Background model of the ANAIS-112 dark matter experiment

TL;DR

The paper details the development and refinement of a background model for the ANAIS-112 dark matter experiment, analyzing three years of data to compare observed spectra with model predictions and assess potential signals.

Contribution

It presents a comprehensive background model for all nine detectors of ANAIS-112 based on early data and improvements from larger exposure, aiding in dark matter detection efforts.

Findings

Background model matches measured spectra within uncertainties

No evidence of annual modulation signal detected

Model improvements enhance future sensitivity analysis

Abstract

The ANAIS (Annual modulation with NaI(Tl) Scintillators) experiment aims at the confirmation or refutation of the DAMA/LIBRA positive annual modulation signal in the low energy detection rate. ANAIS-112, consisting of nine 12.5 kg NaI(Tl) modules, is taking data since August, 2017 at the Canfranc Underground Laboratory (LSC) in Spain. Results from the analysis of three years of data are compatible with the absence of modulation. The background model developed for all nine ANAIS-112 detectors was established from commissioning data and non-blinded events in the first year of data taking. Now, background characterization is being improved profiting from the larger accumulated exposure available. Here, the background model is described and comparisons of model and measurements for energy spectra and counting rate time evolution for three-year exposure (considering different analysis conditions) are presented.