Neutrino oscillations at T2K

H.KakunoUniversity of Tokyo

Neutrino Oscillation Workshop 2008Conca Specchiulla, Italy, September 9, 2008

T2K collaboration

407 members, 65 Institutes, 12 countries

Primary goal of the T2K

...4sin2sin4

4sinsin2sin)(

3122

212

3122

232

132

ELmELmJ

ELmP

r

e

Search for the e appearance: e

Precise measurement of the disappearance:

P( )≈1-sin223sin2(m223L/4E))

Goal : (sin22)~0.01, (m2) <1×10-4 [eV2]

Expected Sensitivity for sin22→down to ~0.01

100

0cossin

0sincos

cos0sin

010

sin0cos

cossin0

sincos0

001

1212

1212

1313

1313

2323

2323

CP

CP

i

i

e

e

T2K experiment

280m, (& 2km)2

Pure beam

750kWCompleted Experiment

Under Construction

- Next generation long-baseline neutrino oscillation experiment- Intense beam is generated by new J-PARC facility

Neutrino beam

OA3°

OA0°

OA2°OA2.5°

energy spectrum (flux × Cross Section)C

Oscillation Prob.@ L=295kmm2=2.5×10-3, 3.010-3[eV2]

( )

Pseudo-Monochromatic beam by Off-Axis method (ref. BNL E899)b

- Off-Axis angle: set to 2.5 degree

p

120m120m0m0m 280m280m 2 km2 km 295 km295 km

on-axison-axis

off-axisoff-axis

2.52.5oo

Super-KSuper-K

-mon-mon

Under discussion

J-PARC accelerator

``

Neutrinobeamline

Neutrino beam

28th Jan. 2008

Linac:Beam commissioning is started in Nov 2006

3GeV RCS:Beam commissioning is started in Sep. 2007

Main Ring(MR):Beam commissioning is started in May 2008,Closed orbit has been establishedAcceleration (30GeV) will be started in Dec. 2008

Commissioning of the neutrino beam-line will be started from Apr 2009

Neutrino beam-line

Primary beam lineProton beam line from the Main Ring to the target

Preparation Section

Arc Section

• 28 superconducting magnets.

• Combined function: D:2.6T, Q:18.6T/m

• 1W/m lossFinal Focus Section

• 10 Normal Conducting magnets• (2 Dipole, 4 Quad, 4 Str)• 250W loss

• 12 Normal Conducting magnets

• (2 Dipole, 5 Quad, 5 Str)• 750W loss

Primary beam-line: monitors

Position : Electro-static monitor (ESM) Profile : Segmented Secondary 　　　 Emission Monitor (SSEM)E : Optical transition Radiation monitor (OTR) in front of the target Intensity : CT (Current Transformer) Loss monitors (BLM): Ion. Chamber

ESM SSEMCryogenic test

OTR

Installation

Monitor center of the beam < 0.5mm and profile(size) of the beam < 0.7mm to protect the target and to maximize the neutrino flux

Secondary beam-line

Target Stationtarget & horn system

Decay VolumeBeam Dump /Muon Pit

- Beam dump 94 graphite blocks

- Muon monitor: Semiconductor array + Ionization chamber

Helium vesselHelium vesselof target station

Decay volume

Beamdump

Muonpit

Secondary beam-line: Target&HornTarget (Graphite)T 26mm(D)x900mm(L)2 Thermal shock @30GeV-750kW:

~ 7MPa (<Tensile strength 27MPa)~ Forced flow Helium gas cooling

736oC

30GeV-750kW

320kA

3rd Horn1st Horn

320kA operationachieved

Full scalemockup test

Horn system Three horn system I=320kA, B=2.1T(max)I• Full scale mock-up of the 3rd horn

-@320kA operation achieved

Long term endurance test

1st and 3rd horns→done, 2nd horn→ongoing

Secondary beam-line:Beam dump&Muon monitor

10m 4m

Helium VesselHelium Vessel

OA 2.5OA 2.5oo

Hadron absorber assembly is completed Installation on October

• Muon monitor:• Spill –by-spill

monitor the muon beam profile center < 3 cm

• Beam intensity measurement accuracy: 3%

• Installation by end 2008

Ionization chamber s

Si PINDiodes

Near Detector (ND280)N

Decayvolume

Beamdump

beam

13th, June, 2008

ND280: facilityN

Current design37m

2.5deg beam center28.5m

Ground level

Off-Axis Neutrino Detector

(Monitor at SK direction)d

INGRID:On-Axis Neutrino Monitor(Monitor at beam direction)d

ND280: On axis detector (INGRID)N Measure -beam profile

-beam direction at 1mrad precision.

iron - scintillator stacks x 16units 7 horizontal , 7 vertical , 2 off-diagonal

INGRID will be ready for beam commissioning: Apr. 1st, 2009.

construction of modules

ND280: Off axis detector Off-axis detector: In Magnetic field

(B=0.2T)( Measure -flux in SK direction :

ND(E). Measure , and e+e fluxes separately. Neutrino Energy CC-QE kinematics.

Cross sections of interactions CC-1CC-QE … BG for E

reconstruction NC-0 production … BG for e detection

Reuse the UA1 magnet (it have been installed) Off-axis detector will be installed in

summer 2009 except for some parts of ECAL. It become ready for physics run from 2009 fall.

SMRD

Installed yoke

Far detector: Super Kamiokande50kt Water Cherenkov detector 20”PMT x 10,000 +Anti counter x 2000SK reconstruction iscompleted in Apr. 2006→Back to 40% Photo coverage.Start full operation in July 2006 (SK-III)22

DAQ-upgrade is ongoingTo be completed by mid September~6 month commissioning before T2K experiment(SK-IV)(

Possible MR Power Improvement ScenarioKEK ROADMAP

Day1(up to Jul.2010)2

Next Step KEK ROADMAP Ultimate

Power(MW)P 0.1 0.45 1.66 ？

Energy(GeV)E 30 30 30

Rep Cycle(sec)R 3.5 3-2 1.92

No. of Bunch 6 8 8Particle/Bunch 1.2×1013 <4.1×1013 8.3×1013

Particle/Ring 7.2×1013 <3.3×1014 6.7×1014

LINAC(MeV)L 181 181 400

RCS h=2 h=2 or 1 h=1

After 2010, plan depends on financial situationGoal at initial stage: T2K Physics run with 100kW beam × 107 sec by 2010 summer.

“We request total integrated beam power larger　than 0.75MW × 15000h (15000 h ＝ 5yrs ×3000h) at any proton energies between 30 and 50 GeV.”

T2KFull Proposal

Physics sensitivity e appearance

T2K 90%CL sensitivity sin2223 = 1.0 is assumed.~ 5 years @ full intensity(750kW)~

Stat. error+ Syst. error for BG subtraction (10%)+

(OA2.5(OA2.5°° ))))

~0.01 @ m213=2.510-3[ev2], =0

sin2213 = 0.1# of events in 0.35~0.85 [GeV] Signal … 103 Beam e BG … 13 BG from … 10

Physics sensitivity (cont'd)P disappearance : P( )=1-sin223sin2(1.27 m2

23L/E)) Goal : (sin22)~0.01, (m2

) <1×10-4 [eV2]

K2K … hep-ex/0606032SK… Phys. Rev. Lett. 93,101801(2004),MINOS... hep-ex/0806.2237M

(OA2.5(OA2.5°° ))))

2.5

2.6

2.7

2.8

2.9

m2 [

10-3 e

V2 ]

--68%CL--90%CL--99%CL

K2K & SK &MINOS

~ 5years @ full Intensity

MC

Statistics ×50

Stat. Error only

Hadron Production measurement at CERN SPS (NA61 experiment)C

obsNDNFSK R /

exp

Neutrino flux is estimated from the flux at the near detector

To estimate the error of Far/Near ratio:

Error from F/N ratio

1

1%

10%

T2K goal

0.15(m232)[10-4eV2]

0.5%(sin2223))

<4%(Nbg) for e app.

w/ NA61

Measure the hadron production for30-50GeV protons on thin and thick carbon target at NA61

Detector Existing at CERN SPS 2ndary beam line Used by NA49 (Heavy ion)U

Beam First data taking in Oct. 2007 and more data in 2008

Uncertainty from the Hadron production model can be

controlled

-cp

=0-

cp=90

-cp

=270

E/L

Osc

illat

ion

pro

b.

Future If sin22 is measured at T2K and is found large ( > ~0.01),

CP-violation study is possible

Strategy

- Measure 1st and 2nd maximum of oscillation w/ different E/L and/or

- Measure with both and beams

-Neutrino oscillation w/ different E/L will provide information of

cp

-Oscillation prob. is different between neutrino and anti-neutrino→cp→ -cp)

wheree

atmospheric

Interference

solar

CPV

1st oscillation maximum

2nd oscillation maximum

Future(cont’d)F

Okinoshima

KamiokaKorea

Various scenarios(upgrade of the far detector) are proposed:

See slides of NP08: http://j-parc.jp/NP08

Hyper Kamiokande

Liquid Ar TPC

Summary T2K is a Long Baseline experiment w/ high intensity beam by JPARC accelerator Beam line construction is on schedule - Although very tight

- Almost all beam line components will be installed in FY2008 Beam commissioning will start Apr. 2009 Off-axis detector will be ready by 2009 fall run - except for a part of ECAL We aim to obtain 1st physics result from 100kW107sec beam operation by 2010 summer.

Search for e & 13 measurement.

Precise measurement of 23 & m223 via disappearance.

- If e is observed and is found large, - look for CPV. -Various upgrade options are under study

backup

Introduction

3

2

1

1212

1212

1313

1313

2323

2323

100

0cossin

0sincos

cos0sin

010

sin0cos

cossin0

sincos0

001

i

ie

e

e

mixing matrix: 1312, 23

SK Atmospheric+Long BL(K2K, MINOS)+

Solar, KamLANDLong BL

13

, : Unknown

Is 23

=/4?Is

13 non-zero?

CP-violation?

Commissioning schedule

DRY RUNDRY RUN

Install Septum Magnets

[CONSTRUCTIONCONSTRUCTION] [INSTALATION][INSTALATION] [COMMISSIONING][COMMISSIONING]

1st STAGE: Establish

Closed Orbit

Inspect PPS Rad.shield (12/25)R

Install Fx Kickers& Sx devices

2nd STAGE: Acceleration

(30GeV)(

3rd STAGE: Fast

Extraction

☼☼☼☼

☼☼High Intensity

Run

☼☼ ☼☼☼☼

NOW

1st stage of the MR beam commissioning is successfulCommissioning of the neutrino beam will start from Apr. 2009High intensity beam with six bunches from Sep. 2009

Now preparing neutrino beam-line components toward the neutrino beam commissioning

Error from F/N ratio

1

1%

10%

T2K goal

0.150.5~1(m232)[10-4eV2]

0.5%1.5~3%(sin2223))

<4%15%(Nbg) for e app.

w/ NA61If R~20%

Assumed Systematic ErrorsAssumed Systematic Errors

Normalizationnon-QE/QE ratio

Energy scale

5%

5%

1%

0.010.01 1×101×10-4-4eVeV22

• Errors will be reduced byErrors will be reduced by near detector and near detector and pion production pion production measurementsmeasurements

(sin(sin22 2 2)) ((mm22))

Spectrum Shape 20%

Beam Width 5%

Sta

tistic

alE

rro

r

OA2.5OA2.5oo

5510102121 POT POT

Sta

tistic

alE

rror

Systematic error

Sta

t.

Sta

t.

Primary beam-line: Magnets Superconducting combined function magnets D:2.6T, Q:18.6T/m

All the magnets are installed

Evacuation and cooling starts in Autumn

Normal-conducting magnets All the magnets are installed

Dipole Quad SteerPrep Sect 2(H) 5 3(H)+2(V)

FF Sect 2(V) 4 2(H)+2(V)Combined(Dipile+Quad)

ARC Sect 14 “doublets”

Transport to tunnelTransport to tunnelFeb.8, 2008Feb.8, 2008

~11m

J-PARC milestone

Hardware upgrade is necessary for 1MW.

0.75 MW

Goal at initial stage: T2K Physics run with 100kW beam × 107 sec by 2010 summer.

“We request total integrated beam power larger　than 0.75MW × 15000h at any proton energies between 30 and 50 GeV.”

15000 h ＝ 5×3000h ≒5×107sec

-cp

=0-

cp=90

-cp

=270

E/L

Osc

illat

ion

pro

b.

Future

Upgrade of the proton beam power: 0.75MW->1.66MW

Upgrade Far detector e.g. Hyper Kamiokande (~1Mt)H

If sin22 measured @ T2K > 0.01, CP-violation study is possible

Strategy:

Neutrino oscillation w/ different E/L will provide information of

cp

See slides of NP08:http://j-parc.jp/NP08/