P-type Point Contact (PPC) High-Purity Germanium Detector Performance at Low Temperatures

Observing rare events such as neutrinoless double beta decay (0νββ) requires good energy resolution and low background rates. The GERDA experiment has met these requirements by operating PPC detectors in a liquid argon active veto. However, 39Ar β decays create high backgrounds at low energy. Instead, liquid neon has been proposed, but PPC detectors have not been tested at such low temperatures where charge trapping may degrade energy resolution. At these temperatures, position-dependent trapping increases, reducing the total charge collected from events. A single-detector cryostat was cooled to liquid neon temperature and energy resolution was analyzed at various temperatures after correcting for charge trapping via the technique used in the MAJORANA DEMONSTRATOR. If the charge trapping effect can be appropriately corrected for, good energy resolution can be recovered even at low temperatures. This would allow LEGEND, a next-generation 0νββ search, to employ liquid neon and pursue an additional low-energy physics program, including searches for WIMP scattering and solar axions.