Low background germanium spectrometry - The bottom line

A brief summary of the various sources of background affecting germanium diode gamma-ray spectrometers and the relative magnitude of each is given. Methods for eliminating each are discussed along with practical cost/benefit ratios. Examples of operating detectors having backgrounds more than six orders of magnitude lower than typical anticoincidence shielded low-background laboratory systems are presented. Consideration of background contributed by samples to be analyzed will define practical levels of desirable system background. The bottom line is realistically attained when the major contributions to the background come from cosmogenically produced 68Ge and double-beta decay of 76Ge in the detector. The true bottom line is reached with isotopically enriched detectors which eliminate these two chemically inseparable radioactive impurities. Data from isotopically enriched detectors are presented