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Physik-Institut Group of Laura Baudis

The upgraded low-background germanium counting facility Gator for high-sensitivity γ-ray spectrometry

Our group operates the high-purity germanium counting facility Gator at the Gran Sasso Underground Laboratory in Italy, at an average depth of 3600 meter water equivalent.

Gator is dedicated to low-background γ-ray spectrometry and is employed for material screening and selection in ultra-low background, rare-event search experiments in astroparticle physics. The detector is equipped with a passive shield made of layers of copper, lead and polyethylene, and the sample cavity is purged with gaseous nitrogen maintained at positive pressure for radon suppression.

In our recent publication we describe the latest upgrades and performance of Gator, which currently yields a background rate of (82.0±0.7) counts/(kg⋅day) in the energy region 100 keV to 2700 keV, a 20% reduction compared to the previously reported rate. We further show the stability of various operation parameters as a function of time, summarize the sample analysis procedure, and demonstrate Gator's sensitivity by examining one material sample, a candidate photosensor for the DARWIN experiment.