ANAIS-112: updated results on annual modulation with three-year exposure

TL;DR

The ANAIS-112 experiment, using ultrapure NaI(Tl) detectors over three years, reanalyzed data with machine learning filtering, improving sensitivity to dark matter annual modulation signals and aiming to test DAMA/LIBRA results by 2025.

Contribution

This work updates the ANAIS-112 results with a new machine-learning based data filtering, enhancing sensitivity to dark matter signals and providing future testing prospects for DAMA/LIBRA.

Findings

No modulation detected in three-year data

Reanalysis improves sensitivity to DAMA/LIBRA signal

Testing DAMA/LIBRA at 5σ possible by 2025

Abstract

The ANAIS experiment is intended to search for dark matter annual modulation with ultrapure NaI(Tl) scintillators in order to provide a model independent confirmation or refutation of the long-standing DAMA/LIBRA positive annual modulation signal in the low energy detection rate, using the same target and technique. Other experiments exclude the region of parameters singled out by DAMA/LIBRA. However, these experiments use different target materials, so the comparison of their results depends on the models assumed for the dark matter particle and its distribution in the galactic halo. ANAIS-112, consisting of nine 12.5 kg NaI(Tl) modules produced by Alpha Spectra Inc., disposed in a 3$\times$3 matrix configuration, is taking data smoothly with excellent performance at the Canfranc Underground Laboratory, Spain, since August, 2017. Last published results corresponding to three-year exposure were compatible with the absence of modulation and incompatible with DAMA/LIBRA for a sensitivity above 2.5$\sigma$ C.L. Present status of the experiment and a reanalysis of the first 3 years data using new filtering protocols based on machine-learning techniques are reported. This reanalysis allows to improve the sensitivity previously achieved for the DAMA/LIBRA signal. Updated sensitivity prospects are also presented: with the improved filtering, testing the DAMA/LIBRA signal at 5$\sigma$ will be within reach in 2025.