Scintillation and Semiconductor y-Ray Detectors

In liquid nitrogen (LN2) cooled detectors, the detector element (and in some cases preamplifier components), are housed in a clean vacuum chamber, which is attached to or inserted in a LN2 Dewar. The detector is in thermal contact with the liquid nitrogen, which cools it to around 77°K or —200°C. At these temperatures, reverse leakage currents are in the range of 10 —10 amperes. A cross-sectional view of a typical liquid nitrogen cryostat is shown in Fig. 6.2. 

While Ge(Li) detectors are primarily used for y-ray spectroscopy in the energy range of 50 keV to 10 MeV, the Planar pure Ge detectors have inherently good response down to very low energies (2-200 keV). 

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