Aksel Hallin NNN08, Paris September 12, 2008 SNOLAB Aksel Hallin NNN08, Paris September 12, 2008

Surface Facility 2km overburden (6000mwe) Underground Laboratory

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

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

SNO+ is… we plan to fill SNO with liquid scintillator 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

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

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

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

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.

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

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

Draining SNO and Boating Inspections

Looking Out From Inside the SNO AV

SNO Cavity Drained and Inspected

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

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

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

DC-3600 CLEAN Room MC-360

Argon as a target medium for direct WIMP detection Rate above thresh (events/kg/day) c 40Ar Rate ~ A2F (coherent) No. nucleons form factor Less loss of coherence for lighter nuclei, argon can provide useful information even with relatively high energy threshold 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

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

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 Decay in bulk detector tagged by a-particle energy LAr a Cryostat Wall 210Po on surface Daughters from radon decay can be implanted into surfaces (to sub-micron depth) Decay from surface Releases untagged recoiling nucleus or Low-energy a

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

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

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 *

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

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

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 6x10-8 b/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

Montreal, Queen’s, Alberta, Laurentian, IUSB, Prague, BTI, SNOLAB 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!

SNO+ Collaboration University of Pennsylvania: University of Alberta: 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

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)