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1
Future Neutrino Physics at JHF
Takashi KobayashiIPNS, KEKDec. 5, 2000
PS External Review @ KEK
Contents1. Introduction2. JHF ν experiment3. Physics Sensitivity4. Future Extensions5. Summary
2
Y.Itow, Y.Obayashi, Y.Totsuka (ICRR)Y.Hayato, H.Ishino, T.Kobayashi, K.Nakamura, M.Sakuda
(KEK)T.Hara (Kobe)
T.Nakaya, K.Nishikawa (Kyoto)T.Hasegawa, K.Ishihara, A.Suzuki (Tohoku)
A.Konaka (TRIUMF)
JHF Neutrino Working Group
Dec.99: Working group formed.Mar.00: Letter of Intent prepared (http://neutrino.kek.jp/jhfnu)Now : Working to prepare a proposal
3
Neutrino Oscillationilil U νν Σ=Neutrino Mixing
Weakeigenstates
Masseigenstates
Maki-Nakagawa-Sakata Matrix
−⋅
⋅
−⋅
−=
=
−1313
1313
2323
23231212
1212
321
321
321
0010
0
00010001
00
001
10000
cs
sc
ecssccs
sc
UUUUUUUUU
Ui
eee
δτττ
µµµ
Oscillation Probability
( ) ( ) ( ) ( )∑<
→
∆−−⋅⋅−==
ji
ijljmjlimimllmml L
Em
iUUUUtP2
exp1Re202
**2δνν
seigenvalue mass: , energy, neutrino: length,flight : 222ijiij mmmmEL −≡∆
Pl m≠δml ⇔ ∆mij ≠0LFV
sij=sinθij, cij=cosθij
4
Oscillation probabilities
( )νµ θθ EmP atme /27.1sin2sinsin 2213
223
2 ∆⋅⋅≈→
( )ντµ θθ EmP atm /27.1sin2sincos 2223
213
4 ∆⋅⋅≈→
)(1 sterileex PPPP →→→→ ++−= µτµµµ
( )νθ EmP atmxe /27.1sin2sin1 2213
2 ∆⋅−≈→
contribution from ∆m12 is small
ννννe appearance
ννννµµµµ disappearance
~~~~0.5
Cf. Chooz (ννννe disappearance)
~~~~1
⋅∆≈
∆≡∆≈∆<<∆
LmEmmmm
atm
atm2
2213
223
212
ν
when
Neutral Current (NC) measurementsterileactiveNC PPN →→ −=∝ µµ 1
eµθ2sin2
12
3
∆matm2
5
CP violation
∆−
∆+
∆×
⋅⋅=→
ELm
ELm
ELm
CPVP e
2sin
2sin
2sin
cos)2sin2sin2(sinsin)(231
223
212
12132312 θθθθδµ
LMA solution for solar neutrino∆m12~10-4eV2, sin2θ12~0.8
θ13 is non zero
CPV effect in lepton sector could be detectable
No CPV in disappearance from unitarity
6
Physics motivation1. Test our current picture of 3 flavor neutrino oscillation
Spectrum shape of νµ disappearanceTest exotic models (decay, extra dimensions,….)
Appearance of νe at the same ∆m2 as νµ disappearanceNC measurements
• No additional “neutrino”?
2. Precise measurement of ∆∆∆∆m2 and mixing angles (θθθθ23, θθθθ13)mixing matrix in quark sector: well knownunderstanding of mixing in lepton sector understanding of mass structure
hints on physics beyond the SM (GUTs,…)3. Discovery of ννννe appearance
Open possibility to detect CPV effect in lepton sector
7
JHF νννν experiment
8
OverviewOverview
~1GeV νννν beamKamioka
JAERI(Tokaimura)
ννννννννµµµµµµµµ→→→→→→→→ ννννννννxx disappearanceννννννννµµµµµµµµ→→→→→→→→ ννννννννee appearanceNC measurement
~~~~1 MW 50 GeV PS( conventional νννν beam)
Super-K: 50 ktonWater Cherenkov
9
Principle– Super-Kamiokande at 295km as far detector
– Beam energy is tuned to be at the oscillation maximum.• High sensitivity • Less background
– Neutrino energy reconstruction by using Quasi-elastic(QE) interaction.
• Oscillation pattern measurement• BG due to miss-reconstruction of inelastic interaction
– Greatly improved by using narrow band beam (NBB)
∆m2=2~5x10-3eV2
Eνννν=0.5~1.2GeV
10
Neutrino Energy ReconstructionAssume CC quasi elastic (CCQE) reaction
lllN
llN
pEmmEmE
θν cos22
+−−
=
νl + n → l + p
νννν
l-
p
(El , pl)θθθθl
QE dominate at ~~~~1GeV
+-200MeV
QE
inelastic
11
600MeV Linac
3GeV PS
50GeV PS
N
FD
Neutrino Beam Line
To SK
JHF project and neutrino beam line
Construction2001~~~~2006
0.00520.410.77Power(MW)
0.450.530.292Rate(Hz)
640330Int.(1012ppp)
1212050E(GeV)
K2KMINOSJHF
JAERI@Tokai-mura(60km N.E. of KEK)
1021POT(130day)≡≡≡≡ “1 year”
(Expect approval in Dec.2000)
Super conducting magnetis essential for ν beam line(B field and running cost)
12
Neutrino Beam @ JHF
Wide Band Beam (WBB)– 2 Horns almost the same as K2K
Narrow Band Beam (NBB)
–Horn(s) + Bending
Off Axis Beam (OAB)
–Another option of NBB
Three beam configurations
13
Wide Band Beam
2 horns (almost same design as K2K)
020406080
100120140160180
0 1 2 3 4 5Eν (GeV)
10-2
10-1
1
10
10 2
0 2 4 6 8 10 12 14Eν (GeV)
JHF(10 POT 1yr)21~
JHF w/ osc.( m =3.5x10 )∆ 2 -3
K2K(10 POT 5yr)20~
N (/
100M
eV/2
2.5k
t/yr
)in
tN
(/10
0MeV
/22.
5kt/
yr)
int
Target : Cu 1cmφ x 30cmHorn : 250kADecay Pipe : 50m x 1.5mφ
Gcalor
~~~~4200 ννννµµµµ int./22.5kt/yrννννe:0.8%
IntenseWide sensitivity in ∆m2
BG from HE tailSyst. err from spectrum extrapolation
14
Narrow Band Beam
Horn10°
020406080
100120140160180
0 1 2 3 4 5Eν (GeV)
Nin
t (/1
00M
eV/2
2.5k
t/yr)
10-2
10-1
1
10
10 2
Nin
t (/1
00M
eV/2
2.5k
t/yr)
0 2 4 6 8 10 12 14Eν (GeV)
Target : Cu 1cmφ x 30cmHorn : 250kADecay Pipe : 155m x 1.5mφ
Dipole : 50cm(V)x70cm(H)x2m(L)0.58T (10deg@2GeV/c)
Gcalor
~~~~830 int./22.5kt/yrννννe:0.8%(0.3% @ peak)
Updated from LOI(factor ~2 increased by adding 2nd horn)
Less HE tailLess sys err from spectrum“counting experiment”Easy to tune Eν
15
Off Axis Beam (another NBB option)
WBB w/ intentionally misaligned beam line from det. axis
(ref.: BNL-E889 Proposal)
θTarget Horns Decay Pipe
Far Det.
Decay Kinematics
Quasi Monochromatic Beam
16
Off axis beam
0
50
100
150
200
250
300
350
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5Eν (GeV)
Nin
t (/1
00M
eV/2
2.5k
t/yr)
10-1
1
10
10 2
10 3
Nin
t (/2
00M
eV/2
2.5k
t/yr)
0 1 2 3 4 5 6 7 8 9 10Eν (GeV)
2°°°°~~~~2200 int./22.5kt/yrννννe: 0.8% (0.2% @ peak)
BNL-E889 Horns90m decay pipe
High int. narrow band beamMore HE tail than NBBHard to tune Eν
17
Comparison of Beams
(same decay pipe length=50m)
OAB2°
OAB0°
LE2π(2horns)
Wide
18
Current design of target station and decay volume
WBB/NBB/OAB can be switched by replacing opticsDecay volume is shared (flat pipe)
Design being optimized: flux, radiation shielding, cost
mu-pit(NBB)
mu-pit(WBB/OAB)
Decay VolumeTarget & Horns
NBB
WBB OAB
Iron shield
Dump
19
Physics Sensitivity
20
Strategy and GoalStrategy and GoalFirst 1 year WBB
pin down ∆∆∆∆m232 to ±10% levelNC measurement
5year NBB or OABprecise measurement of θθθθ23 and θθθθ13.
Sensitivity (goal):δsin22θ23 ~ 0.01sin22θ13 ~ 5×10−3 (90% CL)δ∆m232 ~ 1.5×10−−−−4444eV2
at (sin22θ=1.0, ∆m2 =3.2×10−−−−3333eV2)
21
ννννµµµµ disappearance1ring FC µµµµ-like
Ratio aft. BG subt.
Fit w/ 1-sin22θ・sin2(1.27∆m2L/E)
TotalInelastic
reconstructed
22
ννννµµµµ disappearance
0.04
2x10-4
0.025
2x10-4
WBB NBBPossible syst. errors
Inelastic cross section20%
Spectrum measured at FD4%E
Spectrum difference (near to far)10%
Energy measurement3%
1year
δ(sin22θ)~0.01in 5 years
23
ννννe appearance (θθθθ13)
• Signal– 1ring e-like ring– At energy of νµ disappearance dip
• Backgrounds– νµ NC π0 production
• Lower E photon is missed
– Beam νe comtamination• Broad E dist. Can be reduced w/ energy window.• 0.2-0.3% of νµ at peak of NBB/OAB
24
ππππ0 BG rejection (updated from LOI)
cos νeθ
cos νeθ
νµ
νe
νµ νµ νµ
νe νe νe
E E Eγ γ γ2 1 2/( + )
E E Eγ γ γ2 1 2/( + )
Force to find 2nd ring in 1-ring e-like sample
“e” dir. Energy frac.of 2nd ring
likelihood Inv. mass
Factor ~~~~10 improvement in BG rejectionwhile ννννe eff. decrease is only 30%
Preliminary
25
Prel
imin
ary
Expected signalSig: 49(εεεε=18.4%)BG: 20(εεεε=0.1%)
Sig: 58(εεεε=50.4%)BG: 9(εεεε=0.2%)
Sig: 121.5(εεεε=53.4%)BG: 19(εεεε=0.2%)
e/π0 cut tightened to reduce BG
WBB
OAB(2deg)
NBB
sin22θθθθµµµµe=0.05 (Chooz limit)
26
Sensitivity on ννννµµµµ ννννe appearance
Dashed lines: MINOS Ph2le, Ph2me, Ph2he from right(A.Para, hep-ph/0005012)
Preliminary
2
5x10
27
NC/CC sensitive to νs
∆∆∆∆m2 (eV2)
NC
/CC
Rat
io
ννννττττ
ννννs
>200event/year expected
NC Enriched Sample
2ring e-like(m=mπ0) 77%NC
1ring e-like(no µ-decay) 88%NC
Multi ring(no µ-decay) 73%NC
sterileactiveNC PPN →→ −=∝ µµ 1# of NC events
NC measurement
28
Comparison with other LBL projects• ICANOE (2005~~~~)
CERN SPS(400GeV) Gran Sasso LBL (732km)Eν ~20GeVOptimized for ντ search
• MINOS (2003~~~~)Fermilab Main Injector (120GeV) Soudan mine (730km)Eν>3GeVνµ disappearance: δ(∆m2)~2.4x10-4eV2, δ(sin22θ23)~0.06 νe appearance : δ(sin22θµe)>0.04 @∆m2=3x10-3eV2
(read from A.Para, ICHEP2000 by T.K.)
Complementary to JHFνννν
5x10-3eV2
3.8x10-3eV2
(E/L)(π/2)/1.27
>3GeV*
~1GeV
Eν
WBB
NBB/WBB/OAB
Beam
2500/yr*Hadr. Cal.Iron cal.MINOS
3200/yr(WBB)QEWater Cherenkov
JHFν
CC eventEν rec’nstDet.
*:PH2(Low) optionJHF project has much higher potential.
29
Future Extensions• PS upgrade to 4MW and 1Mton water Cherenkov detector
– 2 order increase in statistics– CPV if νe appearance discovered in the 1st phase
• O(100) νe events/year if θ13=0.1x(Chooz limit)
– (Proton decay)
• Very LBL experiment (1000-2000km)– ~300(1200)CC events/100kt/yr @ 2000(1000)km w/ 6GeV NBB– Sign of ∆m2s– Matter effect– CPV
30
SummaryJHFνννν project
~MW 50GeV PS @ JHFSuper-Kamiokande@ 295km as far detectorLow energy(~1GeV) conventional νµ beam tuned at osc. max.Energy reconstruction by using QENBB/OAB to reduce background and syst. err.
Physics sensitivityδsin22θ23 ~ 0.01sin22θ13 ~ 5×10−3 (90% CL)δ∆m232 ~ 1.5×10−−−−4444eV2
at (sin22θ=1.0, ∆m2 =3.2×10−−−−3333eV2)νs existence can be tested.
Design and R&D work have just been started.JHFν is not included in current budget request.Full approval within a few yearsData taking in 2006-7
31
Beam monitoring at near site1. Pi kinematics just aft. production
1.difficult to place ring imaging detector as K2K due to severe radiation2.Simple threshold type Cherenkov could be possiblity
2. Muon monitorpulse-by-pulse monitoring ofProfile (beam direction)intensity(targetting eff., horn current)
3. Neutrino monitor (front detector:FD)1.High rate (NBB~30k int/100ton/day)2.Absolute neutrino flux for normalization3.Energy spectrum4. νe contamination5.Neutrino interactionDesign and R&D have been just started.fiber-readout liquid scintillator
32
Super Kamiokande (far detector)Super Kamiokande (far detector)
41.4m
39.3m50kton stainless steel tank
Outer detector 1867 of 8” PMT
Inner detector11146 of 20” PMT
Ikeno-yamaKamioka, Gifu
Mozumi Atotsu
3km 2km
1km(2700mwe)
33
νµ disappearanceExpected allowed region of K2K
(1020POT)
10-4
10-3
10-2
10-1
0 0.5 1
sin22θ=1∆m2=0.005
10-4
10-3
10-2
10-1
0 0.5 1
sin22θ=1∆m2=0.0028
sin 22 θ
∆m
(eV
)2
2
MC
MC
10-4
10-3
10-2
10-1
1
0 0.2 0.4 0.6 0.8 1
sin 22 θ
∆m
(eV
)2
2
ν νµ→ τ 90% C.L
Kam.
SK(2.8x10 eV ,1.0)-3 2
sin 2 > 0.882 θ
Allowed region of SK
34
Decay pipe lengthΦpk)
0
0.5
1
1.5
2
2.5
3
0 20 40 60 80 100 120 140 160 180 200Decay pipe length (m)
Re
lati
ve fl
ux
OAB2deg
NBB
35
νe/νµ ratio
νe/νµ Ratio
10-4
10-3
10-2
10-1
0 1 2 3 4 5 6 7 8 9 10Eν (GeV)
Rat
io
νe/νµ Ratio
10-4
10-3
10-2
10-1
0 1 2 3 4 5 6 7 8 9 10Eν (GeV)
Rat
io
NBB OAB2deg
0.2%
36
Comparison between NBBs
0
50
100
150
200
250
300
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5Eν (GeV)
ν µ N
tot (
/22
.5kt
/1021
PO
T)
37
NBB-OAB comparisonLE2π - OAB Comparison
050
100150200250300350400450500
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2Eν (GeV)
ν µ N
tot (
/22
.5kt
/102
1 PO
T)