Since the 1930s, astronomers, observing systems larger than a single star, have found evidence that the mass of the universe is dominated by a form of matter which has never been seen directly in the laboratory. Physicists are attempting to find direct evidence of particle dark matter scattering with ordinary nuclei. Because the interactions impart such small kinetic energies to the recoiling nuclei (~1-100 keV), these searches must amplify tiny signals - in the midst of a gale of background from cosmic rays and radioactivity. The two experiments which I am performing (with collaborators at Fermilab, and the University of Chicago, in the COUPP experiment and Canadian and Czech Universities in the PICASSO experiment) employ superheated fluids as the dark matter targets. These targets can simultaneously amplify these tiny recoil signals and are inherently immune to most of the backgrounds which other techniques must struggle with. I will discuss this technique, our recent results and future plans.
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