1. 1 Recent Results from Neutrino Experiments and Plans for the Neutrino Super Beam in Japan Discovery of neutrino oscillations  finite neutrino masses ( 2 and 3 ) (1998 – present) Small as expected Mixing among neutrino flavors expected Quark mixing implies small mixing Y.Totsuka, KEK NSS-2003, 031021

2. 2 e   () = 1 2 3 () U e1 U  1 U  1 ( U e2 U  2 U  2 U e3 U  3 U  3 ) c 12 c 13 s 12 c 13 s 13 e -i  -s 12 c 23 -c 12 s 13 s 23 e -i  c 12 c 23 -s 12 s 13 s 23 e -i  c 13 s 23 s 12 s 23 -c 12 s 13 c 23 e -i  -c 12 s 23 -s 12 s 13 c 23 e -i  c 13 s 23 U ( Maki-Nakagawa-Sakata Matrix) = s ij =sin  ij, c ij =cos  ij,  =CP Mixing matrix ( ) Free moving states (mass eigenstates) Interacting states Discovery of large mixing angles,  23 and  12

3. 3 p, He Atmosphere Atmospheric neutrinos - I e Earth Super-K ±±  ±± e±e± Expected event rate is uncertain by ~15%  : e = 2 : 1 (low energy) known better than 5% Up-down symmetry for E > 1 GeV

4. 4 ４０ｍ ４１．４ｍ Super-Kamiokande (1996) 1996- 50000ton water 11146 50cm  PMT (40% photo coverage) 1000m underground Min det. energy ~ 5 MeV Basic reactions  + N   + X e + N  e + X

5. 5 SK-II Cosmic ray muon sample 20inch PMT with Acrylic + FRP vessel Super-Kamiokande II Accident on Nov 12, 2001 Repaired and restarted in Dec, 2002 Inner detector with ~5200 20” PMTs Outer detector with 1885 8” PMTs

6. 6  2 =170.8/170 d.o.f. at (sin 2 2  23,  m 23 2 )=(1.00, 2.0x10 -3 eV 2 )  2 =445.2/172 d.o.f. (null oscillation) 1489 day FC+PC data + 1646 day upward going muon data

7. 7 Allowed region of the oscillation parameters Assuming      oscillation Best fit  2 min = 170.8/170 d.o.f at (sin 2 2  23   m 23 2 ) = (1.0, 2.0 x 10 -3 eV 2 ) 90% CL allowed region sin 2 2  23  > 0.9 1.3x10 -3 <  m 23 2 <3.0x10 -3 (eV 2 ) Assuming null oscillation  2 = 445.2/172 d.o.f (complete SK-I dataset) Soudan-2 MACRO Super-K 68% CL 90% CL 99% CL

8. 8 K2K 250km Long baseline neutrino oscillation experiment 12 GeV PS at KEK Neutrino beamline  ~ 1.3GeV  98% purity Beam monitors and near detector  beam direction   measurement   flux and spectrum Far detector  flux and spectrum

9. 9 Best fit 1R  spectrum & Nsk Best fit point (sin 2 2  23,  m 23 2 ) = (1.0, 2.8x10 -3 eV 2 ) KS test prob.(shape): 79% N SK =54 (Obs.=56) Very good agreement in shape & N SK with atmospheric neutrinos Expected w/o oscillation Normalized w/o oscillation Normalized with best fit oscillation Total number of obs. Events: 5616 (Jan03-Apr03) Expected w/o oscillation: 80.6 +7.3-8.0 24 +2.3-2.1

10. 10 Comparison with SK atm observation K2K(1R  shape+N SK ) SK (FC+PC+up  ) 90%CL

11. 11 Solar image

12. 12 SNO: e  e (ES); e d  epp (CC); d  pn, Cl(n,  )Cl, (NC) Electronics hut Control room 1000 ton heavy water (12m  acrylic vessel) 9456 of 8 inch PMTs INCO’s Creighnton mine Sudbury, ON, Canada 2km SNO 1700+5300 ton light water (17.8m  stainless steel support, 34mh x 22m  barrel-shaped cavity) (6010mwe) photo coverage55% (R<7m) cosmic ray muons~70 events/day fiducial volume0.7kt (R,5.5m) Trigger rate (data) 6~8Hz (~2MeV threshold) Trigger efficiency100%@~3MeV From compton e- from 16 N source (~5 MeV) vertex resolution16cm energy resolution16% angular resolution27 ℃ NaCl in D 2 O

13. 13  CC =  e  ES =  e +0.154  ,   NC =  e +  ,  SNO  CC = 1.7+-0.05+-0.09  ES = 2.39 +-0.12  NC = 5.09 SK  ES = 2.32+-0.03 Evidence for an active non- e component ！ [x10 6 /cm 2 /s] Super-K + SNO combined (as of 2002) +0.24 - 0.23 +0.44 +0.46 - 0.43 +0.08 - 0.07  SK ES

14. 14 SNO rates and day/night spectra and Super-K zenith spectra e   oscillation -3 -4 -5 -6 -7 -8 -9 -10 -11 log  m 2 (eV 2 ) -4-3-201 Log tan 2 

15. 15 Kam-LAND 1000m 3 liquid scintillator 3000m 3 oil+water shield 1300 17-inch PMTs + 600 20-inch PMTs Anti- e from reactors (L~170km) Detect e + from e + p  e + + n (Eth = 1.8 MeV) Observation started on 22 Jan 2002

16. 16 Kam-LAND result 145.1 live days, 162 ton year exposure Te > 2.6 MeV, 86.8+-5.6 ev expected 56 ev observed with 1 BG estimated Te > 0.9MeV 124.8+-7.5 ev expected 86 ev observed with 2.9 +-1.1BG estimated

17. 17 KamLAND confirms the LMA solution!

18. 18 FIG. 5: Global neutrino oscillation contours. (a) Solar global: D 2 O day and night spectra, salt CC, NC, ES fluxes, SK, Cl, Ga. The best-fit point is  m 2 = 6.5 × 10 -5, tan 2  = 0.40, f B = 1.04, with 2/d.o.f.=70.2/81. (b) Solar global + KamLAND. The best-fit point is  m 2 = 7.1 × 10 -5, tan 2  = 0.41, f B = 1.02. In both (a) and (b) the 8 B flux is free and the hep flux is fixed. f B = 8 B flux measured / SSM. Nucl-ex/0309004v1 6Sep2003 SNO

19. 19 ντντ νe νμνμ  31 ？ CP? Atmospheric neutrinos Solar neutrinos K2K neutrinos  m 23 2 = 1.3 - 3.0×10 -3 eV 2 sin 2 2  23 = 0.9 – 1.0  m 12 2 = 6 - 9×10 -5 eV 2 sin 2 2  12 = 0.7 – 0.9 KamLAND What to do next Measure  31 and  m 31 2 (~  m 23 2 )   m 12 2,  m 23 2,  12,  23 precisely Quarks: sin 2 2  12 = 0.188 +-0.007 sin 2 2  23 = 0.0064+-0.0010

20. 20     e, electron appearance P(    e  ) = 4c 13 2 s 13 2 s 23 2 sin 2 (  m 31 2 L/4E )(1 + 2a(1-2s 13 2 )/  m 31 2 ) + 8c 13 2 s 12 s 13 s 23 (c 12 c 23 cos  – s 12 s 13 s 23 ) ×cos(  m 23 2 L/4E  ) sin(  m 31 2 L/4E ) sin(  m 21 2 L/4E ) - 8c 13 2 c 12 c 23 s 12 s 13 s 23 sin  ×sin(  m 23 2 L/4E  ) sin(  m 31 2 L/4E ) sin(  m 21 2 L/4E ) + 4s 12 2 c 13 2 (c 12 2 c 23 2 + s 12 2 s 23 2 s 13 2 - 2c 12 c 23 s 12 s 23 s 13 cos  ) sin 2 (  m 21 2 L/4E ) -8c 13 2 s 13 2 s 23 2 (1 – 2s 13 2 )(aL/4E ) ×cos(  m 23 2 L/4E  ) sin(  m 31 2 L/4E ), where a [eV 2 ] = 2√2G F n e E = 7.6×10 -5  [g/cm 3 ] E [GeV], red terms change sign for anti-neutrinos P(   e ) – P(   e ) P(   e ) + P(   e ) ～  m 12 2 L 4E sin2  12 sin  13 sin  A CP =

21. 21 Strategy and Sensitivity Goal (Phase I) ~ 5 years Precisely measure  23 and  m 23 2. e appearance search Sensitivity goals  sin 2 2  23 ~ 0.01  m 23 2 < 1x10 -4 eV 2 sin 2 2  13 ~ 0.006 (90% CL) Study neutrino interactions at the near detector

22. 22 T2K (Tokai-to-Kamioka) J-PARC Hyper-Kamiokande

23. 23 J-PARC Joint Project by KEK and JAERI 3 GeV RCS: spallation-neutron and muon sources Life and material sciences 50 GeV MR: slow and fast extracted protons Kaon physics Neutrino physics (long baseline oscillations) LINAC: intense proton source ADS (180 MeV,

24. 24

25. 25 injection energy 400 MeV （ 180 MeV ） extraction energy 3 GeV harmonic number ２ repetition rate 25 Hz # of protons / pulse 0.83 E14 average beam current 333μA beam power 1 MW 3 GeV RCS Magnetic alloy cavity

26. 26 50 GeV MR Beam energy: 50 GeV (40 at phase 1) 1 cycle: 3.53s 8 bunches in 9RF buckets Bunch spacing: 598ns Spill width ~ 5  s Bunch length ~ 36ns (±3  ) 6ns (1  # of protons:3.3×10 14 ppp Beam current: 15  A (slow extraction) Rf frequency: 1.68 (inj.) – 1.73 (ext.) MHz  flux* at SK = 1.9×10 7 / cm 2 yr (1yr = 10 21 pot: 123 days at.75MW) *2.5°Off Axis, 130m decay pipe 3.53s 1.9s fast Injection: 0.17s acceleration: 1.96s extraction : 0.7 s current down: 0.7 s total:: 3.53s slow 0.17 1.96 0.7

27. 27 600MeV Linac 3GeV PS 50GeV PS N Near Detector (280m) Neutrino Beam Line To Super-Kamiokande (295km away) Neutrino beam line Construction 2001 ～ 2007 JHFMINOSK2K E(GeV)5012012 Int.(10 12 ppp)330406 Rate(Hz)0.30.530.45 Power(MW)0.750.410.0052 JAERI@Tokai-mura (60km N.E. of KEK) (Approval in Dec.2000)

28. 28 Off Axis Beam WBB with a misaligned beam line from the det. axis High intensity at low energy: 4500 int./22.5kt/yr Contamination e : 0.8%(0.2% @ peak) Decay Kinematics E  (GeV) E (GeV) 0 0.4 0.8 1.2 1.6 2 E (GeV) 2x10 -3 eV 2, L = 295km p  140m0m280m2 km295 km on-axis off-axis

29. 29 Fast extraction section neutrino beamline

30. 30 Arc Section combined function SC magnets OR Dipole QuadrupoleCombined

31. 31 Focusing Section solid graphite, 30mm in diam, 900mm long Target station

32. 32 Horn system I=~300kA, three short horns Need to tolerate big heat load from radiation Stress analysis is in progress Carbon target

33. 33 Side View Top view 4MW beam can be accepted. max.120 o (half year continuous operation) (Temperature is controllable under 100 o by intermittent operation) Decay Volume Water cooling pipe 50 o 14 o ~3.5deg 130m from target To Super-K ~1.3deg

34. 34 Near detector at 2km from the target 9.2m 16.2m 8m 4m Total mass : 1077ton Fid. Mass : 100ton Near detector should look like Far detector looks like beam

35. 35 0.28km Far/near ratio (OA 2deg) spectrum 0.28km 1.5km 295km 2.0km

36. 36

37. 37 Strategy and Sensitivity Goal (Phase II) Intensity upgrade to 4 MW 1 Mton far detector, Hyper-Kamiokande Search for CP violation

38. 38 Hyper-Kamiokande (1Mt water) Precision neutrino oscillation study Proton decay search R&D (complete in 2 years) Cavity excavation and its stability New light detector: Hybrid Photo- Detector, HPD (50cm  )

39. 39 Sensitivity (3  ) to CPV (T2K Phase II) Chooz excluded @  m 31 ~3x10 -3 eV 2  >~27deg  >~14deg Preliminary 4MW, 1Mt Fid.Vol. 2yr for  6.8yr for  T2K1 3  discovery  m 21 =5x10 -5 eV 2  12 =  /8  m 32 =  m 31 =3x10 -3 eV 2  23 =  /4

40. 40 Conclusions Rapid progress in measuring masses and mixing of neutrinos  m 23 2 = 1.3 - 3.0×10 -3 eV 2, sin 2 2  23 = 0.9 – 1.0  m 12 2 = 6 - 9×10 -5 eV 2, sin 2 2  12 = 0.7 – 0.9 Their precisions need to be improved  23 and  are still unknown J-PARC can produce  beam 100 times stronger than K2K (proton beam power; 0.75 MW) Sensitivities; sin 2 2  31 > 0.006 (90%CL) If  31 measured, a further upgrade will be considered proton beam power; 4 MW 1 Mton Hyper-K A lot of uncertainties in future  Linear collider, budget deficit, etc

41. 41 Supplement

42. 42 JSNS 23 neutron beam lines