Super-Kamiokande Roger Wendell, Duke University NNN 2010 Toyama, Japan
The Super-Kamiokande Collaboration The Super-Kamiokande Collaboration 1 Kamioka Observatory, ICRR, Univ. of Tokyo, Japan 19 Niigata University, Japan From PRD81, 2 RCCN, ICRR, Univ. of Tokyo, Japan 20 Okayama University, Japan 3 IPMU, Univ. of Tokyo, Japan 21 Osaka University, Japan 092004 (2010) 4 Boston University, USA 22 Seoul National University, Korea 5 Brookhaven National Laboratory, USA 23 Shizuoka University, Japan 24 Shizuoka University of Welfare, Japan 6 University of California, Irvine, USA 7 California State University, Dominguez Hills, USA 25 Sungkyunkwan University, Korea 26 Tokai University, Japan 8 Chonnam National University, Korea 9 Duke University, USA 27 University of Tokyo, Japan 28 Tsinghua University, China 10 Gifu University, Japan 11 University of Hawaii, USA 29 Warsaw University, Poland 30 University of Washington, USA 12 Kanagawa, University, Japan 13 KEK, Japan Autonomous University of Madrid, Spain (Nov.2008~) 14 Kobe University, Japan 15 Kyoto University, Japan ~120 collaborators 16 Miyagi University of Education, Japan 17 STE, Nagoya University, Japan 31 institutions, 6 countries 18 SUNY, Stony Brook, USA
Super-Kamiokande Super-Kamiokande 50 kton water Cherenkov detector 22.5 kton fiducial volume Depth of 2700 m.w.e cosmic ray background ~3 Hz Roughly ~10 Solar ν events ~10 Atmospheric ν per day Inner detector (ID) ~11,146 50 cm PMTs ~ 2ns timing resolution Outer detector (OD) 1,885 20 cm PMTs Multi-purpose detector: (this talk) Solar neutrinos Supernova neutrinos ( Relic SN's ) Atmospheric neutrinos Nucleon decay Beam neutrinos: K2K, T2K ( R. Wilson, today) Exotic particles
Super-K : Generations SK-1/3/4 SK-2 Analyses Analyses Data Update
SK-IV Upgraded DAQ system SK-IV Upgraded DAQ system IEEE Trans. Nucl. Sci. 57 (2010) 428 SK-I,II,III: partial data above threshold were read (1.3 µ sec window x3kHz) SK-IV: All hits are read, then apply complex triggers by software. Event build Precise analysis Periodic trigger Clock with variable in parallel in (17 µ sec x 60kHz) New time windows real-time Collect all hits every 17 µ sec . Electronics PMT (QBEE) signals Readout (Ethernet) T2K GPS from J-PARC Typical event time windows: Super-Low-Energy (SLE) events (<~6.5MeV): -0.5/+1.0 µ sec high rate (~3kHz) Normal events(>~6.5MeV): -5/+35 µ sec decay electrons Supernova Relic ν (SRN) candidates(>~10MeV, No OD): -5/+535 µ sec neutrons T2K events: -512/+512 µ sec at T2K beam spill timing x5 Wider dynamic range for charge measurement of each channel (>2000pC) No dead time up to ~6MHz/10sec for Supernova burst neutrinos x100 Apply precise event reconstruction to remove more low-e BG events in real-time
Solar Neutrinos
Introduction to Recent Solar and SN ν Developments Introduction to Recent Solar and SN ν Developments SK-IV solar ν data, new 8 B flux measurement SK-I + II + III Oscillation Fits 2- and 3-Flavor This talk Updated Supernova Relic Neutrino analysis Neutron Tagging in SK-IV , Poster by H. Zhang Supernova burst DAQ system, Poster by T. Yokozawa Status of SK Gadolinium R&D project, Poster by A. Kibayashi Search for GUT Monopoles, Poster by K.Ueno
Typical Low Energy Event Typical Low Energy Event (color: time) OD ID • Timing information vertex position • Ring pattern direction E e = 9.1MeV cos θ sun = 0.95 • Number of hit PMTs energy ~6hit / MeV (SK-I, III, IV) (software improvement) Energy: 14% Vertex: 87cm Direction: 26 o SK-I Resolutions: Energy: 14% Vertex: 55cm Direction: 23 o SK-III
8 B Flux SK-IV 8 B Flux 567 days SK-IV SK-IV Flux 2.28±0.04 (10 6 /cm 2 /s) Preliminary SK-III official:1 2.32±0.04±0.05 (10 6 /cm 2 /s) Events/day/kton/bin BLACK: SK3 RED : SK4 Fluxes in SK-IV are consistent with those from SK-III ● SK-IV data looks good so analysis under way ● Following oscillation analyses are for SK-I+II+III
Oscillation Analysis Data Set and Inputs Oscillation Analysis Data Set and Inputs SK SK-I 1496 days, spectrum 5.0-20MeV + D/N : E ≥ 5.0MeV SK-II 791 days, spectrum 7.0-20MeV + D/N : E ≥ 7.5MeV SK-III 548 days, spectrum 5.0-20.0MeV + D/N : E ≥ 5.0MeV SNO CC flux (Phase-I & II & III) NC flux (Phase-III & LETA combined) ( = 5.14 ± 0.2 × 10 6 cm -2 s -1 ) Day/Night asymmetry (Phase-I & II) Global Data Radiochemical : Cl, Ga Ga rate: 66.1+/-3.1 SNU (All Ga global) , PRC 80 , 015807(2009) Cl rate: 2.56+/-0.23 , Astrophys. J. 496 (1998) 505 Borexino 7 Be rate: 48 +/- 4 cpd/100tons, PRL 101 , 091302(2008) KamLAND : 2008 Items in red are updates since the analysis presented in 8 B spectrum : Winter(2006) PRD 78 , 032002 (2008)
Two-Flavor analysis of SK-I+II+III w/ Flux Constraint Two-Flavor analysis of SK-I+II+III w/ Flux Constraint 95% C.L. Solar global Solar+KamLAND Preliminary LMA only * 8 B rate is Add in global constrained by the and KamLAND SNO (NCD + LETA) Neutral Current Flux Solar Global + KamLAND Min χ 2 = 48.8 Min χ 2 = 57.7 ∆ m 2 = 6.1×10 -5 eV 2 ∆ m 2 = 7.6×10 -5 eV 2 tan 2 θ = 0.48 tan 2 θ = 0.44 Φ B8 = 0.89× Φ B8,SSM Φ B8 = 0.89× Φ B8,SSM
Three-Flavor Analysis ( including SK-I+II+III ) Three-Flavor Analysis ( including SK-I+II+III ) Preliminary Solar global 68, 95, 99.7% C.L. KamLAND Solar+KamLAND Solar Global sin 2 θ 13 = 0.06 @95%C.L. In both fits best θ 13 is small but Solar Global + KamLAND consistent with 0 Sin 2 θ 13 = 0.025 +0.18 -0.16 ( < 0.059 at 95%C.L.) ● arXiv:1010.0118
Supernova Relic Neutrinos
Supernova Relic Neutrino Search Supernova Relic Neutrino Search Ando , NJP 6 (2004) 170 Large background from solar Neutrinos Look for Spallation, these Atmosheric ν , also background Supernova explosions occurred commonly throughout the history of the universe ● Expect a diffuse ν flux Measurement of diffuse flux ⇒ galactic evolution, matter distribution in the universe ● Current limit , 1.2 / cm 2 / s at 90% C.L. SK-I Malek et al. PRL 90 , 061101 (2003) Solar neutrinos are a considerable background at low energies Search for inverse beta decay interactions 16 < E e+ < 80 MeV
Improved SN Relic Search in SK-I+II+III Improved SN Relic Search in Preliminary Update of the Inverse-beta decay cross-section (overall decrease) ● Strumia-Vissani PLB 564 (2003) 42 Use Poisson probability based likelihoods during fitting Efficiency was 58% in SK-I Improvements to data selection now: ● Change in Cherenkov angle cut (next slide) 78% (SK-I ) ● Spallation and solar angle cuts 69% (SK-II) 77% (SK-III) After the event selection there are 3 Types of events remaining Neutral current Elastic Scattering Low angle events Signal Events Isotropic Events p ν N 42 o ν e + 25-45 o ν μ, π e n reconstructed angle near 90 o (invisible) Each of these categories has a different Cherenkov angle distribution
SN Relic Fitting in SN Relic Fitting in SK-I+II+III Remaining events populate different regions of the distribution ● Previous analysis selected 37 ° < θ c < 50 ° ● Fit the backgrounds outside of the signal region simultaneously to better constrain their contribution in the overlap (Three regions) MC signal region ATM. ν e CC isotropic region μ / π low region (NC) NC elastic (μ / π) Cherenkov Angle ° Cherenkov Angle °
Supernova Relic Neutrino Fit , SK-I+II+III Supernova Relic Neutrino Fit , 38-50 degrees Preliminary data 20-38 degrees 78-90 degrees Relic* (low region) (NC ES region) all BG ν μ CC ν e CC NC elastic μ / π > C. thr. * Ando , NJP 6 (2004) 170 E (MeV) E (MeV) E (MeV) Combined fit shows good agreement in both the signal and non-signal regions
Supernova Relic Neutrino Fit Supernova Relic Neutrino Fit Preliminary SK-I+II+III combined likelihood combined 90% c.l. o l g L i k e SK-I l h i SK-II o o d SK-III combined ev/yr in 22.5 ktons ev/yr in 22.5 ktons combined 90% c.l.: SK-I alone fit prefers almost no signal < 5.1 ev / yr / 22.5 ktons interacting SK-II and SK-III Fits allow more relic ν < 2.7 /cm 2 /s (>16 MeV) < 1.9 /cm 2 /s (scaled to >18 MeV) Slightly larger than published limit
Comparison With Published Limit , SK-I Comparison With Published Limit , Preliminary /cm 2 /s >18 MeV Analysis Change Published limit 1.2 cross section update to Strumia-Vissani 1.2 → 1.4 Gaussian statistics → Poissonian statistics 1.4 → 1.9 in fit New SK-I Analysis: 1.9 → 1.6 E THRESH 18 → 16 MeV ε = 52% → 78 % (small statistical correlation in samples) improved fitting method takes into account NC New SK-I/II/III combined fit 1.6 → 1.9
Atmospheric ν Roughly ν e : ν µ ~ 1:2
Introduction to Recent Atmospheric Neutrino Updates Introduction to Recent Atmospheric Neutrino Updates » SK-IV Data » Oscillation Analyses Using SK-I+II+III » Update to the search oscillation induced τ -neutrinos » Searches for Rare particles and processes (nucleon decay)
SK-IV Atmospheric Neutrino Data SK-IV Atmospheric Neutrino Data Preliminary Sub-GeV e-like Multi-GeV e-like Multi-GeV µ -like Unoscillated SK-IV MC » SK-IV Data look good, consistent with SK-III » No oscillation result yet, but analyses are coming • Oscillations already appearing Partially Contained Remainder of the Talk will concentrate on SK-I+II+III unless otherwise noted
Recommend
More recommend
