Ultra compact, hand-held HPGe detector assembly for field use

HPGe detectors are mainly used under laboratory conditions. There are, however, field applications, which require a very high level of portability of high-resolution spectrometric equipment. Examples are radioactivity measurements in the environment, in the nuclear industry, international safeguards and the in-situ characterization by experts of an item, which caused an alarm of a fixed, automated radiation portal monitor (RPM), but the isotope identification with a scintillation detector based, hand-held radionuclide identification device (RID) was not successful. A small size, low weight Dewar for such detectors has been developed according to the following requirements: extremely short cooling down time of <1.5 hours, liquid nitrogen holding time >20 hours, easy filling, not requiring pressurization with a filling time of <10 min, a fast way to empty the Dewar if required and use in horizontal and upright orientations. The Dewar is equipped with a standard charge sensitive preamplifier and can carry planar detector up to and area of 2000 mm2 and co-axial detectors with a efficiency of up to 20%. If it is combined with a small, low power mini multi channel analyzer, e.g., the MMCA (www.gbs-elektronik.de) the battery life of the gamma spectrometer reaches 9 hours, which can be matched with modern, Centrino based notebook computers.