Recent Results from Neutrino Experiments and Plans for the Neutrino Super Beam in Japan

1. Recent Results from Neutrino Experiments and Plans for the Neutrino Super Beam in Japan Y.Totsuka, KEK NSS-2003, 031021 • Discovery of neutrino oscillations finite neutrino masses (n2 and n3) (1998 – present) • Small as expected • Mixing among neutrino flavors expected • Quark mixing implies small mixing

2. Mixing matrix Interacting states Free moving states (mass eigenstates) ( ) ( ) ( ) ne nm nt n1 n2 n3 Ue1 Um1 Ut1 Ue2 Um2 Ut2 Ue3 Um3 Ut3 = U (Maki-Nakagawa-Sakata Matrix) = ) ( sij=sinqij,cij=cosqij, d=CP • Discovery of large mixing angles, q23 and q12

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

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

5. 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 SK-II Cosmic ray muon sample

6. 1489 day FC+PC data + 1646 day upward going muon data c2=170.8/170 d.o.f. at (sin22q23, Dm232)=(1.00, 2.0x10-3eV2) c2=445.2/172 d.o.f. (null oscillation)

7. Allowed region of the oscillation parameters (complete SK-I dataset) • Assuming nm nt oscillation • Best fit • c2min = 170.8/170 d.o.f • at (sin22q23,Dm232) = (1.0, 2.0 x 10-3 eV2) • 90% CL allowed region • sin22q23> 0.9 • 1.3x10-3 < Dm232 <3.0x10-3(eV2) • Assuming null oscillation • c2 = 445.2/172 d.o.f Soudan-2 MACRO Super-K 68% CL 90% CL 99% CL

8. K2K Long baseline neutrino oscillation experiment • 12 GeV PS at KEK • Neutrino beamline • <En> ~ 1.3GeV • 98% purity • Beam monitors and near detector • beam direction • p measurement • nm flux and spectrum • Far detector • nm flux and spectrum 250km

9. Best fit 1Rm spectrum & Nsk Total number of obs. Events: 56 16 (Jan03-Apr03) Expected w/o oscillation: 80.6+7.3-8.024 +2.3-2.1 • Best fit point (sin22q23 , Dm232)=(1.0, 2.8x10-3eV2) • KS test prob.(shape): 79% • NSK=54 (Obs.=56) • Very good agreement in shape & NSK with atmospheric neutrinos Expected w/o oscillation Normalized w/o oscillation Normalized with best fit oscillation

10. Comparison with SK atm n observation 90%CL SK (FC+PC+upm) K2K(1Rm shape+NSK)

11. Solar image

12. SNO: ne  ne(ES); ned epp (CC); nd  npn, Cl(n,g)Cl, (NC) INCO’s Creighnton mine Sudbury, ON, Canada Control room Electronics hut 9456 of 8 inch PMTs 2km • photo coverage 55% (R<7m) • cosmic ray muons ~70 events/day • fiducial volume 0.7kt (R,5.5m) • Trigger rate (data) 6~8Hz (~2MeV threshold) • Trigger efficiency 100%@~3MeV • From compton e- from 16N source (~5 MeV) • vertex resolution 16cm • energy resolution 16% • angular resolution 27℃ • NaCl in D2O (6010mwe) SNO 1000 ton heavy water (12mf acrylic vessel) 1700+5300 ton light water (17.8mf stainless steel support, 34mh x 22mf barrel-shaped cavity)

13. f SK ES Super-K + SNO combined (as of 2002) 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-ne component！ [x106/cm2/s] CC =e ES =e +0.154, NC=e +, +0.24 - 0.23 +0.44 +0.46 - 0.43 - 0.43 +0.08 - 0.07

14. and Super-K zenith spectra SNO rates and day/night spectra ne nm oscillation -3 -4 -5 -6 log Dm2 (eV2) -7 -8 -9 -10 -11 -4 -3 -2 -1 0 1 Log tan2q

15. Kam-LAND • 1000m3 liquid scintillator • 3000m3 oil+water shield • 1300 17-inch PMTs + 600 20-inch PMTs • Anti-ne from reactors (L~170km) • Detect e+ from ne + p  e+ + n (Eth = 1.8 MeV) • Observation started on 22 Jan 2002

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. KamLAND confirms the LMA solution!

18. SNO FIG. 5: Global neutrino oscillation contours. (a) Solar global: D2O day and night spectra, salt CC, NC, ES fluxes, SK, Cl, Ga. The best-fit point is Dm2 = 6.5 × 10-5, tan2q = 0.40, fB= 1.04, with 2/d.o.f.=70.2/81. (b) Solar global + KamLAND. The best-fit point is Dm2 = 7.1 × 10-5, tan2q = 0.41, fB= 1.02. In both (a) and (b) the 8B flux is free and the hep flux is fixed. fB= 8B flux measured / SSM. Nucl-ex/0309004v1 6Sep2003

19. ντ Dm232 = 1.3 - 3.0×10-3 eV2 sin22q23 = 0.9 – 1.0 K2K neutrinos q31？ Atmospheric neutrinos CP? νμ νe Solar neutrinos KamLAND Dm122 = 6 - 9×10-5 eV2 sin22q12 = 0.7 – 0.9 What to do next • Measure • q31 and Dm312 (~ Dm232) • d • Dm122, Dm232, q12, q23 precisely • Quarks: • sin22q12 = 0.188 +-0.007 • sin22q23 = 0.0064+-0.0010

20. P(nm ne) – P(nm  ne) P(nm ne) + P(nm  ne) Dm122L 4En sin2q12 sinq13 ACP = ～ sind nm ne , electron appearance P(nμ ne) = 4c132s132s232 sin2(Dm312L/4En)(1 + 2a(1-2s132)/Dm312) + 8c132s12s13s23(c12c23 cosd – s12s13s23) ×cos(Dm232L/4En ) sin(Dm312L/4En) sin(Dm212L/4En) - 8c132c12c23s12s13s23 sind ×sin(Dm232L/4En ) sin(Dm312L/4En) sin(Dm212L/4En) + 4s122c132(c122c232 + s122s232s132 - 2c12c23s12s23s13 cosd) sin2(Dm212L/4En) -8c132s132s232(1 – 2s132)(aL/4En) ×cos(Dm232L/4En ) sin(Dm312L/4En) , where a [eV2] = 2√2GFneEn = 7.6×10-5r [g/cm3] En [GeV] , red terms change sign for anti-neutrinos

21. Strategy and Sensitivity Goal (Phase I) • ~ 5 years • Precisely measure q23 and Dm232. • ne appearance search • Sensitivity goals • dsin22q23 ~ 0.01 • dDm232 < 1x10-4 eV2 • sin22q13 ~ 0.006 (90% CL) • Study neutrino interactions at the near detector

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

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,

25. 3 GeV RCS • injection energy400 MeV（180 MeV） • extraction energy3 GeV • harmonic number　 ２ • repetition rate25 Hz • # of protons / pulse0.83 E14 • average beam current333μA • beam power1 MW Magnetic alloy cavity

26. 50 GeV MR 3.53s • Beam energy: 50 GeV (40 at phase 1) • 1 cycle: 3.53s • 8 bunches in 9RF buckets • Bunch spacing: 598ns • Spill width ~ 5ms • Bunch length ~ 36ns (±3s) 6ns (1s) • # of protons: 3.3×1014 ppp • Beam current: 15mA (slow extraction) • Rf frequency: 1.68 (inj.) – 1.73 (ext.) MHz • nm flux* at SK = 1.9×107 / cm2yr(1yr = 1021 pot: 123 days at .75MW) slow 1.9s 1.96 0.7 fast 0.7 0.17 Injection : 0.17s acceleration : 1.96s extraction : 0.7 s current down : 0.7 s total: : 3.53s *2.5°Off Axis, 130m decay pipe

27. Neutrino beam line N JAERI@Tokai-mura (60km N.E. of KEK) 50GeV PS Construction 2001～2007 3GeV PS 600MeV Linac (Approval in Dec.2000) Near Detector (280m) Neutrino Beam Line To Super-Kamiokande (295km away)

28. p p n off-axis on-axis 0m 140m 280m 2 km 295 km Off Axis Beam • WBB with a misaligned beam line from the det. axis • High intensity at low energy: 4500 int./22.5kt/yr • Contamination ne: 0.8%(0.2% @ peak) Decay Kinematics En (GeV) 0 0.4 0.8 1.2 1.6 2 Ep (GeV) En (GeV) 2x10-3eV2, L = 295km

29. Fast extraction section neutrino beamline

30. Dipole OR Quadrupole Combined Arc Section combined function SC magnets

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

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

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

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

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

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

38. 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 (50cmf) Hyper-Kamiokande (1Mt water)

39. Chooz excluded 4MW, 1Mt Fid.Vol. 2yr for nm 6.8yr for nm @Dm31~3x10-3eV2 d>~14deg d>~27deg Preliminary Dm21=5x10-5eV2 q12=p/8 Dm32=Dm31=3x10-3eV2 q23=p/4 T2K1 3s discovery Sensitivity (3s) to CPV (T2K Phase II)

40. Conclusions • Rapid progress in measuring masses and mixing of neutrinos • Dm232 = 1.3 - 3.0×10-3 eV2, sin22q23 = 0.9 – 1.0 • Dm122 = 6 - 9×10-5 eV2, sin22q12 = 0.7 – 0.9 • Their precisions need to be improved • q23 and d are still unknown • J-PARC can produce nm beam 100 times stronger than K2K (proton beam power; 0.75 MW) • Sensitivities; sin22q31 > 0.006 (90%CL) • If q31 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. Supplement

42. JSNS23 neutron beam lines