Ionization yield in silicon for eV-scale electron-recoil processes
Karthik Ramanathan, Noah Kurinsky
Abstract
The development of single charge resolving, macroscopic silicon detectors has opened a window into rare processes at the $\mathcal{O}(\mathrm{eV})$ scale. In order to reconstruct the energy of a given event, or model the charge signal obtained for a given amount of energy absorbed by the electrons in a detector, an accurate charge yield model is needed. In this paper we review existing measurements of charge yield in silicon, focusing in particular on the region below 1 keV. We highlight a calibration gap between 12--50 eV (referred to as the ``UV-gap'') and employ a phenomenological model of impact ionization to explore the likely charge yield in this energy regime. Finally, we explore the impact of variations in this model on a test case, that of dark matter scattering off electrons, to illustrate the scientific impact of uncertainties in charge yield.