Status of J-PARC Neutrino Project T2K (Tokai-to-Kamioka)

1. NNN05@Aussois Apr.8, 2005 Status of J-PARC Neutrino ProjectT2K (Tokai-to-Kamioka) Takashi Kobayashi (KEK) • Contents • Introduction of T2K experiment • Sensitivities • Status of Construction • Summary

2. T2K experiment Phase2: 4 MW ? Phase2: Hyper-K Long baseline neutrino oscillation experiment from Tokai toKamioka. ~1GeV nm beam (100 of K2K) Super-K: 50 kton Water Cherenkov J-PARC 0.75MW 50GeV PS Kamioka Tokai Physics goals • Discovery ofnmneappearance • Precise meas. of disappearancenmnx • Discovery of CP violation (Phase2) 3

3. T2K collaboration • Formed in May 2003 • 12 countries, 53 institutions ~150 collaborators • Spokesperson: K.Nishikawa • Canada:TRIUMF, U. Alberta, York U., U. Toronto,U. Victoria, U. Regina • China:IHEP(Inst. Of High Energy Phys.) • France:CEA Saclay • Italy:U. Roma, U. Bari, U. Napoli, U. Padova • Japan:ICRR, U. Tokyo, KEK, Tohoku U., Hiroshima U., Kyoto U., Kobe U., Osaka City U., • U. Tokyo, Miyagi U. of Education • Korea:Seoul National U., Chonnam National U., Dongshin U., Kangwon U., • Kyungpook National U., KyungSang National U.,SungKyunKwan U., Yonsei U. • Poland:Warsaw U. • Russia:INR • Spain:U. Barcelona, U. Valencia • Switzerland:U. Geneva, ETH • UK:RAL, Imperial College London, Queen Mary Westfield College London, U. Liverpool • USA:UCI, SUNY-SB, U. Rochester, U. Pennsylvania, Boston U., CSU, Duke, • Dominguez Hills, BNL, UCB/LBL, U. Hawaii, ANL, MIT, LSU, LANL, U. Washington 2

4. MW Proton Facility : J-PARC • Unique facility • 3GeV+50GeV • Multi-purposes • Materials and life sci. • Nucl. and part. phys. • Nucl. transmutation Materials and Life Science Experimental Facility Hadron Experimental Facility Nuclear Transmutation Construction 2001~2008 Neutrino to Kamiokande 3 GeV Synchrotron (25 Hz, 1MW) 50 GeV Synchrotron (0.75 MW) Linac (350m) J-PARC = Japan Proton Accelerator Research Complex

5. Location of JAERI at Tokai-village JAERI=Japan Atomic Energy Research Institute Kamioka Tokai-village 60km KEK Tsukuba Tokyo Narita

6. Components Primary proton beam line Normal conducting magnets Superconducting arc Proton beam monitors Target/Horn system Decay pipe (130m) Cover OA angle 2~3 deg. Beam dump muon monitors Near neutrino detector Special Features Superconducting combined function magnets Off-axis beam Neutrino facility in J-PARC 1.Introduction Proton beam transport Target Station 3NBT 130m decay pipe 280m m-pit Near detector Construction: JFY2004~2008

7. Narrow intense beam: Off-axis beam Super-K. q Decay Pipe Target Horns 振動確率＠ Dm2=3x10-3eV2 First Application (ref.: BNL-E889 Proposal) OA0° nm flux p decay Kinematics OA2° OA2.5° 0° OA3° En (GeV) 1 2° 2.5° 3° 0 8 5 Statistics at SK (OAB 2.5 deg, 1 yr, 22.5 kt) ~ 2200nmtot ~ 1600nmCC ne~0.4% atnmpeak 0 2 pp (GeV/c) • Quasi Monochromatic Beam • x 2~3 intense than NBB • Tuned at oscillation maximum

8. Detector complex Neutrino spectra at diff. dist 1.5km 295km 0.28km Not approved! • Muon monitors @ ~140m • Fast (spill-by-spill) monitoring of beam direction/intensity • First near detector@280m • Flux/spectrum/ne • intensity/direction • Second near detector @ ~2km • Almost same En spectrum as for SK • Water Cherenkov can work • Far detector @ 295km • Super-Kamiokande (50kt) p p n 0m 140m 280m 2 km 295 km dominant syst. in K2K

9. Conceptual Design of Near Detector @ 280m Off-axis detector n spectrum Cross sect. ne contami. UA1 mag, FGD, TPC, Ecal,.. On axis detector Monitor beam dir. Grid layout Off-axis Detector Hole UA1 mag On-axis

10. Far Detectors 2nd Phase (201x~?) Hyper-Kamiokande(~540kt) 1st Phase (2009~, ≥5yrs) Super-Kamiokande(22.5kt)

11. Common decay pipe for SK/HK covering 2~3 deg OA angle SK ~8km HK Beam eye Candidate site for HK Decay pipe Cover this region

12. Sensitivity: nmnm disappearance d(sin2 2q) d(Dm2) Effect of systematic error on param meas. Expected precision Stat. only (OA2.5) --68%CL (Dln L=0.5) --90%CL (Dln L=1.36) --99%CL (Dln L=3.32) Goal d(sin22q23)~0.01 d(Dm232)~<1×10-4 Stat. error norm (+5%) NQE (+5%) ESK (+1%) beam shape (±20%) beam width (5%)

13. Sensitivity: ne appearance Discovery of neappearance (q13,Dm13) 10-1 (Pe, qe) e sin22q13 >0.006(90%) ne En p 10-2 CHOOZ excluded ~20 Dm132 (eV2) Signal+BG 40 30 BG 10-3 Dm2 = 3x10-3eV2 sin22q13 = 0.1 20 W/ 10% error for BG subtraction 10 OA2o 5years 10-4 10-3 10-2 10-1 1 0 0 1 2 3 4 sin22q13 Enrec(GeV) 7 Assuming sin2q23=0.5, d=0, no matter

14. 3s Sensitivity for CPV in T2K-II 4MW, 540kt 2yr for nm 6~7yr for nm CHOOZ excluded sin22q13<0.12@Dm312~3x10-3eV2 Dm212=6.9x10-5eV2 Dm322=2.8x10-3eV2 q12=0.594 q23=p/4 stat+5%syst. stat+2%syst. (signal+BG) stat only stat+10%syst. no BG signal stat only T2K 3s discovery T2K-I 90% 3s CP sensitivity : |d|>20o for sin22q13>0.01 with 2% syst.

15. Status of R&D, Design, Construction

16. January, 2005

17. Fast extraction part Ring orbit Fast ext. beam 3NBT Decay Volume (excavated) Jan.28, 2005

18. 50 GeV Synchrotron Construction Area B

19. Superconducting magnets T.Ogitsu, T.Nakamoto, et.al., Cryogenic Sci. Center, KEK • 28 combined function magnets in arc part • Dipole Field: 2.587 T, Quad. Field: 18.62 T/m • Reduce cost while keeping large acceptance • Use common parts with LHC to reduce cost/risk • First full size prototype completed • Cooled, current loaded • 7700A (ope. curr. @50GeV + 5%) achieved w/o any spontaneous quenching (Mar.4) • In FY2005, mass production of magnets will start Prototype coils completed by Oct. 2004 Feb.21,2005

20. Shell Welding Completed (Dec21,04) Put in vertical cryostat for cooling/current loading test (Feb.21,2005) Vacuum Vessel from Spain

21. Target Area Target, horns are installed. Filled with Helium gas (reduce Tritium, NOx production) Highly radio-activated (~1Sv/h, cf ~10Sv@JCO, Dose meter alarm: 0.3mSv/h) Need remote-controlled maintenance system Need cooling (Helium vessel, radiation shield,..)

22. Target Carbon Graphite: 30mm(D)x900mm(L), 2 interaction length (70% int.) Energy deposit: 58kJ/spill (~20kW) Equivalent stress (DT~200K) ~ 7MPa (<Tensile strength of 37MPa) Cooled at outer surface R&D and Design Status Helium cooling method designed Prototype of Graphite target made Feasibility of machining proved Radiation damage of Graphite tested Nakadaira/Ichikawa Prototype production • Feasibility of machining Graphite tested • Thin (2mm) inner cooling pipe • Will be used for Helium flow test

23. Horn system Focus secondary pions into decay volume Field shape optimization completed 320kA pulse current synchronized w/ beam Made of Aluminum alloy (A6061) Ichikawa, w/ U. Colorado Target beam 1st Horn 2nd Horn 3rd Horn Perfect horn (accept. 180º) Horn On T2K horn nm flux Horn Off En (GeV)

24. Horn design & test status One of the designs of Stripline connection Cooling power test of splay nozzle Heater imitating Inner conductor Colorado U w/ Outer conductor of the 1st horn Inner conductor of the 1st horn

25. Decay Volume Cover Off Axis angle : 2º~3º Square box shape made with water cooled iron plates (T<60ºC) Filled by 1atm Helium gas Construction started Crossing 50m part w/ 3NBT by June 15, 2005 Remaining part in 2007&2008 Tada/Yamada Construction Started in 2004 3NBT (BT bet. 3GeV&MLF) constructed in 2005 6m thick concrete structure OA2o OA3o Target Station Decay Volume ~110m Dump Cross section:2.2m(W)x2.8m(H) 3.0m(W)x4.6m(H) beam Cooling channels(Plate coil)

26. Decay pipe construction Mar.21, 2005 Feb. 9, 2005

27. Decay volume Apr. 5

28. Schedule • Construction takes 5 yrs (2004~2008JFY) • Experiment start in 2009JFY Now

29. Summary • T2K Experiment • High sensitivity superbeam experiment • Narrow, intense beam with Off-axis technique • Physics goals • ne appearance: sin22q13 > 0.006 (90%CL) • nm disappearance: d(Dm232)~10-4eV2, d(sin22q23)~1% • Search for CPV(phase 2): d>~20deg • Neutrino beam line construction started • Intensive R&D and design work of beam line components • Start experiment in 2009

30. Conceptual Design of 2km detector L.Ar W.Ch. MRD n

31. Development of sensitivity and comparison with other projects K2K excluded (2003) w/ Design J-PARC Intensity Low sens. Excluded by reactor ne disapp. exp K2K final sens.? (2005?) MINOS(FNAL) ICARUS(CERN) Sensitivity on sin22q13 T2K 90%C.L. sensitivity High sens. 0.006 in five yr Beam power is essential to achieve this goal in time

32. 2. Recent Activities • Construction Started • Decay Volume (crossing 50m part with 3NBT) • Intensive R&D and design work for beam line components • SC mag: 1 full size prototype made in house and 1 by company • Prototypes for Graphite target, horn made • And so on. (Later some are introduced.) • Final detailed design for facility • Aug. 2004 ~ Mar. 2005 • (T2K Collaboration) Meeting in Aug. 2004 • Reuse of UA1 magnet for near detector • Draft budget for JFY2005 (Dec.2005) • Facility: Full • Instruments: Nearlly full • 9.9  8.15Oku\ (Not reduced, but delayed.) • n-TAC: • Dec. 2003: Valuable advices • Next n-TAC in Apr. 26-28, 2005

33. Expected Beam Power

34. Budget Decision for 2005 (Finance Dept.) Phase 1 completion in JFY2007 is barely possible ! Need a big increase in JFY2006.

35. Budget Issues • Funding for the entire JAERI has been decreased. • Yet, a big rise is needed for JFY2005 for timely completion. • Influence came to the JAERI budget reduction in JFY2005 for development of instruments from 3.4 to 1.2 Oku Yen. • JAERI and JNC will merge together in October, 2005. • Influence to us is unknown. • Budget for KEK portion of J-PARC. • Need a further increase in JFY2005. • New proposal from KEK to MEXT for the “cost associated with the movement to Tokai” was approved, starting from JFY2005. (6.6 Oku Yen for JFY2005. An increased funding for JFY2006 and JFY2007 is expected.) • Other Funding Source(s). • Ibaraki Prefecture decided to contribute to J-PARC by preparing 24 Oku Yen. Primary interest: 2 neutron beam lines for industrial usage. • Shortage in Budget. • Experimental devices: Little funds. • Research buildings, lodging, assembly areas, etc.: No funds. • No contingencies in Japan: Possible overrun (could be the next IAC issue).

36. Single turn fast extraction 8 bunches/~5ms 3.3x1014proton/pulse 3.53 sec cycle e=6p mm.mr, Dp/p=0.31% @50GeV Total bending = 84.5o Primary beam line 1.Introduction Preparation section Normal conducting 750W loss • Arc Section (R=105m) • Superconductingcombined function magnets • First application in the world • Reduce cost comp. w/ separated function • Larger acceptance • 1W/m loss Final Focusing Section Normal conducting 250W loss

37. Sensitivity for Mixing Angle sin22q13~0.018 (3s) sin22q13~0.006 (90%) 0.5xsin22q13 Background systematic error required to be ~ less than 10%

38. n / n CC interaction spectrum for CPV meas. nm: 2 years nm: 6.8 years nm cross section difference NCC(/100MeV/22.5kt/year) nm Wrong sign BG (x10 nm case)

39. Expected signal and BG (SK full sim) Very Preliminary nm:2yr, nm:6.8yr 4MW 0.54Mt sin22q13=0.02 Dm212=6.9x10-5eV2 Dm322=2.8x10-3eV2 q12=0.594 q23=p/4 q13=0.05 (sin22q13=0.01)