Energy-Dependent Light Quenching in CaWO$_4$ Crystals at mK Temperatures

Understand

Scintillating CaWO$_4$ 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$_4$ 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.