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Solar Neutrino Results

Solar Neutrino Results. Tadao Mitsui Research Center for Neutrino Science, Tohoku University. July 26, 2004 6th International Workshop on Neutrino Factories & Superbeams. Osaka University, Osaka, Japan. Solar and reactor neutrinos. Results from Super-Kamiokande and SNO

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Solar Neutrino Results

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  1. Solar Neutrino Results Tadao Mitsui Research Center for Neutrino Science, Tohoku University July 26, 20046th International Workshop on Neutrino Factories & Superbeams Osaka University, Osaka, Japan

  2. Solar and reactor neutrinos • Results from Super-Kamiokande and SNO • Reactor results from KamLAND • Radiochemical results and earlier works • Near future prospects (*2) (*1) (*1) neutrinograph of the sun by Super-K, (*2) hep-ph/0406294

  3. Chlorine (1964 ~ 1994) • First solar neutrino observation • Established solar neutrino deficit • 615-ton C2Cl4, ne(37Cl, 37Ar)e- • Final result: 2.56 ± 0.16 ± 0.16 SNU • SSM (BP04) expectation: 8.5  1.8 SNU • Data/SSM = 0.30 ± 0.03 Still important input in the current global analysis for solar neutrino 0.813 MeV 8B, 7Be SSM BP04: J.N. Bahcall and M.H. Pinsonneault PRL 92, 121301 SNU: 1 n interaction / sec each 1036 target atoms

  4. Kamiokande (1987 ~ 1995) • First measurement of time, direction, energy of solar-n • Data/SSM=0.55 ± 0.04 ± 0.07 • Upgraded to Super-K 7 MeV 8B PRD 44 (1991) 2241

  5. Gallium experiments • Sensitive to pp neutrino (main component of solar-n) • ne(71Ga, 71Ge)e- • 68.1 ± 3.75 SNU (GALLEX + GNO + SAGE) • SSM (BP04): 131+12-10 SNU • Data / SSM = 0.52 ± 0.03 new results (*1) 0.233 MeV pp, 7Be, 8B (*1) C.M. Cattadori, Neutrino 2004

  6. Four solutions that were allowedonly with fluxes (Cl, Ga, Kamiokande) (LMA) Mikheyev-Smirnov- Wolfenstein (MSW) ~106 range in Dm2

  7. Super-Kamiokande (1996 ~ ) • 50 kton water cherenkov • 22.5 kton fiducial • ~ 15 events / day (> 5 MeV) ( 8B, (hep) ) n + e-n + e- well remembers n energy, direction

  8. Super-Kamiokande-I (1496 days) May 31, 1996 - July 13, 2001 M. Nakahata, Neutrino 2004, PLB 539, 179

  9. Super-Kamiokande-I (1496 days) May 31, 1996 - July 13, 2001 M. Nakahata, Neutrino2004, PLB 539, 179

  10. SK-I: energy and zenith angle 2-D spectrum“zenith spectrum” Allowed (with SSM 8B flux) Excluded without 8B flux (rate) PLB 539, 179

  11. SMA, Just-so: excluded by energy spectrum

  12. LOW, LMA: constrained by day/night Expected “regeneration” of ne during night: too large compared with the data

  13. Only LMA at 98% C.L. May 2002 • Asdf Ga + Cl + SK + SNO rates + SK zenith spectrum PLB 539, 179

  14. Sudbury Neutrino Observatory (SNO) 1999 ~ 1000 ton D2O 12-m diameter acrylic vessel 1700 ton H2O Support structure for 9500 8-inch PMTs 5300 ton outer H2O

  15. Unique sensitivity to neutrino flavor CC: charged current ne + d  p + p + e- • fCC = fe • fNC = fe +fm + ft = f(all active n) • fES = fe + 0.154  (fm + ft) • Determine fe, fm/t + 1 redundancy energy, (direction) NC: neutral current ne + d  p + n + n nm n + d 3He + 6.25-MeV g (phase I) nt ES: elastic scattering (also SK) ne + e-ne + e- energy, direction nm nt

  16. Results: extraction of 3 reactions PRL 89, 011301, results from 306.4 days cos qsun - 60.9 CC: 1967.7+61.9 events NC: 576.5+49.5 events ES: 263.6+26.4 events - 48.9 - 25.6 Vertex Energy

  17. Deduced nm/t “appearance” Evidence for flavor transformation Significance for non-zero fm/t SK-ES + SNO-CC: 3.3s PRL 87(2001), 071301 SK-ES + SNO-CC,NC,ES: 5.5s • PRL 89(2002), 011301 With SNO-phse-II (salt) data fBP04 = 5.79 (±23%) SSM “verified” M. Nakahata, NOON2004

  18. Only LMA at 99.5% C.L. July 2002 from day/night spectral shape analysis PRL 89, 011302 SNO day/night spectra + all solar +1.3 - 1.2 -ADN = 7.0 %  4.9% %

  19. KamLAND A. Suzuki, Neutrino 98 • Reactor ne experiment • To reach solar-n solution • 100 improvement on Dm2 sensitivity 100 1 100 Chooz Palo Verde LMA

  20. Powerful commercial reactors

  21. First results from KamLAND Dec. 2002 PRL 90, 021802 ne disappearance: 99.95 % C.L.

  22. Impact of KamLAND http://hitoshi.berkeley.edu/neutrino/ assuming CPT invariance

  23. LMA-I and LMA-II from spectral shape analysis LMA-II: Dm2~1510-5 eV2 LMA-I: Dm2~710-5 eV2 PRL 90, 021802 95 % C.L.

  24. LMA: precise studySK-I reanalysis: un-binned (time, energy) PRD 69, 011104 (R) Sept. 2003 Dm2=6.310-5 eV2, tan2q=0.55 • To use all information of zenith angle dependence during night • Un-binned maximum likelihood method for time and energy

  25. Consistent results Un-binned (PLD 69, 011104) Binned (PLB 539, 179)

  26. Day/night: statistical error 25% reduced Binned (PLB 539, 179) Un-binned (PLD 69, 011104) +1.3 - 1.2 +1.3 - 1.2 ADN = - 1.8 %  1.6% % ADN = - 2.1 %  2.0% % (at best fit LMA) LMA-II disfavored observed (± 1s) LMA-I LMA-II expected

  27. After SK un-binned analysisLMA-II is excluded at >95 % C.L. Sept. 2003 All solar All solar + KamLAND 1st result 95% C.L. allowed M. Nakahata, Neutrino 2004 PRD 69, 011104 (R)

  28. SNO enhanced neutral current (salt) phase Sept. 2003 PRL 92, 181301 NC: neutral current Phase-I (Nov. 99 - May 01) Total eff. 39.9% ne + d  p + n + n nm 14.4% (phase-I) n + d 3He + 6.25-MeV g nt 2 ton NaCl dissolved Phase-II (July 01 - Sep 03) g(6 MeV) ne + d  p + n + n n nm n + 35Cl 36Cl + 8.6-MeV g’s nt Single cherenkov ring Isotropic event

  29. Energy spectra: not assumed but measured cos qsun Isotropy Vertex Energy Not used to extract reactions

  30. CC / NC = fe / factive without assuming 8B spectral shape CC/NC No oscillation 1.0 SNO salt result Maximal mixing 0.5 Maximal mixing excluded at 5.4s 1.0

  31. After SNO-salt,LMA-II is excluded at >99% 3s LMA-II PRL 92, 181301

  32. SNO CC/NC disfavors LMA-II, and also maximal-mixing LMA-II SNO salt result (CC/NC=0.306) Maximal mixing hep-ph/0309299 P.C. Holanda & A.Yu. Smirnov

  33. KamLAND: 2nd reactor results with 4.7 data hep-ex/0406035 A. Kozlov (Working Group 1)

  34. Verification of standard solar model J.N. Bahcall, M.C. Gonzalez-Garcia, C. Pena-Garay, hep-ph/0406294 All flux free parameter 90, 95, 99%, 3s 90, 95, 99%, 3s

  35. Verification of standard solar model J.N. Bahcall, M.C. Gonzalez-Garcia, C. Pena-Garay, hep-ph/0406294 All flux BP04 Oscillation: robust against solar model 95, 99%, 3s 90, 95, 99%, 3s KamLAND global analysis

  36. Solar neutrino measurement flux at production hep-ph/0406294 f  “measured” / SSM(BP04) • Without KamLAND, and GNO new results: fpp = 1.02 ± 0.02 (1s) fB = 0.88 ± 0.04 fBe = 0.91 + 0.25 / - 0.62 • With KamLAND, and GNO new results: fpp = 1.01 ± 0.02 fB = 0.87 ± 0.04 fBe = 1.03 + 0.24 / - 1.03 Small difference despite KamLAND new result Solar-n: robust against neutrino oscillation

  37. Near future: SNO 3He phase J.F. Wilkerson, Neutrino 2004 • 3He proportional counter: to detect n from NC • Event-by-event separation • Better CC energy spectrum

  38. Near future: SNO 3He phase J.F. Wilkerson, Neutrino 2004 • All 40 3He strings installed (April, 2004) • Will run for 2.5 years  2 precision of present SNO result

  39. Near future: full reconstruction of SK • 11,146 PMTs with protection cases • Full reconstruction from 2005 (plan) • SK-III from ~2006 Acrylic + FRP cases

  40. Near future: full reconstruction of SK M. Nakahata, Neutrino 2004

  41. Near future: Borexino C. Galbiati, Neutrino 2004 Toward 7Be solar-n observation

  42. Near future: KamLAND-II • 210Pb: ~105 reduction needed • R&D almost finished: achieved ~104 reduction with test bench • SiO2 adsorption: achieved 95% reduction • Complex purification system Toward 7Be solar-n observation

  43. Summary • Solar neutrino oscillation: MSW-LMA is the solution • Dm2 = 8.2 +0.6-0.510-5 eV2 tan2q = 0.40 +0.09-0.07 (a global analysis by KamLAND) • Standard solar model verified with 5% accuracy (8B) • Further precise study in the near future (SNO 3He, SK-III, Borexino, KamLAND-II etc)  solar astrophysics, search for new phenomena

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