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Nd double beta decay search with SNO+

Nd double beta decay search with SNO+. K. Zuber, on behalf of the SNO+ collaboration. The SNO Detector. n. +. Þ. +. +. -. CC. d. p. p. e. e. n. +. Þ. +. +. n. NC. d. p. n. x. x. ES. -. -. +. Þ. +. e. e. x. x. SNO – The smoking gun. 1000 t heavy water (D 2 0).

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Nd double beta decay search with SNO+

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  1. Nd double beta decay search with SNO+ K. Zuber, on behalf of the SNO+ collaboration

  2. The SNO Detector

  3. n + Þ + + - CC d p p e e n + Þ + + n NC d p n x x ES - - + Þ + e e x x SNO – The smoking gun 1000 t heavy water (D20) n n

  4. Original plan • 28 Nov. 2006: SNO finished data taking Future plans: • SNO+ : 1000 t Liquid scintillator real time low energy solar neutrinos (pep),geoneutrinos, reactor neutrinos • SNO++: 1000t Nd-loaded scintillator double beta decay, geo- + reactor neutrinos NOW: Do the Nd-loaded first! Can be quick and on a large scale

  5. SNO+ First collaboration meeting at Queens Univ. , May 30-31 (2007)

  6. SNO+- 1st collab. meeting

  7. Test <mn> = 0.150 eV Klapdor-Kleingrothaus et al., Phys. Lett. B 586, 198, (2004) 0n: 1000 events per year with 1% natural Nd-loaded liquid scintillator in SNO++ simulation: one year of data maximum likelihood statistical test of the shape to extract 0n and 2n components…~240 units of Dc2 significance after only 1 year!

  8. made by Yeh, Garnov, Hahn at BNL Nd-carboxylate in Pseudocumene window with >6 m light attenuation length {

  9. Concentration and Light Output • at 1% loading (natural Nd), there is too much light absorption by Nd • 47±6 pe/MeV (from Monte Carlo) • at 0.1% loading (isotopically enriched to 56%) our Monte Carlo predicts • 400±21 pe/MeV (from Monte Carlo) • good enough to do the experiment

  10. Nd LS Works! small Nd-LS detector with a, b, g sources demonstrates it works as scintillator external 241Am a 207Bi conversion electrons Compton edge 137Cs

  11. Petresa Plant – Bécancour, QC

  12. 2000–2003 Program : Menphis facility Evaporator Dye laser chain Yag laser Copper vapor laser Design : 2001 Building : 2002 1st test : early 2003 1st full scale exp. : june 2003

  13. AV Hold-down • working on mechanical design • SNO had rope basket support for the AV in an old design (+10% density difference D2O-H2O) • believes optimization of above design can hold down 15% buoyancy (scintillator density r = 0.85)

  14. SNO+ Double Beta Sensitivity 1 yr, 500 kg isotope, mn = 150 meV

  15. Statistical Sensitivity in SNO+ corresponds to 0.1% natural Nd LS in SNO+ 56 kg isotope 500 kg isotope • 3 sigma detection on at least 5 out of 10 fake data sets • 2n/0n decay rates are from Elliott & Vogel, Ann. Rev. Nucl. Part. Sci. 52, 115 (2002)

  16. Statistical Sensitivity • for 50% enriched 150Nd (0.1% Nd LS in SNO+) • statistical sensitivity is down to 30 meV • assumed background levels (U, Th) in the Nd LS to be at the same level as KamLAND scintillator • systematic error in energy response will be the limit of the experiment and not the statistics • preliminary studies show that if we understand the resolution tails at the 10−4 level, we will preserve sensitivity around 50 meV

  17. SNO+ “broad-brush” schedule • 2007: removal of SNO heavy water, SNO+ design • 2008: SNO+ installation • 2009: Fill, run with pure scintillator • 2010: Add Nd

  18. Summary SNO+ plans to use a large amount of Nd-loaded scintillator withinthe existing SNO infrastructure Could be rather fast Seeking for more collaborators Need some reliable 150Nd matrix element calculations

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