Measurements of the Cerenkov light emitted by a TeO2 crystal

TL;DR

This study demonstrates that Cerenkov light emitted by TeO2 crystals can be detected and used to discriminate between different particles, potentially enhancing the sensitivity of rare event searches like neutrinoless double beta decay.

Contribution

The paper provides the first analysis of Cerenkov light emission in TeO2 crystals at room temperature, indicating its potential for particle discrimination in bolometric detectors.

Findings

Cerenkov light is promptly emitted by TeO2 when traversed by cosmic rays.

The emitted light shows clear directionality.

Cerenkov light is likely the main component of the light signal in TeO2 crystals.

Abstract

Bolometers have proven to be good instruments to search for rare processes because of their excellent energy resolution and their extremely low intrinsic background. In this kind of detectors, the capability of discriminating alpha particles from electrons represents an important aspect for the background reduction. One possibility for obtaining such a discrimination is provided by the detection of the Cerenkov light which, at the low energies of the natural radioactivity, is only emitted by electrons. In this paper, the results of the analysis of the light emitted by a TeO2 crystal at room temperature when transversed by a cosmic ray are reported. Light is promptly emitted after the particle crossing and a clear evidence of its directionality is also found. These results represent a strong indication that Cerenkov light is the main, if not even the only, component of the light signal in a TeO2 crystal. They open the possibility to make large improvements in the performance of experiments based on this kind of materials