Discrimination of Recoil Backgrounds in Scintillating Calorimeters

Understand

The alpha decay of $\n{{}^{210}Po}$ is a dangerous background to rare event searches.

• Here, we describe observations related to this alpha decay in the Cryogenic Rare Event Search with Superconducting Thermometers (CRESST).
• We find that lead nuclei show a scintillation light yield in our $\n{CaWO_4}$ crystals of $0.0142\pm0.0013$ relative to electrons of the same energy.
• We describe a way to discriminate this source of nuclear recoil background by means of a scintillating foil, and demonstrate its effectiveness.