A broad range of observations -- from galaxies and superclusters to distant supernovae and the cosmic microwave background radiation -- tell us that about 85% of the matter in the universe is not made of ordinary particles, but exists in some dark form. Deciphering the nature of this dark matter is of fundamental importance to cosmology, astrophysics, and high-energy particle physics. A leading hypothesis is that it is comprised of Weakly Interacting Massive Particles, or WIMPs, that were produced moments after the Big Bang. If WIMPs exist and are the dark matter, then their presence in our Milky Way may be detectable via scattering from atomic nuclei in a terrestrial detector.
The Cryogenic Dark Matter Search (CDMS) Collaboration has pioneered the use of cryogenic phonon-mediated devices to detect the rare scattering of WIMPs on nuclei and distinguish them from backgrounds. With this powerful technology, they have operated for four years the CDMS-II experiment with 30 detectors deep underground in the Soudan mine in Minnesota, and obtained the best limit worldwide at high WIMP masses. This award will fund the base program of this group to focus primarily on detector characterization and optimization, rapid-turnaround initial cryogenic screening of full-scale CDMS production detectors, rapid-turnaround Tc-testing of tungsten film samples from the detector production line, detector fabrication support, collaborative work with scientists and technical staff at new CDMS detector fabrication and substrate polishing facilities, and assistance with CDMS-related materials analysis.
Not only are its scientific results important for astrophysics and particle physics, but its technological development will also push the envelope of phonon-mediated detectors, whose applications are increasingly widespread. In addition to working with students from Santa Clara University (SCU), an undergraduate institution, the PI actively mentors undergraduates, graduate students and junior research staff at other CDMS institutions. The close proximity of SCU to Stanford, UC Berkeley and SLAC makes close collaborations with these groups particularly easy - and tremendously beneficial to SCU students. Lastly, the SCU group does some outreach with K-12 students in the San Francisco Bay Area and supports the public outreach program at Soudan as part of the SuperCDMS collaboration.
