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

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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

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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)