1. Results from Sudbury Neutrino Observatory Huaizhang Deng University of Pennsylvania

2. The SNO Collaboration Canada Carleton University Laurentian University Queen’s University TRIUMF University of British Columbia University of Guelph University of Oxford Rutherford Laboratory/ University of Sussex Brookhaven National Laboratory Lawrence Berkeley National Laboratory Los Alamos National Laboratory University of Pennsylvania University of Texas at Austin University of Washington U.K. U.S.A.

3. Outline Overview of SNO experiment Solar neutrino results from phase I and II Nucleon decay limit Antineutrino search Status of phase III

4. Solar neutrinos

5. The Sudbury Neutrino Observatory 2092 meters deep underground 1000 tons of ultrapure D 2 O in a 12 meter diameter acrylic vessel 7000 tons of ultrapure H 2 O as shield 9500 PMTs mounted on a 18 meter diameter frame 40 helium proportional counters with total length of 398 m

6. Goals of SNO Solar Neutrinos: –Measure mixing parameters, especially θ 12. –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 Neutrino –Proton Decay –Neutron – Antineutron Oscillations. –Supernovae.

7. Neutrino interaction in SNO e−e− e−e− n Only e, Good measurement of E, Weak angle correlation 1-1/3cos  ⊙  e + 0.154( μ +  ), Some energy information Strong angle correlation Low statistics  e + μ + , No angle and energy information after thermalization

8. D 2 O phase (November 1999 – May 2001) Energy Distribution (MeV) Radial Distribution (R 3, R AV =1) Solar Direction Distribution Model dependent

9. Salt phase (July 2001 – September 2003) Energy Distribution (MeV) Radial Distribution (R 3, R AV =1) Solar Direction Distribution Isotropy Distribution All new due to multiple  ’s NC Shifted to higher energy NC Changed due to larger σ Unchanged Model dependent

10. Phase III (December 2003 – 2006) PMTs NCDs 3 He 2H2H p n pt or , E > 2.2 MeV Neutrons can be detected besides through Čerenkov light events. Reduce the correlation between NC and CC measurements.

11. Backgrounds Instrumental backgrounds Low energy  ’s and  ’s from U and Th decay chain  misrecontruction  energy resolution Neutrons  photodisintegration of deutrons by  ’s  cosmic ray muons  Atmospheric neurtinos  ( ,n) processes  natural fission  anti-neutrinos  ’s (proportional counter only)

12. Measuring low energy background The low energy backgroundAdd Rn in D 2 O (unmixed)Add Rn in D 2 O (mixed)Fit to the low energy events with Rn in D 2 O

13. energy Isotropy radius direction Signal extraction in salt phase

14. Neutrino flux results D 2 O phasesalt phase (unit 10 6 /cm 2 /s)

15. Oscillation parameters Maximal mixing is excluded by 5.4σ LMA I only at >99%

16. Nucleon decay limit The invisible (N  3 ) nucleon decay in 16 O produce the de-excitation  ’s For vanishing neutron, BR(E  =6.18MeV)=44% and BR(E  =7.03MeV)=2% For vanishing proton, BR(E  =6.32MeV)=41% and BR(E  =7.0 MeV)=4% For neutron modes :  inv > 1.9 × 10 29 year For proton modes :  inv > 2.1 × 10 29 year RR R NC RR RR R  and R NC didn’t change while other parameters changed from D 2 O phase to salt phase RR (Phys. Rev. Lett. 92, 102004, 2004)

17. Electron antineutrino search Differential limit Integral limit at 90% CL: Ф < 3.4 × 10 4 cm -2 s -1 experimentEnergy (MeV)Limit (%) KamLAND8.3-14.80.028 SNO4.0-14.80.81 SK8.0-20.00.8 LSD8.8-18.81.95 Kamiokande12.0-13.05.07 E (MeV) Flux (cm -1 s -1 MeV -1 )

18. 5 cm Cu anode wire (50  m) 3 He-CF 4 gas mix Fused silica insulator CVD nickel counter body (0.36 mm thick) Delay line termination Vectran braid Acrylic ROV ball Acrylic anchor ball Length of NCD Strings: 9  11 m From phase II to phase III 8/28/2003 end of salt phase start salt removal 10/3/2003 end of salt removal start 2 nd D 2 O phase 10/27/2003 end of 2 nd D 2 O phase old optics restored 12/3/2003 first counter deployed 2/12/2004 last counter deployed start deployment of proportional counters 4/23/2004 removal of deployment equipment, start phase III commissioning 10/??/2004 start of production data taking of phase III N 3 He 4 He

19. Data from proportional counters  3 He 2H2H p n pt or , E > 2.2 MeV  20 15 10 5 0 5 4 3 2 10  track  wire current Time (μs) 80 60 40 20 0 10 8 6 4 20 Microdischarge current Time (μs) p and t have total energy 764 keV neutron produces two particles while background has only one particle backgrounds come from wall 4 He string provides pure background

20. Conclusions Measure the 8 B solar flux without assumption about energy dependence of neutrino survival probability Restrict the mixing parameters, and exclude maximal mixing in solar sector New limit on invisible nucleon decay Commissioning helium proportional counter system Will run for 2.5 years with helium proportional counters.

22. Solar neutrino oscillation Flavor eigenstates are not mass eigenstates : In vacuum In matter x x e Z e e e e W + e

23. Solar neutrino problem