Feasibility study of a ZnWO4 scintillator for exploiting materials signature in cryogenic WIMP dark matter searches

AbstractThe mass number dependence of the WIMP–nucleus scattering offers a method for identifying a true WIMP signal over aneutron background. In this Letter we present a study on using a combination of ZnWO 4 and CaWO 4 absorbers to exploit thismaterials signature for WIMP detection. Using monochromatic X-ray radiation we examined the temperature variation of theluminescence properties for both materials and showed that at low temperature (8 K) ZnWO 4 exhibits ∼10% higher light yieldthan CaWO 4 . Analysis of relevant optical properties indicates that ZnWO 4 is a suitable cryogenic scintillator. We show thatalready modest exposure in the region of ∼5 kgyr should allow the detection of WIMP interaction for cross sections at thelevel of current experimental sensitivities. The combination of these two tungstates could form the basis of the first multi-targetdetector capable of WIMP identification through materials signature.  2005 Elsevier B.V. All rights reserved. 1. IntroductionMost modern experiments aiming to detect WIMPdark matter are employing some form of active dis-crimination between nuclear recoil (the signal) andelectron recoil (backgrounds). One of these discrim-ination techniques, used by CRESST and also ROSE-BUD, is event by event discrimination through mea-suring a combination of phonon and scintillation sig-