1. News from the Sudbury Neutrino Observatory Simon JM Peeters July 2007 o SNO overview o Results phases I & II o hep neutrinos and DSNB o Update on the III rd phase

2. Simon JM Peeters, June 2007 2 Acrylic vessel (AV) 12 m diameter 1700 tonnes H 2 O inner shielding 1000 tonnes D 2 O 5300 tonnes H 2 O outer shielding ~9500 PMTs, 54% coverage Creighton mine Sudbury, CA The Sudbury Neutrino Observatory (Herb Chen 1985: Use deuterium) "The Sudbury Neutrino Observatory", The SNO Collaboration Nuclear Instruments and Methods in Physics Research A449 (2000) pp. 172-207 6800 feet (~2km) underground

3. Simon JM Peeters, June 2007 3 Neutrino reactions on D 2 O (sensitivity only to high energy component of solar s: 8 B and hep) CC : sensitive to electron neutrino flavour only. Electron energy directly correlated with energy. NC : sensitive to all neutrino flavours. ES : mostly electron flavour, direction (confirms origin solar e ) ~ 1o times smaller interaction cross section  NC    SSM  CC /  NC  P( e  e )

4. Simon JM Peeters, June 2007 4 The SNO program 199819992000200120022003200420052006 Comm. D2OD2O D2OD2O Salt (NaCl) 3 He Counters γ γ γ 35 Cl 36 Cl 36 Cl* n n captures on chlorine σ = 44b 8.6 MeV multiple γs n captures on 3 He prop. counter array σ = 5330b 0.764 MeV n + 3 He  p + 3 H p 3H3H 5 cm n 3 He n captures on deuterium σ = 0.0005b 6.25 MeV γ γ 2H2H 3 H* n 3H3H 306 days 391 days ~376 days (prelim)

5. Simon JM Peeters, June 2007 5 Neutrino flavour change, phase I PRL 87, 071301, 2001 Direct Evidence for Neutrino Flavour Transformation: PRL 89, 011301, 2002 PRL 89, 011302, 2002 Measurement of the electron neutrino and total 8 B solar neutrino fluxes with the Sudbury Neutrino Observatory Phase 1 Data Set Phys. Rev. C 75, 045502 (2007) (76 pages)  SNO ES  SNO CC  SSM  SNO NC

6. Simon JM Peeters, June 2007 6 Neutrino flavour change, phase II oSalt analysis 1 Phys. Rev. C 72 055502 (2005) Electron Energy Spectra, Fluxes, and Day-Night Asymmetries of 8 B Solar Neutrinos from the 391-Day Salt Phase SNO Data Set. global fit result (inc day/night): Phys. Rev. Lett. 92181301 (2004)

7. Simon JM Peeters, June 2007 7 High(er) energy neutrinos: hep & DSNB (phase I data) hep neutrinos (SSM 8x10 3 cm -2 s -1 ) main background: 8 B solar neutrinos (normalize with low-energy (6-12 MeV) fit, taking into account neutrino oscillations) 2 events observed, consistent with exp. background (3.13±0.60) Φ hep < 2.3 x 10 4 cm -2 s -1 hep DSNB Astrophys. J. 653, 1545, 2006 DSNB el. neutrinos main background: atmospheric neutrinos No events observed, consistent with exp. background (0.18±0.04) Φ DSNB < 70 cm -2 s -1 (in E window)

8. Simon JM Peeters, June 2007 8 Phase III The Neutral Current Detection Array Array of 3 He (+CF 4 ) proportional counters to capture neutrons: avoids statistical separation CC/NC Geometry trade-off: ~8% light loss in centre vs ~ 26% capt. eff. Extremely low background (CVD nickel): ~65 alphas m -2 day -1 An array of low-background 3He proportional counters for the Sudbury Neutrino Observatory arXiv:0705.3665 [nucl-ex], accepted by NIMA. preliminary

9. Simon JM Peeters, June 2007 9 3 He neutron detection & calibration n captures on 3 He prop. counter array σ = 5330b 0.764 MeV n + 3 He  p + 3 H p 3H3H 5 cm n 3 He Alpha Background Neutrons Fit Tail due to space charge and geometrical effects final analysis to include: pulse shape information geometrical event distribution (more info: poster B. Jamieson) No spherical symmetry: Replace point source calibration with uniform source: mix in 24 Na (2.7 MeV , T 1/2 =15 hrs) UNIFORM NEUTRON SOURCE

10. Simon JM Peeters, June 2007 10 The end game oPhase III analysis is ongoing (as well as analyses combining phases: neutrino flavour change, lower energy threshold analysis, periodicities, hep/DSNB, muons, exotic channels) oNCDs have been removed (possible future use) oD 2 O has been removed oState of detector examined for new experiment: SNO+

11. Simon JM Peeters, June 2007 11 The End

12. Simon JM Peeters, June 2007 12

13. Simon JM Peeters, June 2007 13 Day-night analysis A = 2(  N -  D ) (  N +  D )  CC,ES asymmetry: e regeneration inside the Earth  NC asymmetry: Admixture of sterile neutrinos or unexpected matter interactions inside the Earth LMA: small A CC, A ES & A NC = 0 Combined with D2O phase and SK: A e = 0.035 ± 0.027* (*NC=0, shape constr.)

14. Simon JM Peeters, June 2007 14 CC spectrum CC spectrum consistent with LMA, undistorted 8 B

15. Simon JM Peeters, June 2007 15 Calibrations energy (a.u.)

16. Simon JM Peeters, June 2007 16 Neutron calibration phase I, II

17. Simon JM Peeters, June 2007 17 24 Na calibration o 24 Na: 15 hr halflife, 2.7 MeV   n oTake brine, put in a reactor to produce 24 Na, inject into the world’s cleanest detector! oAccurately measure source strength oMix 1 ktonne quickly enough oSource of neutrons similar to NC oExpect O(2%) error on neutron capture efficiency PRELIMINARY