The ANAIS Dark Matter Project: Status and Prospects

TL;DR

The ANAIS experiment seeks to confirm DAMA/LIBRA's annual modulation signal using NaI(Tl) detectors, with recent improvements in crystal purity and background reduction enhancing its sensitivity to low-energy dark matter interactions.

Contribution

This paper reports on the progress of the ANAIS project, including the development of more radiopure crystals and preliminary results from the upgraded setup aiming to detect dark matter signals.

Findings

High light collection efficiency achieved

Improved crystal radiopurity demonstrated

Background reduction enhances detection prospects

Abstract

The ANAIS (Annual modulation with NaI(Tl) Scintillators) experiment aims at the confirmation of the DAMA/LIBRA positive annual modulation signal using the same target and technique at the Canfranc Underground Laboratory (LSC). A first step, named ANAIS-25 (two 12.5 kg NaI(Tl) modules) taking data from December 2012 to February 2015, provided interesting outcomes: very high light collection efficiency, that could allow to lower the analysis energy threshold down to the level of 1 keVee, and a good understanding of the different background components, in particular the cosmogenic activated isotopes in the crystal bulk and other radioactive contaminations of the NaI crystal/powder. But those prototypes clearly pointed to the need for improved crystal radiopurity, in particular for $^{210}$Pb contamination. Since then, improvements in the purification and growing procedures in order to reduce background in the very low energy region have been implemented and a new 12.5 kg module has been constructed and installed between the former two crystals, forming the ANAIS-37 setup. Very preliminary results of this setup evidence the improvement on radiopurity of the new crystal and are presented here. In addition, background simulations and prospects for the full experiment are discussed.