1 / 36

Solar Neutrinos in S uper- K amiokande ICHEP2014 @Valencia July 4 2014

Solar Neutrinos in S uper- K amiokande ICHEP2014 @Valencia July 4 2014 . Hiroyuki Sekiya ICRR, University of Tokyo for the Super-K Collaboration. 1. Super- Kamiokande. Physics targets of Super- Kamiokande. Proton decay. Relic SN ν. WIMPs. Atmospheric ν. Solar ν. TeV. GeV.

munin
Download Presentation

Solar Neutrinos in S uper- K amiokande ICHEP2014 @Valencia July 4 2014

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Solar Neutrinos inSuper-KamiokandeICHEP2014 @Valencia July 4 2014 Hiroyuki Sekiya ICRR, University of Tokyo for the Super-K Collaboration 1

  2. Super-Kamiokande Physics targets of Super-Kamiokande Proton decay Relic SN ν WIMPs Atmospheric ν Solar ν TeV GeV MeV ~3.5 ~20 ~100 ~1 2 50kton pure water Cherenkov detector 1km (2.7km w.e) underground in Kamioka 11129 50cm PMTs in Inner Detector 1885 20cm PMTs in Outer Detector

  3. Solar neutrinos observation Super-K n + e- n + e- ne

  4. The results: Solar global fit preliminary Combined solar fit with KamLAND Without reactor θ13 constraint sin2θ13=0.0242±0.0026 Solar KamLAND Solar+KamLAND Solar KamLAND Solar+KamLAND ~2σ tension in Δm221 between solar and KamLAND Non-zero q13at 2s from solar+KamLAND Good agreement with Daya Bay, RENO & DC (Neutrino2014) sin2θ13=0.0221±0.0012 Reactor This SK update and other latest results are combined.

  5. Motivation • Search for the direct signals of the MSW effect Solar matter effect Energy spectrum distortion Earth matter effect Flux day-night asymmetry Neutrino survival probability Regenerate neby earth matter effect JHEP 0311:004(2003) Vacuum oscillation dominant Solar+KamLAND sin2θ12=0.308 Δm221=7.50x10-5eV2 up-turn! Solar sin2θ12=0.311 Δm221=4.85x10-5eV2 Matter oscillation dominant

  6. Improvements in SK-IV • New analysis in low energy bins Remaining BG-electrons from 214Bi should have more multiple-scatterings than signal-electrons have: MSG 4.0-4.5 MeV bin SK-III SK-IV 3.5-4.0MeV 0.45<MSG MSG < 0.35 0.35<MSG<0.45 4.0-4.5MeV • Reduced systematic error • 1.7% for flux cf. SK-I: 3.2% SK-III: 2.1% Achieved 3.5 MeV(kin.) energy threshold 8.6ssignal is observed with MSG Reduced 222Rn BG

  7. 8B solar n in SK-I+II+III+IV preliminary FSK(8B) =2.344±0.034 x 106cm-1s-1 FSK+SNO(8B) =5.30 x 106cm-1s-1 +0.17 -0.11 preliminary ~70k solar neutrino events 8B n could be the BG for DM search through NC coherent scattering. 8B nsignals

  8. Recoil electron spectra Data/MC(unoscillated) preliminary Kinetic energy (MeV)

  9. N.B. All SK phase are combined without regard to energy resolution or systematics in this figure SK-I+II+III+IV spectrum Solar+KamLAND sin2θ12=0.308 Δm221=7.50x10-5eV2 Solar sin2θ12=0.311 Δm221=4.85x10-5eV2 Neutrino energy spectrum is convoluted in the electron recoil spectrum. For de-convolution, generic functions are used as a survival probability; f8B=5.25 x 106/(cm2∙sec) fhep=7.88 x 103/(cm2∙sec) SK recoil electron spectrum constrain the fit parameters (ci,ei) of the function and the allowed Pee(En) is derived using the allowed (ci,ei).

  10. Allowed Pee(En) for SK preliminary Solar+KamLAND sin2θ12=0.308 Δm221=7.50x10-5eV2 SK Solar sin2θ12=0.311 Δm221=4.85x10-5eV2 • MSW (solar+KamLAND) is consistent at ~1.6σ • MSW (solar) fits better (at ~0.7σ)

  11. Allowed Pee(En) for SK+SNO preliminary Solar+KamLAND sin2θ12=0.308 Δm221=7.50x10-5eV2 SK SK+SNO SNO Solar sin2θ12=0.311 Δm221=4.85x10-5eV2 • SK and SNO are complementary for the shape constraint • MSW is consistent at 1σ

  12. Global view of Pee(En) preliminary all solar (pp) Borexino (pep) Borexino (8B) Borexino (7Be) SK+SNO Homestake +SK+SNO (CNO)

  13. θz Earth Flux zenith angle distribution SK-I - IV combined (Eth=4.5 MeV for SK-I,III,IV 6.5 MeV for SK-II) Solar best fit sin2θ12=0.311 Δm221=4.85x10-5eV2 Solar+KamLAND sin2θ12=0.308 Δm221=7.50x10-5eV2 Sun preliminary

  14. Day/Night asymmetry amplitude preliminary • Energy-dependence of the variation Rate/Rateaverage expected Δm221=4.84x10-5 eV2 sin2θ12=0.311 sin2θ13=0.025 First observation of day/night asymmetry at 3ssignificance level

  15. Δm221dependence sin2θ12=0.311, sin2θ13=0.025 preliminary 1σ Solar 1σ KamLAND Solar region differ from zero by 2.9~3.0σ agree with expect by 1.0σ 3.0σ 2.9σ 2.8σ expected SK-I,II,III,IV best fit KamLAND region differ from zero by more than 2.8σ agree with expect by 1.3σ

  16. Summary • SK has observed ~70000 solar n interactions, by far the largest sample of solar neutrino events in the world. • SK data provide the first indication (at 2.8~3.0 s) of terrestrial matter effects on 8B solar n oscillation. • SK gives the world’s strongest constraints on the shape of the survival probability Pee(Eν) in the transition region between vacuum oscillations and MSW resonance. • SK spectrum results are consistent with MSW up-turn prediction within ~1s. • SK measurements strongly constrain neutrino oscillation parameters: • SK gives world’s best constraint on Δm212using neutrinos. • There is a 2stension between SK’s neutrino and KamLAND’s anti-neutrino measurement of Δm212. • Last month SK started taking data at ~2.5 MeV at ~100% trigger efficiency. Stay tuned for very low energy SK neutrino.

  17. Extra slides

  18. Full summary SK has observed ~70000 solar neutrino interactions in ~4500days (1.5 solar cycles), by far the largest sample of solar neutrino events in the world. SK data provide the first indication (at 2.8~3.0 sigma) of terrestrial matter effects on 8B solar neutrino oscillation. This is the first observation using a single detector and identical neutrino beams that matter affects neutrino oscillations. SK has successfully lowered the analysis threshold to ~3.5 MeV kinetic recoil electron energy. SK gives the world’s strongest constraints on the shape of the survival probability Pee(Eν) in the transition region between vacuum oscillations and MSW resonance. SK spectrum results slightly disfavor the MSW resonance curves, but are consistent with MSW prediction within 1-1.7 sigma. SK measurements strongly constrain neutrino oscillation parameters: SK uniquely selects the Large Mixing Angle MSW region by >3sigma, gives world’s best constraint on solar Δm2 using neutrinos, and significantly contributes to the measurement of the solar angle. There is a 2 sigma tension between SK’s neutrino and KamLAND’s anti-neutrino measurement of the solar Δm2. Last month SK started taking data at ~2.5 MeV at ~100% trigger efficiency. Stay tuned for very low energy SK solar neutrino

  19. Wide-band Intelligent Trigger 100% trigger efficiency above 2.5MeV(kin.) Just started Reconstruction and Reduction just after Front-end

  20. Oscillation parameter

  21. Improvements in SK-IV Event rate becomes low and stable in SK-IV 4.0-4.5 MeV bin SK-III SK-IV • Reduced systematic error • 1.7% for flux cf. SK-I: 3.2% SK-III: 2.1% achieved 3.5 MeV(kin.) energy threshold 7.5s level signal is observed at 3.5MeV bin Reduced BG

  22. significance of the signal The MSG non-zero signal significance is 8.6 sigma (2.4129/0.2811) 3.5- 4.0 MeV Data/SSM=0.4596+0.0546-0.0535 Flux=2.4129+0.2866-0.2811

  23. SK+SNO 8B total flux For each oscillation parameter set there is a minimum chi2 and a 8B error term describing the parabolic increase of the chi2 with deviations from the best chi2. The reduced chi2 vs. 8B flux is below. The jump is due to the relatively coarse grid in theta12. 5.30+0.17-0.11x10^6/(cm2 sec), which is a (+3%,-2%) error on the total 8B for SK+SNO compared to the 1.5% error of SK's ES flux by itself.

  24. Systematic errors Total 1.7 %

  25. 8B solar n in SK-I+II+III+IV 8B nsignals

  26. Data set for global solar analysis The most up-to-date data are used f8B=5.25 x 106/(cm2∙sec) fhep=7.88 x 103/(cm2∙sec) • SK: • SK-I 1496 days, spectrum 4.5-19.5 MeV(kin.)+D/N:Ekin>4.5 MeV • SK-II 791 days, spectrum 6.5-19.5 MeV(kin.)+D/N: Ekin>7.0 MeV • SK-III 548 days, spectrum 4.0-19.5 MeV(kin.)+D/N: Ekin>4.5 MeV • SK-IV 1669 days, spectrum 3.5-19.5 MeV(kin.)+D/N: Ekin>4.5 MeV • SNO: • Parameterized analysis (c0, c1, c2, a0, a1) of all SNO phased. (PRC88, 025501 (2013)) • Same method is applied to both SK and SNO with a0 and a1 to LMA expectation • Radiochemical: Cl, Ga • Ga rate: 66.1±3.1 SNU (All Ga global) (PRC80, 015807 (2009)) • Cl rate: 2.56±0.23 SNU(Astrophys. J.496, 505 (1998) ) • Borexino: Latest 7Be flux (PRL 107, 141302 (2011)) • KamLAND reactor : Latest (3-flavor) analysis (PRD88, 3, 033001 (2013)) • 8B spectrum: Winter 2006 (PRC73, 73, 025503 (2006)) • 8B and hep flux

  27. Day/Night (sin2θ12=0.311, sin2θ13=0.025) preliminary expected time variation as a function of cosθz Rate/Rateaverage α : day-night asym. scaling factor

  28. exponential parameterization Solar+KamLAND sin2θ12=0.308 Δm221=7.50x10-5eV2 Solar sin2θ12=0.311 Δm221=4.85x10-5eV2 • SK spectrum, red : exponential, green : quadratic preliminary

  29. N.B. All SK phase are combined without regard to energy resolution or systematics in this figure SK-I+II+III+IV spectrum Solar+KamLAND sin2θ12=0.308 Δm221=7.50x10-5eV2 Solar sin2θ12=0.311 Δm221=4.85x10-5eV2 Neutrino energy spectrum is convoluted in the electron recoil spectrum. For de-convolution, a generic quadratic function is used as a survival probability; f8B=5.25 x 106/(cm2∙sec) fhep=7.88 x 103/(cm2∙sec) SK recoil electron spectrum constrain the fit parameters (ci) of the function and the allowed Pee(En) is derived using the allowed (ci).

  30. Multiple scattering goodness 3.5-4.0MeV MSG > 0.45 Induced multiple scattering goodness(MSG) in SK-IV analysis. Although the 214Bi decay-electrons (majority of low energy BG) fluctuate up above 5.0MeV, they truly have energy less than 3.3MeV and should have more multiple scattering than true 5.0MeV electrons. MSG < 0.35 4.0-4.5MeV MSG > 0.45 MSG < 0.35

  31. MSG For each PMThitpair, the vectors to the Chrenkov ring cross points are the direction candidates MSG = vector sum of the candidates/ scalar sum of the candidates MSG of multiple scattering events should be small

  32. Comparison with others SNO KamLAND Super-K BOREXINO Super-K spectrum is the most precise!

  33. Solar Neutrinos Pee p+p➝d+e++νe (99.77%) all solar p+e-+p➝d+νe (0.23%) BOREXINO BORE- XINO pep pp MSW (solar&KL) d+p➝3He+γ MSW (solar) SK & SNO 3Ηe+α➝7Be+γ 15.08% 3Ηe+3Ηe➝α+2p 84.92% 3He+p➝α+e++νe Cl BORE- XINO 8B 7Be+e-➝7Li+νe99.9% 7Be 7Be+p➝8B+γ 0.1% Hep 8B+➝8Be*+e++νe 7Li+p➝α+α; 8Be*➝α+α

  34. Super-K water transparency @ Cherenkov light wavelength Measured by decay e-e+ from cosmic m-m+ SK-IV SK-III Started automatic temperature control anti-correlated with Supply water temperature

  35. Convection suppression in SK 3.5MeV-4.5MeV Event distribution Temperature gradation in Z Return to Water system The difference is only 0.2 oC Purified Water supply r2 Very precisely temperature-controlled (±0.01oC) water is supplied to the bottom.

More Related