Daily Modulation Constraints on Light Dark Matter with DAMIC-M

TL;DR

This study searches for daily modulation signals caused by light dark matter interactions in the DAMIC-M detector, finding no significant modulation but setting improved constraints on dark matter particles below 1.2 MeV/c2.

Contribution

It introduces a novel search for daily modulation of light dark matter using DAMIC-M, providing the first constraints in this specific mass range based on temporal analysis.

Findings

No significant daily modulation detected.

Constraints on dark matter mass below 1.2 MeV/c2 are improved.

Detector demonstrated excellent temporal stability.

Abstract

The flux of Hidden Sector particles from the Galactic halo reaching an underground detector can be significantly attenuated by interactions within the Earth for sufficiently large scattering crosssections. This attenuation gives rise to a characteristic daily modulation in the detection rate, due to Earth's rotation. We present results from a search for such a modulation using a 1.257 kg-day dataset collected with the DAMIC-M Low Background Chamber. A model-independent analysis reveals no significant modulation in the 1e- event rate over periods from 1 to 48 h, highlighting the excellent temporal stability of the detector. In a complementary model-dependent analysis, we target the expected daily modulation signature of Hidden Sector particles, with masses in the range [0.53,2] MeV/c2, interacting with electrons via a dark photon mediator. By leveraging the expected temporal evolution of the signal, we set improved constraints on Dark Matter masses below 1.2 MeV/c2, surpassing our previous limits.