Hans Kraus

Abstract:

Results of the CRESST experiment at Gran Sasso using 262-g sapphire calorimeters with tungsten phase transition thermometers are presented. Calibration and analysis methods are described. Data taken in 2000 have been used to place limits on WIMP dark matter particles in the Galactic halo. The sapphire defectors are especially sensitive to low-mass WIMPs with spin-dependent interaction and improve on existing limits in this region. (C) 2003 MAIK "Nauka/Interperiodica".

Abstract:

Results of the CRESST experiment at Gran Sasso using 262 g sapphire calorimeters with tungsten phase transition thermometers are presented. Calibration and analysis methods are described. Data taken in 2000 have been used to place limits on WIMP dark matter particles in the galactic halo. The sapphire detectors are especially sensitive for low-mass WIMPS with spin-dependent interaction and improve on existing limits in this region.

Abstract:

Using heat pulses, we studied the elastic scattering of THz phonons in sapphire and calcium tungstate, two materials of interest as absorbers in composite detectors of particles and photons. For sapphire, we modelled the power dependences of specularly reflected and bulk scattered phonons, whilst for calcium tungstate the transmitted diffusive signal was measured. In both materials, the measured rate was consistent with Rayleigh scattering by isotopes, of oxygen in Al2O3 and of tungsten in CaWO4. In addition, strongly non-linear effects were observed in CaWO4. (C) 2002 Elsevier Science B.V. All rights reserved.

Abstract:

Cryogenic detectors are detectors based upon detection mechanisms which require low temperatures in the sub-kelvin range, such as superconductivity. This article introduces the two main representatives of cryogenic detectors, superconducting tunnel junctions and low-temperature calorimeters with superconducting thermometers. The operating principles, signal generation and noise sources are discussed in each case. These detectors are already applied to experiments in particle-astrophysics and in optical astronomy. They are considered as the next generation instrumentation in certain areas of astrophysics, material analysis and high-resolution spectroscopy. Since 1996, they are also considered for applications in time-of-flight spectrometry of heavy bio-molecules. Successful applications of both detectors types in this area are briefly reviewed. © 2002 Elsevier Science B.V. All rights reserved.