Background model of NaI(Tl) detectors for the ANAIS Dark Matter Project

TL;DR

This paper develops a detailed background model for NaI(Tl) detectors used in the ANAIS dark matter experiment, crucial for identifying rare event signals and confirming previous findings.

Contribution

It provides a comprehensive background model for NaI(Tl) detectors and evaluates the effectiveness of anticoincidence rejection in the ANAIS setup.

Findings

Background sources characterized for the detectors.

Preliminary background analysis of a new crystal.

Anticoincidence rejection enhances signal detection.

Abstract

A thorough understanding of the background sources is mandatory in any experiment searching for rare events. The ANAIS (Annual Modulation with NaI(Tl) Scintillators) experiment aims at the confirmation of the DAMA/LIBRA signal at the Canfranc Underground Laboratory (LSC). Two NaI(Tl) crystals of 12.5 kg each produced by Alpha Spectra have been taking data since December 2012. The complete background model of these detectors and more precisely in the region of interest will be described. Preliminary background analysis of a new 12.5 kg crystal received at Canfranc in March 2015 will be presented too. Finally, the power of anticoincidence rejection in the region of interest has been analyzed in a 4x 5 12.5 kg detector matrix.