https://doi.org/10.1140/epjc/s10052-014-2957-5
Letter
Energy-dependent light quenching in CaWO crystals at mK temperatures
1
Physik-Department, Technische Universität München, 85748 , Garching, Germany
2
Max-Planck-Institut für Physik, 80805 , Munich, Germany
3
CIUC, Departamento de Fisica, Universidade de Coimbra, 3004 516 , Coimbra, Portugal
4
INFN, Laboratori Nazionali del Gran Sasso, 67010 , Assergi, Italy
5
Walther-Meißner-Institut für Tieftemperaturforschung, 85748 , Garching, Germany
6
Physikalisches Institut, Eberhard-Karls-Universität Tübingen, 72076 , Tübingen, Germany
7
Department of Physics, University of Oxford, Oxford, OX1 3RH, UK
8
Institut für Hochenergiephysik der Österreichischen Akademie der Wissenschaften, 1050 , Vienna, Austria
9
Maier-Leibnitz-Laboratorium, Ludwig-Maximilians-Universität München, 85748 , Garching, Germany
* e-mail: strauss@mpp.mpg.de
Received:
17
February
2014
Accepted:
3
July
2014
Published online:
25
July
2014
Scintillating CaWO single crystals are a promising multi-element target for rare-event searches and are currently used in the direct dark matter experiment CRESST (Cryogenic Rare Event Search with Superconducting Thermometers). The relative light output of different particle interactions in CaWO is quantified by quenching factors (QFs). These are essential for an active background discrimination and the identification of a possible signal induced by weakly interacting massive particles (WIMPs). We present the first precise measurements of the QFs of O, Ca and W at mK temperatures by irradiating a cryogenic detector with a fast neutron beam. A clear energy dependence of the QF of O and, less pronounced, of Ca was observed for the first time. Furthermore, in CRESST neutron-calibration data a variation of the QFs among different CaWO single crystals was found. For typical CRESST detectors the QFs in the region-of-interest (10–40 keV) are %, % and %. The latest CRESST data (run32) is reanalyzed using these fundamentally new results on light quenching in CaWO having moderate influence on the WIMP analysis. Their relevance for future CRESST runs and for the clarification of previously published results of direct dark matter experiments is emphasised.
© SIF and Springer-Verlag Berlin Heidelberg, 2014