Low-level gamma-ray spectrometry using Ge-detectors

The technological advances that have taken place during the past 45 years in the fabrication of high purity germanium crystals have had a significant impact on low-level gamma-ray spectrometry. Today, Ge-detectors with high purity Ge-crystals of 2 kg are readily available and detectors with crystals up to 5 kg can be produced. Use of large area crystals results in high detection efficiencies, which can serve to reduce detection limits or to make faster measurements of low activity samples possible. The second major development that has contributed to lowering detection limits has been research on identifying and reducing the background components in gamma-ray spectrometry systems. This paper deals with the major technical factors affecting the performance of low-background HPGe-detectors and provides an overview of the major areas of application.