1. Status of T2K Takashi Kobayashi KEK For T2K collaboration 1 June 14, 2010 Neutrino 2010 @Athens, Greece

2. The T2K Collaboration Canada TRIUMF U. Alberta U. B. Columbia U. Regina U. Toronto U. Victoria York U. France CEA Saclay IPN Lyon LLR E. Poly. LPNHE Paris Germany U. Aachen ~500 members, 61 Institutes, 12 countries Italy INFN, U. Roma INFN, U. Napoli INFN, U. Padova INFN, U. Bari Japan ICRR Kamioka ICRR RCCN KEK Kobe U. Kyoto U. Miyagi U. Edu. Osaka City U. U. Tokyo Poland A. Soltan, Warsaw H.Niewodniczanski, Cracow T. U. Warsaw U. Silesia, Katowice U. Warsaw U. Wroclaw Russia INR S. Korea N. U. Chonnam U. Dongshin U. Sejong N. U. Seoul U. Sungkyunkwan STFC/RAL STFC/Daresbury USA Boston U. B.N.L. Colorado S. U. Duke U. Louisiana S. U. Stony Brook U. U. C. Irvine U. Colorado U. Pittsburgh U. Rochester U. Washington Spain IFIC, Valencia IFAE (Barcelona) Switzerland U. Bern U. Geneva ETH Zurich United Kingdom Imperial C. London Queen Mary U. L. Lancaster U. Liverpool U. Oxford U. Sheffield U. Warwick U.

3. 3 T2K (Tokai to Kamioka) experiment  High intensity  beam from J-PARC MR to Super-Kamiokande @ 295km  Discovery of e appearance  Determine  13  Last unknown mixing angle  Open possibility to explore CPV in lepton sector  Precise meas. of  disappearance   23,  m 23 2  Really maximum mixing? Any symmetry? Anytihng unexpected? sin  12 ~0.5, sin  23 ~0.7, sin   <0.2)

4. 4 Remarkable Features of T2K  High intensity neutrino beam from J-PARC  First “Super beam” experiment w/ O(MW) beam  Narrow spectrum tuned at the oscillation maximum.  First application of “Off-axis beam” (cf. BNL-E889 proposal)  Less background, High sensitivity  World largest water Cherenkov detector SuperKamiokande  High efficiency for low energy  Good PID (e/  ) capability  Neutrino energy reconstruction by using Quasi-elastic (QE) interaction ( l +n  l - + p)   ~80MeV  Oscillation pattern measurement  BG due to miss-reconstruction of inelastic interaction  Greatly improved by using narrow spectrum

5. 5 >10times improvement 3.75MWx10 7 s Expected Sensitivity of T2K 5 5 Goal @ 3.75MWx10 7 s: (sin 2 2  )~0.01, (m 2  ) <1×10 -4 [eV 2 ]   e appearance  disappearance  CP =0 MINOS, PRL 101, 131802 (2008)

6. 6  2.5 deg Off-axis  Peak ~600MeV  Quasi-Elastic interaction dominate  Less Non-QE background  Muon monitors @ ~120m  Muon > 5GeV  Spill-by-spill monitoring of direction/intensity  Near detector @280m  On-axis detector “INGRID”  Intensity and direction (profile)  Off-axis (toward SK direction)  Absolute flux/spectrum/ e  Far detector Super-Kamiokande @ 295km Experimental Setup p  120m0m280m 295 km on-axis off-axis 2.5 o -mon  flux (arb. unit) Near detectors Super-Kamiokande MC (GFULUKA)

7. 7 J-PARC Facility (KEK/JAEA ） Bird’s eye photo in January of 2008 South to North Neutrino Beams (to Kamioka) JFY2009 Beams Main ring JFY2008 Beams 3 GeV Synchrotron CY2007 Beams Linac Design Intensity 750kW Construction JFY2001~2008

8. 8 Neutrino facility for T2K at J-PARC Target Primary beamline (superconducting) Electromagnetic horn Neutrino monitor bld. 8 Muon monitors  Fast Extracted (FX) beam from MR (30GeV)  6bunches (8 from Fall 2010) 581ns apart  Proton beam transport  Superconducting combined function magnets  Graphite target (26mm  x90cm)  3 horns @ 320kA (250kA by summer)  110m of decay volume  SK direction is given by GPS survey at 2  rad precision Construction (JFY2004~2008) COMPLETED as scheduled!

9. 9 2 Near Detectors Scintillator tracker & Iron sandwich UA1 magnet (Donated From CERN)  INGRID & off-axis completed in 2009 (Except side ECAL)  Side ECAL installation in Summer 2010  Commissioning completed SMRD In magnet yoke

10. 10 Far Detector: SK-IV  ICRR, Univ. of Tokyo  50kt Water Cherenkov detector operational since 1996  11129 20" PMTs in inner detector (ID), 1885 8" PMTs in outer detector (OD)  Readout electronics has been renewed in 2008 summer.  dead time less DAQ system  SK is working very stably  Beam related events are selected by event timing using GPS system.

11. Milestones  1999: Nishikawa&Totsuka proposed to measure e appearance as a next critical step toward CP measurement  2001: “The JHF-Kamioka Neutrino Project” report (hep- ex/0106019)  April 2004:  Officially approved by Japanese Government and 5yr Construction started  T2K international collaboration officially formed  March 2009: Construction completed as scheduled  April 23, 2009: First neutrino beam production and commissioning started  January 2010: Data accumulation for oscillation search started!  Feb. 24, 2010: First T2K Event in Super-Kamiokande! 11

12. Beam commissioning 12 Target size Horizontal:  1mm Vertical:  2mm Beam orbit is tuned within 2mm from design orbit. (Critical for controlling beam loss) SSEM in SSEM out SSEM foil: 5x10 -5 loss → real loss << 0.5W @50kW No significant beam loss w/o SSEM Beam loss along proton beam line OTR detector just in front of target worked very well! OTR beam Potision meas. Linearity

13. Beam commissioning 13 MUON MONITOR MEASUREMENTS Horn focusing effect clearly seen Alighment &Targeting check Beam wid. ~4mm(1  ) Target size  Functionality of all components confirmed  Beam commissioning COMPLETED Linear upto 70kW within 1%

14. Started data taking for oscillation! 14 70kW 50kW  Delivered # of protons: 2.34×10 19 (Jan-May)  Continuous run @ ~50kW level  Trial upto 100kW done (2010)

15. Proton beam stability  Beam position on target have to be controlled < 1mm  To control direction of secondary beam within 1mrad  To avoid destroying the target from non uniform thermal stress on target (at higher power)  Succeeded to control <1mm during long term operation Correlation btw p beam position on target vs MUMON center 1mrad ~3mm Horn lens effect RMS 0.4mm Current B B p beam ++ ++

16. Beam direction & intensity stability measured by Muon monitor 16  Beam direction is controlled well within 1mrad  Secondary beam intensity (normalized by proton intensity) stable within 1%  (reflects stability of targeting, horn focusing, etc)  Stable well within our physics requirements JanFebMar Detector intrinsic resolution <1.5mm Apr May 0 -10 10 Profile center (cm) Mu(Si) Total Q/N p JanFebMarApr May RMS/MEAN < 1% (whole period)

17. INGRID measurements 17  Bunch structure clearly seen as expected  Event rate is stable for wide range of intensity  Beam direction well controlled within requirement (<1mrad)

18. Off-axis detector performances Very small number of bad channels Hit Efficiencies >99% For all layers (FGD) 32 0.4%  ~8% (400~500MeV/c) dE/dx from TPC

19. Off-axis detector measurements 19 Event rate are stable FGD cluster timing FGD ECAL P0D

20. Super-Kamiokande Event Selection  J-PARC neutrino events selected by event timing using GPS  SK analysis is very well established  >20yrs of experiences w/ Water Cherenkov detector  Event selection & cut values are fixed already UNBIASED SELECTON  Selection criteria 20 For  disappearance analysisFor 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  -like ring e-like ring No decay electron Inv. mass w/ forced-found 2 nd ring < 105MeV E rec < 1250MeV

21. Observed SK events 21  Event time distribution clearly show beam structure  Observed # of Fully contained events: 22 (by Mid. May)  Expected non-beam BG: <10 -2 evts FC OD LE FC LE: Low energy triggered events OD: Outer detector events FC: Fully contained events

22. SK events Single-ring  -like event Two-ring event Pink diamonds are placed on the wall in the beam direction starting from the reconstructed vertex.

23. Analysis Strategy  Predict SK observations (   e ): N  /e (E rec  P osc ) BASED ON T2K&NA61 measurements as precisely as necessary  Then compare w/ SK observation  Intensive analysis of beam, near detector, NA61 and SK are on going 23 (omitting integral of E true ) Flux at SKOsc. Prob. Cross sect. Det. Eff. SK Det. Responce E rec : Reconstructed neutrino energy E true : True neutrino energy Far-to-near extrapolation factor SK fluxFlux at ND Normalization & Spectrum from ND measurements Hadron production measurement NA61

24. Hadron production measurement  CERN NA61  Pilot run in 2007 and high statistics data in 2009  p (30GeV) + C (thin target 4% λ I and T2K replica target )  Preliminary results on  production from 2007 thin target data were released.  They are being implemented in T2K beam MC. Preliminary NA61 π +, 20% syst. error Preliminary MC=GFLUKA

25. Future plan  Until end of June, 2010  ~50kW  Jul – Fall, 2010 (Summer shutdown)  New Kicker magnets and power supply installation (6  8bunch)  Horn power supply replacement (Old K2K  New!)  Remaining ECAL installation  After Nov. 2010  From ~100kW toward design power 25

26. Summary  Construction completed Mar.2009 as scheduled  First beam on Apr.23, 2009  Data accumulation for oscillation search started in Jan. 2010  Continuous operation at ~50kW level  Accumulated 2.34E19 protons (Until June 1 st, 2010)  Observed # of FC events: 22 (by Mid May)  After Summer: from ~100kW toward design power  Intensive analysis going on to extract physics!  Goal  Accumulate 0.75MW x 5x10 7 sec (=3.75MWx10 7 sec)  Discover e appearance  sin 2 2  13 down to 0.018 (3  ), 0.008 (90%CL)  Precise measurement of  disappearance   (  m 23 2 )~1x10 -4 eV 2,  (sin 2 2  23 )~1% 26

27. Posters on T2K 1. Masashi Otani (Kyoto U.), “The Result from the T2K Neutrino Beam Monitor INGRID” 2. Suzuki Kento (Kyoto U.), “T2K Beam Study with the Muon Monitor” 3. Tatsuya Kikawa (Kyoto U), “Development of the new T2K on-axis neutrino detector INGRID proton module” 4. Gavin Davies (Lancaster U.), “Understanding and Calibrating the Calorimeter for the T2K Near Detector” 5. Takatomi Yano (Kobe U.), “The Side Muon Range Detector for the T2K experiment” 6. Masahiro Shibata (KEK), “Commissioning of the neutrino beam facility for the first superbeam experiment T2K” 7. Georgios Christodoulou (U. of Liverpool), “T2K : Electron Neutrino Analysis at the Near Detector (ND280)” 8. Luigi Esposito (ETHZ), “NA61 data for T2K flux calculations” 9. Tomasz Palczewski, “Particle production cross-sections by 30GeV protons ” 10. Jeremy Maxime Argyriades (Geneva) “SHINE-NA61 experiment and applications for neutrino fluxes” 27