The Sudbury Neutrino Observatory

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The Sudbury Neutrino Observatory. Neil McCauley University of Pennsylvania NuFact 04 27 th July 2004. Summary. Introduction to SNO. Solar Neutrino Analysis. Other Physics Topics. Deployment and Commissioning of 3 He Proportional Counters. Conclusions. The SNO Collaboration. - PowerPoint PPT Presentation


  • The Sudbury Neutrino Observatory.Neil McCauleyUniversity of Pennsylvania

    NuFact 0427th July 2004

  • SummaryIntroduction to SNO.Solar Neutrino Analysis.Other Physics Topics.Deployment and Commissioning of 3He Proportional Counters.Conclusions.

  • The SNO CollaborationT. Kutter, C.W. Nally, S.M. Oser, T. Tsui, C.E. Waltham, J.WendlandUniversity of British Columbia

    J. Boger, R.L. Hahn, R. Lange, M. YehBrookhaven National Laboratory

    A.Bellerive, X. Dai, F. Dalnoki-Veress, R.S. Dosanjh, D.R. Grant, C.K. Hargrove, R.J. Hemingway, I. Levine, C. Mifflin, E. Rollin, O. Simard, D. Sinclair, N. Starinsky, G. Tesic, D. WallerCarleton University

    P. Jagam, H. Labranche, J. Law, I.T. Lawson, B.G. Nickel, R.W. Ollerhead, J.J. Simpson University of Guelph

    B. Aharmim J. Farine, F. Fleurot, E.D. Hallman, A. Krger, S. Luoma, M.H. Schwendener, R. Tafirout, C.J. VirtueLaurentian University

    Y.D. Chan, X. Chen, C. Currat, K.M. Heeger, K.T. Lesko, A.D. Marino, E.B. Norman, C.E. Okada, A.W.P. Poon, S.S.E. Rosendahl, R.G. StokstadLawrence Berkeley National Laboratory

    M.G. Boulay, T.J. Bowles, S.J. Brice, M.R. Dragowsky, S.R. Elliott, M.M. Fowler, A.S. Hamer, J. Heise, A. Hime, G.G. Miller, R.G. Van de Water, J.B. Wilhelmy, J.M. WoutersLos Alamos National LaboratoryS.D. Biller, M.G. Bowler, B.T. Cleveland, G. Doucas, J.A. Dunmore, H. Fergani, K. Frame, N.A. Jelley, J.C. Loach, S. Majerus, G. McGregor, S.J.M. Peeters,C.J. Sims, M. Thorman, H. Wan Chan Tseung, N. West, J.R. Wilson, K. ZuberOxford University

    E.W. Beier, H. Deng, M. Dunford, W. Frati, W.J. Heintzelman, C.C.M. Kyba, N. McCauley, M.S Neubauer, V.L. Rusu, R. Van Berg, P. WittichUniversity of Pennsylvania

    S.N. Ahmed, M. Chen, F.A. Duncan, E.D. Earle, H.C. Evans, G.T. Ewan, B. G Fulsom, K. Graham, A.L. Hallin, W.B. Handler, P.J. Harvey, L.L Kormos, M.S. Kos, C.B. Krauss, A.V. Krumins, J.R. Leslie, R. MacLellan, H.B. Mak, J. Maneira, A.B. McDonald, B.A. Moffat,A.J. Noble, C.V. Ouellet, B.C. Robertson, P. Skensved, M. Thomas, Y.TakeuchiQueens University

    D.L. WarkRutherford Laboratory and University of Sussex

    R.L. HelmerTRIUMF

    A.E. Anthony, J.C. Hall, M. Huang, J.R. Klein, S. SeibertUniversity of Texas at Austin

    T.V. Bullard, G.A. Cox, P.J. Doe, C.A. Duba, J.A. Formaggio, N. Gagnon, R. Hazama, M.A. Howe, S. McGee, K.K.S. Miknaitis, N.S. Oblath, J.L. Orrell, K. Rielage, R.G.H. Robertson, M.W.E. Smith, L.C. Stonehill, B.L. Wall, J.F. WilkersonUniversity of Washington

  • The Sudbury Neutrino Observatory6800 ft levelINCOs Creighton Mine Sudbury, Ontario

  • Signals in SNO

  • Where is the physics?Solar Neutrinos:Measure mixing parameters.Measure CC/NC ratio Measures q12.Search for direct signatures of neutrino oscillation. Day Night AsymmetrySpectral Distortions.Rare solar neutrino searches.Solar AntineutrinosNeutrinos from the hep reaction.Other Physics:Atmospheric NeutrinosProton DecayNeutron Antineutron Oscillations.Supernovae.Taken from hep-ph/0406328 Note the linear scale.10-46x10-5

  • The Phases of SNO.Phase 1: Pure D2O.Nov 1999 May 2001 : 306.4 days.Neutrons Capture on DNeed spectral information to separate CC and NC.Phase 2: D2O+NaClJul 2001-Sep 2003 : ~ 391 days.Neutrons Capture on 35ClStatistically separate neutrons and electrons via event isotropy.Phase 3: 3He Counters (NCD)2004-Dec 2006Neutrons capture on 3HeEvent by event separation of neutrons and electrons.

  • Why add salt?Increase in Capture Cross Section.Increase in visible Cerenkov energy.Increased Neutron Statistics.Detection efficiency: 14.4% 39.9%Multiple g-rays in the final state.Can statistically separate neutron events from electrons using event isotropy.

  • Event Isotropy.Decompose the hit pattern into spherical harmonics.Choose the combination that best separates CC and NC.b14=b1+4b4Uncertainty on b14 mean 0.87%

  • BackgroundsRadioactive BackgroundsU Chain 214BiTh Chain 208TlSodium Activation 24NaNeutrons.Cherenkov Tail.(a,n) reactions on carbon.External Neutrons.CosmogenicNeutrons from atmospheric neutrinos.Instrumental BackgroundsNow include external neutrons as a free parameter in the fit.

  • Signal Extraction Phase 1Maximum Likelihood fit to PDFs.Variables:Teff (R/RAV)3cos(q)

    Background PDFs fixed.

  • New PDFsESNCCCE/MeV(r/600cm)3cos(q)b14The Changes for the salt phase require new PDFsNow have 4 variables with the addition of b14. CC/ES PDFs unchanged.New NC PDF Update to signal extraction b14 depends upon energy2D PDFs.Addition of external neutrons to the fit.

  • Salt Results 254 livedays.Results from July01-Oct02.Spectrum for CC and ES unconstrained.Blind Analysis.Fit for external neutrons.Kinetic EnergyRadiusDirectionIsotropy

  • Flux Measurements.Salty D2O

    Pure D2OUnit x106 cm-2s-1

  • Upcoming Salt Results.Use the full salt data set.~391 days.~176 days during the day.~214 days during the night.Same energy threshold as the first salt paper (T=5.5MeV).Also includeDay Night Results.Full Spectral Analysis.Long paper in preparation.

  • Other Physics TopicsSNO can search from more than solar neutrinos

  • Invisible Nucleon Decay Limits.For invisible nucleon decay in 16OCan search for excitation gs.

    Comparing the pure D2O and salt phases

    tinv>1.9x1029 years for neutron modes.tinv>2.1x1029 years for proton modes.

    PRL 92, 102004, 2004

    Vanishing Neutron6.18MeV 44%BR 7.03MeV 2%BRVanishing Proton6.32MeV 41%BR7.00MeV 4%BR

  • Anti Neutrino Search.Look for ne+D e++n+nQ=4.03MeVDouble and triple coincidence search.nn coincidence threshold at 4.03MeVDirect Detection.Low Reactor background at SNO.Pure D2O < 3.4x104cm-2s-1 (90%CL)hep-ex/0407029Not competitive with KamLand ne < 3.7x102cm-2s-1 (90%CL)

    SNO Limits.SK Limits.

  • Phase 3: The NCD phase.Use 3He proportional counters.Uniquely identify neutron events.3He+np+TMeasure Charge vs Time in the proportional counters.40 Strings on 1 m grid.Total Active length 398m.Expect capture efficiency:~25% on 3He~20% on DAim to measure CC/NC to ~7%

  • Signals in the NCDs.Digitize the charge vs time signal from the NCDs.Neutron events have two particles.Radioactive backgrounds have one.Neutron Free Window in charge vs rise time.Benchtest Data.4He Strings provide control sample.

  • New Analysis ChallengesNCD DataCalibration.Instrumental Backgrounds.Separation of neutron signal from alpha background.Understanding end effects.Z position from reflection.System deadtime.External neutrons.PMT DataLight occultation from NCDs.U/Th in/on the NCDs.Understanding/checking previous analysis inputsReconstructionEnergyIsotropyEvent Selection CutsSignal Extraction.Loss of spherical symmetry.Constraints on neutrons from NCDs.

  • From Salt to NCDs.NCD Configuration Optimization:End of Salt Phase:End of Salt Removal: End of Second Pure D2O Phase:First NCD deployed:Last String Deployed:Removal of Deployment Hardware:Commissioning of Manipulator:End of Commissioning Phase:Sep-Dec 200228 Aug 20033 Oct 200327 Oct 20033 Dec 200312 Feb 200423 Apr 2004Jun 2004Oct 2004

  • The Second Pure D2O Phase.The second pure D2O phase was used to verify the return to baseline.Optical Response.Energy Scale.Cleaning of the water.MnOrganicsNeutron Response.

    Extensive period of calibration.Start of Salt Removal

  • NCD Deployment3He CountersRadio Purity
  • NCD Deployment

  • NCD Commissioning.Learn about the new detector.CalibrationInstrumental Backgrounds.Interaction of NCD and PMT systems.Learn how to run the detector.Are the NCDs running OK?What to look for.Updates to monitoring tools.Automation of proceduresNCD electronics calibration.Data Processing.Data Flow.Aim to finish commissioning in the autumn.

    A Neutron EventA Fork Event

  • ConclusionsSNO Results:Solve the solar neutrino problem and demonstrate neutrino flavour change.Restrict the measured values of the solar mixing parameters.Future results can help further restrain the mixing parameters, particularly q12.The NCD array is deployed in the detector.Commissioning of the full system now underway.

  • The Solar Neutrino ProblemNeutrino Flavor Change?Something else?

  • Measuring Cherenkov Tails : A Radon Spike Calibration.+ Monte Carlo for Th and Na

    -> deck clean room (DCR) enclosure protecting the most sensitive access point to the SNO detector


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