LUX-ZEPLIN

Abstract:

European Underground Rare Event Calorimeter Array (EURECA) will be an astro-particle physics facility in the Laboratoire Souterrain de Modane, aiming to directly detect galactic dark matter. 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. The aim is to explore WIMP - nucleon scalar cross sections in the 10-9 - 10-10 picobarn region with a target mass of up to one ton. A major advantage of EURECA is the planned use of more than just one target material (multi target experiment for WIMP identification).

Abstract:

CRESST (Cryogenic Rare Event Search with Superconducting Thermometers) is a low temperature experiment dedicated to the direct dark matter detection via nuclear recoil. It is located in Hall A of the Laboratori Nazionali del Gran Sasso, Italy. Scintillating CaWO4 crystals operated at a few mK are utilized as target forWIMPs (Weakly Interacting Massive Particles), which are expected to scatter predominantly on the heavy tungsten nuclei. As for background rejection, CRESST uses the phonon-light technique, where two different quantities of an interaction are recorded: the heat production in the CaWO4crystal and the simultaneous emission of scintillation light, which is monitored by a second low-temperature detector, the light detector. The information provided by both detectors allows a powerful background discrimination on an event by event basis. After a major upgrade phase, CRESST-II has now successfully completed a commissioning run during 2007, the results of which are presented in this article.

Abstract:

Following the investigations of the structure and scintillation properties of Ca-doped zinc tungstate powder [phys. stat. sol. (a) 204. 730 (2007)] a single-crystal of ZnWO4-Ca (0.5 mol%) was grown and characterised. The relative light output, energy resolution and decay characteristics were measured for pure and Ca-doped ZnWO4 scintillators. An increase in the light yield of ~40% compared with the undoped crystal, and an energy resolution 9.6% (137Cs) were obtained for Ca-doped ZnWO4. The observed improvement is attributed to the reduction of self-absorption (bleaching) of the crystal. The cause of bleaching as well as the possible contribution of scattering is discussed. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.

Abstract:

European Underground Rare Event Calorimeter Array (EURECA) will be an astro-particle physics facility in the Laboratoire Souterrain de Modane, aiming to directly detect galactic dark matter. 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. The aim is to explore WIMP - nucleon scalar cross sections in the 10 - 10 picobarn region with a target mass of up to one ton. A major advantage of EURECA is the planned use of more than just one target material (multi target experiment for WIMP identification).

Abstract:

The perspective of using CaMoO4 as a scintillation target in cryogenic rare event searches has provided strong motivation for the optimisation of this material. A single crystal of CaMoO4, exhibiting high optical quality, was produced and its scintillation light response to particle excitation and its decay time constant were investigated over the 7-300K temperature range. The scintillation at room temperature is strongly affected by thermal quenching. The main decay time constant is found to be 15.7 +/- 0.4 mu s at T= 300K; cooling to 7K increases the scintillation decay time constant to 380 +/- 20 mu s. The scintillation efficiency of the CaMoO4 crystal was evaluated by comparison with a reference CaWO4 crystal measured under the same conditions; we estimate the light output of CaMoO4 to be 55 +/- 20% that of CaWO4 at 294K and 95 +/- 30% at 7K. The study confirmed that calcium molybdate optimised for high light yield is a very attractive material for use in cryogenic phonon-scintillation detectors in rare event searches. (c) 2007 Elsevier B.V. All rights reserved.