title: Low-level γ-ray spectrometry at the underground laboratory Garching.
abstract: Two low-background setups for material screening based on HPGe detectors were built in the Garching Underground Laboratory with an overburden of ~10 m.w.e. They include several layers of passive shielding as well as an active muon veto. The first setup (GEM) comprises a 150% efficiency HPGe detector which can optionally be surrounded by a NaI(Tl) scintillation detector that serves as anti-Compton veto. The second setup (LoAx) consists of two smaller HPGe detectors which are arranged face-to-face to cover a larger solid angle around the sample and to allow coincidence measurements. For a 5.6 kg piece of copper after 11 days of measurement we have reached a sensitivity for (226)Ra and (228)Ra/(228)Th of ~5 mBq kg(-1) with the GEM setup. In the LoAx setup we have achieved limits of less than 100 mBq kg(-1) for (234)Th and (210)Pb with a 156 g sample of PPO wavelength shifter after 18 days of measurement.
authors.affiliation: Physik-Department E15, Technische Universität München, 85748 Garching, Germany.
authors.forename: M v
authors.initials: Mv
authors.lastname: Sivers
authors.affiliation: Physik-Department E15, Technische Universität München, 85748 Garching, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Hofmann
authors.affiliation: Physik-Department E15, Technische Universität München, 85748 Garching, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Mannel
authors.affiliation: Physik-Department E15, Technische Universität München, 85748 Garching, Germany.
authors.forename: F v
authors.initials: Fv
authors.lastname: Feilitzsch
authors.affiliation: Physik-Department E15, Technische Universität München, 85748 Garching, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Oberauer
authors.affiliation: Physik-Department E15, Technische Universität München, 85748 Garching, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Potzel
authors.affiliation: Physik-Department E15, Technische Universität München, 85748 Garching, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Schönert
keywords: HPGe detectors; Low-level gamma-ray spectrometry; Underground laboratory