Detector Optimization for the SuperCDMS Experiment

Santa Clara University, Santa Clara CA

Investigators

Abstract

Results from several observational astronomy experiments show that about 85% of the matter in the universe is not made of ordinary particles. Deciphering the nature of this dark matter would be of fundamental importance to cosmology, astrophysics, high-energy particle physics, and our understanding of gravity. A leading hypothesis is that dark matter is comprised of Weakly Interacting Massive Particles, or WIMPs, an elementary particle beyond the Standard Model of particle physics, but predicted in various extensions including Supersymmetry. The Cryogenic Dark Matter Search (CDMS) Collaboration, supported jointly by NSF and DOE, has pioneered the use of low temperature phonon-mediated detectors based on superconducting thin-film sensors to distinguish the rare scattering of such WIMPs on nuclei from other background events. Using our powerful technology in the Soudan mine, CDMS is currently (July 05) the most sensitive WIMP search experiment in the world, by a factor of ten. The two years of funding provided by this NSF award will help support the Santa Clara University (SCU) group continue its active participation in the operation of the CDMS experiment at Soudan. The funding will also partially support the group's continued work on superconducting sensor technologies for cryogenic detector applications. This work includes physics and technology-focused investigations of superconducting aluminum alloy sensors (potentially of interest for SuperCDMS and other experiments), as well as continued work with CDMS collaborators on feasible extensions of the current tungsten-based technology to larger substrates for SuperCDMS. The SCU group will continue to be responsible for using existing, fast turn-around, dilution-refrigerator facilities at Stanford University to provide the CDMS collaboration with rapid characterization of superconducting films. Evaluations of future sensor technologies based on both physics reach and promise for enhanced device fabrication yields will be ongoing throughout this two year funding period. The SCU group includes the P.I. and typically two undergraduates. The group benefits tremendously from its strong ties to groups at nearby institutions, particularly Stanford and UC Berkeley. CDMS collaborators at these institutions generously provide the SCU group access to their extensive cryogenic and device fabrication facilities and their support has allowed the SCU group to perform a variety of physics experiments related to CDMS and beyond, that otherwise would have been cost-prohibitive for the SCU group alone.