The Sudbury Neutrino Observatory and The Bruno Pontecorvo Prize

1. The Sudbury Neutrino Observatory and The Bruno Pontecorvo Prize

2. I am deeply honoured to receive the Bruno Pontecorvo Prize on behalf of myself and my many colleagues in the Sudbury Neutrino Observatory Scientific Collaboration

3. J. C. Barton, S. D. Biller, R. A. Black, R. Boardman, M. G. Bowler, J. Cameron, B. T. Cleveland, G. Doucas, J. A. Dunmore, A. P. Ferraris, H. Fergani, K.Frame, H. Heron, C. Howard, N. A. Jelley, A. B. Knox, M. Lay, J. C. Loach, W. Locke, J. Lyon, N. McCaulay, S. Majerus, G. McGregor, M. Moorhead, M. Omori, S. J. M. Peeters, C. J. Sims, N. W. Tanner, R. Taplin, M. Thorman, P. T. Trent, D. H. Wan Chan Tseung, N. West, J. R. Wilson, K. Zuber Oxford University E. W. Beier, D. F. Cowen, J. Deng, M. Dunford, E. D. Frank, W. Frati, W. J. Heintzelman, P.T. Keener, C. C. M. Kyba, N. McCauley,D. S. McDonald, M.S.Neubauer, F. M. Newcomer,V. L. Rusu, R. Van Berg, P. Wittich. University of Pennsylvania M.M. Lowry, Princeton University S.N. Ahmed, E. Bonvin, M. G. Boulay, M. Chen, E. T. H. Clifford, Y. Dai, F. A. Duncan, E. D. Earle,H. C. Evans, G.T. Ewan, R. J. Ford, B. G. Fulsom, K. Graham, W. B. Handler, A. L. Hallin, A. S. Hamer*, P. J. Harvey, R. Heaton, J. D. Hepburn, C. Jillings, M. S. Kos, L. L. Kormos, R. Kouzes, C. B. Krauss, A. V. Krumins, H. W. Lee, J. R. Leslie, R. MacLellan, H. B. Mak, J. Maneira, A. B. McDonald, W. McLatchie, B. A. Moffat, A. J. Noble, C. Ouellet, T. J. Radcliffe, B.C. Robertson, P. Skensved, B. Sur. Y. Takeuchi, M. Thomson Queen’s University D.L. Wark, Rutherford Laboratory and University of Sussex R.L. Helmer, TRIUMF A.E. Anthony, J.C. Hall, J.R. Klein University of Texas at Austin Q. R. Ahmad, M. C. Browne, T.V. Bullard, T. H. Burritt, G. A. Cox, P. J. Doe, C. A. Duba, S. R. Elliott, R. Fardon, J. A. Formaggio, J.V. Germani, A. A. Hamian, R. Hazama, K. M. Heeger, M. A. Howe, S. McGee, R. Meijer Drees, K. K. S. Miknaitis, N. S. Oblath, J. L. Orrell, K. Rielage, R. G. H. Robertson, K. Schaffer, M. W. E. Smith, T. D. Steiger, L. C. Stonehill, B. L. Wall, J. F. Wilkerson. University of Washington G. Milton, B. Sur, AECL, Chalk River *deceased The SNO Collaboration S. Gil, J. Heise, R.L. Helmer, R.J. Komar, T. Kutter, S. M. Oser, C.W. Nally, H.S. Ng, R. Schubank, Y. Tserkovnyak, T. Tsui, C.E. Waltham, J. Wendland University of British Columbia J. Boger, R. L Hahn, R. Lange J.K. Rowley, M. Yeh Brookhaven National Laboratory I. Blevis, A. Bellerive, X. Dai, F. Dalnoki-Veress, R. S. Dosanjh, W. Davidson, J. Farine, D.R. Grant, C. K. Hargrove, R. J. Hemingway, I. Levine, K. McFarlane, H. Mes, C. Mifflin, V.M. Novikov, M. O'Neill, E. Rollin, M. Shatkay, C. Shewchuk, O. Simard, D. Sinclair, N. Starinsky, G. Tesic, D. Waller Carleton University T. Andersen, K. Cameron, M.C. Chon, P. Jagam, J. Karn, H. Labranche, J. Law, I.T. Lawson,B. G. Nickel, R. W. Ollerhead, J. J. Simpson, N. Tagg, J.X. Wang University of Guelph B. Aharmim, J. Bigu, J.H.M. Cowan, J. Farine, F. Fleurot, N. Gagnon, E. D. Hallman, R. U. Haq, J. Hewett, J.G. Hykawy, G. Jonkmans, A. Kruger, S. Luoma, A. Roberge, E. Saettler, M.H. Schwendener, H. Seifert, R. Tafirout, C. J. Virtue Laurentian University Y. D. Chan, X. Chen, C. A. Currat, M.C.P. Isaac, K. M. Heeger, K. T. Lesko, A.D. Marino, E.B. Norman, C.E. Okada, A.W. P. Poon, S. S. E. Rosendahl, A. R. Smith, A. Schuelke, 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. Goldschmidt, A. Hime, J. Heise, K. Kirch, G. G. Miller, P. Thornewell, R. G. Van de Water, J. B. Wilhelmy, J. M. Wouters. Los Alamos National Laboratory R.G. Allen, G. Buhler, H.H. Chen* University of California, Irvine J. D. Anglin, M. Bercovitch, W. F. Davidson, R. S. Storey* National Research Council of Canada

4. SNO and Bruno Pontecorvo • We are particularly honored because of the strong respect that we have • for Bruno Pontecorvo and the brilliant insight that he brought to the field • of Neutrino Physics. • Our experiment was conceived to provide a direct test of whether • neutrinos from the core of Sun undergo flavor change before reaching Earth. • - The concept of flavour change was put forward by in a paper by Gribov and • Pontecorvo in 1967, shortly after the initial measurements of Ray Davis • showed too few neutrinos from the Sun. • We have provided clear evidence that neutrinos change their flavour, confirming • the proposal of Gribov and Pontecorvo and the accuracy of solar models. • Our measurements can be combined with other measurements to confirm • that the dominant mechanism for neutrino flavour change is oscillation of massive • neutrinos - a mechanism proposed by Bruno Pontecorvo in 1957.

5. “SolarNeutrino Problem” Solar Fluxes: Bahcall et al Experiment vs Solar Models 1970 - 2001 Smaller than expected flux of electron neutrinos: Neutrino Flavor Change or Solar Model Effects?

6. Solar Model Independent Measurements: SuperKamiokande, SNO (Using 8B Solar Neutrinos) SuperKamiokande Measurements • Matter-Enhanced Oscillations – MSW Effects • - Distortion of the spectrum • - Regeneration in the Earth (Day/Night Effects) • Other Time Dependent Effects • - Seasonal effects (Earth-Sun Distance, Neutrino Magnetic Moments ..) • - Long Term: Solar cycle … (Neutrino Magnetic Moments …) None of the above effects are seen with clear signals of oscillations Sudbury Neutrino Observatory However: • Charged Current to Neutral Current comparisons • - Electron Neutrino flux compared to Total Active Neutrino flux

7. Unique Signatures in SNO (D2O) Charged-Current (CC) e+d  e-+p+p Ethresh = 1.4 MeV eonly Neutral-Current (NC) x+d x+n+p Ethresh = 2.2 MeV Equally sensitive to e nmt 3 ways to detect neutrons Elastic Scattering (ES) x+e- x+e- x, but enhanced fore

8. Solar Neutrino Physics From SNO Fx Fx FCC+ (FES - FCC) x (1/0.15) Fnc = = Flavor change + active neutrino appearance FCC ne June 2001 (with SK) 3.3 s = FES ne + 0.15 (nm+ nt) ne FCC 5.3 s April 2002 = FNC ne +nm+ nt Sept. 2003 > 7 s (With salt) Total 8B Solar Neutrino Flux June 2001 April 2002 ~10% Sept. 2003

9. Sudbury Neutrino Observatory 1000 tonnes D2O Support Structure for 9500 PMTs, 60% coverage 12 m Diameter Acrylic Vessel 1700 tonnes Inner Shielding H2O 5300 tonnes Outer Shield H2O Urylon Liner and Radon Seal

10. One million pieces transported and assembled under ultra-clean conditions. More than 60,000 showers and counting…

11. Observables PMT Measurements • position • time • charge Reconstructed event • vertex • direction • energy • isotropy

12. 35Cl+n 2H+n 8.6 MeV 6.25 MeV 3H 36Cl 3 neutron (NC) detection methods Phase I (D2O) Nov. 99 - May 01 Phase II (salt) July 01 - Sep. 03 Phase III (3He) Summer 04-Dec. 06 n captures on 2H(n, g)3H Effc. ~14.4% NC and CC separation by energy, radial, and directional distributions 2 t NaCl. n captures on 35Cl(n, g)36Cl Effc. ~40% NC and CC separation by event isotropy 40 proportional counters 3He(n, p)3H Effc. ~ 30% capture Measure NC rate with entirely different detection system. 5 cm n 3H p 3He n + 3He  p + 3H

13. Angle to Sun Isotropy Kinetic Energy Signal Extraction for Salt “Blind” Analysis performed by adding in an unknown number of neutrons generated by muons Data from July 26, 2001 to Oct. 10, 2002 254.2 live days 3055 candidate events: 1339.6 +63.8-61.5 CC 1344.2 +69.8-69.0 NC 170.3 +23.9-20.1 ES Radial Profile Phys.Rev.Lett. 92 (2004) 181301

14. Results from SNO Salt Phase (2003): Agreement: Pure D2O measurements (2001,02) 8B shape unconstrained 8B shape constrained Total active neutrino (8B) flux = Solar Model -> Restriction on sterile neutrinos (Bahcall et al 2004) Clear evidence for Flavor Change (> 7 s) through independent measurements of F(ne) and F(nTotal Active)

15. Neutrino properties • The most favored explanation for the data to date is Neutrino • Oscillation of massive neutrinos. (As proposed by Pontecorvo) • Others are ruled out as dominant, but could be small sub-dominant • Flavor Changing Neutral Currents, • Resonant Spin Flavor Precession for solar neutrinos … • Violation of Equivalence Principle, Lorentz Invariance …… • Sterile neutrinos.

16. If neutrinos have mass: As proposed originally by Pontecorvo: For three neutrinos: Pontecorvo-Maki-Nakagawa-Sakata matrix (Double b decay only) ? ? ? Solar,Reactor Atmospheric CP Violating Phase Reactor,LBL Majorana Phases Range defined for Dm12, Dm23 For two neutrino oscillation in a vacuum: (valid approximation in many cases)

17. After SNO Salt Data: Closing in on Dm122, q12 LMA MSW only at > 99.73 % CL Kamland parameters agree with solar Solar Solar + Kamland reactor --90% --95% --99% --99.73% Maximal Mixing disallowed at 5.4 s : q12 = 32.5 +- 1.7 o MSW: m2 > m1 Future SNO (and SNO+) measurements will improve the accuracy further.

18. SNO SNOLAB: 2 km Underground (20 times lower cosmic ray flux than Gran Sasso) 15 Letters of Interest from International Community: bb decay, Dark Matter, Solar n. Completion 2007

19. Many Connections Between Bruno Pontecorvo And SNO • Science: • He proposed chlorine as a detection medium for reactor and solar neutrinos • Developed proportional counters – used by Davis and SNO 3He detectors • Proposed neutrino oscillations • Proposed oscillations as the explanation for the solar neutrino problem

21. Many Connections Between Bruno Pontecorvo And SNO • Science: • He proposed chlorine as a detection medium for reactor and solar neutrinos • Developed proportional counters – used by Davis and SNO 3He detectors • Proposed neutrino oscillations • Proposed oscillations as the explanation for the solar neutrino problem • Indirectly: • One of the principal scientists developing the heavy water nuclear reactor • Therefore – Canadian reserves of heavy water available for SNO. • He developed well logging with neutron sources • Main SNO calibration: 16N produced with a neutron source • developed for well logging

22. Many Connections Between Bruno Pontecorvo And SNO • Science: • He proposed chlorine as a detection medium for reactor and solar neutrinos • Developed proportional counters – used by Davis and SNO 3He detectors • Proposed neutrino oscillations • Proposed oscillations as the explanation for the solar neutrino problem • Indirectly: • One of the principal scientists developing the heavy water nuclear reactor • Therefore – Canadian reserves of heavy water available for SNO. • He developed well logging with neutron sources • Main SNO calibration: 16N produced with a neutron source • developed for well logging • International support: • An important letter of support at a critical time for SNO in 1988

25. Many Connections Between Bruno Pontecorvo And SNO • Science: • He proposed chlorine as a detection medium for reactor and solar neutrinos • Developed proportional counters – used by Davis and SNO 3He detectors • Proposed neutrino oscillations • Proposed oscillations as the explanation for the solar neutrino problem • Indirectly: • One of the principal scientists developing the heavy water nuclear reactor • Therefore – Canadian reserves of heavy water available for SNO. • He developed well logging with neutron sources • Main SNO calibration: 16N produced with a neutron source • developed for well logging • International support: • An important letter of support at a critical time for SNO in 1988 • Personal: • My first 12 years of basic research were at Chalk River. • I knew many of Pontecorvo’s Chalk River collaborators personally • - Hanna, Carmichael, Hincks, Sargeant. • Bruno Pontecorvo and I played tennis on the same courts in Deep River • – 30 years separated in time and light years separated in ability!

26. First Tennis Champion at Chalk River – 1948 Bruno Pontecorvo

27. I was honored to meet Bruno Pontecorvo at Neutrino 1992 in Granada, Spain and to provide a tour of the SNO exhibit at the Canadian Pavillion at EXPO 1992 in Seville and to have discussions about his Canadian colleagues. His science, his sense of humour and his athletic ability captivated me. Today is a wonderful honor for me and for our project team to receive the Bruno Pontecorvo Prize named after such a great scientist.