Preliminary Conclusions EAC Review at SNOLAB

1. Preliminary ConclusionsEAC Review at SNOLAB August 28, 2009 Stew Smith For the EAC

2. SNO+ • The committee applauds the SNO+ collaboration for obtaining CFI funding and their progress in many areas in the last year • Impressive, wide program of geo/solar/reactor neutrinos and 0ν2β • Maintains high priority as a flagship experiment for SNOLab • We emphasize the need for SNO+ to work with SNOLab management to address the serious safety issues involved in refurbishing and installation, and to hold safety/technical reviews in a timely manner. • SNO+ has the potential to lead the field in 0ν2β • Concerned by the collapse of the plan to obtain enriched Nd • Critical component to the long-term prospects of the experiment • The collaboration is encouraged to vigorously pursue alternatives • SNO+ will also face competition on a short timescale. • The collaboration should maintain the construction/ commissioning schedule towards starting the physics run in 2011 SNOLAB EAC Closeout

3. Single phase LAr (LNe) WIMP Dark Matter detectors The EAC acknowledges the joint efforts of the various collaborations to develop a powerful single phase LAr/LNe WIMP detector. DEAP-1 7 kg LAr – demonstrator for PSD: 10-9 &cleanliness: 1α / (m2 day) It‘s running – congratulation for major progress! ►background reduction by factor 10 (surface grinding/cleaning) ►PSD power of 7x10-9 demonstrated (faster DAQ, prototype for DEAP-3600) ►Rn filter successfully tested ►powerful test tools: Rn spiking, Rn emanation measurements still open questions , origin of Rn background – location of Ra parent not yet identified! The EAC encourages the collaboration to continue vigorously the R&D efforts and recommends full support in order to reach a detailed understanding of the backgrounds and the measures for their efficient reduction. If needed, full support for relocation should be provided.

4. DEAP 3600 DEAP-3600 1000 kg fiducial mass - sensitvitiy 10-46 cm2 use of LAr depleted Ar-39 considered - DEAP-1 R&D crucial under construction – location Cube hall ► manpower strengthened (project engineer) ► major progress in various areas, including PMTs of improved performance identified and selected manufacturer for acrylic vessel identified (RPT, did SNO) prototype fast DAQ provided by DEAP-1 ► TPB purity crucial for background level ► final assembly from June to December 2011 – agressive schedule! The EAC acknowledges progress in the construction of DEAP-3600, and welcomes the construction of a 1/3 scale prototype for an exploration of mechanical and thermal issues. It recommends full support for a timely completion of the construction. The EAC is looking forward to the results of the upcoming technical and safety reviews – scheduled for January 2010.

5. Miniclean • miniCLEAN 100 kg fiducial mass - sensitvitiy 2▪10-45 cm2 • prototype for 50 ton detector, LNe, PSD: 10-10 , <1α / (m2 day), • position resolution • under construction – location Cube hall • ► visible progress (inner & outer vessel under production) • ► overall schedule shifted by about 1 year since last EAC***, • cassette protoyping/procurement on critical path, • commissioning now 6/7/10 to 9/19/10 (shortened by 3 months, optimistic) • The EAC acknowledges the progress achieved but remains concerned about delays! Further slippage could (i) compromise the physics competivity of miniCLEAN, and (ii) cause interference with DEAP-3600 installation. • ► Progress on milestones should be continously monitored by SNOLAB. • ***After the talk, the EAC learned that an internal safety review as well as cost • increase have caused part of the delay and shifted a foreseen technical review • with SNOLAB participation.

6. Picasso • We are very pleased by the establishment of stable operation and publication of the recent physics result. -- 11 Graduate students have completed their studies so far! • The discovery of n-alpha discrimination reported to us • a year ago is important, but still not understood. • --Crucial to confirm and characterise this effect. • -- Allows constant temperature running, with increased efficiency. • Simulation effort should be increased, with high priority, to understand spatial resolution, reduce backgrounds, improve calibrations, etc. • We support move to ladder lab at time convenient for SNOLAB. • Request for space for detector construction in surface building is sensible, but should not impact other SNOLAB activities.

7. COUPP • EAC welcomes COUPP’s request for underground space allocation, and is pleased by its development program. • Staging COUPP-60 underground is necessary for reaching its background goal of < 0.01 evt/kg-d. • Equally important is a parallel and rigorous assay program to determine the purity of the target and construction materials to better than the estimated 10-15 g/g(U/Th). Details are lacking, so we encourage the collaboration to begin its development. • EAC is concerned about the safety and operational aspects of the experiment in SNOLAB, and recommend the collaboration to develop comprehensive fail-safe and emergency plans. • EAC recommends space allocation, contingent on • approval of the fail-safe and emergency plan by SNOLAB; and • development of an assay plan for the stated background goal. • EAC encourages COUPP and PICASSO to collaborate on common technical issues crucial to the success of a large scale detector using superheated targets. SNOLAB EAC Closeout

8. SuperCDMS High background reduction is necessary for dark matter experiments. In this regard SuperCMDS is one of the best experiments, as it aims for background free detection of the signal. Its sensitivity is as good as other proposed experiments. So, we strongly recommend SuperCDMS as one of the future experiments at SNOLAB. SuperCDMS is requesting infrastructure and underground space for a test facility in order to test the improved device (iZIP) which will be necessary for larger scale detector. We recommend approval of this request. Necessary financial and human support should be provided as possible. We strongly encourage the budget request to US and Canadian funding agencis for the full scale SuperCDMS experiment. SNOLAB EAC Closeout

9. HALO • EAC supports HALO as a low-cost supernova neutrino detector with interesting physics potential. • We are concerned, however, that progress is still manpower limited, and could be an even more serious problem when Virtue goes on sabbatical. • A careful error analysis should be carried out to understand the impact of low statistics, poorly known cross sections, etc. on extracting physics from the data. • Recommendation: HALO should proceed with installation in the stub area currently planned for it. SNOLAB EAC Closeout

10. EXO gas phase • EXO gas has made very good progress in the last year, including developing a new concept for the detection and tagging approach • They are approaching the new high purity TCP concept on multiple levels and have solved many critical issues • Recommendations & findings: • New nozzle development very promising, further investigations needed • Investigate the EL detection system in terms of resolution and long term stability (could be critical for 22-supression) • Investigate the extraction out of the 10 Bar gas cell • Investigate the moving of the Ba++ towards to nozzle inside the gas cell (including the dynamical switching of electrical fields at 10 Bar) • Overall, need to exclude ‘show-stopper’ issues early! • Continue to develop and incorporate relevant expertise, foster exchange with other groups in the community, e.g. NEXT • We encourage close collaboration with the liquid EXO group to enhance the EXO gas R&D manpower • given the complex nature of the approach of EXO gas, a milestone timetable would be helpful SNOLAB EAC Closeout

11. DAr R&D; DARK SIDE • The committee is impressed by the new approach of harvesting depleted Ar, and the progress of this new collaboration. We look forward to results from running their test vessel in SNOLAB. • The DARK SIDE detector requests placement at SNOLAB for a 20kg prototype and later a 500kg detector system • We recommend a placement of the 20 kg R&D system at SNOLAB, to demonstrate possible advantages w/r to scalability to a multi ton detector • At this point, the committee finds it too premature to judge the 500kg detector system, however we have some concerns with respect to impact of the 500kg system, and encourage a careful evaluation and comparison with competing experiments. • Moreover, we encourage the DarkSide and DEAP groups to explore the depleted Ar capabilities to maximize impact and investments already made SNOLAB EAC Closeout