Constraints on Lightly Ionizing Particles from CDMSlite

TL;DR

This paper reports new direct-detection limits on Lightly Ionizing Particles (LIPs) using the CDMSlite experiment, covering previously unexplored charge, mass, and velocity ranges, and setting the strongest limits for certain charge values.

Contribution

First direct-detection limits on cosmogenically-produced LIPs with very small electric charge, expanding the parameter space explored and excluding non-relativistic LIPs with low velocities.

Findings

Set new upper limits on LIP vertical intensity for charges down to e/160.

Excluded non-relativistic LIPs with βγ as low as 0.1.

Covered a wide range of LIP masses and velocities.

Abstract

The Cryogenic Dark Matter Search low ionization threshold experiment (CDMSlite) achieved efficient detection of very small recoil energies in its germanium target, resulting in sensitivity to Lightly Ionizing Particles (LIPs) in a previously unexplored region of charge, mass, and velocity parameter space. We report first direct-detection limits calculated using the optimum interval method on the vertical intensity of cosmogenically-produced LIPs with an electric charge smaller than $e/(3\times10^5$), as well as the strongest limits for charge $\leq e/160$, with a minimum vertical intensity of $1.36\times10^{-7}$\,cm$^{-2}$s$^{-1}$sr$^{-1}$ at charge $e/160$. These results apply over a wide range of LIP masses (5\,MeV/$c^2$ to 100\,TeV/$c^2$) and cover a wide range of $\beta\gamma$ values (0.1 -- $10^6$), thus excluding non-relativistic LIPs with $\beta\gamma$ as small as 0.1 for the first time.