1. Fermilab, May, 2003 Takaaki Kajita, ICRR, U. Tokyo ・ Introduction ・ JHF-Kamioka neutrino project -overview- ・ Physics in phase-I ・ Phase-II ・ Summary Outline

3. SK atmospheric neutrino data Whole SK-1 data have been analyzed. 1489day FC+PC data + 1678day upward going muon data 1-ring e-like 1-ring μ-like multi-ring μ-like up-going μ Up-going Down-going No osc. Osc. stopping Through going < 1.3GeV > 1.3GeV

4. Oscillation parameters Kamiokande Soudan-2 MACRO SK ν μ →ν τ ９０％Ｃ．Ｌ． Limit on θ 13

5. E E K2K 250km

6. K2K data and oscillation Best fit point (sin 2 2 ,  m 2 ) = (1.0, 2.8x10 -3 eV 2 ) Best fit Normalized by area (single ring events) No osc. N SK (# of event) 56 events observed 80.1+6.2/-5.4 ev. expt’d null oscillation prob. 1.3% + Data: 1999 – July 2001 Consistent with SK atm.

7. Next: MINOS (end of 2004): Detail study of oscillations. Next 2 : JHF-Kamioka neutrino project CNGS (OPERA, ICARUS) (2006) : τ appearance.

9. Main goals ★ Precise determination of neutrino oscillation parameters. Accuracy: sin 2 2θ ・・・・・・ 1% Δm 2 ・・・・・・・・・・ a few % ★ Discovery and measurement of non-zero θ sin 2 2θ ・・・・・・ > 0.01 Main physics goals in JHF-I neutrino exp. 23 13 ★ Discovery and measurement of non-zero CP phase Main physics goal in JHF-II

10. JHF-Kamioka neutrino project –overview- < 1 GeV ν μ beam 0.75 MW 50 GeV PS 50 kton Water Cherenkov ～ 1Mt “ Hyper Kamiokande ” 4MW 50GeV PS Future

11. Present collaboration Canada USA UK Poland France Switzerland Italy Spain Russia Korea Japan China

12. J-PARC(JHF) Facility Construction 2001 ～ 2006 (approved) (0.75MW) Near detectors (280m,2km) beam-line + detectors budget request will be submitted soon. JHFNuMI (FNAL) K2K E(GeV)5012012 Int.(10 12 ppp) 330406 Rate(Hz)0.2750.530.45 Power(MW) 0.750.410.0052 To SK

13. Primary proton beamline –Overview- Preparation section Normal conducting Arc R=105m Super conducting Dipole + Quadrapole combined function magnet Final Focusing Section Normal conducting  Single turn fast extraction  8 bunches/~5  s  3.3x10 14 proton/pulse  3.64 sec cycle  1 ｙｒ ≡10 21 proton on target(POT) 50GeV PS

15. J-PARC construction

16. J-PARC LINAC construction (Apr.03)

17. The beam: Off axis beam  Target Horns Decay Pipe (ref.: BNL-E889 Proposal) E π vs. E ν EπEπ EνEν 0.0 ゜ 1.0 ゜ 1.5 ゜ 2.0 ゜ 3.0 ゜ 5.0 ゜ 2.5±0.5 ゜ Max. osc. energy for 3×10 -3 eV 2 OA3° OA2° OA1° 2200 CC ν μ / year 800 CC ν μ / year

18. Target and horns (preliminary design) 1.5m 0.5m 2.0m 3.5m 2.5m 320kA Target: Graphite (φ=25-30mm) w/ water cooling Horn Temperature rise due to radiation Need much more detailed studies Degre e beam w/ 1pulse R

19. Decay tunnel design 130 meters

20. Decay pipe cooling and heat simulation Non-static heat simulation 0.5yr@4MW, 0.5yr no beam Upto 30yrs Max @ 29.5yr Iron part Max 54 o Concrete Max 121 o

21. Detector system p  140m0m280m2 km295 km 15.2m Total mass : 1000ton Fid. Mass : 100ton ν beam Fine grained scintillater detector 5m 8m Water Cherenkov detector Muon detector Near detector @2km (@50m underground) μν ν SK

22. Event rate & Far/near ratio Distance from target (km) 6 /100ton/spill @280m 0.1 /100ton/spill @2km Water Cherenkov : Impossible @280m (Total mass > 100 tons) ( φ far / φ near )×(L far / L near ) 2 2 1 1 0 0 @280m @2km Not a good place…. OK ! 0123 E ν (GeV)

23. Near detector @1.84km Candidate site (Owner: Tokai- village (local government)) Surface building 55m deep 37m long φ17m Muon detector Kamioka Water Cherenkov Fine grained detector

25. Reconstruction of Eν  + n →  + p -- p ( E , p  )  JHF E ν E μ, θ μ EνEν Non-QE Quasi- elastic Super-K w/ JHF beam For single Ch ring events:

26. Quasi-elastic and other interactions Best fit Normalized by area (single ring events) No osc. High E ν non-quasi-elastic interactions cause problems. Minimize the high energy (above the max. osc. energy) neutrino flux.

27. Single ring (muon-like) in Super-K Data sample: SK Monte Carlo, Fully-contained single- ring, muon-like events. Event fraction Typical JHF neutrino energy Important to run the experiment with low energy beam. π π

28. Measurement of sin 2θ 23 2 For sin 2θ 23 =1.00 2 QE + non-QE Non-QE No osc. Oscillation (sin 2θ 23 =1.00) 2 QE events only 1 % (OA 2deg) δ(sin 2θ 23 ) = 1% δ(Δm 2 ) = 1×10 -4 eV 2 2 2 4 ×10 -3 eV 2 OA 2deg OA 3deg

29. 4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 0.97 0.98 0.99 1.0 Δm 2 (×10 -3 eV 2 ) sin 2 2θ OA 2deg, 90%CL Very preliminary, unofficial Only 5% normalization error considered for systematics Only look at the sensitivity on sin 2 2θ No copy Off-axis angle should be adjusted to about 0.1 deg. Δm 2 dependence of the sensitivity

30. θ 13 Present status: BG (NC π 0 ….) Signal for non- zero θ 13 in JHF- SK (ν μ →ν e ) Allowed

31. ν e beam contamination OAB (2degree) ν e /ν μ ratio=0.2% at the spectrum peak. K-decay  -decay  e 0.2%

32. Number of signal events and BG  m 2 =3x10 -3 eV 2, sin 2 2   =0.1 OAB 2deg., 5yrs  C.C.  N.C.Beam e Osc'd e Generated10713.64080.3292.1301.6 1ring e-like14.3247.168.4203.7 red. eff.0.1%6.1%23.4%67.5% e/  0 sep. 3.523.021.9152.2 red.eff.0.03%0.6%7.5%50.4%.4<E <1.2 1.89.311.1123.2 red.eff.0.02%0.2%3.8%40.8%

33. e/π 0 separation Shower direction w.r.t. beam (1) cos  e :  0 tend to have a forward peak Force to find 2nd ring and… (2) E(  2 )/E(  1 +  2 ): Large for BG (3) Likelihood diff. between 1 and 2-ring assumptions (4) Invariant mass: Small for e BG νeνe Select (1) (2)(3)(4)

34. Measurement of sin 2 2θ 13 sin 2 2θ 13 Δm 2 sin 2θ 13 ν μ (CC+NC) Bean ν e Osc ’ d ν e Signal+BG 0.111.1 123.2145.5 0.0111.1 12.334.5 2 Expected signal for OA 2deg 5yrs ×1/20 CHOO Z limit JHF sensitivity

36. JHF Phase-II 10 6 events ★ 0.77 → 4 MW beam power ★～ 1 Mton detector (Hyper-Kamiokande) CP Violation

37. Assumptions Solid line: w/ matter Dashed line: w/o matter (unless otherwise stated)

38. Neutrino and anti-neutrino runs 10 21 pot/yr (1st phase)  beam wrong sign right sign N CC (Number of CC events) Important to understand the wrong sign contamination 3.4yr ν μ = 1yr ν μ

39. sin 2 2  13 =0.1  m 31 <0  m 31 >0 90%C.L. stat only 90%C.L. stat+2% syst. 3  stat only 3  stat+2% syst. # of e - events including BG # of e + events including BG CP phase Expected CP violation signal(1)

40. sin 2 2  13 =0.01  m 31 <0  m 31 >0 90%C.L. stat only 90%C.L. stat+2% syst. 3  stat only 3  stat+2% syst. # of e - events including BG # of e + events including BG CP phase Expected CP violation signal (2)

41. 3σ CP sensitivity no BG signal stat only (signal+BG) stat only stat+2%syst. stat+5%syst. stat+10%syst. CHOOZ excluded sin 2 2  13 <0.12@  m 31 2 ~3x10 -3 eV 2 JHF-I: No indication for sin 2 2θ 13 3  CP sensitivity : |  |>20 o for sin 2 2  13 >0.01 with 2% syst. sin 2 2θ 13 sinδ

42. Decay Pipe Common for SK/HK SK ~8 km HK Possible site for Hyper-K Beam eye Decay pipe Common off-axis angle (2-3 degrees) for both Super-K and Hyper-K Beam center North-south About 500 – 600 m. Candidate place

43. ● Main goals of JHF-Kamioka neutrino project (Phase-I) ★ Precise determination of neutrino oscillation parameters. Accuracy: sin 2 2θ ・・・・・・ 1% Δm 2 ・・・・・・・・・・ a few % ★ Discovery and measurement of non-zero θ 13 sin 2 2θ ・・・・・・ > 0.01 ● Main goals of JHF-Kamioka neutrino project (Phase-II) ★ Discovery and measurement of non-zero CP phase ● Design works are in progress hoping to start the experiment by (the end of 2007 or) early 2008. 23 13