ Partial Reconstruction, Phys. Rev. D 67, 092004 (2003)

• F. Fang, T. Hojo et al., Measurement of B → ηcK(∗) Branching Fractions, hep-

ex/0208047, Phys. Rev. Lett. 90, 071801 (2003).

• K. Abe et al., Observation of Large CP Violation in the Neutral B Meson System,Phys. Rev. Lett. 87, 091802 (2001)

VITAXerxes Ramyar TATA

PERSONAL DATA

Date of Birth: April 27, 1954Place of Birth: Bombay, IndiaMarital Status: Married

EDUCATION

Bachelor of Science Bombay University, India 1974Master of Science Indian Institute of Technology 1976

Bombay, IndiaPh.D. University of Texas at Austin 1981

EXPERIENCE

Professor University of Hawaii at Manoa 1994-presentAssociate Professor University of Hawaii at Manoa 1988-1994Visiting Scientist KEK, Japan Sept. 1987-Feb. 1988Assistant Scientist University of Wisconsin at Madison 1986-1988Research Associate University of Oregon at Eugene 1985-1986Scientific Associate CERN, Geneva, Switzerland 1984-1985Research Scientist University of Texas at Austin 1984Research Associate University of Oregon at Eugene 1983-1984Lecturer in Physics University of Texas at Austin 1981-1982Research Associate University of Texas at Austin 1981-1983

FELLOWSHIPS

Fellow, American Physical Society (2001)

SCIENTIFIC SERVICE ACTIVITIES

1. Co-leader, Supersymmetry Subgroup for 1994-95 DPF Long Term Plan-ning Study.

2. Lecturer at 1995 Theoretical Advanced Study Institute, Boulder, Co-larado.

3. Co-convenor, SUSY Session at International Workshop on Physics andExperiment at Linear Colliders, Morioka-Appi, 1995.

4. Co-convenor, SUSY Working Group at Snowmass 1996.

5. Lecturer at the IX Jorge Swieca Summer School, Campos do Jordao,Brazil, 1997.

6. Lecturer at the KIAS School for Particle Physics, Seoul, S. Korea, 2001.

7. Lecturer at the International Workshop/School on Frontiers of HighEnergy Physics, Beijing, China (July, 2004).

8. Lecturer at the SLAC Summer Institute, SLAC, Menlo Park, U.S.A.(August, 2004).

9. Lecturer at the 20th Spring School on Particles and Fields, Taipei,Taiwan (April, 2007).

SELECTED PUBLICATIONS

TEXT BOOK

1. H. Baer and X. Tata, Weak Scale Supersymmetry: From Superfieldsto Scattering Events, Cambridge University Press (May 2006).

JOURNAL PUBLICATIONS

1. R.S. Hundi, S. Pakvasa and X.Tata, Addressing the µ − bµ and pro-ton lifetime problems and active neutrino masses in a U(1)′-extendedsupergravity model, Phys. Rev. D (in press).

2. H. Baer, E. Park and X. Tata, Collider, direct and indirect detectionof supersymmetric dark matter, arXiv:0903.0555, New J. Phys. (inpress).

3. A. Box and X. Tata, Threshold and flavor effects in the renormalizationgroup equations of the MSSM II: Dimensionful couplings, Phys. Rev.

D 79, 035004 (2009).

4. H. Baer, A. Mustafayev, E. Park and X. Tata, Collider signals and neu-tralino dark matter detection in relic-density-consistent models withoutuniversality, J. High Energy. Phys. 0805, 058 (2008).

5. H. Baer, E. Park, X. Tata and T. Wang, Collider and dark matter phe-nomenology of models with mirage unification, J. High Energy Phys.

0706, 033 (2007).

6. H. Baer, A. Mustafayev, E. Park and X. Tata, Target dark matterdetection rates in models with a well-tempered neutralino, J. Cosm.

and Astrophys. 01, 017 (2007).

7. H. Baer, A. Mustafayev, S. Profumo and X. Tata, Probing supersym-metry beyond the reach of LEP2 at the Fermilab Tevatron: Low |M3|dark matter models, Phys. Rev. D 75, 035004 (2007).

8. A. Akeroyd et al. Physics interplay of the LHC and ILC, Phys. Rep.426, 47 (2006)

9. H. Baer, T. Krupovnickas and X. Tata, Two photon background andthe reach of a linear collider for supersymmetry in WMAP favoredcoannihilation regions, J. High Energy Physics, 06, 061 (2004).

10. H. Baer, C. Balazs, A. Belyaev, T. Krupovnickas and X. Tata, Updatedreach of CERN LHC and constraints from relic density, b → sγ and aµ

in the mSUGRA model, J. High Energy Physics, 06, 054 (2003).

11. D. Auto, H. Baer, C. Balazs, A. Belyaev, J. Ferrandis and X. Tata,Yukawa coupling unification in supersymmetric models, J. High EnergyPhysics 06, 023 (2003).

12. J. Mizukoshi, X. Tata and Y. Wang, Higgs-mediated leptonic decaysof Bs and Bd mesons as probes of supersymmetry, Phys. Rev. D 66,115003 (2002).

13. H. Baer, C. Balazs, J. Ferrandis and X. Tata, Impact of Muon Anoma-lous Magnetic Moment on Supersymmetric Models, Phys. Rev. D64,035004 (2001).

14. H. Baer, M. Dıaz, P. Quintana and X. Tata, Impact of Physical Princi-ples at Very High Energy Scales on the Superparticle Mass Spectrum,JHEP 04, 016 (2000).

15. H. Baer, M. Dıaz, J. Ferrandis and X. Tata, Superparticle Mass Spectrafrom SO(10) Grand Unified Models with Yukawa Coupling Unification,Phys. Rev. D61, 111701(R) (2000).

16. H. Baer, P. Mercadante, F. Paige, X. Tata and Y. Wang, LHC Reach forgauge Mediated Supersymmetry Breaking via Prompt Photon Chan-nels, Phys. Lett. B435, 109 (1998).

17. H. Baer, C. H. Chen, M. Drees, F. Paige and X. Tata, Supersymmetryreach of Tevatron upgrades: The large tan β case, Phys. Rev. D58,075008 (1998).

18. M. Drees, S. Pakvasa, X. Tata and T. ter Veldhuis, A SupersymmetricResolution of Solar and Atmospheric Neutrino Puzzles, Phys. Rev.

D57, R5335 (1998).

19. H. Baer, C-H. Chen, M. Drees, F. Paige and X. Tata, Collider Phe-nomenology for Supersymmetry with Large tan β, Phys. Rev. Lett.

79, 986 (1997); 80, 642 (1998) (E).

20. H. Baer, R. Munroe and X. Tata, Supersymmetry Studies at FutureLinear Colliders, Phys. Rev. D54, 6735 (1997).

21. H. Baer, C-H. Chen, F. Paige and X. Tata, Signals for Minimal Super-gravity at the CERN Large Hadron Collider II: Multilepton Channels,Phys. Rev. D53, 6241 (1996).

22. H. Baer, C-H. Chen, F. Paige and X. Tata, Signals for Minimal Su-pergravity at the CERN Large Hadron Collider: Multijet plus MissingEnergy Channel, Phys. Rev. D52, 2746 (1995).

23. H. Baer, C. Chen, F. Paige and X. Tata, Detecting Sleptons at HadronColliders and Supercolliders, Phys. Rev. D49, 3283 (1994).

24. Probing Charginos and Neutralinos Beyond the Reach of LEP at theTevatron Collider, H. Baer and X. Tata, Phys.Rev. D47, 2739 (1993).

25. R. Godbole, P. Roy and X. Tata, Tau Signals for R-Parity Breaking atLEP 200, Nucl. Phys. B401, 67 (1993).

26. Observability of γγ Decays of Higgs Bosons from Supersymmetry atHadron Supercolliders, H. Baer, M. Bisset, C. Kao and X. Tata, Phys.Rev.

D46, 1067 (1992).

27. Multi-lepton Signals from Supersymmetry at Hadron Super Colliders,H. Baer, X. Tata and J. Woodside, Phys. Rev. D45, 142 (1992).

28. Detecting Gluinos at Hadron Super Colliders, H. Baer, V. Barger,D. Karatas and X. Tata, Phys. Rev. D36, 96 (1987).

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