Characterizing Low Energy Surface Events on Ge Detectors in LEGEND

The LEGEND experiment is searching for neutrinoless double beta decay (0νββ) in 76Ge using high purity enriched germanium (HPGe) detectors. This search requires a deep understanding of the backgrounds present in our spectrum. While most background rejection efforts focus on the region near Qββ = 2039 keV, the energy at which 0νββ is expected to occur in 76Ge, the great energy resolution and low energy thresholds of HPGe allows us to search for physics beyond the Standard Model, typically at low energies (< 100 keV). The MAJORANA DEMONSTRATOR, a precursor to LEGEND, found that low energy electron and photon signals originating near detector surfaces can be energy degraded, similar to how high energy alphas can be degraded and show up near Qββ. KrSTC, a test-stand at the University of Washington, was designed to study this low energy degradation with an 83mKr source, a radioactive gas that produces monoenergetic electrons and photons with energies < 35 keV. Data taking has revealed a distortion in the low energy spectrum consistent with the energy degradation observed by MAJORANA. In this talk, I will present this data along with simulations that suggest surface charge accumulation may be the dominant cause of this energy loss, an effect that is also relevant for LEGEND.