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DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+
Neutrinoless double beta decay with SNO+
Freija Descamps for the SNO+ collaboration
- 0!"" with SNO+- Backgrounds- Schedule
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DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+
SNO+ detector
Deck with DAQ SNO+ operator
~780T LAB liquid organic
scintillator+WLS
acrylic vessel⌀ 12m
5cm thick
~9500 PMTs54% coverage
rock
~7kT ultra-pure water
shield
6000 m.w.e
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DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+
Liquid scintillator ✤ Solvent: Linear AlkylBenzene
(LAB)✤ Long attenuation length✤ Safe: low toxicity and high flash point✤ Chemically compatible with acrylic✤ #-" separation through decay-time
✤ High light yield ~10000𝛄/MeV✤ Wavelength shifter
NIM A640, 119-122 (2011)
Petresa plantBécancour, QC
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DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+
0νββ with the SNO+ detector
Neutrino-less double beta decay
✤ (add ~800kg of 130Te)
Deck with DAQ SNO+ operator
~780T LAB liquid organic
scintillator+ WLS
acrylic vessel⌀ 12m
5cm thick
~9500 PMTs54% coverage
rock
~7kT ultra-pure water
shield
6000 m.w.e
✤ Trade-off energy resolution for higher statistics
✤ Low backgrounds✤ External shielding✤ Scintillator self-shielding✤ LAB purification by
distillation✤ Re-use existing detector✤ Scalable
SNO+ approach:
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DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+
130Te advantages
✤ 34% natural abundance✤ Load high amount of natural isotope✤ Relatively inexpensive compared to
enriched isotope✤ 2!"" rate is relatively low
(~100 times lower than 150Nd)✤ Lower background✤ Less sensitive to poor energy
resolution✤ Improved optical properties
✤ No inherent optical absorption lines✤ Higher intrinsic light yield
✤ Nd-LS (0.5%): 8400𝛄/MeV✤ Te-LS (0.5%): 9400𝛄/MeV
Te loaded LS
Nd loaded LS
scaled PMT response
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DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+
Te loadingOld loading technique
✤ Dissolve telluric acid (H6O6Te) in water
✤ Combine with LAB using a surfactant
✤ Good optical properties✤ Stable > 1 year explicitly
demonstrated for 0.3% loading
New loading technique (M. Yeh et al., paper in progress)
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DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+
Backgrounds
Cosmogenice.g. 11C, 60Co
External AV, PMTs,
H2O, ropes
InternalLS,surfactant,
water, AV leaching,
internal ropes
✤ 39Ar✤ 210Bi✤ 11C✤ 14C✤ 40K✤ 85Kr✤ 210Pb✤ 210Po✤ U chain✤ Th chain
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DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+
U and Th chains✤ LS target level
✤ ~2.5 x 10-15 gU/gcocktail
✤ ~3 x 10-16 gTh/gcocktail
✤ Direct background # and " emissions
✤ Purification techniques✤ Coincidence techniques are
under investigation, ex.:✤ "-# ⇾ 214Bi-214Po✤ "-# ⇾ 212Bi-212Po ✤ #-" ⇾ 212Bi-208Tl✤ 95-99.9% rejection
✤ 2.6 MeV gamma from external 208Tl suppressed by fiducialization
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DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+
Cosmogenic isotopes✤ Short and long living isotopes can be produced by cosmogenic activation of natural
tellurium.✤ Isotopes (Q> 2 MeV, T1/2 > 20 days)
✤ rates from ACTIVIA, sea level (n,p)-flux from Armstrong and Gehrels.✤ for E<200 MeV: TENDL database for cross-sections.
✤ Necessary purification factors have been determined.
✤ 2 stages:✤ Above ground: 2 passes
✤ Dissolve Te(OH)6 in water✤ Re-crystalize using nitric acid✤ Rinse with ethanol
✤ Below ground: 2 passes✤ Dissolve in 80˚C water✤ Cool down to re-crystalize thermally✤ 50% yield
✤ 3-6 months cool-down
>104 reduction
>102 reduction
=> Cosmogenic isotopes are negligible
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DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+
SNO+ spectrum
✤ x50 reduction in 212BiPo✤ <m!>=200 meV✤ Negligible cosmogenic
isotopes
✤ 3.5m (20%) fiducial volume cut✤ 2 years✤ > 99.99% efficient 214Bi tag✤ 97% efficient internal 208Tl tag
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DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+
✤ Water level just below PMTs: now.✤ Larger scale Te(OH)6 purification test: ongoing.✤ Order for initial Te(OH)6 production: imminent.✤ Completion of water-fill: end of 2013.✤ Water running: start of 2014.✤ Scintillator transition: mid-2014.✤ Introduction of Te: end of 2014/start of 2015.
Conclusion
Schedule
✤ SNO+: a large liquid scintillator approach to 0!""✤ Natural Te will be added to the liquid scintillator
✤ 0.3% loading (~800kg 130Te)✤ Possibility of increased loading
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water level currently at 9ft (2.75m)
Thank You
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