1. 1 Tokai 2 Kamioka Status and Prospects Antonin Vacheret for the T2K Collaboration Tuesday 7th September NOW 2010, Otranto, Lecce, Italy

2. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 2 Overview T2K physics goalsT2K physics goals Experimental sensitivityExperimental sensitivity Overview of the experimentOverview of the experiment Status and prospectsStatus and prospects

3. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 3 Neutrino oscillation matrix Neutrino oscillation described by unitary matrix U MNSP 3 mixing angles ( θ 12, θ 23, θ 13 ) 1 CP violation phase (δ) 2 mass 2 differences (Δm 2 ij = m 2 i - m 2 j ) value of θ 13 is only constrained by datavalue of θ 13 is only constrained by data δ is unknownδ is unknown sign of Δm 2 atm is not yet knownsign of Δm 2 atm is not yet known Necessary to complete oscillation picture ! Δm 2 atm ντντ νμνμ νeνe m12m12 0 m22m22 m32m32 Δm 2 solar NH IH m22m22 m12m12 m32m32 Δm 2 solar ?? Δm 2 atm = 0 ? cij = cos θij, sij = sin θij

4. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 4 T2K Goals measure last unknown mixing angle θ 13 using ν μ ➞ ν e appearancemeasure last unknown mixing angle θ 13 using ν μ ➞ ν e appearance potentially open up δ CP search in neutrino sector measure precisely the atmospheric parameters using ν μ ➞ ν μ disappearancemeasure precisely the atmospheric parameters using ν μ ➞ ν μ disappearance is there a symmetry between 2nd and 3rd generation ?

5. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 5 ν μ ➞ ν e appearance Sensitivity down to 0.006 @ Δm 2 23 = 2.5 x 10 -3 eV 2 3.75 MW x 10 7 s δ CP = 0 x 10

6. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 6 ν μ disappearance Enter precise measurement era : δ(sin 2 2Θ 23 ) ~ 0.01δ(sin 2 2Θ 23 ) ~ 0.01 δ(Δm 2 13 ) ~ 1 x 10 -4 eV 2δ(Δm 2 13 ) ~ 1 x 10 -4 eV 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. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 7 J-PARC Intense proton beam : 750 KW at design value Far detector Super-Kamiokande : 50 kT Water Cherenkov detector - high statistics CCQE event reconstructed with high efficiency & purity Unique baseline : first Off-axis neutrino beam (angle @ 2.5º) Narrow band beam ideal for ν e searchNarrow band beam ideal for ν e search peak energy at oscillation maximum < 1 GeV : Quasi-elastic (CCQE) processes dominatepeak energy at oscillation maximum < 1 GeV : Quasi-elastic (CCQE) processes dominate - low contamination from other ν flavour ( 0.5% ν e ) - Background from misreconstructed high energy neutrinos significantly reduced Near detectors @ 280 m Measure on axis and off-axis beamMeasure on axis and off-axis beam p   120m0m280m 295 km on-axis off-axis 2.5 o -mon The T2K baseline The T2K baseline J-PARC 30 GeV proton beam Super-Kamiokande Near detectors

8. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 8 Analysis strategy Number of reconstructed events (ν μ and ν e ) at SK can be predicted 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 parameters : omit integral on E ν true SK Det response Det eff. Cross section beam 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 & E ν spectrum from T2K ND

9. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 9 The T2K Collaboration

10. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 10 The 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 Construction JFY2001~2008 750 kW (design value)

11. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 11 The neutrino beam line 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 proton transportSuperconducting combined function magnets for proton transport Primary beam monitors Intensity(CT), position(ESM), profile(SSEM), beam loss(IC), beam profile at target (OTR)Intensity(CT), position(ESM), profile(SSEM), beam loss(IC), beam profile at target (OTR) 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 with Helium Beam dump Hadron absorber graphite modules Hadron absorber graphite modules Secondary beam monitors muon profile after beam dump : ionisation chambers and SiPIN (MUMON)muon profile after beam dump : ionisation chambers and SiPIN (MUMON) Emulsion exposures (low intensity)Emulsion exposures (low intensity) Neutrino detectors at 280 m Super-K direction given by GPS π,μ protons ν ν to SK neutrino beam line Horns Graphite target MUMON Neutrino near detectors complex

12. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 12 INGRID On-axis monitor On-Axis detector is crucial for off-axis measurements : monitor beam direction, intensity and mean energymonitor beam direction, intensity and mean energy beam coverage ~ 10 x 10 m 2beam coverage ~ 10 x 10 m 2 Off-axis angle measurement accuracy goal is 1 mrad (< 15 MeV on off-axis peak energy)Off-axis angle measurement accuracy goal is 1 mrad (< 15 MeV on off-axis peak energy) beam position resolution ~ 7cm corresponding to ~3 mm shift at proton targetbeam position resolution ~ 7cm corresponding to ~3 mm shift at proton target ~ 10 k ν interactions per day at full power 2 remaining diagonal modules and 1 full plastic “proton” module to be installed for next T2K run2 remaining diagonal modules and 1 full plastic “proton” module to be installed for next T2K run ν INGRID “cross” is formed with 14 identical modules + 2 diagonal modules made of plastic scintillator planes and 6.5 cm thick Iron planes surrounded by veto planes ν beam

13. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 13 The Off-axis near detector 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 (NCπ 0 )Super-K background measurements (NCπ 0 ) Two target regions : The P0D (Brass/Plastic segmented) : π 0 detectorThe P0D (Brass/Plastic segmented) : π 0 detector The tracker region : Fined grained plastic detector and TPCThe tracker region : Fined grained plastic detector and TPC Both region have passive water planesBoth region have passive water planes Large Calorimeter coverage (Plastic/Pb segmented) Additional NCπ 0 production measurement in tracker and PID, hermicity, active vetoAdditional NCπ 0 production measurement in tracker and PID, hermicity, active veto Side Muon ranging detector Neutrino Rate, Side muons, cosmics triggerNeutrino Rate, Side muons, cosmics trigger Precise cross-section measurements with very large statistics !!! ND280 P0D Tracker ECals Yoke/SMRD UA1 Magnet (CERN donation) ν beam 8 m

14. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 14 Near Detector Technologies Scintillator + WLS fibre read out by novel MPPC ND280 Low cost high performance and uniformity detector elementLow cost high performance and uniformity detector element novel solid state photosensor insensitive to magnetic fieldnovel solid state photosensor insensitive to magnetic field Photon counting, high PDE, low power consumption, ceramic packagePhoton counting, high PDE, low power consumption, ceramic package ~ 56 800 channels~ 56 800 channels T2K first experiment to use MPPC at such a large scaleT2K first experiment to use MPPC at such a large scale 1.3mm 50μm Front end Board AFTER ASIC (FGD & TPC) TRIP-t ASIC (others) HAMAMATSU MPPC 667 Pixels array Various shapes of Plastic scintillator with Y-11 fibre 10 mm P0DFGD TPC Very Large TPC based on MicroMegas read out 3x large modules with double wall structure3x large modules with double wall structure Sensitive volume 180 x 200 x 70 cmSensitive volume 180 x 200 x 70 cm Precise assembly, commissioning and alignment within mmPrecise assembly, commissioning and alignment within mm 124 000 channels124 000 channels

15. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 15 The Far detector : Super Kamiokande IV 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) Super-K in operation since 1996 Dead-timeless read out electronics and DAQ upgrade in 2008Dead-timeless read out electronics and DAQ upgrade in 2008 GPS system used to select time arrival of beam eventsGPS system used to select time arrival of beam events Water transparency (light att. length) 90 m

16. 16 T2K Status

17. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 17 Beam performance First T2K run completed ( January to June 2010) 3.3 x 10 19 protons accumulated for T2K analysis3.3 x 10 19 protons accumulated for T2K analysis 50 kW stable operation with trials at 100 kW 50 kW stable operation with trials at 100 kW Super-K live fraction in excess of 99%Super-K live fraction in excess of 99% 50 kW 80 kW

18. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 18 Beam Monitors Proton beam precisely tuned (less than 1 mm deviation at target) to minimise beam loss and control secondary beam spill by spill MUMON : profile center < +/- 1 mrad ( ΔE ν peak ~2%/mrad)

19. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 19 Beam 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 mm σ = 4.13 mm μ= 0.85 mm σ = 4.19 mm

20. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 20 CERN NA-61/SHINE Neutrino beam depends upon secondary beam geometry and hadron distribution off target NA-61/SHINE : dedicated hadron production experiment using T2K target to reduce uncertainties in hadron production models Pilot run in 2007 and high statistics run in 2009 : p(30 GeV) with Carbon thin target and T2K replica targetPilot run in 2007 and high statistics run in 2009 : p(30 GeV) with Carbon thin target and T2K replica target preliminary results from 2007 used in T2K beam MCpreliminary results from 2007 used in T2K beam MC MC=GFLUKA Preliminary

21. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 21 INGRID measurements First event Beam Profile X Beam Profile Center X Beam Profile Y Beam Profile Center Y

22. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 22 ND280 off-axis detector performance Interaction vertex reconstruction off-axis beam profile clearly visible in both target regions (FGD and P0D)off-axis beam profile clearly visible in both target regions (FGD and P0D) Particle identification (TPC dEdx) crucial for measuring ν μ and beam ν e spectracrucial for measuring ν μ and beam ν e spectra Vertex X-Y distribution P0D FGD ⊗ ν beam direction Energy loss beam TPC negative tracks TPC positive tracks

23. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 23 ND280 timing & rate stability 18 FGD activity in time with beam Daily DsECal cluster rates P0D reconstructed vertices

24. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 24 ND280 off-axis neutrino events

25. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 25 Super-K time distribution Very good synchronisation with T2K beam achievedVery good synchronisation with T2K beam achieved ∆T 0 = SK trig time -T2K beam trigger time Bunch residual time (nsec) RMS ~ 26 ns

26. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 26 Super-K ν events P μ = 1025 MeV/c 1 decay-e P μ = 1438 MeV/c 2 decay-e μ-like multi-rings event single μ-like ring event

27. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 27 T2K neutrino events at Super-K CategoryNumber total POT3.23 x 10 19 Fully Contained (FC)33 Fiducial volume cut + visible energy > 30 MeV (FCFV) 23

28. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 28 Super-K Outer detector results ODC : OD contained ODEX : OD exiting ODEN : OD entering from ID

29. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 29 Summary Jan-Jun 2010 T2K run completed Continuous beam operation at ~ 50 kWContinuous beam operation at ~ 50 kW Good overall stability of beam and detector performanceGood overall stability of beam and detector performance accumulated 3.23 x 10 19 PoTaccumulated 3.23 x 10 19 PoT measured 23 neutrino beam events (FCFV) at Super-Kmeasured 23 neutrino beam events (FCFV) at Super-K analyses are ongoing at near and far detectorsanalyses are ongoing at near and far detectors Summer-fall Shut down Calorimeter modules installation and commissioning : full coverage at ND280Calorimeter modules installation and commissioning : full coverage at ND280 new kicker magnet & power supplies installednew kicker magnet & power supplies installed INGRID modules assembly and installationINGRID modules assembly and installation new kicker magnet installed ND280 ECal modules installation INGRID proton module

30. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 30 Prospects for next year Next T2K run scheduled this fall Expected beam at 150 kW x 10 7 s until july 2011Expected beam at 150 kW x 10 7 s until july 2011 High statistics at near detectorsHigh statistics at near detectors Sensitivity to sin 2 2θ 13 ~ 0.05Sensitivity to sin 2 2θ 13 ~ 0.05 July 20113.75 MW x 10 7 s

31. 31 The End

32. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 32 Beam power

33. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 33 Super Kamiokande event selection J-PARC neutrino events selected using GPS time SK selection and cuts values are fixed for T2K Unbiased selectionUnbiased selection For ν μ disappearance analysis For ν e appearance search Timing coincidence w/ beam timing (+TOF) Fully contained (No OD activity) Vertex in fiducial volume (Vertex >2m from wall) Evis > 30MeVEvis > 100MeV # of ring =1 μ-like ringe-like ring No decay electron Inv. mass w/ forced-found 2 nd ring < 105MeV E ν rec < 1250MeV

34. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 34 Precision measurement and systematics Precision measurement of  23, Δ m 2 23 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%)  (sin 2 2   )~0.01  (Δm 2 23 ) <1×10 -4 eV 2 Goal

35. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 35 T2K sensitivity and discovery potential

36. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 36 θ 13 sensitivity with varying δ CP NH

37. Antonin Vacheret, Imperial College London NOW 2010, 7th September Otranto Lecce Italy 37 θ 13 sensitivity with varying δ CP IH