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The Sudbury Neutrino Observatory.

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.

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The Sudbury Neutrino Observatory.

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  1. The Sudbury Neutrino Observatory. Neil McCauley University of Pennsylvania NuFact 04 27th July 2004

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

  3. The SNO Collaboration T. Kutter, C.W. Nally, S.M. Oser, T. Tsui, C.E. Waltham, J.Wendland University of British Columbia J. Boger, R.L. Hahn, R. Lange, M. Yeh Brookhaven 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. Waller Carleton 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. Krüger, S. Luoma, M.H. Schwendener, R. Tafirout, C.J. Virtue Laurentian 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. Stokstad Lawrence 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. Wouters Los Alamos National Laboratory S.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. Zuber Oxford 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. Wittich University 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.Takeuchi Queen’s University D.L. Wark Rutherford Laboratory and University of Sussex R.L. Helmer TRIUMF A.E. Anthony, J.C. Hall, M. Huang, J.R. Klein, S. Seibert University 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. Wilkerson University of Washington

  4. 2039m to surface 1000 tonnes of D2O 12m diameter acrylic vessel 17m diameter PMT support structure with ~9500 PMTs 7000 tonnes of H2O Norite rock Urylon liner and radon seal The Sudbury Neutrino Observatory 6800 ft level INCO’s Creighton Mine Sudbury, Ontario

  5. Charged Current • D+nep+p+e- • Electron energy closely corresponds to neutrino energy. • Weak directional sensitivity. FCC=Fe • Neutral Current • D+nxp+n+nx • Equally sensitive to all active neutrino flavors. • Threshold 2.2MeV. FNC=Fe + Fmt • Elastic Scattering • e-+nxe-+nx • Good directional sensitivity. • Enhanced ne sensitivity. FES=Fe + 0.154Fmt Signals in SNO

  6. Where is the physics? • Solar Neutrinos: • Measure mixing parameters. • Measure CC/NC ratio • Measures q12. • Search for direct signatures of neutrino oscillation. • Day – Night Asymmetry • Spectral Distortions. • Rare solar neutrino searches. • Solar Antineutrinos • Neutrinos from the hep reaction. • Other Physics: • Atmospheric Neutrinos • Proton Decay • Neutron – Antineutron Oscillations. • Supernovae. 10-4 6x10-5 Taken from hep-ph/0406328 Note the linear scale.

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

  8. 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.

  9. Event Isotropy. • Decompose the hit pattern into spherical harmonics. • Choose the combination that best separates CC and NC. • b14=b1+4b4 • Uncertainty on b14 mean 0.87%

  10. New Calibration: controlled Radon spike. Backgrounds • Radioactive Backgrounds • U Chain – 214Bi • Th Chain – 208Tl • Sodium Activation – 24Na • Neutrons. • Cherenkov Tail. • (a,n) reactions on carbon. • External Neutrons. • Cosmogenic • Neutrons from atmospheric neutrinos. • Instrumental Backgrounds Now include external neutrons as a free parameter in the fit.

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

  12. New PDFs CC ES NC • The Changes for the salt phase require new PDFs • Now have 4 variables with the addition of b14. • CC/ES PDFs unchanged. • New NC PDF • Update to signal extraction • b14 depends upon energy • 2D PDFs. • Addition of external neutrons to the fit. E/MeV (r/600cm)3 cos(q) b14

  13. Salt Results – 254 livedays. • Results from July01-Oct02. • Spectrum for CC and ES unconstrained. • Blind Analysis. • Fit for external neutrons. Kinetic Energy Radius Direction Isotropy

  14. Salty D2O Pure D2O Flux Measurements. Unit x106 cm-2s-1

  15. 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 include • Day – Night Results. • Full Spectral Analysis. • Long paper in preparation.

  16. Other Physics Topics SNO can search from more than solar neutrinos……

  17. Invisible Nucleon Decay Limits. • For invisible nucleon decay in 16O • Can 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 Neutron 6.18MeV 44%BR 7.03MeV 2%BR Vanishing Proton 6.32MeV 41%BR 7.00MeV 4%BR

  18. Anti Neutrino Search. • Look for ne+D → e++n+n Q=4.03MeV • Double and triple coincidence search. • nn coincidence threshold at 4.03MeV • Direct Detection. • Low Reactor background at SNO. • Pure D2O Results. • ne < 3.4x104cm-2s-1 (90%CL) • hep-ex/0407029 • Not competitive with KamLand • ne < 3.7x102cm-2s-1 (90%CL) SNO Limits. SK Limits.

  19. Phase 3: The NCD phase. • Use 3He proportional counters. • Uniquely identify neutron events. • 3He+n→p+T • Measure 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 D • Aim to measure CC/NC to ~7%

  20. 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.

  21. NCD Data Calibration. Instrumental Backgrounds. Separation of neutron signal from alpha background. Understanding end effects. Z position from reflection. System deadtime. External neutrons. PMT Data Light occultation from NCDs. U/Th in/on the NCDs. Understanding/checking previous analysis inputs Reconstruction Energy Isotropy Event Selection Cuts Signal Extraction. Loss of spherical symmetry. Constraints on neutrons from NCDs. New Analysis Challenges

  22. 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 2002 28 Aug 2003 3 Oct 2003 27 Oct 2003 3 Dec 2003 12 Feb 2004 23 Apr 2004 Jun 2004 Oct 2004

  23. 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. • Mn • Organics • Neutron Response. • Extensive period of calibration. Start of Salt Removal

  24. NCD Deployment Deck Clean Room Boathook Handle • 3He Counters • Radio Purity <10ppt U/Th. • 500X Cleaner than best previous detectors. • Development and construction 1991-2004. • Anchors deployed during AV construction. • To Deploy NCDs. • Attach counter to hauldown mechanism. • Use ROV to bring counter in the D2O. • Laser weld additional counters to string above the neck. • Leak test and test with Neutron Source. • Attach to anchor point. • Secure Cable • Repeat. Hauldown Crank GVC Controls D2O Level Boathook 7 m Cable Attachment Ring Global View Camera NCD 12 m Shuttle Float Hauldown System Anchor Attachment Site Pulley Float

  25. NCD Deployment

  26. NCD Commissioning. • Learn about the new detector. • Calibration • Instrumental 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 procedures • NCD electronics calibration. • Data Processing. • Data Flow. • Aim to finish commissioning in the autumn. A Neutron Event A “Fork” Event

  27. Conclusions • SNO 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.

  28. The Solar Neutrino Problem Neutrino Flavor Change? Something else?

  29. Measuring Cherenkov Tails : A Radon Spike Calibration. Compare with pure D2O measurement. + Monte Carlo for Th and Na

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