EXPERIMENTS ON WIMPS, SIMPS, AND HOT DARK-MATTER

The particle which constitutes more than 90% of the mass of the universe is not one of those in the Standard Model of particle physics. The search for this dark matter particle has now eliminated or severely restricted many candidates. While accelerator-produced results and indirect searches have helped, the most extensive exclusions have come from attempts at direct detection using semiconductor ionization detectors. The region excluded by direct detection extends over 12 orders of magnitude in particle mass and 20 orders of magnitude in cross section for Dirac particles. The need is now to get to cross sections less than one-tenth the weak cross section for Dirac masses > 20 GeV and to use detectors having nuclei with spin for Majorana masses greater than or similar to 10 GeV. Light neutrinos, while not detectable directly, can be eliminated as dominant dark matter if the 17-keV neutrino exists.