First search for a dark matter annual modulation signal with NaI(Tl) in the Southern Hemisphere by DM-Ice17

TL;DR

This paper reports the first search for dark matter annual modulation signals using NaI(Tl) detectors in the Southern Hemisphere, with results showing no modulation and setting new limits on dark matter interactions.

Contribution

It demonstrates the feasibility of deploying and operating NaI(Tl) detectors at the South Pole for dark matter searches and provides the first Southern Hemisphere constraints on dark matter.

Findings

No significant annual modulation detected in 3.6 years of data.

Established South Pole ice as a viable location for future dark matter experiments.

Set the strongest limits on WIMP dark matter from a Southern Hemisphere detector.

Abstract

We present the first search for a dark matter annual modulation signal in the Southern Hemisphere conducted with NaI(Tl) detectors, performed by the DM-Ice17 experiment. Nuclear recoils from dark matter interactions are expected to yield an annually modulated signal independent of location within the Earth's hemispheres. DM-Ice17, the first step in the DM-Ice experimental program, consists of 17 kg of NaI(Tl) located at the South Pole under 2200 m.w.e. overburden of Antarctic glacial ice. Taken over 3.6 years for a total exposure of 60.8 kg yr, DM-Ice17 data are consistent with no modulation in the energy range of 4-20 keV, providing the strongest limits on weakly interacting massive particle dark matter from a direct detection experiment located in the Southern Hemisphere. The successful deployment and stable long-term operation of DM-Ice17 establishes the South Pole ice as a viable location for future dark matter searches and in particular for a high-sensitivity NaI(Tl) dark matter experiment to directly test the DAMA/LIBRA claim of the observation of dark matter.