11

J-PARCJ-PARCNeutrino Experiment (Neutrino Experiment (T2KT2K))

T.Nakaya T.Nakaya Kyoto UniversityKyoto University

ICEPP Sympo.@ HakubaFeb 15-18, 2004

22

January 2004

LOI to the J-PARC office (Jan, 2003)Japan: 45, US:38, Canada: 19, Europe: 31, other Asia: 14

33

• A next goal of neutrino experiments is to explore the neutrinA next goal of neutrino experiments is to explore the neutrino oscillation phenomena beyond the discovery phase.o oscillation phenomena beyond the discovery phase.– Three generation Matrix (NMS matrix)Three generation Matrix (NMS matrix)– CP ViolationCP Violation,, matter effect, the sign of matter effect, the sign of mm2323

22

– Unexpected physics behind the oscillation phenomena.Unexpected physics behind the oscillation phenomena.

• More complete studies with high statistics by J-PACR neutriMore complete studies with high statistics by J-PACR neutrino experiment: no experiment: – more precisionmore precision

• 2323, , mm222323, oscillation curve, non-oscillation scenario, oscillation curve, non-oscillation scenario

– more sensitivity to a rare processmore sensitivity to a rare process• 1313 ( ( ee), CP Violation, unexpected phenomena.), CP Violation, unexpected phenomena.

1. Introduction1. Introduction

44

~1GeV beamKamiokaJAERI(Tokai)

0.75MW 50 GeV PS

( conventional beam)

Super-K: 22.5 kt

J-PARC 0.75MW + Super-Kamiokande

Start at the beginning of 2009

(hep-ex/0106019)

( Future: Super-JPARC 4MW + Hyper-K ~ J-PARC+SK 200 )

J-PARC Neutrino ExperimentJ-PARC Neutrino Experiment

55

• High statistics by a high intense High statistics by a high intense beam beam• Tune ETune E at the oscillation maximum at the oscillation maximum• Narrow band beam to reduce BGNarrow band beam to reduce BG• Sub-GeV Sub-GeV beam for Water Cherenkov beam for Water Cherenkov

0.75MW JHF 50GeV-PS(4MW Super JHF)

Off-Axis beam Super-Kamiokande(Hyper-Kamiokande)

Strategy

66

• Dec.20,2003Dec.20,2003– Neutrino project on the draft budget from Neutrino project on the draft budget from

MOFMOF

– 5 years project from JFY2004 ~ JFY20085 years project from JFY2004 ~ JFY2008– Start the experiment at the end of JFY2008.Start the experiment at the end of JFY2008.

J-PARC neutrino J-PARC neutrino facility approved! facility approved!

NewsNews

77

Nuclear and ParticleExperimental Facility

Materials and Life ScienceExperimental Facility

Neutrino experimental hall

Linac(350m)

3 GeV Synchrotron(25 Hz, 1MW)

Nuclear Transmutation

J-PARCJ-PARC (Japan Proton Accelerator Research Complex)

50 GeV Synchrotron(0.75 MW)

J-PARC = Japan Proton Accelerator Research Complex

Construction started in 2001

88

December, 2003

to Kamiokato Kamioka

99

World’s Proton AcceleratorsWorld’s Proton Accelerators

1010

J-PARC Neutrino FacilityJ-PARC Neutrino FacilityJ-PARC Construction2001～ 2007

(0.77MW)

8 bunches/~5s 3.3x1014proton/pulse 3.94 (3.64) sec cycle 1 ｙｒ≡ 1021POT (130 days) Near detectors (280m,2km)

Target station

Decay volume

Transport line(Super-cond. Mag.)

1111

decay pipe

Near detector

TargetStation

-pit280m

130m

3NBT

Special FeaturesSpecial Features Superconducting magnetsSuperconducting magnets

Off-axis beamOff-axis beam

ComponentsComponents Primary proton beam linePrimary proton beam line

Normal conducting magnetsNormal conducting magnets

Superconducting arcSuperconducting arc

Proton beam monitors Proton beam monitors

Target/Horn systemTarget/Horn system

Decay pipe (130m)Decay pipe (130m) cross w/ 3NBTcross w/ 3NBT

Cover Off-Axis angle 2~3 deg. Cover Off-Axis angle 2~3 deg.

Beam dumpBeam dump

muon monitorsmuon monitors

Near neutrino detectorsNear neutrino detectors

1212

Development of Superconducting Development of Superconducting magnetsmagnets

Test winding of a coil

Cryo.Sci.C. KEKArc Section(R=105m)SuperconductingSuperconducting combined functioncombined function magnets

•First application in the world•Reduce cost (4028mags).•Larger acceptance

1313

OA3°OA2°OA1°

Osc. Prob.=sin2(1.27m2L/E)

m2=3x10-3eV2

L=295km

Off Axis Beam (2Off Axis Beam (2 - 3 - 3 ))

WBB w/ intentionally misaligned beam line from det. axis

(ref.: BNL-E889 proposal: http://minos.phy.bnl.gov/nwg/papers/E889)

Target

Horns Decay Pipe

Far Det.

～ 3000 CC int./22.5kt/yre: 1.0% (0.2% @ peak);

Decay Kinematics

E

E

=2.0

=1.0

=0

0

1

5)cos(2

22

pE

mmE

Eo

sc.

ma

x.

=3.0

1414

flux for CP violation search (2flux for CP violation search (2ndnd phase?) phase?)

-15%@peak

1021POT/yr(1st phase)

Sign flip by change of horn polarity

FluxCC interaction

Wrong sign BG

cross sectiondifference

1515

DetectorsDetectors

• Muon monitors @ ~140mMuon monitors @ ~140m– Fast (spill-by-spill) monitoring of beaFast (spill-by-spill) monitoring of bea

m direction/intensitym direction/intensity• First Front detectorFirst Front detector @280m@280m

– Neutrino FluxdirectionNeutrino Fluxdirection– Study neutrino interactions.Study neutrino interactions.

• Second Front Detector @ ~2kmSecond Front Detector @ ~2km– Almost same Almost same EE spectrum as for SK spectrum as for SK– Water Cherenkov can workWater Cherenkov can work

• Far detector @ 295kmFar detector @ 295km– Super-Kamiokande (50kt)Super-Kamiokande (50kt)

1.5km

295km

0.28km

Neutrino spectra at diff. dist

dominant syst. in K2K

p

140m0m 280m 2 km 295 km

1616

Far detectorFar detectorSuper-KamiokandeSuper-Kamiokande

（ since Apr 1９９６）

４０ｍ

４１

．４

ｍ50,000 ton water Cherenkov detector 　

(22.5 kton fiducial volume)

1717

Far detector SK is back Far detector SK is back !!

Sep.-2002, before water filling

Jan.-2003, fully contained event

Full water 10-Dec.-2002w/ half coverage (20%)

Acrylic + FRP vessel

Back to full coverage (40%) Scheduled in winter of 2005

1818

Assume CC Quasi Elastic (QE) reaction

cos

22

pEm

mEmE

N

N

p

beam energy

EE reconstruction in Water Cherenkov reconstruction in Water Cherenkov

+ n → + p

(E , p)

ccQEcc-inelastic

E(reconstruct) – E (True) (MeV)

=80MeV

1R-FC

1919

★Precise measurement of neutrino mixing matrix

Accuracy: sin22θ23 ・・・・・・ 1%

Δm223

・・・・・・・・・・ a few % (<

1×10-4 eV2)

★Discovery and measurement of non-zero θ13

　　　　　　　　　　　　 sin22θ13 ・・・・・・ > 0.006

1st Evidence of 3-flavor mixing !

1st step to a CP measurement

Physics Goal at the 1st phase Physics Goal at the 1st phase

2020

3-flavor 3-flavor Oscillation Oscillation

ELmP e /27.1sin2sinsin 223

213

223

2

ELmP x /27.1sin2sincos1 223

223

213

4

Oscillation Probabilities when213

223

212 mmm

e appearance

disappearance

common

21

3

m2atm

m2sun

e

~1

~0.5

2121

ee appearance in T2K (phase 1) appearance in T2K (phase 1)

e0

1RFC w/ 0 cut 22.5kt FV

Back ground for e appearance search• Intrinsic e component in initial beam• Merged 0 ring from

Requirement 10% uncertainty for BG estimation

2222

Tight e/Tight e/00 separation separation• Shower direction from the beam axisShower direction from the beam axis

– coscosee: : from coherent from coherent 00 tends to have a forward peak tends to have a forward peak

• Force to find 2nd ring and…Force to find 2nd ring and…– E(E(22)/E()/E(11++22): The second ring energy is larger for BG): The second ring energy is larger for BG– Likelihood diff. between 1-ring and 2-ringsLikelihood diff. between 1-ring and 2-rings– Invariant mass: Small for Invariant mass: Small for ee

cose

cose E(2)/E(1+2)

E(2)/E(1+2)

Likelihood

Likelihood

M

M

e

BG

2323

sinsin22221313 from from ee appearance (5 years running) appearance (5 years running)

sinsin222211

33

Background in Super-K Background in Super-K (as of Oct 25, (as of Oct 25, 2001)2001) SignaSigna

llSignal Signal + BG+ BG ee ee totaltotal

0.10.1 12.012.0(*)(*) 10.710.7 1.71.7 0.50.5 24.924.9 114.6114.6 139.5139.5

0.010.01 12.012.0(*)(*) 10.710.7 1.71.7 0.50.5 24.924.9 11.511.5 36.436.4

0.5 sin2213

m2

Off axis 2 deg, 5 years

Off axis 2 deg, 5 yearsat

Sin2213>0.006 C

HO

OZ

exc

lud

ed

(*) will be improved

eff. =42%(66% for QE)

2424

disappearancedisappearance

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

2525

→→ confirmation w/ NC interactionconfirmation w/ NC interactionNC NC 00 interaction interaction (( + N → + N → 　　 + N + + N + 00))

e e CCCC + NC( + NC(~0.5CC~0.5CC) ) ~0 (sin~0 (sin22221313~0)~0) CCCC + NC( + NC(~0.5CC~0.5CC) ) ~0 (maximum oscillation)~0 (maximum oscillation)

NCNC

##00 is sensitive to is sensitive to flux flux.. Limit on Limit on s s ((f(f(ss)~0.1)~0.1))

s

=390±44#0 +

#e-

lik

e

m2323.510-3

CC

NC

26

31322

132

232

132

13

212

13231223122

132

232

122

232

122

132

12

21313223131223122

13

21313223131223122313122

13

3122

232

132

13

sincos4

)21(8

sin)cos2(4

sinsinsinsin8

sinsincos)cos(8

sin4)(

E

aLSSSC

SSSCCSSSCCCS

SSSCCC

SSSCCSSSC

SSCP e

seigenvalue mass: ,

energy, neutrino: length,flight :

,4/

222

2

ijiij

ijij

mmmm

EL

ELm

Sij=sinij, Cij=cosij

T2K oscillation probability (Consider the difference from a reactor measurement)

][]/[6.7

3 GeV

E

cmga

CP conserving

CP

solar

matter effect

[eV2]

-, a -a for e

13

27

e oscillation probability in T2K

sin2213=0.01

matter

total13CPCPsolar

2828

SummarySummary• Precision study of neutrino oscillationPrecision study of neutrino oscillation

– Next step after the discovery Next step after the discovery – We may find a hint for next break-through.We may find a hint for next break-through.

• J-PARC neutrino experiment (2008~)J-PARC neutrino experiment (2008~)– J-PARC 50GeV-PS+Off Axis beam+Super-KJ-PARC 50GeV-PS+Off Axis beam+Super-K– Narrow band beam at the oscillation maximum Narrow band beam at the oscillation maximum

(~ 1GeV)(~ 1GeV)– ee appearance, discovery of appearance, discovery of 1313

(sin (sin 1313>0.006,90%CL)>0.006,90%CL)

2929

Supplement Supplement

3030

ee contamination in the beam contamination in the beamOff-Axis Beam

~1/500

from K

e from + K

Intrinsic background: e /(peak)~ 0.002