SNO and the new SNOLAB SNO: Heavy Water Phase Complete Status of SNOLAB Future experiments at SNOLAB: (Dark Matter, Double beta, Solar, geo-, supernova ) Art McDonald, SNO Institute Director For the SNO Collaboration Neutrino Telescopes, Venice, 2007

Unique Signatures in SNO (D 2 O) Charged-Current (CC) e +d  e - +p+p E thresh = 1.4 MeV e only e only Elastic Scattering (ES) x +e -  x +e - x, but enhanced for e Neutral-Current (NC) x + d  x + n+p E thresh = 2.2 MeV Equally sensitive to e   3 ways to detect neutrons

Phase II (salt) July 01 - Sep. 03 Phase III ( 3 He) Nov Nov. 06 Phase I (D 2 O) Nov May 01 3 neutron (NC) detection methods (systematically different) n captures on 2 H(n,  ) 3 H Effc. ~14.4% NC and CC separation by energy, radial, and directional distributions 40 proportional counters 3 He(n, p) 3 H Effc. ~ 30% capture Measure NC rate with entirely different detection system. 2 t NaCl. n captures on 35 Cl(n,  ) 36 Cl Effc. ~40% NC and CC separation by event isotropy 36 Cl 35 Cl+n 8.6 MeV 3H3H 2 H+n 6.25 MeV n + 3 He  p + 3 H p 3H3H 5 cm n 3 He

Sudbury Neutrino Observatory 1700 tonnes Inner Shielding H 2 O 1000 tonnes D 2 O ($300 M) 5300 tonnes Outer Shield H 2 O 12 m Diameter Acrylic Vessel Support Structure for 9500 PMTs, 60% coverage Urylon Liner and Radon Seal 200 tonnes has been returned

ISOTROPY: NC, CC separation DIRECTION FROM SUN EVENTS VS VOLUME: Bkg < 10% ENERGY SPECTRUM FROM CC REACTION Heavy water SALT PHASE (“Near Background-free” analysis)

High accuracy for    Electron neutrinos   The Total Flux of Active Neutrinos is measured independently (NC) and agrees well with solar model Calculations: (BPS07), (Turck-Chieze et al 04) CC, NC FLUXES MEASURED INDEPENDENTLY Flavor change determined by > 7  Implies Matter Interactions (Folgi, Lisi 2004)

- SNO: CC/NC flux defines tan 2    < 1 (ie Non - Maximal mixing) by more than 5 standard deviations. -The mass hierarchy is defined (m 2 > m 1 ) through the matter interaction (MSW) SOLAR ONLY AFTER NEW SNO SALT DATA SOLAR PLUS KAMLAND (assuming CPT) (Reactor ’s) Large mixing Angle (LMA) Region: MSW LMA for solar predicts very small spectral distortion, small (~ 3 %) day-night asymmetry, as observed by SNO, SK

Final Phase: SNO Phase III Search for spectral distortion Improve solar neutrino flux by breaking the CC and NC correlation (  = in Phase II): CC: Cherenkov Signal  PMT Array NC: n+ 3 He  NCD Array Improvement in  12, as Neutral-Current Detectors (NCD): An array of 3 He proportional counters 40 strings on 1-m grid ~440 m total active length Phase III production data taking began Dec 2004; completed November 2006 CorrelationsD 2 O unconstrained D 2 O constrained Salt unconstrained NCD NC,CC ~0 CC,ES ~-0.2 ES,NC ~0 Blind Analysis Total Radioactivity similar To Phase I, II

Another analysis is almost complete that combines data from the first two SNO Phases and reduces the threshold by ~ 1 MeV. This also provides improved accuracy on CC/NC flux ratio. BLIND ANALYSIS: Add in unknown number of neutrons from muons