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Double Beta Decay in SNO +

Double Beta Decay in SNO +. Huaizhang Deng University of Pennsylvania. Collaboration. Brookhaven National Laboratory: R. Hahn, M. Yeh, Y. Williamson, A. Garnov Carleton University: K. Graham Idaho State University: K. Keeter, J. Popp, E. Tatar

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Double Beta Decay in SNO +

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  1. Double Beta Decay in SNO+ Huaizhang Deng University of Pennsylvania

  2. Collaboration • Brookhaven National Laboratory: R. Hahn, M. Yeh, Y. Williamson, A. Garnov • Carleton University: K. Graham • Idaho State University: K. Keeter, J. Popp, E. Tatar • Laurentian University: D. Hallman, C. Virtue, A. Labelle • LIP Lisbon: S. Andringa, N. Barros, J. Maneira • Queen's University: • M. Boulay, M. Chen, X. Dai, E. Guillian, P. Harvey, C. Kraus, C. Lan, A. McDonald, S. Quirk, P. Skensved, V. Novikov, A. Wright, A. Chia, M. Gobien, J. Lau • SNOLAB: • B. Cleveland, F. Duncan, R. Ford, N. Gagnon, J. Heise, C. Jillings, • I. Lawson • Technical University of Munich: F. v. Feilitzsch, L. Oberauer • University of Alberta: A. Hallin, C. Krauss • University of Pennsylvania: • G. Beier, H. Deng, B. Heintzelman, J. Secrest, T. Shokair • University of Sussex: K. Zuber • University of Texas at Austin: J. Klein

  3. Outline • 150Nd double beta decay • The SNO+ detector • 150Nd loaded scintillator in SNO+ detector • The sensitivity of SNO+ to m • Comparison with other experiments • Conclusions

  4. Double Beta Decay Neutrinos are Majorana particles (Z, N) (Z+2, N-2) Neutrinos have masses Candidates: 48Ca, 76Ge, 82Se, 100Mo, 130Te 136Xe, 150Nd …

  5. Neodymium - 150Nd 28% 150Nd 150Sm + 2e + 2  = 2.9x1019 year 14% 150Nd 150Sm + 2e Q = 3.37 MeV  = ? year 5.6% 0% F. Avignone, Nucl. Phys. B (proc. Suppl) 143 (2005) m=40 meV V.A. Rodin et al., Nucl. Phys. A 766, 107 (2006) m=50 meV

  6. Sudbury Neutrinoless Observatory (SNO+) Sudbury Neutrino Observatory (SNO) • 2092 meters deep underground • 1000 tons of ultrapure D2O • in a 12 meter diameter • acrylic vessel • 1000 tons of ultrapure liquid • scintillator in a 12 meter • diameter acrylic vessel Already Exists ! • 7000 tons of ultrapure H2O • as shield • 9500 PMTs mounted on a • 18 meter diameter frame • electronics, DAQ, • understanding of our detector

  7. SNOLab SNO+

  8. Scintillator in SNO+ • compatible with acrylic, undiluted • high light yield (because it’s undiluted) • Pure, light attenuation length in excess of 20 m at 420 nm • high flash point (130°C) safe • low toxicity safe • low cost (relative to other organic solvents) • smallest scattering of all scintillating solvents investigated • Petresa Canada plant in Quebec makes 120 kton/year, $1600 per ton delivered.

  9. LAB and Fluor • works fine with standard fluors • PPO, butyl-PBD, PPD • 2 g/L concentration works fine LAB-PPO energy transfer efficiency Method 1 (fluorescence emission method): measure the fluorescence excitation and emission of PPO-LAB solution; excitation at 318nm (LAB excitation), integrate emission range from 320 to 550nm (PPO emission)Method 2 (decay time method): excitation at 250nm, emission 360nm, measure the decay times of PPO-LAB solution, compare to the decay time of pure PPO

  10. Light Yield

  11. Attenuation preliminary measurement

  12. Decay Times of Scintillations

  13. Nd Loaded LAB

  14. Other Studies • Acrylic vessel holding structure • Long time stability of Nd loaded LAB with acrylic • Optics of Nd loaded LAB • Upgrade of electronic system • Modification of software packages, Monte Carlo

  15. Energy Spectrum in SNO+

  16. Extract Number of 0 Events

  17. Discovery Potential 3 sigma indication five sigma discovery

  18. Comparison Fabrice Piquemal, Lepton Photon 2007 Calculation with NME from Rodim et al., Suhonen et al., Caurier et al. PMN07

  19. Conclusions • The 150Nd is a good candidate for 0 decay due to large Q and favorable nuclear matrix element • The Nd can be dissolved into SNO+ liquid scintillator with long term stability and good optics. • The large statistics compensate the relatively poor energy resolution in SNO+. The sensitivity to neutrino mass is comparable with other experiments • The SNO detector has been built. We could start SNO+ soon.

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