SNO Mark Chen Queens University SNO Collaboration Queens

SNO+ Mark Chen Queen’s University

SNO+ Collaboration Queen’s M. Chen, M. Boulay, X. Dai, E. Guillian, A. Hallin, P. Harvey, C. Hearns, C. Kraus, C. Lan, A. Mc. Donald, V. Novikov, S. Quirk, P. Skensved, A. Wright, U. Bissbort Carleton K. Graham Laurentian D. Hallman, C. Virtue Trent J. Jury SNOLAB B. Cleveland, F. Duncan, R. Ford, I. Lawson Brookhaven National Lab D. Hahn, M. Yeh, A. Garnov, a subset of the SNO Idaho State University collaboration will K. Keeter University of Texas at Austin continue with SNO+ J. Klein University of Pennsylvania G. Beier (for Nd double beta decay) LIP Lisbon J. Maneira, N. Barros, S. Andringa Technical University Munich L. Oberauer, F. v. Feilitzsch (for Nd double beta decay) Sussex K. Zuber • potential collaborators from outside SNO (Italy, Russia) have indicated some interest

Outline • SNO+ physics overview – – – double beta decay pep solar neutrinos geo-neutrinos reactor neutrino oscillation confirmation supernova neutrino detection • technical progress • cost and schedule • collaboration resources

Double Beta Decay: SNO++ • SNO plus liquid scintillator plus double beta isotopes: SNO++ • add bb isotopes to liquid scintillator – dissolved Xe gas (2%) – organometallic chemical loading (Nd, Se, Te) – dispersion of nanoparticles (Nd 2 O 3, Te. O 2) • enormous quantities (high statistics) and low backgrounds help compensate for the poor energy resolution of liquid scintillator • possibly source in–source out capability

Candidate Selection

150 Nd table from F. Avignone Neutrino 2004 • 3. 37 Me. V endpoint • (9. 7 ± 0. 7 ± 1. 0) × 1018 yr 2 nbb half-life measured by NEMO-III • isotopic abundance 5. 6% 1% natural Nd-loaded liquid scintillator in SNO++ has 560 kg of 150 Nd compared to 37 g in NEMO-III • cost: $1/g for metallic Nd; cheaper as Nd salt…on the web Nd. Cl 3 sold in lot sizes of 100 kg, 1 ton, 10 tons

2 n bb Background • good energy resolution needed • but whopping statistics helps compensate for poor resolution and… turns this into an endpoint shape distortion measure rather than a peak search

Test <mn> = 0. 150 e. V 0 n: 1000 events per year with 1% natural Nd-loaded liquid scintillator in SNO++ Klapdor-Kleingrothaus et al. , Phys. Lett. B 586, 198, (2004) simulation: one year of data maximum likelihood statistical test of the shape to extract 0 n and 2 n components…~240 units of Dc 2 significance after only 1 year!

made by Yeh, Garnov, Hahn at BNL Nd-carboxylate in Pseudocumene window with >6 m light attenuation length {

Enriched Nd Scintillator • at 1% loading (natural Nd), there is too much light absorption by Nd – 47± 6 pe/Me. V (from Monte Carlo) • at 0. 1% loading (isotopically enriched to 56%) our Monte Carlo predicts – 400± 21 pe/Me. V (from Monte Carlo) – good enough to do the experiment

Nd LS Works! external 241 Am a Compton edge 137 Cs 207 Bi conversion electrons

SNO++ Double Beta Sensitivity • insensitive to internal radon backgrounds • insensitive to external backgrounds (2. 6 Me. V gamma) • internal Th is the main concern – and 2 n background, of course • homogeneous, well defined background model • for mn = 50 me. V, 0 n signal is ~60 events/yr in the upperhalf of the peak, with S: B about 1: 1 – based upon Kam. LAND Th levels in scintillator and known 2 n double beta decay backgrounds – gives a 5 s exclusion of 50 me. V after one year • …shows the advantage of huge amounts of isotope, thus high statistics

Nd-150 Consortium • Super. NEMO and SNO+, MOON and DCBA have joined together to try to maintain an existing French AVLIS facility that is capable of making 100’s of kg of enriched Nd – a facility that enriched 204 kg of U (to 2. 5% from 0. 7%) in several hundred hours (i. e. about 1 week)

2000– 2003 Program : Menphis facility Evaporator Dye laser chain Yag laser Copper vapor laser Design : 2001 Building : 2002 1 st test : early 2003 1 st full scale exp. : june 2003

Reactor Antineutrinos • SNO+ can confirm reactor neutrino oscillations • an interesting test! – move Kam. LAND’s spectral distortion to higher energies by going to a slightly longer baseline

SNO+ Spectral Distortion T. Araki et al. , hep-ex/0406035 (2004) oscillated rate: 180 events (per 1032 proton-years) unoscillated expectation: 320 events 1 kiloton CH 2 scintillator: 0. 86 × 1032 protons

Baselines: 240 and 340 km Bruce Pickering Darlington

SNO+ Technical Progress • liquid scintillator identified – linear alkylbenzene • • compatible with acrylic, undiluted high light yield pure (light attenuation length in excess of 20 m at 420 nm) low cost high flash point low toxicity smallest scattering of all scintillating solvents investigated density r = 0. 86 g/cm 3 – SNO+ light output (photoelectrons/Me. V) will be approximately 4× that of Kam. LAND

SNO+ Monte Carlo • light yield simulations Kam. LAND scintillator in SNO+ 629 ± 25 pe/Me. V above no acrylic 711 ± 27 pe/Me. V Kam. LAND scintillator and 50 mg/L bis. MSB 826 ± 24 pe/Me. V above no acrylic 878 ± 29 pe/Me. V Kam. LAND (20% PC in ~300 pe/Me. V for 22% dodecane, 1. 52 g/L PPO) photocathode coverage SNO+ has 54% PMT coverage; acrylic vessel only diminishes light ouput by ~10%

LAB Scintillator Optimization “safe” scintillators LAB has 75% greater light yield than Kam. LAND scintillator

Light Attenuation Length Petresa LAB as received attenuation length exceeds 10 m preliminary measurement ~10 m

Scintillator Purification • optical – at BNL and at Queen’s • improves light attenuation length, removing impurities that absorb light, especially at lower wavelengths – alumina column and vacuum distillation both work • radioactivity (e. g. 210 Pb) – at Queen’s • alumina: 98 -99% extraction efficiency • distillation: >99. 9% extraction efficiency, single pass

Scintillator-Acrylic Compatibility • ASTM D 543 “Standard Practices for Evaluating the Resistance of Plastics to Chemical Reagents”

Acrylic Vessel Hold-down • “rope net” being designed to hold down 15% density difference • alternative: machine reverse rope grooves in existing belly plates SNO+

Cost ($ CAD) incremental cost to convert SNO to SNO+ liquid scintillator $2. 0 M AV conversion $1. 5 M scintillator purification $7. 0 M (includes fluid handling logistics, safety) cover gas, glove box $0. 3 M DAQ upgrade $0. 5 M total: $11. 3 M incremental cost for 500 kg enriched Nd (rough estimate) feasibility study $0. 4 M (international total: 1 -3 M€) running facility $1. 5 M purchase Nd $1. 0 M (the intent is to sell back depleted Nd)

Schedule 01/2007 to 04/2007 temporary construction during SNO decommissioning (inspect AV, radon-free cover gas) 05/2007 to 10/2007 design of AV conversion 05/2007 to 12/2007 engineering of scintillator fluid process 01/2008 to 11/2008 AV conversion construction 03/2008 to 05/2008 scintillator procurement logistics and contracts 05/2008 to 04/2009 scintillator purification construction 05/2009 to start SNO+ filling

SNOLAB infrastructure requirements • Integration with SNO decommissioning • Need approval for LAB scintillator from Inco • Distillation of LAB is being planned u/g and will require 100 k. W-1 MW of power and cooling

SNOLAB R&D needs • Support for investigations into novel purification techniques (nanofiltration) • Radon-reduced (radon-free) air

Cash Flow Table 2007/08 2008/09 SNO+ $2. 0 M $9. 3 M Nd initiative $0. 4 M $1. 7 M + $0. 8 M