Results on MeV-scale dark matter from a gram-scale cryogenic calorimeter operated above ground

TL;DR

This study demonstrates a gram-scale cryogenic calorimeter operating above ground with an ultra-low energy threshold, enabling new constraints on MeV-scale dark matter particles despite high background noise.

Contribution

It introduces a high-sensitivity, above-ground cryogenic detector for light dark matter, achieving unprecedented low energy thresholds and setting first limits in the 140-500 MeV/c^2 mass range.

Findings

Achieved an energy threshold of 19.7 eV in a gram-scale detector.

Set the first limits on dark matter-nucleon cross section for 140-500 MeV/c^2 masses.

Operated successfully above ground in a high-background environment.

Abstract

Models for light dark matter particles with masses below 1 GeV/c$^2$ are a natural and well-motivated alternative to so-far unobserved weakly interacting massive particles. Gram-scale cryogenic calorimeters provide the required detector performance to detect these particles and extend the direct dark matter search program of CRESST. A prototype 0.5 g sapphire detector developed for the $\nu$-cleus experiment has achieved an energy threshold of $E_{th}=(19.7\pm 0.9)$ eV, which is one order of magnitude lower than previous results and independent of the type of particle interaction. The result presented here is obtained in a setup above ground without significant shielding against ambient and cosmogenic radiation. Although operated in a high-background environment, the detector probes a new range of light-mass dark matter particles previously not accessible by direct searches. We report the first limit on the spin-independent dark matter particle-nucleon cross section for masses between 140 MeV/c$^2$ and 500 MeV/c$^2$.