Semiconductor Detectors for Gamma-Ray Spectrometry

Selection of detector type and size should be controlled by its application, both immediate and long-term. In addition to cost, important performance characteristics of a semiconductor detector for gamma-ray spectrometry are the resolution, efficiency and peak-to-Compton ratio. 

Hgure 4 Schematic cross-sectional view of a semiconductor detector for gamma-ray spectrometry with liquid nitrogen Dewar. 

Lithium drifted germanium detectors were in use during the first years of semiconductor detectors application for gamma-ray spectrometry. They showed good resolution and efficiency but had to be kept at the temperature of liquid nitrogen all the time. 

Gallium arsenide is a material with some theoretical promise as a semiconductor detector which although abandoned for the present could ultimately have a place in gamma spectrometry due to improvements in the technology of manufacture of the material for the electronics industry. The other materials listed in Table 3.1 have all been considered as potential materials for gamma spectrometry, but discarded for one reason or another. In practice, the material almost universally used for gamma-ray spectrometry is germanium and we shall not deal in detail with other types of detector, with the exception of scintillation detectors, which will be discussed separately in Chapter 10. 

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