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

The SNO Detector

SNO – The smoking gun 1000 t heavy water (D 2 0) CC - eppd  e NC xx  npd ES --  ee x x

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

SNO+ First collaboration meeting at Queens Univ., May (2007)

SNO+- 1 st collab. meeting

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

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

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 Concentration and Light Output

external 241 Am  Compton edge 137 Cs 207 Bi conversion electrons Nd LS Works! small Nd-LS detector with , ,  sources demonstrates it works as scintillator

Petresa Plant – B é cancour, QC

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

AV Hold-down working on mechanical design working on mechanical design SNO had rope basket support for the AV in an old design (+10% density difference D 2 O-H 2 O) SNO had rope basket support for the AV in an old design (+10% density difference D 2 O-H 2 O) believes optimization of above design can hold down 15% buoyancy (scintillator density  = 0.85) believes optimization of above design can hold down 15% buoyancy (scintillator density  = 0.85)

SNO+ Double Beta Sensitivity 1 yr, 500 kg isotope, m = 150 meV

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

for 50% enriched 150 Nd (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 Statistical Sensitivity

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

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