SNO and the new SNOLAB Art Mc Donald

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

Unique Signatures in SNO (D 2 O) Charged-Current (CC) e+d e-+p+p Ethresh = 1. 4 Me. V e only Neutral-Current (NC) x+d x+n+p Ethresh = 2. 2 Me. V Equally sensitive to e m t Elastic Scattering (ES) x+e- x+e x, but enhanced for e 3 ways to detect neutrons

3 neutron (NC) detection methods (systematically different) Phase I (D 2 O) Phase II (salt) Nov. 99 - May 01 July 01 - Sep. 03 n captures on 2 H(n, g)3 H Effc. ~14. 4% NC and CC separation by energy, radial, and directional distributions 2 t Na. Cl. n captures on 35 Cl(n, g)36 Cl Effc. ~40% NC and CC separation by event isotropy 2 H+n 35 Cl+n Phase III (3 He) Nov. 04 - Nov. 06 40 proportional counters 3 He(n, p)3 H Effc. ~ 30% capture Measure NC rate with entirely different detection system. 5 cm 8. 6 Me. V n 6. 25 Me. V 3 H p 3 He 3 H 36 Cl n + 3 He p + 3 H

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

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

Flavor change determined by > 7 s. CC, NC FLUXES MEASURED INDEPENDENTLY nm , The Total Flux of Active nt Neutrinos is measured independently (NC) and agrees Electron neutrinos well with solar model Calculations: 4. 7 +- 0. 5 (BPS 07), 5. 31 +- 0. 6 (Turck-Chieze et al 04) High accuracy for q 12. Implies Matter Interactions (Folgi, Lisi 2004)

SOLAR ONLY AFTER NEW SNO SALT DATA Large mixing Angle (LMA) Region: MSW - SNO: CC/NC flux defines tan 2 q 12 < 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) LMA for solar n predicts very small spectral distortion, small (~ 3 %) day-night asymmetry, as observed by SNO, SK SOLAR PLUS KAMLAND (assuming CPT) (Reactor n’s)

Final Phase: SNO Phase III Total Radioactivity similar To Phase I, II Neutral-Current Detectors (NCD): An array of 3 He proportional counters 40 strings on 1 -m grid ~440 m total active length • Search for spectral distortion • Improve solar neutrino flux by breaking the CC and NC correlation ( = -0. 53 in Phase II): CC: Cherenkov Signal PMT Array NC: n+3 He NCD Array • Improvement in 12, as Correlations D 2 O unconstrained D 2 O constrained Salt unconstrained NCD NC, CC -0. 950 -0. 521 ~0 CC, ES -0. 208 -0. 162 -0. 156 ~-0. 2 ES, NC -0. 297 -0. 105 -0. 064 ~0 Blind Analysis Phase III production data taking began Dec 2004; completed November 2006

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