The GeMSE facility for low-background γ-ray spectrometry

Abstract

We describe a new high-purity germanium (HPGe) detector setup for low-background γ-ray spectrometry. The GeMSE facility (Germanium Material and meteorite Screening Experiment) is dedicated to material screening for rare event searches in astroparticle physics as well as to the characterization of meteorites. It is installed in a medium depth (∼620 m.w.e.) underground laboratory in Switzerland in a multi-layer shielding and is equipped with an active muon veto. We have reached a very competitive integral background rate of (246 ± 2) counts/day (100-2700 keV) and measured a sensitivity of ∼0.5-0.6 mBq/kg for long-lived isotopes from the 238 U/ 232 Th chains in a ∼1 kg sample screened for ∼27 days. An extrapolation to higher sample masses and measurement times suggests a maximum sensitivity in the O(50) µBq/kg range. We describe the data analysis based on Bayesian statistics, background simulations, the efficiency calibration and first sample measurements.

Radionuclide activities in recent chondrite falls determined by gamma‐ray spectrometry: Implications for terrestrial age estimates

“…For Huaxi and Xining, A and B denote subsamples from the respective meteorites. procedure reproduces detection efficiencies, in the relevant energy range, with accuracies better than 2% as determined by previous measurements with calibrated samples (von Sivers et al 2016). Average bulk densities of the respective chondrite groups (Consolmagno et al 2008) were generally used as input when running the simulations.…”

“…Total measurement times were 1-3 weeks for each individual sample. The GeMSE facility and the general analytical procedures are described in detail in von Sivers et al (2016). All measured radionuclides, along with the corresponding half-lives and gamma lines, are listed in Table 2.…”

“…The radionuclide record preserved in observed meteorite falls and meteorite finds can also be used to verify fall observations and provide accurate terrestrial age determinations. Since early 2016, the lowbackground Germanium Material and Meteorite Screening Experiment (GeMSE) (von Sivers et al 2016), situated in a tunnel below Vue-des-Alpes in the Swiss Jura mountains, has dedicated substantial screening time to meteorite fall samples. The goals of the campaign are a set of cosmogenic radionuclide measurements which can be used to evaluate measurements used to screen Oman finds and at the same time explore methods to increase measurement precision and improve measurement routines in ongoing and future projects.…”

The XENON1T dark matter experiment

“…It was optimized for linear operation within the entire dynamic range of the ADCs (see Sect. [36,37]. One connector was placed above the TPC and the second one in front of the Conflat flanges in the gaseous xenon.…”

Material radioassay and selection for the XENON1T dark matter experiment

“…Therefore all of the screened batches were used in the final construction. Additionally, a measurement of a representative sample of the high-voltage connectors mounted in custom-made PTFE holders, as produced for the final assembly, was performed with a new HPGe spectrometer, GeMSE, and showed consistent results [36].…”