Particle Dark Matter and Solar Axion Searches with a small germanium detector at the Canfranc Underground Laboratory

TL;DR

This study uses a small germanium detector at the Canfranc Underground Laboratory to search for particle dark matter and solar axions, achieving improved background levels and setting new bounds on WIMPs and axion-photon coupling.

Contribution

It reports new experimental limits on low-mass WIMPs and axion-photon coupling using an upgraded germanium detector with reduced background noise.

Findings

Improved WIMP exclusion limits for low masses.

Set a new limit on axion-photon coupling.

Achieved a background reduction of about one order of magnitude.

Abstract

A small, natural abundance, germanium detector (COSME) has been operating recently at the Canfranc Underground Laboratory (Spanish Pyrenees) in improved conditions of shielding and overburden with respect to a previous operation of the same detector. An exposure of 72.7 kg day in these conditions has at present a background improvement of about one order of magnitude compared to the former operation of the detector. These new data have been applied to a direct search for WIMPs and solar axions. New WIMP exclusion plots improving the current bounds for low masses are reported. The paper also presents a limit on the axion-photon coupling obtained from the analysis of the data looking for a Primakoff axion-to-photon conversion and Bragg scattering inside the crystal.