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Neutrino Physics at SNOLAB: SNO+ Experimental Program 2008-2010

Explore the experimental program at SNOLAB's Surface Facility, an underground laboratory located 2km underburden. Discover the planned upgrades, neutrino physics goals, and the unique 150Nd double-beta decay experiment being conducted. Learn about the SNO+ project and its significant contributions to neutrino research.

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Neutrino Physics at SNOLAB: SNO+ Experimental Program 2008-2010

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  1. SNOLAB AkselHallin NNN08, Paris September 12, 2008

  2. Surface Facility 2km overburden (6000mwe) Underground Laboratory

  3. SNOLAB Underground Facility Utilities include: * Personnel facilities * UG railroad for material transport * 2MW power * 1 MW cooling * Ultra pure water plant 3,000m2 / 30,000 m3 experimental halls class 2000 clean rooms. Intended to house 3 major experiments (10-20m) + 2-3 medium scale (5m) 2km depth = 6000mwe over burden MEI & HIME astro/ph 0512125

  4. Experimental Program 2008: DEAP/CLEAN 3600, MiniCLEAN 360 2010: EXO? Cube Hall Cryopit 2008: HALO? 2010: SuperCDMS ? Now:PICASSO-II Now:DEAP-1 Ladder Labs 2009: SNO+ Utility Area SNO Cavern Personnel facilities

  5. Sudbury Neutrino Observatory SNO+ is… • we plan to fill SNO with liquid scintillator • we also plan to dope the scintillator with neodymium to conduct a double beta decay experiment (first run is with Nd) • to do this we need to: • install hold down ropes for the acrylic vessel • buy the liquid scintillator • build a liquid scintillator purification system • minor upgrades to the cover gas • minor upgrades to the DAQ/electronics • change the calibration system and sources • SNO+ is partially-funded for these activities by NSERC and seeks full capital funding in the current CFI LEF/NIF competition

  6. SNO+ Physics Goals SNO+ Physics Program • search for neutrinoless double beta decay • neutrino physics • solar neutrinos • geo antineutrinos • reactor antineutrinos • supernova neutrinos

  7. 500 kg of 150Nd and <mn> = 100 meV • 6.4% FWHM at Q-value • 3 years livetime • U, Th at KamLAND levels • note: 8B solar neutrinos are a background! • 214Bi (from radon) is practically negligible • 212Po-208Tl tag (3 min) might be used to veto 208Tl backgrounds; 212Bi-212Po (300 ns) events constrain the amount of 208Tl only internal Th and 8B solar neutrino backgrounds are important

  8. Why 150Nd? • 3.37 MeV endpoint (2nd highest of all bb isotopes) • above most backgrounds from natural radioactivity • largest phase space factor of all bb isotopes • e.g. factor of 33 greater compared with 76Ge • for the same effective Majorana neutrino mass, the 0nbb rate in 150Nd is the fastest • cost of NdCl3 is $86,000 for 1 ton (not expensive) • upcoming experiments use Ge, Xe, Te; we can deploy a large and comparable amount of Nd

  9. Neutrino Mass Sensitivity With natural Nd SNO+ is sensitive to effective neutrino masses as low as 100 meV. [meV] [meV] With 10X enriched Nd our sensitivity extends to 40 meV.

  10. SNO+ pep Solar Neutrino Signal 3600 pep events/(kton·year), for electron recoils >0.8 MeV

  11. Survival Probability for Solar Neutrinos: All Experimental Data Distilled figure from TAUP 2007 (pre-Borexino 2008)

  12. Draining SNO and Boating Inspections

  13. Looking Out From Inside the SNO AV

  14. SNO Cavity Drained and Inspected

  15. Work in Progress • acrylic vessel hold down design • scintillator purification design • liquid scintillator characterization

  16. List of R&D Developments for SNO+ • developed the use of linear alkylbenzene as a solvent for large liquid scintillator detectors • high flash point, low toxicity, high light yield, long transmission length, inexpensive! • developed Nd-loaded liquid scintillator (using same technique as for In, Gd loading) • developed purification techniques to remove Ra, Th from Nd and Nd liquid scintillator • physics potential: pep and CNO solar neutrinos, geoneutrino continental crust probe, double beta with Nd in liquid scintillator

  17. Top Access DEAP/CLEAN Dark Matter Search MiniCLEAN 360 DEAP/CLEAN 3600

  18. DC-3600 CLEAN Room MC-360

  19. 40Ar c 40Ar Rate ~ A2F (coherent) c form factor No. nucleons Less loss of coherence for lighter nuclei, argon can provide useful information even with relatively high energy threshold Argon as a target medium for direct WIMP detection Rate above thresh (events/kg/day) with “standard” assumptions about the WIMP halo and distribution and for a 100 GeV WIMP Projected pulse shape discrimination (PSD) in argon allows threshold of approx. 20 keVee (60 keVr) 1000 kg argon target allows 10-46 cm2 sensitivity (SI) with 20-40 keVee window

  20. DEAP/CLEAN-3600 detector 85 cm radius acrylic sphere contains 3600 kg LAr (55 cm, 1000 kg fiducial) 266 8” PMTs (warm) 50 cm acrylic light guides and fillers for neutron shielding (from PMTs) Only LAr, acrylic, and WLS (10 g) inside of neutron shield 8.5 m diameter water shielding tank

  21. Decay in bulk detector tagged by a-particle energy Cryostat Wall LAr a 210Po on surface a Sources of backgrounds for WIMP search • We want WIMP search sensitive to <1 event/year/1000 kg • need to reduce backgrounds to that level • b/g events. Use singlet/triplet time distribution in LAr to • discriminate b/g from nuclear recoils • neutron-induced nuclear recoils • Need to suppress all potential neutron sources! • 3. surface contamination Daughters from radon decay can be implanted into surfaces (to sub-micron depth) Decay from surface Releases untagged recoiling nucleus or Low-energy a

  22. Backgrounds in DEAP/CLEAN-3600 • b-g’s (dominated by 39Ar b-decays) argon from atmospheric source 109 per year x20 depleted argon (UG source) 6x107 per year (removed with PSD -model projection for 109 events -demonstrated for 6x107 events) • Nuclear recoils from neutrons m-induced <<1 @ SNOLAB with 2 km rock shield (a,n) from rock <<1 8.5m H2O shield tank (a,n) from PMTs < 1 50cm acrylic LGs (a,n) from acrylic <<1 ppt acrylic • Surface contamination Requirement of < 1 event/m2/day from surfaces, background removed with position reconstruction (s=10 cm @ 20 keV) Need intrinsically clean surface material (~10 ppt) and need to remove deposited radon daughter activity

  23. Backgrounds (g’s) Background suppression with PSD in DEAP-1 Yellow: Prompt light region Blue: Late light region DEAP-1 at SNOLAB Background suppression better than 6x10-8 120-240 pe Signal (nuclear recoil)

  24. Acrylic Vessel Resurfacer for Implanted Radon Daughter Removal Deployed through vessel neck/sealed glovebox in inert(radon-free) environment Abrasive sanding pads will remove ~10 microns of acrylic from entire vessel in approx 24 hours, surfaces then as clean as bulk acrylic Procedure can be repeated in the event of accidental surface contamination *

  25. DEAP-1 underground data Low-PMT voltage runs to sample high-energy a events Decay of 222Rn after detector fill

  26. DEAP-1 underground data Consistent with 222Rn and some embedded 210Po Need to further reduce contamination

  27. Conclusions and Summary Experimental goal is background-free dark matter search with sensitivity to SI WIMP-nucleon cross-section of 10-46 cm2 Design for passive shielding and surface contamination removal: AV+resurfacer, acrylic light guides,8.5 m shield tank Completing engineering and physics optimization, acrylic bonding tests and other R&D, continued DEAP-1 operation at SNOLAB Highest ratings from SNOLAB EAC for scientific priority and readiness, allocated space in the SNOLAB cube hall Installation begins 2008, data collection start 2010 Demonstrated 6x10-8b/g rejection, sensitive to 10-9 at SNOLAB with 4 months of PSD data (120-240 pe, 40-80 keVee) DEAP-1 currently limited by surface a-contamination, working to reduce

  28. PICASSO Montreal, Queen’s, Alberta, Laurentian, IUSB, Prague, BTI, SNOLAB • Spin-dependent DM search with superheated C4F10 Droplets • Ongoing 2.6 kg phase taking data • 28 of 32 detectors u/g • New  -n neutron discrimination • effect  boost in sensitivity expected!

  29. SNO+ Collaboration University of Pennsylvania: E. Beier, H. Deng, W.J. Heintzelman, J. Klein, G. Orebi Gann, J. Secrest, T. Sokhair Queen's University: M. Boulay, M. Chen, X. Dai, E. Guillian, P.J. Harvey, C. Kraus, X. Liu, A. McDonald, H.O’Keeffe, P. Skensved, A. Wright SNOLAB: B. Cleveland, F. Duncan, R. Ford, C.J. Jillings, I. Lawson University of Sussex: E. Falk-Harris, S. Peeters Dresden University of Technology: K. Zuber University of Washington: M. Howe, K. Schnorr, N. Tolich, J. Wilkerson University of Alberta: R. Hakobyan, A. Hallin, M. Hedayatipoor, C. Krauss, C. Ng Brookhaven National Laboratory: R. Hahn, Y. Williamson, M. Yeh Idaho National Laboratory: J. Baker Idaho State University: J. Heise, K. Keeter, J. Popp, E. Tatar, C. Taylor Laurentian University: E.D. Hallman, S. Korte, A. Labelle, C. Virtue LIP Lisbon: S. Andringa, N. Barros, J. Maneira Oxford University: S. Biller, N. Jelley, P. Jones, J. Wilson-Hawke

  30. DEAP&CLEAN International Collaboration Boston University D. Gastler and E. Kearns Carleton University K. Graham Los Alamos National Laboratory C. Alexander, S.R. Elliott, G. Garvey, V. Gehman, V. Guiseppe, A. Hime, W. Louis, S. McKenney, G. Mills, K. Rielage, L. Rodriguez, L. Stonehill, R. Van de Water, H. White, and J.M. Wouters MIT Joe Formaggio NIST, Boulder K. Coakley Queen’s University M.G. Boulay, B. Cai, M.C.Chen, J.J. Lidgard, P. Harvey, A.B. McDonald, P. Pasuthip, T. Pollman, P. Skensved Laurentian University/ SNOLAB F. Duncan, C.J. Jillings, I. Lawson, B. Cleveland SNOLAB I. Lawson, K. McFarlane University of Alberta Aksel Hallin, Jan Soukup, Kevin Olsen University of New Mexico Dinesh Loomba University of North Carolina R. Henning University of South Dakota D.M. Mei University of Texas, Austin J.R. Klein and S. Seibert Yale University L. Kastens, W. Lippincott, D.N. McKinsey, K. Ni, and J. Nikkel +TRIUMF (Fabrice Retiere) , W. Rau (Queen’s)

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