A BGO scintillating bolometer as dark matter detector prototype

A 46 g BGO (Bi4Ge3O12) scintillating bolometer has been tested at 20 mK as a prototype for dark matter direct detection in the frame of the ROSEBUD (Rare Objects SEarch with Bolometers UndergrounD) collaboration. The bolometer has been operated first in Orsay and then in an ultra-low background environment at the Canfranc Underground Laboratory. We analyze its response both in heat and light, and its particle discrimination capability. Light yield under γ-ray excitation at several energies (from 88.0 to 1633.3 keV) and the relative light output for different particles (β/γ, α and neutrons) have been estimated. The analysis focuses on the discrimination of nuclear recoils, like those produced by hypothetical weakly interacting massive particles (WIMPs), against electron recoils, produced by β/γ radioactive background.