Probing light DM via the Migdal effect with spherical proportional counter

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)similar to O(10) MeV, and the derived bounds on the DM-nucleus scattering cross section 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.

Automated summary

The Spherical Proportional Counter (SPC) with a single electron detection threshold is found to be effective in the direct detection of light sub-GeV dark matter (DM) in the DARKSPHERE detector. By considering different DM velocity distributions, it is shown that the DM mass can be probed down to as low as O(10) MeV, and the derived bounds on the DM-nucleus scattering cross section are highly sensitive to the high-velocity tails of the DM velocity distribution.