Constraints on Lightly Ionizing Particles from CDMSlite

Area of Science:

• Particle Physics
• Cosmology
• Astrophysics

Background:

• The nature of dark matter remains one of the most significant unsolved problems in physics.
• Detecting dark matter candidates, such as lightly ionizing particles (LIPs), requires highly sensitive experiments capable of measuring small energy depositions.

Purpose of the Study:

• To establish direct-detection limits on the vertical intensity of cosmogenically produced LIPs.
• To explore a new parameter space for LIPs concerning their charge, mass, and velocity.

Main Methods:

• Utilizing the Cryogenic Dark Matter Search low ionization threshold experiment (CDMSlite) with a germanium target.
• Employing the optimum interval method for data analysis to derive LIP intensity limits.
• Achieving efficient detection of very small recoil energies.

Main Results:

• Established first direct-detection limits on LIPs with electric charge smaller than e/(3×10^5).
• Set the strongest limits to date for LIPs with charge ≤e/160, reaching a minimum vertical intensity of 1.36×10^-7 cm^-2 s^-1 sr^-1.
• Covered a broad range of LIP masses (5 MeV/c^2 to 100 TeV/c^2) and velocities (βγ from 0.1 to 10^6).

Conclusions:

• CDMSlite has successfully constrained the parameter space for LIPs, particularly for nonrelativistic LIPs (βγ as low as 0.1).
• The results exclude a significant region for LIPs, contributing to the ongoing search for dark matter candidates.