Date post: | 21-Dec-2015 |
Category: |
Documents |
View: | 216 times |
Download: | 0 times |
DOE Germantown, June 23, 2005 1 of 25
Saltdome Shower Array (SalSA)
A GZK Neutrino Detector For High Energy Physics & Particle Astrophysics
David Saltzberg (UCLA)
Peter Gorham (University of Hawaii at Manoa)
Gary Varner (University of Hawaii at Manoa)
representing the SalSA collaboration
DOE Germantown, June 23, 2005 2 of 25
SALSA Collaboration
Kernfysisch Versneller Instituut (Netherlands)
Deutsches Elektronen Synchrotron (Germany)
Louisiana State University
University of Kansas
University of Utah Endeavour Corporation
University of Delaware University of Hawaii U.C.L.A. S.L.A.C. and Stanford University
Ohio State Univesity UC Irvine
UC Berkeleyand LBNL
University of Minnesota
UT Austin
Washington University
DOE Germantown, June 23, 2005 3 of 25
Livingston (via Panofsky) Plot
UHE Cosmic Rays don’t go on plot because cross-section already saturated
UHE neutrino cross section is 10-7 protons room for new physics enhancements
LHC
SalSA (ECM~100 TeV)
2010
1 PeV
1 EeV
ILC
How do weenter this region?
DOE Germantown, June 23, 2005 4 of 25
Particle Physics at the Energy Frontier
High energy can be a energy-frontier beam:
15-150 TeV center of momentum particle physics
Beyond LHC search for large extra dimensions micro-black-hole production TeV strings
Std. model
Large extradimensions
Anchordoqui et al. Astro-ph/0307228
GZK
DOE Germantown, June 23, 2005 5 of 25
A “GZK neutrino beam”must be available
Neutrinos at 1017-19 eV required by standard-model physics
Whatever Auger finds, GZK neutrinos must be there.
sees cutoffour standard flux calculationdoes not see cutoff sources are local, probably even more neutrinos (possibly, topological defects!)It’s iron Neutrinos from spallation neutrons must be there.
galactic
extragalactic
DOE Germantown, June 23, 2005 6 of 25
Where we might be in just 5 years…
ANITA:Discovery of ~10 GZK
neutrinos
IceCubeDiscovery of bottom-up sourcesDiscovery of ~ 3 GZK neutrinos
AugerDiscovery of a few GZK neutrinos ?
DOE Germantown, June 23, 2005 7 of 25
!
Why we are here today
Auger: Tau neutrino decay events ~1 GZK event per year?
SalSA sensitivity, 3 yrs live 70-230 GZK neutrino events
ANITA sensitivity, 45 days total:~5 to 30 GZK neutrinos
IceCube: high energy cascades ~1.5-3 GZK events in 3 years
A large sample of GZK neutrinos using radio antennas in a 12£ 12 array of boreholes natural Salt Domes
DOE Germantown, June 23, 2005 8 of 25
Probing an extreme regimefor particle physics
l,
p
nucleon
xp
Extreme regime: More likely to scatter off of bottom sea than down valence.
GZK
This is not HERAHERA tests proton structure to x~10-4 (& only 10-2 at “high” Q2)UHE probe proton structure to x~10-8 at high Q2
DOE Germantown, June 23, 2005 9 of 25
Measuring cross sectionup to ECM=150 TeV
30% Cross Section measurement with SalSA easily achievable using Earth as a filter near horizon
Not dependent on GZK shape or absolute intensity
Angular resolution even for non-contained events is sufficient.
Anomalous cross sections from large extra dimensions etc. at Ecm=150 TeV would be clearly visible.
DOE Germantown, June 23, 2005 10 of 25
Particle Physics in Neutrino Sector
GZK neutrinos are the “longest baseline” neutrino experiment:
Longest L/E (proper time) for: extra admixtures & anomalous decays
SUN: L/E ~ 30 m/eVGZK: L/E ~ 109 m/eV
Measured flavor ratios of e::can identify non-standard physics at source
e::
! (5-6):1:1
Neutrino decay leaves a strong imprint on flavor ratios at Earth
DOE Germantown, June 23, 2005 11 of 25
Neutrinos for Astroparticle physics: The only useful messengers >100 TeV
Photons lost above 30TeV: pair production on IR & wave background Protons & Nuclei:
scattered by B-fields or GZK process at all energiesBut the sources extend to 109 TeV
If not particle physicists, who? 7 orders of magnitude of energy will remain unexplored.
at
tenu
atio
n le
ngth
(M
egap
arse
cs)
scale size of Local Group
Every new energy band yields major discoveries
domain of neutrinodominance
IR,CMB,URB ! e+ + e-
DOE Germantown, June 23, 2005 12 of 25
How to go beyond km3
Neutrinos by cosmic accelerators: IceCube et al.Volume £ solid-angle ~ 10 km3-sr~3 GZK neutrino events over lifetimeSize determined by atten ~ 100m and cost.
GZK neutrinosEssentially guaranteed to be thereNeed Volume £ solid-angle approaching 1000 km3-sr (Teraton) Need a detection with atten~500m (w.e.)
DOE Germantown, June 23, 2005 13 of 25
The Askaryan Effect
UHE event will induce an e/ shower:
In electron-gamma shower in matter, there will be ~20% more electrons than positrons.
Compton scattering: + e-(at rest) + e-
Positron annihilation: e+ + e-(at rest) +
lead
e-
dddPCR In solid material RMoliere~ 10cm.
>>RMoliere (microwaves), coherent P N2
DOE Germantown, June 23, 2005 14 of 25
Heritage of PIs’ Related Experiments
GLUEGoldstone, radio telescopes and the Moonfirst limits on >100 EeV neutrinospublished Phys. Rev. Lett. (2004)
FORTESatellite observations of Greenland icepublished in Phys. Rev. D (2003)
ANITABalloon borne observations of Antarctic iceFirst data from Anita Lite (2003)Best limits on >10 EeV neutrinosto be submitted to Physical Review letters
Accelerator measurementsArgonne and SLACAttracted scientists to the techniquePublished in Phys. Rev. Lett. (2001)+to appear in Phys. Rev. D (2005)
Salt Dome Measurementsin situPublished in NIM (2002)
DOE Germantown, June 23, 2005 15 of 25
Funding Heritage
DOE Funding (1999-2005...) made GLUE, Forte, ANITA, Accelerator Experiments, and Salt Dome Measurements possible:
DOE OJI (Outstanding Jr. Investigator awards) Saltzberg and Gorham
DOE ADRP (Advanced Detector Research Program)
DOE University Programs (tasks originated with OJI’s)
NASA Research Opportunities in Space Science (for ANITA)
University intramural support (UH, UCLA, Caltech President’s Fund)
DOE Germantown, June 23, 2005 16 of 25
Accelerator Characterization of Askaryan Effect
200 cm 0 cm
DOE Germantown, June 23, 2005 17 of 25
Radio Coherence:Quadratic Growth + Absolute
Intensity
Shows amplitude expected from detailed simulations (egs/ Geant + Maxwell’s equations)
GZK
DOE Germantown, June 23, 2005 18 of 25
Ultra-wideband data on Askaryan pulse
2000 & 2002 SLAC Experiments confirm extreme coherence of Askaryan radio pulse
60 picosecond pulse widths measured for salt showers. Unique signal reduces background, simplifies triggering, excellent timing for reconstruction.
DOE Germantown, June 23, 2005 19 of 25
SalSA SimulationsCurrently on third generation of several independently developed simulations
GLUE (Goldstone)
ANITA (Antarctic Impulsive Transient Antenna)
SALSA simulations...
DOE Germantown, June 23, 2005 20 of 25
SalSA simulations
A 2.5 km3 array with 225 m spacing, 122=144 strings, 123=1728 antenna nodes, 12 antennas per node, dual polarization ==> Veff ~400 km3 sr w.e. at 1 EeV
Threshold <1017 eV, few 100s antennas hit at 1 EeV, >1000 hits at 10 EeVRate: at least 20 events per year from rock-bottom minimal GZK predictions
DOE Germantown, June 23, 2005 21 of 25
Angular resolution
For GZK energies:0.1o achieved for contained events--inside the array1o achieved for external events 250 m outside of array
DOE Germantown, June 23, 2005 22 of 25
Cherenkov polarization tracking
Radio Cherenkov: polarization measurements are unique
•Cherenkov radiation is 100% linearly polarized
DOE Germantown, June 23, 2005 23 of 25
Neutrino Flavor/Current ID
Simulations show NC/CC and Flavor ID to be effective on large subset of SalSA events80-90% efficiency on neutral vs. charged-current selection above 1 EeV30-50% of CC events will get first-order flavor ID above 1 EeV
~2 km
1018 eV
e,, Neutral Currents (19%)
Single Deep-Inelastic Hadronic Shower
e Charged Current (27%)
EM shower at primary vertexL.P.M. elongation
Charged Current (27%)
2ndary showers: - brem & p.p. - photonuclear
Charged Current (27%)
2ndary showers: - mainly photonuclear
DOE Germantown, June 23, 2005 24 of 25
Existing Neutrino Limits and Potential Future Sensitivity
RICE limits for 3500 hours livetime
GLUE limits 123 hours livetime
ANITA sensitivity, 45 days total: ~5 to 30 GZK neutrinos
IceCube: high energy cascades ~1.5-3 GZK events in 3 years
Auger: Tau neutrino decay events ~1 GZK event per year?
SalSA sensitivity, 3 yrs live 70-230 GZK neutrino events
Salsita: 4 strings 3 events per year
Salsita 3 years
DOE Germantown, June 23, 2005 25 of 25
Plan of Attack
First Proposal (~$4M, see next half of talk)Need to confirm
O(1km w.e.) attenuation lengthlow noise environmentoperability of hardware
PlanSingle borehole in 3-4 candidate domes + analysisAdd 2 more boreholes to measure propagationFor best dome, add 4th borehole A simple 4-borehole prototype array will see 2-3 events/year from minimal GZK models
Second Proposal ($50-100M)the full 12£ 12 array; built out from the prototype.
DOE Germantown, June 23, 2005 26 of 25
continued by Gorham (Part II)...
BACKUP SLIDES FOLLOW
DOE Germantown, June 23, 2005 27 of 25
Neutrino interactions in theStandard Model
n p
e
e
n p
W
/E/E0.36
Ghandhi, Quigg, Reno, Sarcevic
DOE Germantown, June 23, 2005 28 of 25
Particle Astrophysics/Cosmology
Cosmic ray Emax, the maximum acceleration energy
UHECR flux vs. redshift to z = 15-20 (eg. WMAP early bright phase)
Independent sensitivity to dark energy density,
Exotic (“Top-down”) sources; GUT-scale decaying particles from big-bang relics
DOE Germantown, June 23, 2005 29 of 25
Heritage from other SALSA collaborators
SALSA collaborators have a range of relevant experienceGenerally mid-career, active, accomplished, and experienced
Amanda (optical detection in Antarctic Ice) & IceCubeRICE (radio detection from within Antarctic ice)Auger (distributed cosmic-ray detectors)SAUND and other acoustic detection measurementsDecades of experience with Oil Drilling industry Several decades of balloon-borne cosmic-ray experimentsTheory and calculation of Askaryan EffectDecades of experience with Oil Drilling industryAccelerator-based, frontier particle physicsGamma-ray astronomyTwo U.S. National LabsSignificant European interest
DOE Germantown, June 23, 2005 30 of 25
Neutrinos: The only useful messengers at >PeV energies
Photons lost above 30 TeV: pair production on IR & wave background Charged particles: scattered by B-fields or GZK process at all energiesBut the sources extend to 109 TeV !
Conclusion: Study of the highest energy processes and particles throughout the universe requires PeV-ZeV neutrino detectors
Region not observableIn photons orCharged particles
DOE Germantown, June 23, 2005 31 of 25
GZK neutrino sensitivity details, 1 yr
2 independent MC calculations: UCLA & UH
UCLA: Saltzberg 2002 SPIE; also 2005 Nobel symposium
Simplified 10x10 strings, 10 antenna nodes per stringDid not truncate dome, so high energies extended
UH: Gorham et al. Phys.Rev. D 2005, in press
12x12 strings, 12 nodes with realistic trigger sims, salt dome truncatedLower trigger thresholdEven 4-string array sees GZK events in 1 year!
DOE Germantown, June 23, 2005 32 of 25
Neutrino interactions in theStandard Model
n p
e
e
n p
W
/E/E0.36
Ghandhi, Quigg, Reno, Sarcevic
DOE Germantown, June 23, 2005 33 of 25
Topological Defects
Possible “relic” particles (dubbed X) due to symmetry breaking phase transitions in the early Universe:
Masses at the GUT scale (MX~1025 eV).
By why don’t these decay in 10-40 sec?Confine in “topological defects” stable until destroyed/ annihilate
NO COSMIC ACCELERATOR NEEDED: “top-down” scenarioX jets mesons neutrinosX leptons or even all neutrinos
DOE Germantown, June 23, 2005 34 of 25
Topological Defects
Some specific modelsBhattacharjee, Hill, Schramm PRL 69, 567, (1992)Protheroe & Stanev PRL 77,3708 (1996)Sigl, Lee, Bhattacharjee, Yoshida PRD 59,043504 (1998)Barbot, Drees, Halzen, Hooper, PLB 555, 22 (2003)
Basic ideasWere attractive to circumvent GZK cutoff for UHE cosmic rays.Topological defects could be monopoles, superconducting cosmic strings, domain wallsGenerally these models produce hard neutrino spectrum: ~ E-(1-1.5)
“bottom-up” scenarios are more steeply falling: E-2 to E-4
not ruled out by lower energy telescopesconstrained by MeV—GeV isotropic photon fluxes
Neutrino flux vs. energy sensitive to source evolution vs. z of TD’s.
DOE Germantown, June 23, 2005 35 of 25
Neutrino Telescopes for Direct Monopole Detection
Monopoles:Dirac: The presence of even one monopole explains electric charge quantizationMonopoles are typically part of GUTsMasses typically of order GUT scalebut in some models Mmp could even be as low as ~1014 eV.
Observation of monopoles would be revolutionary for HEPParker bound (10-15 cm-2 s-1 sr-1)
c.f. UHECR>1020 eV (~10-21 cm-2 s-1 sr-1)other direct MP searches barely approach Parker boundCaveat: if monopoles catalyze proton decay then (lack of) neutron star heating provides extremely strong limit.
DOE Germantown, June 23, 2005 36 of 25
Neutrino Telescopes for Direct Monopole Detection
Intergalactic magnetic fields sheets (~100 nG over 50 MPc) could accelerate monopoles to energies of ~5£1024 eVLight monopoles would be relativistic so are candidates for radio Cherenkov detectionParker bound (10-15 cm-2 s-1 sr-1)
c.f. UHECR>1020 eV (~10-21 cm-2 s-1 sr-1)other direct MP searches, generally worse than Parker bound
Relativistic monopoles mimic particle with large charge: at least Z~68produce EM showers along path by pair-production, photo-nuclearcontinuously produces shower along its path unique signature
WKW estimate F<10-18 cm-2 s-1 sr-1 for a km3 detector for 1 year.SalSA could do much better: sensitive for Mmp up to 1023 eV, far beyond production at accelerators.
Flux limit better than typical searches
DOE Germantown, June 23, 2005 37 of 25
Polarization tracking
Measured with dual-polarization embedded bowtie antenna array in salt
DOE Germantown, June 23, 2005 38 of 25
Estimated SalSA Energy threshold
Ethresh < 300 PeV (3 x 1018 eV) best for full GZK spectral measurement
Threshold depends on average distance to nearest detector and local antenna trigger voltage above thermal noise
Vnoise = k T f
Tsys = Tsalt+Tamp = 450K
f of order 200 MHz
225 m spacing gives 30 PeVMargin of at least 10£ for GZK neutrino energies