Super-Kamiokande. Roger Wendell, Duke University NNN 2010 Toyama, Japan

Transcription

1 Super-Kamiokande Roger Wendell, Duke University NNN 2010 Toyama, Japan

2 The Super-Kamiokande Collaboration 1 Kamioka Observatory, ICRR, Univ. of Tokyo, Japan 2 RCCN, ICRR, Univ. of Tokyo, Japan 3 IPMU, Univ. of Tokyo, Japan 4 Boston University, USA 5 Brookhaven National Laboratory, USA 6 University of California, Irvine, USA 7 California State University, Dominguez Hills, USA 8 Chonnam National University, Korea 9 Duke University, USA 10 Gifu University, Japan 11 University of Hawaii, USA 12 Kanagawa, University, Japan 13 KEK, Japan 14 Kobe University, Japan 15 Kyoto University, Japan 16 Miyagi University of Education, Japan 17 STE, Nagoya University, Japan 18 SUNY, Stony Brook, USA 19 Niigata University, Japan 20 Okayama University, Japan From PRD81, 21 Osaka University, Japan (2010) 22 Seoul National University, Korea 23 Shizuoka University, Japan 24 Shizuoka University of Welfare, Japan 25 Sungkyunkwan University, Korea 26 Tokai University, Japan 27 University of Tokyo, Japan 28 Tsinghua University, China 29 Warsaw University, Poland 30 University of Washington, USA Autonomous University of Madrid, Spain (Nov.2008~) ~120 collaborators 31 institutions, 6 countries

3 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 events ~10 Atmospheric per day Inner detector (ID) ~11, cm PMTs ~ 2ns timing resolution Outer detector (OD) 1, 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

4 Super-K : Generations SK-1/3/4 Analyses SK-2 Data Update

5 SK-IV Upgraded DAQ system IEEE Trans. Nucl. Sci. 57 (2010) 428 SK-I,II,III: partial data above threshold were read (1.3µ sec window x3khz) SK-IV: All hits are read, then apply complex triggers by software. Periodic trigger New PMT signals Electronics (17µ sec x 60kHz) Clock Collect all hits every 17µ sec. Event build Precise analysis with variable in parallel in time windows real-time (QBEE) Readout (Ethernet) T2K GPS from J-PARC Typical event time windows: Super-Low-Energy (SLE) events (<~6.5MeV): -0.5/+1.0µ sec high rate (~3kHz) Normal events(>~6.5mev): -5/+35µ sec decay electrons Supernova Relic ν (SRN) candidates(>~10mev, No OD): -5/+535µ sec neutrons T2K events: -512/+512µ sec at T2K beam spill timing x5 Wider dynamic range for charge measurement of each channel (>2000pC) x100 No dead time up to ~6MHz/10sec for Supernova burst neutrinos Apply precise event reconstruction to remove more low-e BG events in real-time

6 Solar Neutrinos

7 Introduction to Recent Solar and SN Developments SK-IV solar data, new 8B flux measurement SK-I + II + III Oscillation Fits 2- and 3-Flavor Updated Supernova Relic Neutrino analysis This talk 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

8 Typical Low Energy Event (color: time) OD ID Timing information vertex position Ring pattern direction Number of hit PMTs energy Ee = 9.1MeV cosθ sun = 0.95 ~6hit / MeV (SK-I, III, IV) Resolutions: Energy: 14% Energy: 14% (software improvement) Vertex: 87cm Vertex: 55cm Direction: 26o SK-I Direction: 23o SK-III

9 SK-IV 8B Flux 567 days Preliminary SK-IV Flux 2.28±0.04 (106/cm2/s) SK-III official:1 2.32±0.04±0.05 (106/cm2/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

10 Oscillation Analysis Data Set and Inputs SK SK-I 1496 days, spectrum MeV + D/N : E 5.0MeV SK-II 791 days, spectrum MeV + D/N : E 7.5MeV SK-III 548 days, spectrum MeV + D/N : E 5.0MeV SNO CC flux (Phase-I & II & III) NC flux (Phase-III & LETA combined) ( = cm-2s-1) Day/Night asymmetry (Phase-I & II) Radiochemical : Cl, Ga Ga rate: 66.1+/-3.1 SNU (All Ga global), PRC80, (2009) Cl rate: 2.56+/-0.23, Astrophys. J. 496 (1998) 505 Global Data Borexino 7 Be rate: 48 +/- 4 cpd/100tons, PRL101, (2008) KamLAND : B spectrum : Winter(2006) Items in red are updates since the analysis presented in PRD78, (2008)

11 Two-Flavor analysis of SK-I+II+III w/ Flux Constraint 95% C.L. Solar global Solar+KamLAND Preliminary * B rate is constrained by the SNO (NCD + LETA) Neutral Current Flux LMA only Add in global and KamLAND Solar Global + KamLAND Min χ 2 = 48.8 m2 = ev2 tan2θ = 0.48 ΦB8 = 0.89 ΦB8,SSM Min χ 2 = 57.7 m2 = ev2 tan2θ = 0.44 ΦB8 = 0.89 ΦB8,SSM

12 Three-Flavor Analysis ( including SK-I+II+III ) Preliminary 68, 95, 99.7% C.L. Solar global KamLAND Solar+KamLAND Solar Global sin2θ 1 3 Solar Global + KamLAND Sin2θ 1 3 = In both fits best 13 is small but consistent with 0 ( < at 95%C.L.) arxiv:

13 Supernova Relic Neutrinos

14 Supernova Relic Neutrino Search Ando, NJP 6 (2004) 170 Large background from solar Neutrinos Look for these Spallation, Atmosheric, also background Supernova explosions occurred commonly throughout the history of the universe Expect a diffuse flux Measurement of diffuse flux galactic evolution, matter distribution in the universe Current limit, 1.2 / cm / s at 90% C.L. SK-I Malek et al. PRL 90, (2003) Solar neutrinos are a considerable background at low energies Search for inverse beta decay interactions 16 < Ee+ < 80 MeV

15 Improved SN Relic Search in SK-I+II+III Preliminary Update of the Inverse-beta decay cross-section (overall decrease) Strumia-Vissani PLB 564 (2003) 42 Use Poisson probability based likelihoods during fitting Improvements to data selection Change in Cherenkov angle cut (next slide) Spallation and solar angle cuts After the event selection there are 3 Types of events remaining Low angle events μ, π o Neutral current Elastic Scattering Signal Events ν Efficiency was 58% in SK-I now: 78% (SK-I ) 69% (SK-II) 77% (SK-III) p o e + 42 e n (invisible) Isotropic Events ν N ν reconstructed angle near 90 o Each of these categories has a different Cherenkov angle distribution

16 SN Relic Fitting in SK-I+II+III Remaining events populate different regions of the distribution Previous analysis selected 37 < < 50 c Fit the backgrounds outside of the signal region simultaneously to better constrain their contribution in the overlap (Three regions) MC signal region low region (μ / π) isotropic region (NC) Cherenkov Angle ATM. νe CC μ/π NC elastic Cherenkov Angle

17 Supernova Relic Neutrino Fit, SK-I+II+III data Relic* all BG degrees degrees (low region) Preliminary degrees (NC ES region) νμ CC νe 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

18 Supernova Relic Neutrino Fit doohil eki Lgol SK-I+II+III combined likelihood Preliminary combined 90% c.l. SK-I SK-II SK-III combined ev/yr in 22.5 ktons combined 90% c.l.: < 5.1 ev / yr / 22.5 ktons interacting < 2.7 /cm2/s (>16 MeV) < 1.9 /cm2/s (scaled to >18 MeV) ev/yr in 22.5 ktons SK-I alone fit prefers almost no signal SK-II and SK-III Fits allow more relic Slightly larger than published limit

19 Comparison With Published Limit, SK-I Analysis Change Preliminary /cm 2 /s >18 MeV Published limit 1.2 cross section update to Strumia-Vissani Gaussian statistics Poissonian statistics in fit New SK-I Analysis: ETHRESH MeV ε = 52% 78 % (small statistical correlation in samples) improved fitting method takes into account NC New SK-I/II/III combined fit

20 Atmospheric Roughly e : ~ 1:2

21 Introduction to Recent Atmospheric Neutrino Updates SK-IV Data Oscillation Analyses Using SK-I+II+III Update to the search oscillation induced -neutrinos Searches for Rare particles and processes (nucleon decay)

22 SK-IV Atmospheric Neutrino Data Sub-GeV e-like Preliminary Multi-GeV e-like Multi-GeV -like Unoscillated SK-IV MC Partially Contained SK-IV Data look good, consistent with SK-III No oscillation result yet, but analyses are coming Oscillations already appearing Remainder of the Talk will concentrate on SK-I+II+III unless otherwise noted

23 Zenith angle & lepton momentum distributions : SK-I+II+III ν µ ν τ oscillation (best fit) null oscillation µ -like e-like momentum Live time: SK-I 1489d (FCPC) 1646d (Upmu) SK-II 799d (FCPC) 827d (Upmu) SK-III 518d (FCPC) 636d (Upmu) M-like samples show large deficits in the upwardgoing bins that are well described by oscillations

24 Global Picture of Oscillations Agrees SK Zenith Analysis (1 ) m232 = ev2 sin > 0.96 ( 90% C.L.) SK L/E Analysis (1 ) m232 = ev2 sin > 0.96 ( 90% C.L.) Experiments are in good agreement about these oscillations SK Data disfavor other types of disappearance strongly, sterile ~7 We should look for oscillation induced appearance!

25 Three-Flavor Oscillations in Matter P( e ) Presence of electrons in the Earth alter the neutrino ineraction potential and induce additional e oscillations Induced by 13 + solar terms Higher energy, 2-10 GeV, (anti-) neutrinos experience resonant enhanced transitions, for normal (inverted) hierarchy Lower energy oscillations, < 1GeV, are moderated by octant of 23 Induced by 13 Matter Driven Solar Terms Interference term sensitive to cp Simultaneously considering all of these effects gives sensitivity to many of the remaining questions on oscillation physics...

26 Full Three-Flavor Oscillation Analysis, Normal Hierarchy Preliminary SK-I+II+III 99% SK-I+II+III 90% SK-I+II+III 68% Chooz Exclusion region No Strong preference for either hierarchy ( 2 = 1.6) 13 is consistent with zero and the Chooz limit No preference for 23 octant or cp Poster by M. Lee

27 Events at Super-K Energy Threshold: 3.5 GeV eo s n o r d a h r or Many light producing particles Most events are deep inelastic scattering interactions H adrons Complicated event topology complicate identification of the leading lepton Use a Neural Network procedure Negligible primary flux Observed tau events would be oscillation induced SK-I MC GOAL : Observe events in the atmospheric data How inconsistent is the no appearance hypothesis?

28 Update Fitting Technique Use an un-binned two-dimensional likelihood fit to extract the most from the data Previous analysis ( PRD 2006 ) fit only in one dimension Events with NN output > 0.5 in this plot BKG-like -like BKG 13 BKG would be here Tau and Background events appear in dramatically different regions of the plot The signal appears exclusively in the upward-going direction

29 Neural Network and Fitting downward-going Signal NN Check output with downward-going data 7 variables in NN : Fraction of energy in leading ring, number of decay electrons, number of ring fragments, visible energy, leading ring's PID, distance to decay-e Neural Network is good at separating signal from background DIS events appear -like because of their many out-going particles To account for this we fit for the fraction of DIS events constrained to an uncertainty of 10%

30 Fit Results SK-I+II+II If no appearance, = 0 Result SK-I SK-II SK-III SK-I+II+III DIS Preliminary Background Signal Fitting Error only -like events (NN > 0.5) Fitted Excess Atm BKG MC Tau signal clearly appears in upwardgoing region DIS fits to +1 normalization fit is 1.63 expectation

31 Observed Expect Systematic Errors Atmospheric oscillation analysis sytematics ( 27 errors ) Tau neutrino cross-section Flux : Up/down Ratio, Horizontal/Vertical Ratio, K/p ratio X-Sec: NC / CC Ratio Detector: Up/Down Energy Calib. Asymm Oscillation Paramaters: Atm. 1 region 0 < 13 < Chooz Leading.+12.5%.-14.2%. % These affect the significance (next page).+6.1%.-5.0%.+1.5%.-0.5%.+0.0%.-13.0% Systematic Preliminary This corresponds to Events

32 Significance Calculation Prepare an asymmetric gaussian centered about the best fit from the data with widths corresponding to the systematic errors (previous page) The integral of the PDF below zero (corresponding to no appearance) is a measure of the significance Central value of SK-I+II+III Fit SK I+II+III : Integral below zero = corresponds to 3.8 The Expected signficance : 2.6 ( 2.9 without systematics ) Preliminary SK data are inconsistent with no appearance at 3.8

33 Rare Particles and Proton Decay

34 Search for Diffuse Dark Matter Annihilation assume 100% BR EXAMPLE: illustration of 5.6 GeV WIMP annihila1tion signal in SK Distinctive signatures: Mχ = 5.6 GeV Monoenergetic Eν = Mχ Isotropic Search in atmospheric neutrino data from SK-I, -II & III Mχ = 5.6 GeV livetime: FC/PC 2806 days, UPMU 3109 days Simulate signal in NUMU, NUE and NUTAU FIT: for each tested WIMP mass, find the best configuration of ATM MC + DM signal that would match DATA the best using all SK samples: e-like + mu-like FC+PC+UPMU (wide energy range) cosθ Momentum [GeV/c] DATA SK1,2,3 ATM MC with oscillations SK two-flavor best fit DM signal shape enhanced for illustration signal is before FIT

35 Fit Results FIT based on Evis & cosθ distr., systematics included (120 sys. terms fitted) No allowed excess of DM-induced ν s for Mχ in range 3GeV 3 TeV Limit on <σ v> Focus on signal arising from Milky Way halo (diffuse flux) Conservative upper limit on WIMP total self-annihilation cross section <σ V> MW J Ω integrated intensity over all sky related to DM halo density profile; includes information about DM density cusp in GC (*) H.Yuksel et al., Phys. Rev. D76, (2007), arxiv: [astro-ph] *) rage ( e v A o Hal excluded above

36 Nucleon Decay Limits, 2010 Proton is predicted to be stable in the standard model GUT model, SuperSymetric Models predict various types (and lifetimes!) of proton decay Super-K protons neutrons This talk

37 Search for p e+ + 0, SK-I+II+III+IV Signal MC Background MC p e Cut 2 or 3 Rings All e-like 85 < 0 mass < 185 MeV 0 Decay electron Total Mass Cut Data efficiency (%) SK4 MC 535.2d ± SK-IV / B > yr Only (32.9 kton yr ) Preliminary Data Still no Candidates! Into the next decade! / B > yr SK-I-IV combined (205.7 kton yr )

38 Summary SK-IV is underway, Solar and Atmospheric data look good New Solar results including global fits with SK-I+II+III Supernova Relic Neutrino Analysis has been updated ~ 1.9 ev/cm /s New Atmospheric results including oscillations and nucleon decay No oscillation induced tau events disfavored at 3.8 Tour of Kamioka Observatory will include Super-K, so come have a look!