A wealth of observations shows that the universe is composed of >96% invisible matter and energy. The nature of these missing components is one of the most fundamental mysteries in physics. The leading candidate for the invisible ?dark matter? is a subatomic particle left over from the big bang known as the Weakly Interacting Massive Particle (WIMP). Such particles are also predicted by supersymmetry, a favored class of new particle models. If WIMPs exist, they are also the dominant mass in our own Milky Way. Although they only rarely interact with conventional matter, they should nonetheless be detectable by sufficiently sensitive detectors on Earth through their direct interaction with, and the ensuing recoil of, nuclei in a target material. The primary challenge in detecting them is reducing natural and cosmogenic radioactivity by up to 10 orders of magnitude.
The Large Underground Xenon (LUX) collaboration has assembled a team to carry out an ambitious program of constructing and operating a 300 kg total, 100 kg fiducial mass, dual-phase xenon detector. A large detector is required to not only set an improved sensitivity limit, but also to accumulate WIMP statistics in a reasonable time if a signal is detected. The LUX design emphasizes using simple technologies, in particular for the design of the cryostat and the use of a water shield, to scale to large size as rapidly as possible. Thus the LUX program will develop the technologies required for 1-10 ton dark matter detectors.
This award provides support for the Case group to carry out its responsibilities in the LUX program. The group has a crucial role in LUX, being responsible for the cryostat and cryogenics, coordinating the integration and surface test program at Case, removing Kr from Xe, and screening parts for Rn emanation. They also have a small but active R&D program, aimed at technologies needed for a next-phase, very large-scale experiment.
Among the broader impacts, the techniques themselves can be further scaled up and applied to other fundamental experiments such as double beta decay and solar neutrinos. As with other particle detection techniques, new methods of position sensitivity and particle discrimination may give rise to new medical diagnostic techniques, or applications to Homeland Security and nuclear control.
