Measure of low radioactive contamination and nuclear recoil quenching factor using cryogenic particle detectors

For double beta decay and dark matter experiments the determination of the radioactive contamination of materials used is of fundamental importance. The cryogenic particle detectors allow the realization of detectors with various types of materials and in this way the radioactivity is measured in a calorimetric approach with very high sensitivity. In particular a new complete analysis for different types of leads, modern and ancient roman, was realized and here presented. The detector sensitivity for a nuclear recoil event is a crucial point in the dark matter experiments. The nuclear recoil detection efficiency for cryogenic particle detectors was directly measured using two TeO₂ crystals facing one with other and performing a coincidence-anticoincidence analysis of the collected data. The determination of the quenching factor for low energy nuclear recoils in the TeO₂ cryogenic detectors shows that these devices are very sensitive to a possible dark matter particle interaction. In cryogenic detectors a nuclear recoil generates signals with the same amplitude of an electron with the same energy. The performed measure and the data analysis will be discussed in detail. Finally the experimental setup and the preliminary test of the new array of TeO₂ cryogenic detectors for double beta decay and dark matter search will be discussed in detail.