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ICEPP Sympo. @ Hakuba Feb 15-18, 2004. J-PARC Neutrino Experiment ( T2K ). T.Nakaya Kyoto University. January 2004. LOI to the J-PARC office (Jan, 2003) Japan: 45, US:38, Canada: 19, Europe: 31, other Asia: 14. 1. Introduction.

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J parc neutrino experiment t2k

ICEPP Sympo.

@ Hakuba

Feb 15-18, 2004

J-PARCNeutrino Experiment (T2K)

T.Nakaya

Kyoto University


January 2004

LOI to the J-PARC office (Jan, 2003)

Japan: 45, US:38, Canada: 19, Europe: 31, other Asia: 14


1. Introduction

  • A next goal of neutrino experiments is to explore the neutrino oscillation phenomena beyond the discovery phase.

    • Three generation Matrix (NMS matrix)

    • CP Violation,matter effect, the sign of Dm232

    • Unexpected physics behind the oscillation phenomena.

  • More complete studies with high statistics by J-PACR neutrino experiment:

    • more precision

      • q23, Dm223, oscillation curve, non-oscillation scenario

    • more sensitivity to a rare process

      • q13 (nmne), CP Violation, unexpected phenomena.


J parc neutrino experiment
J-PARC Neutrino Experiment

(hep-ex/0106019)

Start at the beginning of 2009

Kamioka

~1GeV n beam

JAERI

(Tokai)

Super-K: 22.5 kt

0.75MW 50 GeV PS

( conventional n beam)

J-PARC 0.75MW + Super-Kamiokande

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


Strategy

  • High statistics by a high intense n beam

  • Tune En at the oscillation maximum

  • Narrow band beam to reduce BG

  • Sub-GeV n beam for Water Cherenkov

0.75MW JHF 50GeV-PS

(4MW Super JHF)

Super-Kamiokande

(Hyper-Kamiokande)

Off-Axis n beam


News

  • Dec.20,2003

    • Neutrino project on the draft budget from MOF

    • 5 years project from JFY2004 ~ JFY2008

    • Start the experiment at the end of JFY2008.

J-PARC neutrino facility approved!


J parc japan proton accelerator research complex
J-PARC(Japan Proton Accelerator Research Complex)

Construction started in 2001

Nuclear and Particle

Experimental Facility

Materials and Life Science

Experimental Facility

Nuclear Transmutation

Neutrino experimental hall

3 GeV Synchrotron

(25 Hz, 1MW)

50 GeV Synchrotron

(0.75 MW)

Linac

(350m)

J-PARC = Japan Proton Accelerator Research Complex


December, 2003

n to Kamioka

December, 2003



J parc neutrino facility
J-PARC Neutrino Facility

J-PARC Construction

2001~2007

Transport line

(Super-cond. Mag.)

(0.77MW)

Target station

Decay volume

  • 8 bunches/~5ms

  • 3.3x1014proton/pulse

  • 3.94 (3.64) sec cycle

  • 1yr≡1021POT (130 days)

Near detectors (280m,2km)


Special Features

Superconducting magnets

Off-axis beam

Components

Primary proton beam line

Normal conducting magnets

Superconducting arc

Proton beam monitors

Target/Horn system

Decay pipe (130m)

cross w/ 3NBT

Cover Off-Axis angle 2~3 deg.

Beam dump

muon monitors

Near neutrino detectors

Proton beam transport

Target

Station

3NBT

130m

decay pipe

280m

m-pit

Near detector


Development of superconducting magnets
Development of Superconducting magnets

  • Arc Section(R=105m)

  • Superconductingcombined functionmagnets

    • First application in the world

    • Reduce cost (4028mags).

    • Larger acceptance

Cryo.Sci.C. KEK

Test winding of a coil


Off axis beam 2 3
Off Axis Beam (2 - 3 )

Far Det.

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

Decay Pipe

q

Horns

Osc. Prob.=sin2(1.27Dm2L/En)

Target

WBB w/ intentionally misaligned

beam line from det. axis

Dm2=3x10-3eV2

L=295km

Decay Kinematics

osc.max.

nm

q=0

En

OA1°

q=1.0

OA2°

OA3°

1

q=2.0

q=3.0

0

5

Ep

~3000 CC int./22.5kt/yr

ne: 1.0% (0.2% @ peak);

En


N m n m flux for cp violation search 2 nd phase

nm

nm/nm flux for CP violation search (2nd phase?)

CC interaction

Flux

nm

cross section

difference

nm

-15%@peak

Sign flip by change of horn polarity

nm

Wrong sign BG

1021POT/yr

(1st phase)


Detectors
Detectors

p

p

n

  • Muon monitors @ ~140m

    • Fast (spill-by-spill) monitoring of beam direction/intensity

  • First Front [email protected]

    • Neutrino Fluxdirection

    • Study neutrino interactions.

  • Second Front Detector @ ~2km

    • Almost same En spectrum as for SK

    • Water Cherenkov can work

  • Far detector @ 295km

    • Super-Kamiokande (50kt)

0m

140m

280m

2 km

295 km

Neutrino spectra at diff. dist

1.5km

295km

0.28km

dominant syst. in K2K


Far detector super kamiokande
Far detectorSuper-Kamiokande

41.4m

40m

(since Apr 1996)

50,000 tonwater Cherenkov detector

(22.5 kton fiducial volume)


Far detector sk is back
Far detector SK is back !

Full water 10-Dec.-2002

w/ half coverage (20%)

Jan.-2003, fully contained event

Back to full coverage (40%)

Scheduled in winter of 2005

Acrylic + FRP vessel

Sep.-2002, before water filling


E n reconstruction in water cherenkov

nm + n → m + p

(Em, pm)

n

s=80MeV

En(reconstruct) – En (True) (MeV)

En reconstruction in Water Cherenkov

Assume CC Quasi Elastic (QE) reaction

m

p

1R-FCm

cc-inelastic

ccQE

beam energy


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

★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


3 flavor oscillation

ne

n3

nt

nm

Dm2atm

n2

n1

Dm2sun

Oscillation Probabilities when

  • q23: nm disappearance

  • q13: ne appearance

common

3-flavor Oscillation

~1

~0.5


N e appearance in t2k phase 1

m

e

p0

ne appearance in T2K (phase 1)

1RFC w/ p0 cut

22.5kt FV

  • Back ground for ne appearance search

    • Intrinsic ne component in initial beam

    • Merged p0 ring from nm

Requirement 10% uncertainty for BG estimation


Tight e p 0 separation
Tight e/p0 separation

  • Shower direction from the beam axis

    • cosqne: g from coherent p0 tends to have a forward peak

  • Force to find 2nd ring and…

    • E(g2)/E(g1+g2): The second ring energy is larger for BG

    • Likelihood diff. between 1-ring and 2-rings

    • Invariant mass: Small for ne

nmBG 

cosqne

E(g2)/E(g1+g2)

Likelihood

Mgg

ne

cosqne

E(g2)/E(g1+g2)

Likelihood

Mgg


Sin 2 2 q 13 from n e appearance 5 years running
sin22q13 from ne appearance (5 years running)

at

Off axis 2 deg, 5 years

CHOOZ excluded

Dm2

Off axis 2 deg, 5 years

eff. =42%

(66% for QE)

Sin22q13>0.006

0.5 sin22q13

(*) will be improved


N m disappearance

(log)

Dm2=3×10-3 sin22q=1.0

sin22q

~3%

Dm2

nm disappearance

1ring FC m-like

dsin22q

Oscillation with

Dm2=3×10-3

sin22q=1.0

d(sin22q)

OAB-2degree

Non-QE

0.01

310-3

True Dm2

Reconstructed En (MeV)

dsin22q23 ~ 0.01

dDm232< 1×10-4eV2


N m n t confirmation w nc interaction
nm →nt confirmation w/ NC interaction

  • NC p0 interaction(n + N →n + N + p0)

    • nmne CC + NC(~0.5CC) ~0 (sin22q13~0)

      nm CC + NC(~0.5CC) ~0 (maximum oscillation)nt NC

      #p0 is sensitive to nt flux.Limit on ns (df(ns)~0.1)

nmnt

CC

nt

t

#p0 + #e-like

D=390±44

nt

NC

nt

nmns

p0

3.510-3

Dm232


T2k n oscillation probability consider the difference from a reactor measurement

CP

d -d, a -a fornmne

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

q13

CP conserving

solar n

matter effect

Sij=sinqij, Cij=cosqij

[eV2]


sin22q13=0.01

total

q13

CP

CP

solar

nmne oscillation probability in T2K

matter


Summary
Summary

  • Precision study of neutrino oscillation

    • Next step after the discovery

    • We may find a hint for next break-through.

  • J-PARC neutrino experiment (2008~)

    • J-PARC 50GeV-PS+Off Axis beam+Super-K

    • Narrow band beam at the oscillation maximum (~ 1GeV)

    • ne appearance, discovery of q13 (sin q13>0.006,90%CL)



N e contamination in the beam
ne contamination in the beam

Off-Axis Beam

~1/500

ne from

m + K

from K

Intrinsic background: ne /nm (peak)~ 0.002


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