Light yield of undoped sapphire at low temperature under particle excitation -: art. no. 264102

In this letter, we report on the performance of scintillating sapphire bolometers developed in the framework of the ROSEBUD (Rare Objects Search with Bolometers UnDerground) Collaboration devoted to dark matter searches. The simultaneous measurement of heat and light allows the discrimination of the type of particle increasing the sensitivity for these searches. A heat versus light negative correlation for gamma events has been observed. Its interpretation, in a simple framework, allows the estimation of the light yield of undoped sapphire at a temperature of about 20 mK under gamma, alpha, and neutron excitation.