nd double beta decay search with sno+ k. zuber, on behalf of the sno+ collaboration
TRANSCRIPT
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Nd double beta decay search with SNO+
K. Zuber, on behalf of the SNO+ collaboration
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The SNO Detector
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SNO – The smoking gun
1000 t heavy water (D20)
CC-eppd
e
NCxx
npd
ES -- ee x x
)(14.0ES
CC
e
e
τμ
++=
€
CC
NC=
ν e
ν e + ν μ + ν τ
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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
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SNO+
First collaboration meeting at Queens Univ. , May 30-31 (2007)
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SNO+- 1st collab. meeting
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0: 1000 events peryear with 1% naturalNd-loaded liquidscintillator in SNO++
Test <m> = 0.150 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
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Nd-carboxylate in Nd-carboxylate in PseudocumenePseudocumene
made by Yeh, Garnov, Hahn at BNL
window with >6 m light attenuation length
{
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• 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
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external 241Am
Compton edge 137Cs207Bi conversionelectrons
Nd LS Works!small Nd-LS detector with , , sources demonstrates it works as scintillator
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Petresa Plant – Petresa Plant – BBéécancour, QCcancour, QC
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2000–2003 Program : Menphis facility
Design : 2001Building : 20021st test : early 20031st full scale exp. : june 2003
EvaporatorDye laser chainYag laserCopper vapor laser
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AV Hold-downAV Hold-down
working on mechanical designworking on mechanical design SNO had rope basket support for the AV SNO had rope basket support for the AV
in an old design (+10% density in an old design (+10% density difference Ddifference D22O-HO-H22O)O)
believes optimization of above design believes optimization of above design can hold down 15% buoyancy can hold down 15% buoyancy (scintillator density (scintillator density = 0.85) = 0.85)
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SNO+ Double Beta SNO+ Double Beta SensitivitySensitivity
1 yr, 500 kg isotope, m = 150 meV
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Statistical Sensitivity in Statistical Sensitivity in SNO+ 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 LSin SNO+
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• 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
Statistical Sensitivity
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SNO+ “broad-brush” schedule
2007: removal of SNO heavy water, SNO+ design
2008: SNO+ installation 2009: Fill, run with pure scintillator 2010: Add Nd
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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