A very low background HPGe detector operating deep underground at 4800 m water equivalent.
A very low background HPGe detector has been installed in the Fréjus underground laboratory in order to investigate radioactive contaminations. The main features and capabilities of the detector are described here.
Gamma background measurements in the Laboratoire Souterrain de Modane
In situ gamma-ray measurements were taken at six locations in the Modane Underground Laboratory. Count rates for gamma radiation within the energy range of 7–2734 keV varied from 15 to 108 γs−1. The arithmetic mean was 79 γs−1 for measurements taken without a collimator. The metamorphic rocks surrounding the Lab are characterized by low activity concentrations of uranium and thorium equal to 12 and 10 Bq kg−1, respectively.
Flash chambers of plastic material
Abstract We describe a type of electrically-pulsed chamber, easy to realize at a low cost even in big size, consisting of a large number of thin, tubular “sensitive cells” of plastic material filled with a noble gas mixture at atmospheric pressure. The luminous discharges that occur in the cells traversed by ionizing particles upon application of the high-voltage sensitizing pulse, yield the tracks - and under certain conditions also the instants of traversal - of the particles themselves, with no severe restriction for their maximum number. Various optical or electrical read-out systems can be utilized to extract the information from the discharged cells. Examples of application of the technique in high-energy and nuclear physics are given.