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Solar Neutrino Experiments A Review

Solar Neutrino Experiments A Review. From Solving the Solar Neutrino Problem to Precision Physics. Alain Bellerive On behalf of the SNO Collaboration Carleton University , Ottawa, Canada. The CAP'09 Congress Moncton, 7-10 June, 2009 . Outline. Introduction

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Solar Neutrino Experiments A Review

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  1. Solar Neutrino Experiments A Review From Solving the Solar Neutrino Problem to Precision Physics Alain Bellerive On behalf of the SNO Collaboration Carleton University, Ottawa, Canada The CAP'09 Congress Moncton, 7-10 June, 2009

  2. Solar Neutrino Experiments A.Bellerive, ICHEP, July 2010 Outline • Introduction • Solar Neutrino Flux (update) • First Generation of Solar Neutrino Experiments • Chlorine – Gallium – Kamiokande • Second Generation of Solar Neutrino Experiment • SuperK– Borexino – SNO • The new stuff for 2010 !!! • Constraints on Oscillation Parameters • Future Prospects

  3. Evidence for Neutrino Mixing First evidence of neutrino oscillation Atmospheric Neutrinos high energies Parallel Session Talk by Dr. Yoshihisa Obayashi Solar Neutrinos low energies Today’s talk !!! Beamstop Neutrinos tunable energies Plenary Talk by Tsuyoshi Nakaya

  4. The First Piece • Solar Neutrino Flux • The Sun produces e in fusion nuclear reactions • Survival probability depends on the neutrino energy • Solar neutrino oscillation occurs inside the Sun h

  5. Neutrino Production in the Sun Borexino Light Element Fusion Reactions Neutrino Production Radius BPS08 p + p 2H + e+ + e 99.75 % ±1% 0.25 % p + e- + p  2H + e ±6% ±6% ±1.1% ~10-5 % 3He + p 4He + e+ + e ±11% 7Be + e- 7Li + e 15 % 8B  8Be* + e+ + e 0.02 % ±16% BPS08: (Bahcall) Pena‐Garay C. & SerenelliA. 2008. arXiv:0811.2424 http://www.sns.ias.edu/~jnb/

  6. Sudbury Neutrino Observatory Alain Bellerive e

  7. Solar Neutrino Mixing Survival Probability 3 Parameters ! Pee ≡P(e→e) Pee=cos4( )[1-sin2(2q)sin2()] Pee≈1-sin2(2q)sin2() where  =1.27Dm2L / E Main Solar Physics: Dm2 & sin(2q ) Experiment: Distance (L) & Energy (E) 13 12 12 12 12 12 The state evolves with time or distance

  8. The Second Piece:First Generation Experiments Chlorine – Gallium - Kamiokande

  9. Solar Neutrino Problem (Pre SNO) νe Pee ~108 km Measured Predicted Neutrino reactions Source: arXiv:hep-ph/0406294

  10. LMA TODAY • Combination of the • Chlorine, Gallium, • SK, and CHOOZ • restricted the mixing • parameters • Pre SNO (~2001) Mixing Parameters SMA LOW m2 (eV2) VAC JustSo2 Allowed Regions tan2 Phys.Rev. D64 (2001) 093007

  11. Arranging the Pieces:Second Generation Experiments SuperK – SNO - Borexino

  12. Super Kamiokande • 8B (and hep) neutrino(s) • detection • nx+ e-→nx+ e- • Sensitive tone, nm, nt • (, + e- )  0.15 × (e+ e-) • High statistics ~15 events/day • Real time measurement allow studies on time variations • Studies energy spectrum • 50 ktons of pure water

  13. Timeline of Super-Kamiokande SK-I SK-II SK-III SK-IV 41.4 m SK-I SK-II SK-III SK-IV Acrylic (front) + FRP (back) 11146 ID PMTs (40% coverage) 5182 ID PMTs (19% coverage) 11129 ID PMTs (40% coverage) Electronics Upgrade Current ~4.5 MeV ~4.0 MeV Target < 4.0 MeV <~3.5 MeV Energy Threshold Total energy Kinetic energy 5.0 MeV ~4.5 MeV 7.0 MeV ~6.5 MeV 5.0 MeV ~4.5 MeV

  14. Solar neutrino data of SK (period I) May 31,1996 – July 13,2001 (1496 days) Ee = 5.0 - 20 MeV 22404226(stat) solar n events 8B flux: 2.35  0.02(stat)  0.08(syst) [x 106 /cm2/sec] Data ≈ 0.41 SSM Phys. Rev. D 73, 112001 (2006)

  15. Daily Variation of SK Rate (Period I)

  16. Borexino • 7Be and 8B neutrinos detection • nx+ e-→nx+ e- • Sensitive tone, nm, nt • (, + e- )  0.2 × (e+ e-) • Challenge: Control of Low Energy Background • Energy window: • [0.16 – 2.0] MeV for 7Be • > 3.0 MeV for 8B

  17. Borexino Detector 18m Work on installation continues Needs to resolve “political situation” Scintillator detector with an active mass of 278 tons of pseudocumene PC buffer and water for shielding to rarioactivity Scintillation light is detected via 2212 inward looking PMTs Energy resolution 5% (at 1 MeV) and position resolution 10‐15 cm

  18. 7Be Analysis Borexino(192 live‐days) After statistical subtraction of 210Po alphas Signature for the monoenergetic 0.862 MeV 7Be neutrinos is the Compton-like edge of the recoil electrons at 665 keV 85Kr Cosmogenic 11C 210Bi + CNO neutrinos

  19. Result of Borexino’s 7Be Analysis Rate(7Be) = 49 ± 3 (stat) ± 4 (syst) cpd/100tons Φ(7Be) = (5.18 ± 0.51) × 109 cm‐2s‐1 Pee = 0.56 ± 0:10 at 0.862 MeV Under the assumption of SSMflux Phys. Rev. Letts. 101, 09132 (2008) Detail by Sandra Savatarelli in parallel session talk Solar neutrino and terrestrial antineutrino fluxes measured with Borexino at LNGS

  20. Image courtesy National Geographic 6000 mwe overburden 1000 tonnes D2O Sudbury Neutrino Observatory 17.8 m 12 m Diameter Acrylic Vessel 1700 tonnes Inner Shield H2O Support Structure for 9500 PMTs, 60% coverage 5300 tonnes Outer Shield H2O

  21. Flavor change ? Pee(E) ≠ 1 ! Key signatures for mixing with SNO CC ES NC

  22. Timeline of SNO 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 Commissioning D2O D2O + Salt D2O + 3He counters D2O 3He counters Install Commission Total of ~1100 live-days Data Analysis Phase I Phase II Phase III 306days 391days 396days PRL 87, 071301, 2001 PRL 89, 011301, 2002 PRL 89, 011302, 2002 PRC 75, 045502, 2007 PRL 92, 181301, 2004 PRC 72, 055502, 2005 PRL101, 111301, 2008 PRC, 055504, 2010 Combined Phase I-II Low Energy Threshold Analysis Upcoming… Phase I-II-III combined analysis

  23. t p 191 573 573 191 SNO NCD’s Phase III n 3He:CF4 gas Cu wire Ni wall 191 keV 573 keV 764 keV PRL101, 111301, 2008

  24. SNO Phases I+II Major Improvements • Tune up the Monte Carlo on calibration data based on 5 years of operational experience - Reduction of systematic uncertainties • Improve optics (especially at large radii) with late light and new energy estimator (improve energy resolution by 6%) Pee typical LMA Energy Threshold D2O phase Teff = 5 → 3.5 MeV Salt phase Teff = 5.5 → 3.5 MeV Improve statistics CC by ~40% NC by ~70% Allow to fit the background wall Night Day E

  25. SNO Phases I+II Direct joint-phase fit of Pee Previous global best-fit LMA point tan212=0.468 m2=7.59x10-5 eV2 12 (8B) = 5.046 in units of 106 cm−2 s−1 +0.159 +0.107 -0.152 -0.123 DAY No distortion, no D/N: 2 = 1.94 / 4 d.o.f. LMA-prediction: 2 = 3.90 / 4 d.o.f. Previous global best-fit LMA point tan212=0.468 m2=7.59x10-5 eV2 Previous global best-fit LMA point tan212=0.468 m2=7.59x10-5 eV2 12 12 ADN NIGHT PRC, 055504, 2010

  26. Global View

  27. Data Sets Solar Oscillation Analysis • Radiochemical : Cl, Ga • Ga rate: 66.1 ±3.1 SNU SAGE+GNO/GALLEX [PRC80, 015807(2009)] • Cl rate: 2.56 ±0.23 [Astrophys. J. 496 (1998) 505] • SK • SK-I 1496 days, zenith spectrum E ≥ 5.0 MeV • SK-II 791 days, spectrum + D/N E ≥ 7.5 MeV • Borexino • 7Be rate: 49 ± 5 cpd/100tons [PRL101, 091302(2008)] • SNO • Phase I + II (PMT Low Energy threshold E ≥ 4.0 MeV) • Phase III (NCD and PMT E ≥ 6.5MeV) • KamLANDreactor experiment: 2008 [PRL100, 221803 (2008)] • 8B spectrum: W. T. Winter et al., PRC 73, 025503 (2006). Plenary Talk by FabricePiquemal

  28. Oscillation Analyses: Global Solar 2 model Best-fit LMA point: tan212 = 0.457 (+0.038 -0.041) m2 = 5.89x10-5 eV2 (+2.13 -2.16) 12 (8B) = 5.104 in units of 106 cm−2 s−1 Δ8B= +3.90 % -2.95

  29. Solar + KamLAND 2-flavor Overlay 2 model

  30. Solar + KamLAND 2-flavor 2 model Best-fit LMA point: tan212 = 0.457 q12=34.06 deg m2 = 7.59 x10-5 eV2 +0.040 -0.029 +1.16 -0.84 +0.20 -0.21 12 (8B) = 5.013 in units of 106 cm−2 s−1 Δ8B = +2.37 % -2.95

  31. Solar + KamLAND 3-flavor 3 model Best-fit LMA point: tan212 = 0.468 m2 = 7.59 x10-5 eV2 +0.042 -0.023 +0.21 12 -0.21 Best-fit: sin213=2.00 +2.09-1.63 x10-2 sin213 < 0.057 (95% C.L.) Remark: SNO and SK global oscillation analyses consistent

  32. Sudbury Neutrino Observatory Alain Bellerive Newest stuff for summer 2010 !!!

  33. Neutrino 2010 Data sample before fiducial volume cut Fiducial volume in SK-III Tight fiducial volume cut is applied in Etotal<5.5MeV to remove the background events. (Rn g-rays from detector wall). Vertex distributions in SK-III Rate/bin 4.5-5.0MeV (12.3kt) 5.0-5.5MeV (13.3kt) 5.5-20MeV (22.5kt) Z R SK detector See poster: Solar neutrino results from SuperK by Hiroyuki Sekiya

  34. Neutrino 2010 Systematic uncertainties on total flux (SK-III) Preliminary Energy region: Etotal=5.0-20.0MeV The systematic error on total flux of SK-III is reduced by precise calibrations and software improvements

  35. Neutrino 2010 Preliminary SK-III solar neutrino results Total live time: 548 days, Etotal ≥ 6.5 MeV 289 days, Etotal < 6.5 MeV Energy region: Etotal=5.0-20.0MeV 8B Flux: 2.32±0.04(stat.)±0.05(syst.) (x106/cm2/s)

  36. 8B Analysis Borexino (487.7 live-days) Rate(8B) = 0.22 ± 0.04(stat) ± 0.01(syst) cpd/100tons Φ(8B) = (2.4 ± 0.4 ± 0.1) × 106 cm‐2 s‐1 (oscillated) arXiv:0808.2868v3 [astro‐ph] accepted by Rev. Phys. D

  37. Impact of Borexino7Be & 8B Analyses Pee Δm2=7.69×10−5 eV2 and tan2θ=0.45 8B (>5 MeV) 7Be 7Be flux: 2.35  0.02(stat)  0.08(syst) [x 106 /cm2/sec] 8B (>3 MeV) BX: Under the assumption of SSM flux SNO: Directly measure Pee

  38. 7Be Day/Night Asymmetry Borexino Preliminary 7Be Day spectrum: 387.46 days 7Be Night spectrum: 401.57 days Statistical error: 2.3 cpd/100t The 7Be flux is obtained from separate full fits of day and night spectra PS: Mass varying neutrino models of P.C. de Holanda rejected at 3σ level

  39. SNO hep neutrino sensitivity (3phase) SSM

  40. SNO Improvement – NCD (3-phase) Pulse shape discrimination to separate neutron(signal) from alpha (background) • Distinguish neutron and alpha pulses • Neutron pulses are created with two particles (a proton and a triton), and alpha pulses are created by a single particle • Timing and Ionization tracks are fundamentally different • After discrimination perform a fit of energy spectrum Signal-to-Background ratio: 0.33 (before cut) → 11.7 (after cut) alpha neutron

  41. Δχ2 SNO Full 3-Phase Expected improvement Pee day All phases combined D2O+Salt+NCD 8B Pee(En) fit Δχ2 ADN

  42. Conclusion & Future • Great physics out of solar neutrino experiments • From solving SNP to precision physics • Direct evidence of solar neutrino oscillation by SNO • Global solar solution favors LMA (Cl+Ga+SK+BX+SNO) • Upcoming new SK I+II+III publications (3-flavor analysis) • SK-IV is capable of a lower energy threshold • More precise 7Be from Borexino with more live-days soon Δ7Be 10%→5% • Expect further improvement with SNO 3-phase analysis • The only model-independent fit of solar survival probability • Δ8B 4%→3.5% Solar Neutrino Experiments A.Bellerive, ICHEP, July 2010

  43. Merci !Thank you! Solar Neutrino Experiments A.Bellerive, ICHEP, July 2010

  44. Solar + KamLAND 3-flavor Overlay Best-fit LMA point: tan212 = 0.468 m2 = 7.59 x10-5 eV2 +0.042 -0.023 +0.21 12 -0.21 Best-fit: sin213=2.00 +2.09-1.63 x10-2 sin213 < 0.057 (95% C.L.)

  45. SNO Survival Probability DAY NIGHT

  46. SNO Survival Probability DAY NIGHT

  47. SNO Survival Probability DAY NIGHT

  48. SNO Survival Probability DAY NIGHT

  49. Test of PDF shapes (distributed Rn spike) Fit to spike energy spectrum allowing energy scale to float: shift is 0±0.6%

  50. Neutrino Mixing As in the quark sector one defines a neutrino mixing matrix which relates the mass and weak eigenstates Mixing Matrix yes Quark: ??? Neutrino: solar atmospheric short-baseline CP violation

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