A New Gamma-ray Spectrometry System for Measurement of Radioactivity Levels in the µ-Bequerel Range

This Academic Thesis deals with the setting up and characterisation of a new underground gamma-ray spectrometry system consisting of 2 HPGe-detectors and a muon shield in a unique lead castle that can be opened using a electric motor. The background count rate of this detector is 220 counts per day and kg Ge, which is the lowest obtained in the underground laboratory HADES so far. The detector has been used in applications ranging from dosimetry and neutron spectrometry to indirect fusion plasma characterisation. In addition measurement of nature's rarest isotope, 180Tam and a measurement determining the half-life of the decay with the lowest Q-value known to man, in 115In, are described.JRC.D.4-Isotope measurement