1
Super muon-neutrino beam
Takashi Kobayashi
IPNS, KEK
Fact02July 1, 2002Imperial CollegeLondon
Contents1. Introduction2. “Super-beam” long baseline experiments3.Physics sensitivity4.Summary
2
Next goals of LBL experiments Establish 3 flavor framework (or find something new)
Discovery of e appearance (13>0?) At the same m2 as disapp. Firm evidence of 3gen. mix. Open possibility to search for CPV
Confirmation of
Appearance NC measurement
Precision measurements of ocs. params. m23,23/m13,13
Test exotic models (decay, extra dimensions,….)
Sign of m2
Search for CPV in lepton sector Give hint on Matter/Anti-matter asymmetry in the universe
3
What’s super muon-neutrino beam?
ProtonBeam
Target FocusingDevices
Decay Pipe
Beam Dump
,K
Pure beam ( 99%)≳e ( 1%) from ≲ e chain and K decay(Ke3)
/ can be switched by flipping polarity of focusing device
““Conventional” neutrino beam productionConventional” neutrino beam production
with MW-class proton beam
For high precision LBL experiments
4
“Super beam LBL experiments”≈ “2nd generation LBL experiments
w/ high intensity conventional beam” High statistics
Beam intensity 100kW ≲ MW (super beam)≳ AND/OR detector mass ~10kt 100~1,000kt
Designed and optimized after the knowledge of Super-Kamiokande/K2K results
Primary goal: e app. CPV, sign of m2
Japan: JHF(off-axis)SK/HK FNAL: Off-axis NuMI, Proton driver upgrade, BNL: Super AGS(off-axis)? CERN: SPLFurejus, Off-axis CNGS
5
Next critical pathe appearance
SignalSignal
Single EM shower
BackgroudBackgroud
e
1. Beam intrinsic e contaminationIdentical signature w/ signalDifferent energy distribution
2. NC 0 production
3. NC multi pion production
x0
x
x
6
Key for e appearance experiment High statistics Small background contamination (beam)
intrinsic e short decay pipe,… off-axis, … less high energy tail less inelastic
Background rejection (beam+detector) event topology (e⇔0) narrow spectrum beam w/ neutrino energy reconstruction additional kinematical constraint
Small systematic error on background estimation near/far spectrum difference cross section detector response
7
High intensity narrow band beam-- Off-axis (OA) beam --
(ref.: BNL-E889 Proposal)
TargetHornsDecay Pipe
Far Det.
Decay Kinematics
Increase statistics @ osc. max.Decrease background from HE tail
1/~ E(GeV)
E(GeV)
E(
GeV
)
5
12
]mrad[
30]GeV[max
E
flux
8
Charged current cross sections
CCqe (+n+p)
InelasticNC0
multi ….
CCqe dominate 1GeV≲Inelastic dominate 1GeV≳
Backgroud
9
Background rejection Event topology
0: for example, additional EM activity? vertex displacement ( flight) angular distribution
intrinsic beam e: no way
E distribution Signal peaked at osc. max. Fake “e” event by 0&beam e broad
OA2deg@JHF
e
Typical OA spectrum
10
E reconstruction
≲1GeV 2-body kinematics
of dominant CCqe Water Ch. works well
≳1GeV Inelastics (nuclear resonances) dominate (Fine grain) sampling calorimeter. Resolution? Full reconstruction of secondary particles?
11
reconstruction ≲1GeV region
CC quasi elastic reaction
cos
22
pEm
mEmE
N
N
+ n → + p
-
p
(E, p)
+ n → + p +
-
p
(E, p)
CCqe
Inelastic (BG)
CCqe
inelastic~80MeV(10%)limited by Femi motionSmall BG
SK FullDet. Sim.
12
Syst. error: far/near spectrum diff.Typical OA beam(80mDV)
280m
295km
K2K case (MC)
FD(300m)(xLSK
2/LFD2)
SK
Important not only for disappearance,but also for sig/BG estimation for e search
Large(~x2) effectaround peak!!
13
(“super-beam”) LBL experiments
Ep(GeV)
Power
(MW)Beam
〈 E
〉(GeV)
L
(km)
Mdet
(kt)
CC
(/yr)
e
@peak
K2K 12 0.005 WB 1.3 250 22.5 ~50 ~1%
MINOS(LE) 120 0.41 WB 3.5 730 5.4 ~2,500 1.2%
CNGS 400 0.3 WB 18 732 ~2 ~5,000 0.8%
JHF-SK 50 0.75 OA 0.7 295 22.5 ~3,000 0.2%
JHF-HK 50 4 OA 0.7 295 1,000 ~600,000 0.2%
OA-NuMI 120 0.3 OA ~2 730? 20kt? ~1,000? 0.5%
OA-NuMI2 120 1.2 OA ~2 730? 20kt? ~4,000? 0.5%
AGS?? 28 1.3 WB/OA ~1 2,500? 1,000? ~1,000?
SPL-Furejus 2.2 4 WB 0.26 130 40(400) 650(0) 0.4%
OA-CNGS 400 0.3 OA 0.8 ~1200 1,000? ~400 0.2%The plans are in very different phases. Most are in optimization phase.JHF-SK most advanced
budget request submittedEXISITING real detector
14
JHF-Kamioka Neutrino Project
~1GeV beamKamiokaJAERI
(Tokaimura)
0.77MW 50 GeV PS
( conventional beam)
Super-K: 22.5 kt
4MW 50 GeV PS
Hyper-K: 1000 kt
Phase-I (0.77MW + Super-Kamiokande)Phase-II (4MW+Hyper-K) ~ Phase-I 200
Plan to start in 2007(hep-ex/0106019)
15
Principle of JHF-Kamioka project Intense Narrow Band Beam by “off-axis”. Beam energy is at the oscillation maximum.
High sensitivity, less background ~1 GeV beam for Quasi-elastic interaction.
E(reconstruct) – E (True) (MeV)
=80MeV
E(
reco
nst
ruct
)
E (True)
events
16
JHF Facility
Construction2001~ 2006 (approved)
JAERI@Tokai-mura(60km N.E. of KEK)
Super Conductingmagnet for beam line
Near detectors@280m and@~2km
1021POT(130day)≡ “1 year”
(0.77MW)
Budget Request of the beam line submitted
17
Expected spectrum
e contamination
0.21%
K-decay
-decay
Very small e/
@ peak~4500 tot int/22.5kt/yr~3000 CC int/22.5kt/yr
OA3°OA2°OA1°
Osc. Prob.=sin2(1.27m2L/E)
m2=3x10-3eV2
L=295km
osc.
max
.
18
Detectors at near site Muon monitors @ ~140m
Behind the beam dump Fast (spill-by-spill) monitoring of beam direction/intensity
First Front detector “Neutrino monitor” @280m Intensity/direction Neutrino interactions
Second Front Detector @ ~2km Almost same E spectrum as for SK Absolute neutrino spectrum Precise estimation of background Investigating possible sites
1.5km
295km
0.28km
Neutrino spectra at diff. dist
280m
19
Far Detectors
48m × 50m ×500m,
Total mass = 1 Mton
40m
41.4m
1st Phase (2007~, ≥5yrs)Super-Kamiokande(22.5kt)
2nd Phase (201x~?)Hyper-Kamiokande(~1Mt)
20
USA: FNAL and BNL plan BNL: Super AGS (1.3MW, LOI submitted) FNAL: Super NUMI (1.6 MW) or the new proton
driver.
Off-axis beams + 2 detectors
100kmFNAL BNL
Soudan
Homestake
WIPP
(hep-ex/0205040,0204037,hep-ph/0204208)
21
OA-NuMIA. Para, M. Szleper, hep-ex/0110032
Osc. max. @ 730km1.8GeV (m2=3x10-3eV2)
K decay0.78deg
FeaturesNuclear resonance region Inelastic background Energy reconstruction?Too large angle Kaon peakBeam goes 3.5deg downward hard to place 2nd near det. Far/near ratio? Para/Szleper’s prescription using Matrix (hep-ex/0110001)
22
Europe: SPLFurejusG
enev
e
Italy
130km
40kt400kt
CERN
SPL @ CERN2.2GeV, 50Hz, 2.3x1014p/pulse 4MWNow under R&D phase
23
DetectorsUNO
(400kton Water Cherenkov)Liquid Ar TPC(~100kton)
24
Physics Sensitivity
25
e appearance in JHF-Kamioka (phase 1)
e0
1.8 events 9.3 events 11.1 events
123.2 events @ sin2213=0.1, m2=3×10-3eV2
Backgrounds
Signal
(5 years running)
2626
ee appearance (continue) appearance (continue)
sin22e=0.05 (sin22e 0.5sin2213)
3×10-3
×20 improvement
CHOOZ
sin22e =1/2sin2213
m2
sin2213<0.006 (90% C.L.)
27
disappearance
1ring FC -like
Non-QE
(log)m2=3×10-3
sin22=1.0
~3%
m2
sin22
sin22m
2eV2
Oscillation with m2=3×10-3
sin22=1.0
Reconstructed E (MeV)
(sin22) OAB-2degree
0.01
True m2
sin22
310-3
28
Sensitivity(3) to CPV(2nd phase)
Chooz excluded@m31~3x10-3eV2
>~27deg
>~14deg
Preliminary
4MW,1Mt2yr for
6.8yr for
JHF1 3 discovery
29
US Super beam• They are studying the physics potential of
several options, which are competitive to JHF-Kamioka project.
CHOOZNUMI-offaxis
|Ue3|2 =1/4sin2213 0.003
30
Possibility to discriminate sign of m2 (Matter effect)
Small matter effect in JHF-SK (~1GeV-295km)
Other longer baseline projects could play complementary role
OA-NuMI MC study
m232true=+
(m2)sol=10-7eV2
sin2sol=0.25sin2atm=0.5
hep-ex/0206025
3
For example,~5yrs of OA-NuMIx20kt(w/ proton driver)
Running time:~1:3(cross sec. diff)
31
Summary Exciting topics in 2nd generation LBL experiment
s. ne appearance CPV, sign of m2, ……
Several “super-beam” experiments are under consideration US, Europe and Japan They are in very different stages.
Earliest beam is expected in 2007 at JHF-Kamioka project Accelerator construction started in 2001. Budget request for facility submitted this year.
32
Summary (II) Physics sensitivity of JHF-Kamioka project
sin213≤0.006 (90%CL) (m2) 3%, ≲ (sin223)~1% can discover CPV if 20≳ o (in 2nd phase)
Experiments are complementary each other JHF-Kamioka hard to see matter effect Longer baseline/higher energy experiments
Fact will come after the (at least) 1st round of super-beam experiments (10~20yrs) If sin213 0.01, JHF-SK may not see, but JHF-HK may.≲ But sensitivity to CPV in JHF-HK reduces CPV in Fact?
33
Future ProspectFuture Prospect
JHF1
sin2213>0.018?
JHF2CPVprecision meas. 13
Proton decay
JHF2Search 13 <10-3
Proton decay
2007
201x
2002 : JHFn budget request&approval2003 : start construction2005 : K2K final results
Future SuperBeam, VLBL, -fact for very small 13, CPV, sign of m220xx
3 discovery
Hint?
3434
(Super) Neutrino Beams(Super) Neutrino Beams<E<E>>(GeV)(GeV)
LL
(km)(km)#CC#CC
/kt/yr/kt/yrL/LL/Losciosci..** f(f(ee) @pe) @pe
akak
K2KK2K 1.31.3 250250 22 0.470.47 ~1%~1%
NuMi (High E)NuMi (High E) 1515 730730 31003100 0.120.12 0.6%0.6%
NuMi (Low E)NuMi (Low E) 3.53.5 730730 469469 0.510.51 1.2%1.2%
CNGSCNGS 17.717.7 732732 24482448 0.100.10 0.8%0.8%
JHF-IJHF-I 0.70.7 295295 133133 1.021.02 0.2%0.2%
Numi off-axisNumi off-axis 2.02.0 730730 ~80~80 0.890.89 0.5%0.5%
JHF-IIJHF-II 0.70.7 295295 691691 1.021.02 0.2%0.2%
SPLSPL 0.260.26 130130 16.316.3 1.211.21 0.4%0.4%
3535
FNAL, BNL to SoudanFNAL, BNL to Soudan
Water Cherenkov like Super-KWater Cherenkov like Super-K
Even
ts/0
.1G
eV
/5years
/10
0kTon
Even
ts/0
.1G
eV
/5years
/10
kTon
1 off-axis
x
36
3. Experiments with the super neutrino beam
37
Contents
1. Introduction2. Physics goals of next generation long baselin
e experiments3. Super-beam experiments4. Physics potential of super-beam experiments5. Comparison with Fact6. Open questions7. Summary
38
Far/near spectrum ratio
0.28km 0.5km
1.0km 1.5km 2.0km
0 1 3 5 (GeV)
2
2
)(
)(
nearnear
farfar
LE
LE
Decay pipe len.LDV=80m
want near det.@ 10≳ xLDV
3939
Sensitivity for Mixing AngleSensitivity for Mixing Anglesi
n22
e s
en
sitiv
ity
~JHF2-HK 1yr
4040
→→ confirmation w/ NC interactionconfirmation w/ NC interaction
NC 0 interaction ( + N → + N + 0) e CC + NC(~0.5CC) ~0 (sin22e~0)
CC + NC(~0.5CC) ~0 (maximum oscillation) NC
#0 is sensitive to flux. Limit on s (f(s)~0.1)
s
=390±44#0 +
#e-
lik
e
m2323.510-3
CC
NC
4141
(High Intensity) Proton Accelerators(High Intensity) Proton Accelerators
Power(MW)
Energy(GeV)
Intensity(1012 ppp)
Rep. rate(Hz)
KEK-PS 0.005 12 6 0.45
AGS 0.14 24 60 0.6
FNAL-MI 0.41 120 40 0.53
SPS 0.3 400 35 0.16
JHF-I 0.77 50 330 0.29
Super-AGS 1.3 28 120 2.5
FNAL-proton driver-I
1.2 16 30 15
SPL 4 2.2 230 50
JHF-II 4 50
Not the construcion stage yet, but R&D stage.
42
Some ideas for OA-NuMI detector(under consideration)
1m
Plastic pellets +RPC (A.Para)
70ton/plane
20m
20m
SOMINOS(Fe+Sci) Szleper+Velasco
5kt, 12m dia., 875planes
43
Super Proton Linac (SPL) @ CERN
H-
RFQ RFQ1 chop. RFQ2 RFQ1 chop. RFQ2 0.52 0.7 0.8 dump
Source Low Energy section DTL Superconducting section
45 keV 3 MeV 120 MeV 2.2 GeV
40MeV 237MeV
11.5 m 55 m 584 m
PS / Isolde
Stretching andcollimation line
Accumulator Ring
Debunching
383MeV
665 m
DTL CCDTLchopping
Parameter Value Unit Mean beam power 4 MW Kinetic energy 2.2 GeV Repetiton rate 50 Hz Pulse duration 3.3 s Pulse intensity 2.27 1014 p/pulse
Under R&D phase
Reuse some parts from LEP