1 tokai 2 kamioka status and prospects antonin vacheret for the t2k collaboration tuesday 7th...

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TTokai okai 22 KKamioka amioka Status and Prospects Status and Prospects Antonin VacheretAntonin Vacheret for the T2K Collaborationfor the T2K CollaborationTuesday 7th SeptemberTuesday 7th SeptemberNOW 2010, Otranto, Lecce, ItalyNOW 2010, Otranto, Lecce, Italy

Antonin Vacheret, Imperial College Antonin Vacheret, Imperial College London London

NOW 2010, 7th September Otranto Lecce NOW 2010, 7th September Otranto Lecce ItalyItaly

2OverviewOverview

• T2K physics goals T2K physics goals

• Experimental sensitivity Experimental sensitivity

• Overview of the experiment Overview of the experiment

• Status and prospectsStatus and prospects



3Neutrino oscillation matrixNeutrino oscillation matrix

Neutrino oscillation described by Neutrino oscillation described by unitary matrix Uunitary matrix UMNSPMNSP

3 mixing angles ( θ3 mixing angles ( θ1212, θ, θ2323, θ, θ1313) )

1 CP violation phase (δ)1 CP violation phase (δ)

2 mass2 mass22 differences (Δm differences (Δm22ij ij = m= m22

ii - m - m22jj))

• value of θvalue of θ13 13 is only constrained by is only constrained by datadata

• δ is unknownδ is unknown

• sign of Δmsign of Δm22atm atm is not yet knownis not yet known

Necessary to complete oscillation Necessary to complete oscillation picture !picture !

Δm2atm

ντνμνe

m12

0

m22

m32

Δm2solar

NH IH

m22

m12

m32

Δm2solar

? ?

Δm2atm

= 0 ?

cij = cos θij, sij = sin θij



4T2K GoalsT2K Goals

• measure last unknown mixing angle θmeasure last unknown mixing angle θ13 13

using νusing νμμ ➞ ν ➞ νee appearance appearance

potentially open up δpotentially open up δCPCP search in neutrino sector search in neutrino sector

• measure precisely the atmospheric measure precisely the atmospheric parameters using νparameters using νμμ ➞ ν ➞ νμ μ disappearancedisappearance

is there a symmetry between 2nd and 3rd generation ? is there a symmetry between 2nd and 3rd generation ?



5ννμμ ➞ ν ➞ νe e appearanceappearance

Sensitivity down to 0.006 @ ΔmSensitivity down to 0.006 @ Δm222323 = 2.5 x 10 = 2.5 x 10-3 -3 eVeV22

3.75 MW x 107s

δCP = 0

x 10



6ννμμ disappearance disappearance

Enter precise measurement era : Enter precise measurement era :

• δ(sinδ(sin222Θ2Θ2323) ~ 0.01 ) ~ 0.01

• δ(Δmδ(Δm221313) ~ 1 x 10) ~ 1 x 10-4-4 eV eV2 2

K2K collaboration Phys. Rev. D. 74 072003

T2K @ 90%CL

Statistics x 50

From MINOS presentation at Neutrino 2010† Super-K collaboration preliminary result



7

J-PARC Intense proton beam : 750 KW at design valueJ-PARC Intense proton beam : 750 KW at design value

Far detector Super-Kamiokande : 50 kT Water Cherenkov Far detector Super-Kamiokande : 50 kT Water Cherenkov detector detector

- high statistics CCQE event reconstructed with high efficiency - high statistics CCQE event reconstructed with high efficiency & purity& purity

Unique baseline : first Off-axis neutrino beam (angle @ 2.5º)Unique baseline : first Off-axis neutrino beam (angle @ 2.5º)

• Narrow band beam ideal for νNarrow band beam ideal for νee search search

• peak energy at oscillation maximum < 1 GeV : Quasi-peak energy at oscillation maximum < 1 GeV : Quasi-elastic (CCQE) processes dominateelastic (CCQE) processes dominate

- low contamination from other ν flavour ( 0.5% ν- low contamination from other ν flavour ( 0.5% νee) )

- Background from misreconstructed high energy neutrinos - Background from misreconstructed high energy neutrinos significantly reduced significantly reduced

Near detectors @ 280 mNear detectors @ 280 m

• Measure on axis and off-axis beam Measure on axis and off-axis beam

p π ν

120m120m0m0m 280m280m 295 km295 km

on-axison-axis

off-axisoff-axis

2.52.5oo

μμ-mon-mon

The T2K baseline The T2K baseline

J-PARC 30 GeV proton beam

Super-Kamiokande

Near detectors



8Analysis strategyAnalysis strategy

Number of reconstructed events (νNumber of reconstructed events (νμ μ and νand νee) at SK can be predicted ) at SK can be predicted using using

• near detectors (off-axis beam, neutrino cross sections)near detectors (off-axis beam, neutrino cross sections)

• hadron production measurements (NA-61)hadron production measurements (NA-61)

Compare prediction with SK observation to extract oscillation Compare prediction with SK observation to extract oscillation parameters : parameters :

omit integral on Eνtrue

SK Det responseDet eff.Cross sectionbeam flux Osc. Prob.

Flux at Near Det :

Flux at SK

Hadron production measurement

Cross section measurements

(SciBooNE, T2K ND) Far to Near extrapolation

factor

Normalisation & Eν spectrum from T2K ND



9The T2K CollaborationThe T2K Collaboration



10The J-PARC facilityThe J-PARC facility

(KEK/JAEA）

Bird’s eye photo in January of 2008

North

Neutrino Beam

2009

30 GeV Main ring

2008

3 GeV Synchrotron

2007

181 (400) MeV Linac

ConstructionJFY2001~2008

750 kW (design value)



11The neutrino beam lineThe neutrino beam line

Fast extracted beam from MR ring Fast extracted beam from MR ring

• 6 bunches/spill (increased to 8 in Fall 2010)6 bunches/spill (increased to 8 in Fall 2010)

• Superconducting combined function magnets for Superconducting combined function magnets for proton transport proton transport

Primary beam monitorsPrimary beam monitors

• Intensity(CT), position(ESM), profile(SSEM), beam Intensity(CT), position(ESM), profile(SSEM), beam loss(IC), beam profile at target (OTR)loss(IC), beam profile at target (OTR)

Target Station Target Station

• graphite core target (26 mm(D) x 900 mm L)graphite core target (26 mm(D) x 900 mm L)

• 3 horns @ 250 kA (320 kA) 3 horns @ 250 kA (320 kA)

Target station connected to decay pipe 110 m long filled Target station connected to decay pipe 110 m long filled with Helium with Helium

Beam dumpBeam dump

• Hadron absorber graphite modulesHadron absorber graphite modules

Secondary beam monitors Secondary beam monitors

• muon profile after beam dump : ionisation muon profile after beam dump : ionisation chambers and SiPIN (MUMON)chambers and SiPIN (MUMON)

• Emulsion exposures (low intensity) Emulsion exposures (low intensity)

Neutrino detectors at 280 mNeutrino detectors at 280 m

Super-K direction given by GPS Super-K direction given by GPS

π,μ

protons

ν

ν

to SK

neutrino beam line

HornsGraphite target

MUMON

Neutrino near detectors complex



12INGRID On-axis monitorINGRID On-axis monitor

On-Axis detector is crucial for off-axis On-Axis detector is crucial for off-axis measurements : measurements :

• monitor beam direction, intensity monitor beam direction, intensity and mean energyand mean energy

• beam coverage ~ 10 x 10 mbeam coverage ~ 10 x 10 m22

• Off-axis angle measurement Off-axis angle measurement accuracy goal is 1 mrad (< 15 accuracy goal is 1 mrad (< 15 MeV on off-axis peak energy)MeV on off-axis peak energy)

• beam position resolution ~ 7cm beam position resolution ~ 7cm corresponding to ~3 mm shift at corresponding to ~3 mm shift at proton targetproton target

~ 10 k ν interactions per day at full power~ 10 k ν interactions per day at full power

• 2 remaining diagonal modules 2 remaining diagonal modules and 1 full plastic “proton” module and 1 full plastic “proton” module to be installed for next T2K run to be installed for next T2K run

ν

INGRID “cross” is formed with 14 identical modules + 2

diagonal modulesmade of plastic scintillator

planes and 6.5 cm thick Iron planes surrounded by veto planes

ν beam



13The Off-axis near detectorThe Off-axis near detector

The Off-axis near detector (ND280) provides The Off-axis near detector (ND280) provides

• Off axis beam measurement based on CCQEOff axis beam measurement based on CCQE

• beam nue contaminationbeam nue contamination

• Super-K background measurements (NCπSuper-K background measurements (NCπ00))

Two target regions : Two target regions :

• The P0D (Brass/Plastic segmented) : πThe P0D (Brass/Plastic segmented) : π00 detector detector

• The tracker region : Fined grained plastic detector The tracker region : Fined grained plastic detector and TPC and TPC

• Both region have passive water planesBoth region have passive water planes

Large Calorimeter coverage (Plastic/Pb segmented)Large Calorimeter coverage (Plastic/Pb segmented)

• Additional NCπAdditional NCπ00 production measurement in tracker production measurement in tracker and PID, hermicity, active veto and PID, hermicity, active veto

Side Muon ranging detector Side Muon ranging detector

• Neutrino Rate, Side muons, cosmics trigger Neutrino Rate, Side muons, cosmics trigger

Precise cross-section measurements with very large Precise cross-section measurements with very large statistics !!!statistics !!!

ND280

P0DTracker

ECals

Yoke/SMRD

UA1 Magnet (CERN donation)

ν beam

8 m



14Near Detector TechnologiesNear Detector Technologies

Scintillator + WLS fibre read out by novel MPPC Scintillator + WLS fibre read out by novel MPPC ND280 ND280

• Low cost high performance and uniformity Low cost high performance and uniformity detector elementdetector element

• novel solid state photosensor insensitive to novel solid state photosensor insensitive to magnetic field magnetic field

• Photon counting, high PDE, low power Photon counting, high PDE, low power consumption, ceramic packageconsumption, ceramic package

• ~ 56 800 channels~ 56 800 channels

• T2K first experiment to use MPPC at such a T2K first experiment to use MPPC at such a large scalelarge scale

1.3mm50μm

Front end BoardAFTER ASIC (FGD & TPC)

TRIP-t ASIC (others)

HAMAMATSU MPPC 667 Pixels array

Various shapes of Plastic scintillator

with Y-11 fibre

10 mm

P0D FGD TPC

Very Large TPC based on MicroMegas Very Large TPC based on MicroMegas read outread out

• 3x large modules with double 3x large modules with double wall structurewall structure

• Sensitive volume 180 x 200 x 70 Sensitive volume 180 x 200 x 70 cmcm

• Precise assembly, Precise assembly, commissioning and alignment commissioning and alignment within mmwithin mm

• 124 000 channels 124 000 channels



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The Far detector : Super The Far detector : Super Kamiokande IVKamiokande IV

50 (22.5 Fid.) kT Water Cherekov detector with 11 129 20” PMTS in inner detector (ID) 50 (22.5 Fid.) kT Water Cherekov detector with 11 129 20” PMTS in inner detector (ID) and 1885 8” PMTS instrumenting outer detector (OD)and 1885 8” PMTS instrumenting outer detector (OD)

Super-K in operation since 1996Super-K in operation since 1996

• Dead-timeless read out electronics and DAQ upgrade in 2008 Dead-timeless read out electronics and DAQ upgrade in 2008

• GPS system used to select time arrival of beam events GPS system used to select time arrival of beam events

Water transparency (light att. length)

90 m

16

T2K StatusT2K Status



17Beam performanceBeam performance

First T2K run completed First T2K run completed ( January to June 2010) ( January to June 2010)

• 3.3 x 103.3 x 1019 19 protons protons accumulated for T2K accumulated for T2K analysis analysis

• 50 kW stable 50 kW stable operation with trials operation with trials at 100 kWat 100 kW

• Super-K live fraction Super-K live fraction in excess of 99% in excess of 99%

50 kW

80 kW



18Beam MonitorsBeam Monitors

Proton beam precisely tuned (less than 1 mm deviation at target) Proton beam precisely tuned (less than 1 mm deviation at target) to minimise beam loss and control secondary beam spill by spillto minimise beam loss and control secondary beam spill by spill

MUMON : profile center < +/- 1 mrad ( ΔEMUMON : profile center < +/- 1 mrad ( ΔEννpeakpeak~2%/mrad)~2%/mrad)



19Beam stability @ targetBeam stability @ target

Extrapolated Position Extrapolated Angle

Extrapolated width

target 26 mm∅

target radius 13 mm

Accumulated beam profile @ target ( Jan-June period)

μ= 0.27 mmσ = 4.13 mm

μ= 0.85 mm

σ = 4.19 mm



20CERN NA-61/SHINECERN NA-61/SHINE

Neutrino beam depends upon secondary beam geometry and hadron distribution Neutrino beam depends upon secondary beam geometry and hadron distribution off targetoff target

NA-61/SHINE : dedicated hadron production experiment using T2K target to NA-61/SHINE : dedicated hadron production experiment using T2K target to reduce uncertainties in hadron production modelsreduce uncertainties in hadron production models

• Pilot run in 2007 and high statistics run in 2009 : p(30 GeV) with Carbon thin Pilot run in 2007 and high statistics run in 2009 : p(30 GeV) with Carbon thin target and T2K replica targettarget and T2K replica target

• preliminary results from 2007 used in T2K beam MCpreliminary results from 2007 used in T2K beam MCMC=GFLUKA

Prel

imin

ary



21INGRID measurementsINGRID measurements

First event Beam Profile X Beam Profile Center X

Beam Profile Y Beam Profile Center Y



22

ND280 off-axis detector ND280 off-axis detector performanceperformance

Interaction vertex Interaction vertex reconstruction reconstruction

• off-axis beam off-axis beam profile clearly profile clearly visible in both visible in both target regions (FGD target regions (FGD and P0D) and P0D)

Particle identification Particle identification (TPC dEdx) (TPC dEdx)

• crucial for crucial for measuring νmeasuring νμμ and and beam νbeam νe e spectra spectra

Vertex X-Y distribution

P0D

FGD

⊗ ν beam direction

Energy loss beam TPC negative tracks

TPC positive tracks



23ND280 timing & rate stabilityND280 timing & rate stability

18

FGD activity in time with beamDaily DsECal cluster rates

P0D reconstructed vertices



24ND280 off-axis neutrino eventsND280 off-axis neutrino events



25Super-K time distribution Super-K time distribution

• Very good Very good synchronisation synchronisation with T2K beam with T2K beam achievedachieved

∆T0 = SK trig time -T2K beam trigger time

Bunch residual time (nsec)

RMS ~ 26 ns



26Super-K ν events Super-K ν events

Pμ = 1025 MeV/c1 decay-e

Pμ = 1438 MeV/c2 decay-e

μ-like multi-rings eventsingle μ-like ring event



27T2K neutrino events at Super-KT2K neutrino events at Super-K

Category Number

total POT 3.23 x 1019

Fully Contained (FC) 33

Fiducial volume cut + visible energy > 30 MeV (FCFV) 23



28Super-K Outer detector resultsSuper-K Outer detector results

ODC : OD containedODEX : OD exitingODEN : OD entering from ID



29SummarySummary

Jan-Jun 2010 T2K run completed Jan-Jun 2010 T2K run completed

• Continuous beam operation at ~ 50 kWContinuous beam operation at ~ 50 kW

• Good overall stability of beam and Good overall stability of beam and detector performancedetector performance

• accumulated 3.23 x 10accumulated 3.23 x 1019 19 PoT PoT

• measured 23 neutrino beam events measured 23 neutrino beam events (FCFV) at Super-K (FCFV) at Super-K

• analyses are ongoing at near and far analyses are ongoing at near and far detectorsdetectors

Summer-fall Shut downSummer-fall Shut down

• Calorimeter modules installation and Calorimeter modules installation and commissioning : full coverage at ND280commissioning : full coverage at ND280

• new kicker magnet & power supplies new kicker magnet & power supplies installedinstalled

• INGRID modules assembly and INGRID modules assembly and installationinstallation

new kicker magnet installed

ND280 ECal modules installation

ING

RID

pro

ton m

odule



30Prospects for next yearProspects for next year

Next T2K run scheduled this fall Next T2K run scheduled this fall

• Expected beam at Expected beam at 150 kW x 10150 kW x 1077s until july s until july 20112011

• High statistics at near High statistics at near detectorsdetectors

• Sensitivity to sinSensitivity to sin222θ2θ13 13 ~ ~ 0.05 0.05

July 2011 3.75 MW x 107s

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The EndThe End



32Beam powerBeam power



33Super Kamiokande event selection Super Kamiokande event selection

J-PARC neutrino events selected using GPS timeJ-PARC neutrino events selected using GPS time

SK selection and cuts values are fixed for T2K SK selection and cuts values are fixed for T2K

• Unbiased selectionUnbiased selection

For νμ disappearance analysis

For νe appearance search

Timing coincidence w/ beam timing (+TOF)

Fully contained (No OD activity)

Vertex in fiducial volume (Vertex >2m from wall)

Evis > 30MeV Evis > 100MeV

# of ring =1

μ-like ring e-like ring

No decay electron

Inv. mass w/ forced-found 2nd ring < 105MeV

Eνrec < 1250MeV



34

Precision measurement and Precision measurement and systematicssystematics

Precision measurement of Precision measurement of θθ2323 , , ΔΔmm222323

possible systematic errors and phase-1 stat.possible systematic errors and phase-1 stat.•Systematic errors• normalization (10%（→ 5%(K2K))• non-qe/qe ratio (20% (to be measured))• E scale (4% (K2K 2%))• Spectrum shape (Fluka/MARS →(Near D.))• Spectrum width (10%)

δ(sin22θ)~0.01 δ(Δm2

23) <1×10-4 eV2

GoalGoal



35

T2K sensitivity and discovery T2K sensitivity and discovery potentialpotential



36θθ13 13 sensitivity with varying δsensitivity with varying δCP CP NHNH



37θθ13 13 sensitivity with varying δsensitivity with varying δCP CP IHIH

1 tokai 2 kamioka status and prospects antonin vacheret for the t2k collaboration tuesday 7th...

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