Probing Light DM through Migdal Effect with Spherical Proportional Counter

Abstract

Owing to its low electronic noise and flexible target materials, the Spherical Proportional Counter (SPC) with a single electron detection threshold can be utilized to search for sub-GeV dark matter (DM). In this work, we investigate the prospects for light DM direct detection through the DM-nucleus Migdal effect in the DARKSPHERE detector. We consider the different DM velocity distributions and momentum-transfer effects. For Xenon and Neon targets, we find that the DM mass $m_{DM}$ can be probed down to as low as $m_{DM}\sim \mathcal{O}$(10) MeV, and the derived bounds on the DM-nucleus scattering cross section ${\bar{\sigma }}_n$ are sensitive to the high-velocity tails of the DM velocity distribution, which can be altered by orders of magnitude for the different DM velocity distributions in the region $m_{DM}<10$ MeV.

Comments: 22 pages, 7 figures