Recommendations for Science at SNOLAB Andrew Hime On behalf of the Experiment Advisory Committee Aug. 17, 2005 SNOLAB Surface Building

Solar Neutrinos  Exploit low-energy solar neutrinos for precision neutrino physics and stellar physics  We endorse development toward SNO+ for pep solar neutrinos and geo-neutrinos. We applaud the technical progress in developing the liquid scintillator and encourage continued R&D, development of the necessary collaboration and proposal to secure funding. We look forward to a receiving a full technical proposal.  How to go beyond SNO+ …Development for a dedicated pp experiment …  We consider miniCLEAN an essential step to realize a large scale LNe pp solar neutrino experiment with potential overlap with the dark matter program. We encourage submission of a technical design proposal.  Noble-Liquid-Tracking technology is a novel and exciting possibility for a very low threshold detector. We encourage submission of a technical proposal at the appropriate time.

Double Beta Decay  Pursue a precision test in the degenerate mass regime with capability to scale in target mass allowing sensitivity to the inverted mass hierarchy …  We strongly endorse Majorana Phase-I (180 kg) using conventional cryostat technology and encourage a detailed assessment of the experimental layout and infrastructure needs.  Two promising paths exist to scale towards 1-tonne … Improved Cu-purity with conventional cryostats v.s. LArGe/GerDA technology with naked-crystals …  GerDA development is underway and in parallel at Gran Sasso and we encourage continued collaboration between Majorana and GerDA in paving the best road to a 1-tonne experiment based on 76Ge.  How to go beyond …  We endorse the R&D program for Barium tagging in Gas-EXO with initial, small-space underground for a 30 cm test-detector. Such developments could lead to a 200 kg first generation detector with longer view of tonne-scale …  COBRA development is underway at Gran Sasso.

Dark Matter  Exploit the “state-of-the-art” …  We strongly endorse the SuperCDMS project as a natural extension of the CDMS program and encourage a detailed assessment of the experimental layout and infrastructure needs.  Develop new technologies with capabilities at the tonne-scale …  XENON development is underway at Gran Sasso.  We welcome a technical proposal from the ZEPLIN-IV/MAX collaboration and invite discussion on the possibility to house ZEPLIN-III.  Very interesting and recent technical developments using LAr provide the possibility for a conceptually simple and relatively inexpensive route to a large-scale detector. Given existing funds and plan to go forward, we strongly encourage submission of a technical proposal for DEAP-I.

Dark Matter … continued  Dedicated spin-dependent WIMP searches …  We endorse the R&D for PICASSO in smaller space (SNO Utility) to demonstrate the 30-liter detector technology & purification capability needed to justify future allocation of larger space to accommodate a 25 kg detector and beyond.  We would welcome an LOI from COUPP.  Detectors with directional sensitivity …  A directionally sensitive WIMP detector holds the promise of WIMP astronomy once information is in hand to define the detector parameters required. The DRIFT technology is the most promising technology at present for directional detection of WIMP dark matter. We strongly encourage a continued R&D program.  Given the impact on SNOLAB real estate and the uncertainty in the mass required for performing WIMP astronomy in directional detectors, we do not, at the present time, endorse DRIFT-III for SNOLAB.

Other Experiments HALO  We are enthusiastic about the use of the NCD array for supernova neutrino detection. We encourage submission of a technical proposal that outlines the scientific case, the infrastructure needs, and the manpower resources available to construct and operate the experiment. TRIGA  This appears like an extremely challenging experiment that does not make use of the planned capabilities at SNOLAB. We do not recommend proceeding with this effort. NOSTOS  We await further information that has been requested and scientific justification for staging the experiment at SNOLAB. LENA  The LOI received for a multi-purpose, liquid scintillator detector is simply too large to be accommodated at SNOLAB. Lithium Detector  A formal LOI for a radiochemical detector of solar neutrinos based upon a lithium target has not been received and appears to lack the scientific scope necessary to contribute significantly to the modern era of solar neutrino physics.

1. Our recommendations are driven by Science. We now need to work together to develop a successful scientific roadmap for SNOLAB. There is significant work to be done: 2. Experimental Layouts & Infrastructure Needs 3. Continued Progress with R&D 4. Demonstration of Technical Feasibility 5. Safety 6. Funding & Schedule 7. Participation & Management