Current status of T2K experiment - University of Tokyo · 2005-02-28 · Feb 21 2005...

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Feb 21 2005 ICEPP@Hakuba2005 1 Current status of T2K experiment ICEPP Symposium @Hakuba Feb 21 st 2005 Jun Kubota (Kyoto University) 1.Introduction 2.T2K experiment 3.Near neutrino detector 4.Summary

Transcript of Current status of T2K experiment - University of Tokyo · 2005-02-28 · Feb 21 2005...

Page 1: Current status of T2K experiment - University of Tokyo · 2005-02-28 · Feb 21 2005 ICEPP@Hakuba2005 1 Current status of T2K experiment ICEPP Symposium @Hakuba Feb 21st 2005 Jun

Feb 21 2005 ICEPP@Hakuba2005 1

Current status ofT2K experiment

ICEPP Symposium @HakubaFeb 21st 2005

Jun Kubota (Kyoto University)

1.Introduction2.T2K experiment3.Near neutrino detector4.Summary

Page 2: Current status of T2K experiment - University of Tokyo · 2005-02-28 · Feb 21 2005 ICEPP@Hakuba2005 1 Current status of T2K experiment ICEPP Symposium @Hakuba Feb 21st 2005 Jun

Feb 21 2005 ICEPP@Hakuba2005 2

Introduction

Mixing parameters

Maki-Nakagawa-Sakata Matrix (Uij)

Δm122 : Solar ν & Reactor experiments 7~8 x 10-5eV2

Δm232 : Atm. ν & Long BaseLine experiments 2~3 x 10-3eV2

3 mass state(2mass difference)

3 mixing angles & 1 CPV phase

Next goal of neutrino experiments…To explore the neutrino oscillation phenomena beyond the discovery phase

|να> = ΣUαi |νi>Mass eigenstatesWeak

(Solar + Reactor) (Atm. ν) (Reactor)

Long baseline experiments

sin2θ=0.2-0.3 sin22θ~1(>0.9) sin22θ<0.1~0.2

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Feb 21 2005 ICEPP@Hakuba2005 3

Remaining questionsHow close θ23 to π/4 ?

Atmospheric neutrino measurementssin22θ > 0.9 (Best fit sin22θ ~ 1, Δm2 = 2~3 x 10-3eV2)

How large is 1st – 3rd generation mixing?Reactor experiment

sin22θ < 0.1~0.2 @ Δm2 ~ 2.5 x 10-3eV2)

How large is the phase δ?

Mass Hierarchy?Does sterile neutrino exist?

………

Precise measurement of θ23 and Δm223

Measurement of θ13

Search for the CP violation

θ13 > 0 or θ13 = 0 ?

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Feb 21 2005 ICEPP@Hakuba2005 4

T2K(Tokai to Kamioka) long baseline neutrino oscillation experiment

J-PARCSK

Approved in Dec.2003Conventional νμ beam0.75MW beam (1st phase)Baseline ~ 295kmBeam energy ~ 1GeV

Will be adjusted tothe oscillation maximum

CP violationProton decay

HyperKamiokande(1Mt)

~4MW2nd phase

νμ disappearanceνe appearanceNC measurements

SuperKamiokande(50kt)

0.75MW1st phase

PhysicsFar detectorBeam power

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Feb 21 2005 ICEPP@Hakuba2005 5

T2K collaborationJapan

KEK, ICRR, U. Tokyo, Tohoku U., Hiroshima U., Kyoto U., Kobe U., Osaka City U., Miyagi U. of EducationUSA

UCI, SUNY-SB, U. Rochester, U. Pennsylvania, Boston U., CSU, Duke U., Dominguez Hills, BNL, UCB/LBL, U. Hawaii, ANL, MIT, LSU, LANL, U. Washington Korea

Seoul National U., Chonnam National U., Dongshin U., kangwon U., Kyungpook National U., KyuSang National U., SungKyunKwan U., Yonsei U.Poland

Warsaw U.Spain

U. Barcelona, U. ValenciaSwitzerland

U. GenevaRussia

INRItaly

U. Roma, U. Bari, U. Napoli, U.PadovaFrance

CEA SaclayCanada

TRIUMF, U. Alberta, York U., U. Toronto, U. Victoria, U. ReginaChina

IHEP (Inst. of High Energy Phys.)UK

RAL, Imperial College London, Queen Mary Westfield College London, U. Liverpool

Formed in May 200312 countries, 53 institutions~150 collaborators (not incl. students)

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Feb 21 2005 ICEPP@Hakuba2005 6

J-PARC overviewJ-PARC=Japan Proton Accelerator Research Complex

NuclearTransmutation

Linac(350m)3GeV Synchrotron(25Hz,1MW)

50GeV Synchrotron(0.75MW)

NeutrinoExperimentalFacility

Material and Life ScienceExperimental Facility

Nuclear and ParticleExperimental Facility

Page 7: Current status of T2K experiment - University of Tokyo · 2005-02-28 · Feb 21 2005 ICEPP@Hakuba2005 1 Current status of T2K experiment ICEPP Symposium @Hakuba Feb 21st 2005 Jun

Feb 21 2005 ICEPP@Hakuba2005 711

February, 2004

Construction statusApr. 2001: J-PARC Phase 1 construction was startedDec.2003: Neutrino experiment was approved!

50GeV Synchrotron (Jan 05)

3GeV Synchrotron(Jan 05)

LINAC (Nov 04)

In 2008, accelerator will be in operation.Start ν experiment physics run in 2009!

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Feb 21 2005 ICEPP@Hakuba2005 8

50G

eV rin

g

target station

De

ca

y v

olu

me

(

Beam dump

( )

Near detector

Muon monitor

( )

Primary proton

beam line

target

Cryogenics

Cryogenics

Extraction point

( )

130m

280m

Proton beam kinetic energy

# of protons / pulse

Beam power

Bunch structure

Bunch length (full width)

Bunch spacing

Spill width

Cycle

50GeV (40GeV@T=0)

3.3x1014

750kW

8 bunches

58ns

598ns

~5μs

3.53sec

Primary Protonbeam line

Extractionpoint

TargetTarget station

muon monitor

beam dump

Near neutrino detector

Dec

ay

volu

me

Neutrino beam line

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Feb 21 2005 ICEPP@Hakuba2005 9

Off-axis beam(2-3deg)(Ref.;BNL-E889 proposal: http://minos.phy.bnl.gov/nwg/papers/E889)

SK

Target & Horn θ = 2~3degDecay volume

Quasi-monochromatic beamBeam energy is tunable to

maximize the sensitibity!

OA 2deg

OA 3deg

Eν(

GeV

)0 2 4 6 8 10

Pπ(GeV/c)

0

0.8

0.4

Expected # of interactions @ SK(OA 2deg)

νμ total : ~4500/22.5kt/yrCC : ~3000/22.5kt/yr

νe ~0.2% at νμ peak

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Feb 21 2005 ICEPP@Hakuba2005 10

Schematic view of the detectorsp π ν

140m0m 280m ~2 km 295 km

Muon monitor @ ~140m

First Front Detector @ 280m

Far Detector @ 295km

(Second Front Detector @ ~2km)

- First (spill-by-spill) monitoringof beam direction & intensity

- Neutrino energy spectrum, intensity and direction

- Study neutrino interaction

- Almost same Eν spectrum as for SK

- Super-Kamiokande(50kt)0

200

400

600

800

1000

1200

1400

1600

1800

x 10 3

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Eν (GeV)

Neutrino spectra at different distance

1.5km

295km

0.28km

Difference of spectraDominant systematic error in K2K

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Feb 21 2005 ICEPP@Hakuba2005 11

Far detectorSuper-Kamiokande

40m

41

.4

m50,000 ton water Cherenkov detector(22.5.kt fiducial volume)

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

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

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Feb 21 2005 ICEPP@Hakuba2005 12

Physics Goal at the 1st phase(5yrs)

Precise measurement of neutrino mixing matrix

Discovery and measurement of non-zero θ13

Accuracy: sin22θ23......1%Δm2

23……a few %(< 1 x 10-4eV2)

sin22θ13......> 0.0061st evidence of 3-flavor mixing!1st step of a CP measurement

νμ disappearance (νμ νx )

νe appearance (νμ νe)

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Feb 21 2005 ICEPP@Hakuba2005 13

3-flavor Oscillation

( )νμ θθ ELmP e /27.1sin2sinsin 223

213

223

2 Δ⋅⋅≈→

( )νμ θθ ELmP x /27.1sin2sincos1 223

223

213

4 Δ⋅⋅−≈→

Oscillation Probabilities when 213

223

212 mmm Δ≈Δ<<Δ

θ13: νe appearance

θ23 : νμ disappearance

common

ν2ν1

ν3

Δm2atm

Δm2sun

νμ ντ

νe

~1

~0.5

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Feb 21 2005 ICEPP@Hakuba2005 14

How to reconstruct neutrino energyCC quasi elastic scattering μ

p

νμ + n → μ + p

νθμ

μμμ

μμν θcos

22

pEmmEm

EN

N

+−−

=

It is possible to reconstruct Eνfrom Pμ and θμ

Inelastic scatteringsνμ + n → μ + p + π

μ

pνθμ

π

CC quasi elastic

Inelastic

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Feb 21 2005 ICEPP@Hakuba2005 15

Measurement of θ23, Δm232

Use 1 ring μ-like events @ SK(= quasi-elastic enriched sample)to reconstruct neutrino energy

μ

p

νμ + n → μ + p

ν

(Eμ , pμ)

Clear deficit is expected to be observedin the reconstructed ν energy

Δm232 = 2.7 x 10-3eV2

(assuming sin22θ23=1.0)No oscillation

non-QE

~OA 2.5deg ~

Δm2

sin22θ

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Feb 21 2005 ICEPP@Hakuba2005 16

Measurement of θ23, Δm232

δ(Δm232) < 1 x 10-4eV2

δ(sin22θ23) ~ 0.01Sensitivities in the 1st phase

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Feb 21 2005 ICEPP@Hakuba2005 17

νe appearance searchθ13 measurement

e

p

νe + n → e + p

ν

(Pe , θe)

Signal events @ SKsingle ring e-like event(νe CC quasi-elastic scattering)

Possible background sources1) Beam νe

νe/νμ flux ~ 0.2%(@peak)2) π0 production

2-ring merged to 1-ring

( )νμ θθ ELmP e /27.1sin2sinsin 223

213

223

2 Δ⋅⋅≈→

Upper limit: sin2θ13 < 0.03 ~ 0.05 (@Δm2 = 2~3 x 10-3eV2)

π0

γ

γ

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Feb 21 2005 ICEPP@Hakuba2005 18

νe appearance search

DIS

1.9

4.3

41

2,410

0.8

2.6

22

71

coherent

6.3

14

74

432

1π0

νμ NC

0.4

0.8

5.9

2,897

νμ CC (oscillated)

164) 0.4GeV<Eνrec<1.2GeV

263) e/π0 separate

642) 1ring e-like

2251) Generated in FV

Beam νeOA 2.5deg5yrs

Expected # of backgroundEvent selection

Select 1ring e-like eventsApply π0 rejection cutEnergy cut (around the oscillation maximum)

Assuming sin22θ23=1.0, Δm232=2.7x10-3eV2

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Feb 21 2005 ICEPP@Hakuba2005 19

Sensitivities in the 1st phase(5yrs)Search for νe appearancew/ beam MC and full SK detector simulation

0

5

10

15

20

25

30

35

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5Reconstructed Eν(GeV)

Expected Signal+BGsin22θ13=0.10sin22θ23=1.0Δm2=0.003eV2

Total BG

BG from νμ+antiνμ

10-4

10-3

10-2

10-1

10-3

10-2

10-1

1

90% C.L. sensitivities

JHF 5yearWBBOAB 2deg.NBB 2GeVπCHOOZ excluded

sin22θμe

Δm2 (

eV2 )

Excludedby CHOOZ

~ x20

OA 2deg., 5yrs

Sensitivity region…sin22θ13>0.006(90%)sin22θ13>0.018(3σ)

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Feb 21 2005 ICEPP@Hakuba2005 20

Near neutrino detector Off-axis detector (w/ magnet)

On-axis detector

νμ and νe fluxes and energy spectraν interaction study

Monitor ν beam

20m Φ

17m

SK direction SK

36m

ν beam center(OA 2.5deg)

28.5

m

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Feb 21 2005 ICEPP@Hakuba2005 21

Off-axis detectors

UA1 magnet@NOMAD experiment

Electron calorimeterMeasure energy of EM shower by beam νe& NC-1π0

Tracking detector-Fine Grained Detectorconsisting of scintillator

Target of ν-TPC

Measure momentum of μ, p and π

Muon Range DetectorMeasure momentum of μ

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Feb 21 2005 ICEPP@Hakuba2005 22

On-axis detector

OA2deg

OA2.5deg

OA3deg

OA 0deg

δ<Eν>/<Eν>~24MeV/mrad

δ(Δm2)=10-4eV2/mrad

Uncertainly of energy scale

Oscillation probability

At least 0.5mrad is needed as a measurement accuracy

It’s necessary to measure ν beam direction w/ high accuracyand control precisely

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Feb 21 2005 ICEPP@Hakuba2005 23

On-axis detector (N-Grid detector)

8m

beam center

-4 0 +4(m)

Φν profile

Monitor neutrino beam direction, profile and stability

8m Tracker Counter

1mν μ

Veto Counter

Iron block

1m

~1.5m

0.1m

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Feb 21 2005 ICEPP@Hakuba2005 24

On-axis detector (N-Grid detector)5 modules at one axis

-4 -2 0 2 4 (m)

6500

5500

4500

Reconstructed ν beam profile

-30 -20 -10 0 10 20 30

-20

-40

020

40

True Beam center

Rec

onst

ruct

ed b

eam

cen

ter

• Good linear relation.• The accuracy of the center is ~5cm.

corresponding to 0.18mard(fulfill the request)

Page 25: Current status of T2K experiment - University of Tokyo · 2005-02-28 · Feb 21 2005 ICEPP@Hakuba2005 1 Current status of T2K experiment ICEPP Symposium @Hakuba Feb 21st 2005 Jun

Feb 21 2005 ICEPP@Hakuba2005 25

SummaryThe first “Super-beam” Long baseline ν experiment

T2K (Tokai to Kamioka) experiment was approvedConstruction was started5 years to complete (JFY 2004~2008)Start physics run in 2009

Try to discover non-zero θ13 (sin22θ13>0.006 @90%C.L.)Precision measurement of θ23 & Δm23

2 (precision x 10)1st step to the CP violation in the lepton sector

Page 26: Current status of T2K experiment - University of Tokyo · 2005-02-28 · Feb 21 2005 ICEPP@Hakuba2005 1 Current status of T2K experiment ICEPP Symposium @Hakuba Feb 21st 2005 Jun

Feb 21 2005 ICEPP@Hakuba2005 26

Supplement

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Feb 21 2005 ICEPP@Hakuba2005 27

Tight e/π0 separation

00.5

11.5

22.5

33.5

0 0.5 10

0.51

1.52

2.5

0 0.25 0.5012345678

-500 0 5000

0.51

1.52

2.53

3.5

0 100 200

00.20.40.60.8

11.2

0 0.5 10

0.20.40.60.8

11.21.41.6

0 0.25 0.50

0.250.5

0.751

1.251.5

1.752

2.25

-500 0 500

νμ

cosθνe

νμ

E(γ2)/(E(γ1)+E(γ2))

νμ

likelihood difference

νμ

inv. mass (MeV)

νe

cosθνe

νe

E(γ2)/(E(γ1)+E(γ2))

νe

likelihood difference

νe

inv. mass (MeV)

00.5

11.5

22.5

33.5

0 100 200cosθνe

cosθνe E(γ2)/E(γ1+γ2)

E(γ2)/E(γ1+γ2)

Likelihood

Likelihood

Mγγ

Mγγ

νe ⇒

νμBG ⇒

Shower direction from the beam axiscosθνe: γ from coherent π0 tends to have a forward peak

Force to find 2nd ring and…E(γ2)/E(γ1+γ2): The second ring energy is larger for BGLikelihood diff. between 1-ring and 2-ringsInvariant mass: Small for νe

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Feb 21 2005 ICEPP@Hakuba2005 28

N-Grid detector

0 2 3 4 51

Eν spectrum

Eν(GeV)

Event Selection[1] ≧2 hits in the scintillator.[2] No Veto Hits[1] & [2]