Observations of galaxies, superclusters, distant supernovae and the cosmic microwave background radiation, tell us that ~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, 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 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 low temperature phonon-mediated detectors to detect the rare scattering of WIMPs on nuclei and to distinguish them from backgrounds. With this powerful technology, operating deep underground in the Soudan mine in Minnesota, this is the most sensitive WIMP search in the world, and their reach is projected to grow by factor of eight by the end of 2007.
This proposal requests funding for the SuperCDMS 25 kg Experiment that will extend the direct-detection reach for WIMP dark matter by an additional two orders of magnitude. The collaboration will combine their preparation for moving to SNOLAB, to reduce the cosmogenic neutron level, with continued running of the CDMS detectors at the Soudan facility.
The technical development will push the envelope of phonon-mediated detectors, which have increasing applications. The project will expand its public outreach program at Soudan, transfer its experience to SNOLAB, will continue their involvement in K-12, collaborate with teachers and support promising high school students from underserved backgrounds.
