Hans Kraus

Abstract:

The CRESST experiment seeks hypothetical WIMP particles that could account for the bulk of dark matter in the Universe. The detectors are cryogenic calorimeters in which WIMPs would scatter elastically on nuclei, releasing phonons. The first phase of the experiment has successfully deployed several 262 g sapphire devices in the Gran Sasso underground laboratories. A main source of background has been identified as microscopic mechanical fracturing of the crystals, and has been eliminated, improving the background rate by up to three orders of magnitude at low energies, leaving a rate close to one count per day per kg and per keV above 10 keV recoil energy. This background now appears to be dominated by radioactivity, and future CRESST scintillating calorimeters which simultaneously measure light and phonons will allow rejection of a great Dart of it.

Abstract:

The existence of dark matter in the Universe is well established and various techniques are applied to either directly or indirectly detect this dark matter. Supersymmetry provides a well-motivated candidate, the WIMP, which many direct searches seek to detect. Some of the present dark matter experiments use cryogenic detectors, operating in the mini-Kelvin temperature range. This article introduces the general concept underlying these detectors, discusses the different types of detectors in use and shows how some of the experiments achieve suppression of background by being able to distinguish between nuclear recoil and electron recoil.