EU Science Hub

Underground laboratory for ultra-low level gamma-ray spectrometry

JRC operates a laboratory for ultralow-level radioactivity measurements inside the 225 m deep underground laboratory HADES, which is operated by EURIDICE and located at the premises of the Belgian Nuclear Research Centre. In HADES, the muon flux (secondary cosmic rays) is a factor of 5000 lower compared to above ground and the flux of protons, neutrons and electrons is reduced to an insignificant level. This reduction of the cosmic ray flux makes the background in gamma-ray spectrometry measurements significantly lower compared to above ground. Therefore it is possible to detect very low amounts of radioactivity, we are talking about levels of some hundred mBq (micro-Becquerel, i.e. a few nuclear disintegrations per day). Eleven specially designed low-background gamma-ray detectors are used for the measurements. In addition there is the possibility of characterising the top deadlayer of a HPGe-detector by using a specially designed scanning system available in HADES. The measurements support projects in a wide range of fields, and over 200 projects have been carried out the past 15 years.

JRC- Geel: stories behind the scenes