Susan Cooper

Abstract:

The upgrade of the CRESST experiment to a 10 kg target of phonon/light detectors necessitates the installation of 66 readout channels in the CRESST cryostat. We report on the status of this upgrade and discuss the issues related to the installation of the correspondingly high number of SQUIDs and wires in an ultra-low temperature environment.

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:

214Po is implanted into surfaces exposed to radon. The implantation rate could be sufficient to explain the rate of low-energy events with anomalously fast scintillation pulses that has been observed in sodium iodide crystals used in a search for WIMP dark matter. The rate should be closely coupled in time to the radon concentration. (C) 2000 Elsevier Science B.V.