Dark Matter Searches for Monopoles and WIMPs

Abstract

By the mid-1970’s, there had been several theoretical suggestions that the dark matter observed kinematically around galaxies and in clusters of galaxies could be made up primarily of an undiscovered elementary particle. Our group took this suggestion seriously and by early 1981 we had begun a search for GUT (grand unification theory) magnetic monopoles in the cosmic rays under the hypothesis that they make up the dominant mass of our galactic halo. We used superconductivity and cryogenic technologies to mount uniquely sensitive inductive detectors. In the first part of this paper we summarize a decade of experiments on three generations of detectors. By the mid-1980’s, there were strong theoretical reasons for extending the search to another type of elementary particle, broadly called weakly interacting massive particles or WIMPs of which the lightest supersymmetric particle or neutralino is the most studied possibility. The second part of the paper summarizes the new cryogenic technologies, also using superconductivity, which have been developed to search for WIMPs, and the status of the dark matter experiment now being installed in the Stanford Underground Facility (SUF) by a collaboration including UC Berkeley (CfPA), LBL, Stanford, UC Santa Barbara, and Baksan.