The performance of a variety of superconducting detectors including athermal phonon detectors and qubits is limited by spurious energy depositions, which create background events, noise, and otherwise degrade device performance. In athermal phonon detectors, at high event energies, these energy depositions appear as the zero charge component of the "Low Energy Excess." At lower event energies,...
Xe and Ar dual-phase detectors cannot detect nuclear recoils with energies below 200 eV because of the limitations of ionization processes. Still, the number of excitations and defects in these detectors, which can store energy and produce delayed or excess background electron and photon emission, is lower than in solid-state sensors. Combined with larger mass, this can provide superior...
A variety of detectors across many different rare event search experiments have reported a rising sub-keV low energy excess (LEE) in the spectra of both total substrate energy deposits eV$_{\mathrm{t}}$ and ionization-producing energy deposits eV$_{\mathrm{ee}}$. It has been hypothesized that non-ionizing substrate events such as stress-induced events from crystal or film relaxation could be a...
