High Purity Germanium (HPGe) gamma-ray detectors have been widely used in the
nuclear and industrial sectors for many applications over many years. The advantages of
HPGe detectors in terms of energy resolution, efficiency, sensitivity, and ease of
spectrum analysis have been clear in a wide range of applications both fixed-installed and
in situ. The drawback to using these detectors, though, has always been the need to cool
them to near cryogenic temperatures. As a general rule, HPGe detectors operate at a
temperature range of 90-120K. To get to these temperatures, liquid nitrogen has
traditionally been used with a cryostat and dewar combination designed to provide the
cooling path. However, using liquid nitrogen, even in a dewar configuration, poses
health risks as well as operational problems.