Neutrinoless double beta decay with SNO+ · DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+ Cosmogenic isotopes Short and long living isotopes can be produced by

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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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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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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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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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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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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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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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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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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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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✤ 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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Neutrinoless double beta decay with SNO+ · DNP Newport News 24 October 2013 Freija Descamps, 0!"" With SNO+ Cosmogenic isotopes Short and long living isotopes can be produced by

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