Speaker
Description
Germanium spectroscopy is a non-destructive screening method that provides precise information on primordial, cosmogenic, and anthropogenic radioactive contaminants using high-resolution $\gamma$-ray spectroscopy. Gator is a high-sensitivity, low-background germanium spectrometer that is installed at the Gran Sasso Underground Laboratory (LNGS) in Italy. It is operated at an average depth of 3600 meter water equivalent and is used for material screening and selection in ultra-low-background, rare-event search experiments in astroparticle physics, such as XENONnT, LEGEND and DARWIN/XLZD, and also used to characterize the radioactivity level in samples from the Bedretto Lab, a proposed underground laboratory in Switzerland with a comparable cosmic muon shielding to LNGS. In addition to being a screening facility, the instrument has also been used to perform high-precision searches for possible violations of the Pauli Exclusion Principle. The 2.2 kg p-type HPGe crystal housed in an electro-refined copper cryostat is equipped with a passive shield made of layers of copper, lead and polyethylene. The sample cavity is purged with gaseous nitrogen maintained at positive pressure for radon suppression. The background rate is (82.0 $\pm$ 0.7) counts/(kg $\cdot$ day) in the energy range 100-2700 keV. The data acquisition system and the electronics were upgraded recently which reduced the low energy electronic noise below 100 keV. This work demonstrates the stability of key operational parameters under operating conditions. The sample analysis procedure is summarized and the sensitivity of Gator is demonstrated by examining one material sample from the Bedretto laboratory site.