Hans Kraus

Abstract:

The scintillation properties of a zinc tungstate crystal, shaped as a hexagonal prism (height 40 mm, diagonal 40 mm) were determined. An energy resolution of 10.7% for the 662 keV γ-line of 137Cs was measured with the scintillator placed in a light collection setup similar to that used by the CRESST dark matter search. The light output and decay kinetics of ZnWO4 were examined over the temperature range 7-300 K and confirmed to be competitive with those of CaWO4. The radioactive contaminations of the ZnWO4 scintillator measured in the Solotvina Underground Laboratory do not exceed 0.1-10 mBq/kg (depending on radionuclide). Our study highlights the excellent feasibility of this ZnWO4 scintillator for a cryogenic dark matter experiment. © 2008 Elsevier B.V. All rights reserved.

Abstract:

The luminescence properties of K3Tb(PO4)2 activated by Eu3+ were studied at excitation over the 120-300 nm wavelength range. It is demonstrated that Tb3+ ions, exhibiting a strong absorption band in the vacuum-ultraviolet (VUV), can provide efficient sensitisation of Eu3+ emission in this wave length range, giving rise to intense red luminescence at 150 nm excitation. A proof is given for the concept of VUV sensitisation enabling the engineering of luminescence materials with enhanced conversion efficiency of VUV radiation into visible light. © 2009 WILEY-VCH Verlag GmbH&Co. KGaA, Weinheim.

Abstract:

EURECA (European Underground Rare Event Calorimeter Array) is an astro-particle physics facility aiming to directly detect galactic dark matter. The Laboratoire Souterrain de Modane has been selected as host laboratory. The EURECA collaboration unites CRESST, EDELWEISS and the Spanish-French experiment ROSEBUD, thus concentrating and focussing effort on cryogenic detector research in Europe into a single facility. EURECA will use a target mass of up to one ton, enough to explore WIMP - nucleon scalar scattering cross sections in the region of 10-9 - 10-10 picobarn. A major advantage of EURECA is the planned use of more than just one target material (multi target experiment for WIMP identification). © EAS, EDP Sciences 2009.

Abstract:

The CRESST II experiment is a dark matter search using cryogenic phonon-scintillation detectors, aiming to detect WIMP dark matter particle interactions. The detector consists of individual, modular and scintillating (CaWO4or ZnWO4) target crystals, each equipped with a phonon sensor for precise determination of the energy deposited in the crystals. Each module is further equipped with a separate cryogenic scintillation light detector, allowing event-by-event background discrimination. An extended commissioning run during 2007 has set an upper limit on theWIMP-nucleon scattering cross section. Attention is currently focussed on the interpretation of a few remaining nuclear recoils candidate events.