Response of a TeO_2 bolometer to alpha particles

TL;DR

This study characterizes the response of TeO2 bolometers to alpha particles, crucial for background understanding in double beta decay experiments, revealing a nearly unity quenching factor and similar pulse shapes for alpha and beta/gamma events.

Contribution

The paper provides the first detailed measurement of the alpha response function and quenching factor of TeO2 bolometers used in double beta decay searches.

Findings

Quenching factor for alpha particles is approximately 1.0076.

Energy resolution follows a standard calorimeter dependence with energy.

Alpha and beta/gamma signals produce indistinguishable pulses.

Abstract

$TeO_2$ crystals are used as bolometers in experiments searching for Double Beta Decay without emission of neutrinos. One of the most important issues in this extremely delicate kind of experiments is the characterization of the background. The knowledge of the response to $\alpha$ particles in the energy range where the signal is expected is therefore a must. In this paper we report the results on the response function of a $TeO_2$ bolometer to $\alpha$'s emitted by $^{147}$Sm dissolved in the crystal at the growth phase. A Quenching Factor of ($1.0076\pm 0.0005$) is found, independent of the temperature in the investigated range. The energy resolution on $\alpha$ peaks shows a standard calorimeter energy dependence: $\sigma\; [\rm{keV}] = (0.56 \pm 0.02) \oplus (0.010 \pm 0.002)\sqrt{E[\rm{keV}]} $. Signal pulses show no difference between $\alpha$ and $\beta\gamma$ particles