A new versatile underground gamma-ray spectrometry system.

The newest development in IRMM's underground analytical facility is a large lead shield lined with copper that is versatile and can host several detectors of different types. The characteristics and the background performance of the shield are described for four different detector configurations involving HPGe-detectors and NaI-detectors. The shield has been designed to swap detectors, while still maintaining a low background.

Study of the double beta decays of 96Ru and 104Ru.

In this work we present new improved experimental limits for the partial half-lives of the double beta processes of (96)Ru and (104)Ru, obtained by means of a γ-ray spectrometry measurement. A disc of metallic Ru of natural isotopic abundance was sandwiched between two HPGe-detectors in the 225 m deep underground laboratory HADES. After 108 days of measurement, the lower bounds for the partial half-lives were up to 6.

Ultra-low background measurements of decayed aerosol filters.

Aerosol samples collected on filter media were analyzed using HPGe detectors employing varying background-reduction techniques in order to experimentally evaluate the opportunity to apply ultra-low background measurement methods to samples collected, for instance, by the Comprehensive Test Ban Treaty International Monitoring System (IMS). In this way, realistic estimates of the impact of low-background methodology on the sensitivity obtained in systems such as the IMS were assessed. The current detectability requirement of stations in the IMS is 30 μBq/m of air for Ba, which would imply ~10 fissions per daily sample.