The expected background spectrum in NaI dark matter detectors and the DAMA result

TL;DR

This paper uses detailed simulations to compare expected radioactive backgrounds in NaI detectors with DAMA measurements, suggesting background uncertainties limit dark matter interpretations of DAMA's annual modulation.

Contribution

It provides a comprehensive simulation-based analysis of background spectra in NaI detectors, challenging the dark matter origin of DAMA's observed modulation.

Findings

Simulated spectra require higher isotope concentrations to match DAMA data.

Background modeling constrains the parameter space for dark matter explanations.

DAMA's modulation signal is likely dominated by background effects.

Abstract

Detailed Monte Carlo simulations of the expected radioactive background rates and spectra in NaI crystals are presented. The obtained spectra are then compared to those measured in the DAMA/NaI and DAMA/LIBRA experiments. The simulations can be made consistent with the measured DAMA spectrum only by assuming higher than reported concentrations of some isotopes and even so leave very little room for the dark matter signal. We conclude that any interpretation of the annual modulation of the event rate observed by DAMA as a dark matter signal, should include full consideration of the background spectrum. This would significantly restrict the range of dark matter models capable of explaining the modulation effect.