Low Energy Physics Searches with Germanium ICPC Detectors

The Majorana Demonstrator (MJD) is a low-background experiment that searched for neutrinoless double-beta decay (0νββ) in high-purity germanium (HPGe) detectors enriched in ⁷⁶Ge. MJD utilized P-type Point Contact (PPC) detectors, but a new high-mass detector geometry was necessary to increase the active mass while maintaining low noise levels in future experiments. The Inverted Coaxial Point Contact (ICPC) Detector, with up to five times greater mass, was deployed in MJD for about six months of data collection. In addition to the search for 0νββ, MJD's low background configuration is sensitive to several other beyond standard model (BSM) phenomena, including baryon decay and bosonic dark matter. MJD has now concluded data taking and the successor experiment, LEGEND-200, is searching for 0νββ, primarily with ICPC detectors. To extend the BSM capabilities of MJD to LEGEND-200 and eventually LEGEND-1000, it is necessary to characterize and understand the behavior of ICPC detectors at energies below 100 keV. This talk will describe the results of this study as well as future prospects and challenges.