NIST is equipped with a high resolution gamma-ray spectrometry system used for activity and impurity measurements of gamma-ray emitting sources used for nuclear power plants, medical and homeland security applications as well as development of standard reference materials.
The NIST high resolution gamma-ray spectrometry system is composed of five High Purity Germanium (HPGe) detectors and a silicon-drifted detector. The HPGe detectors that are used for calibration of gamma-ray emitting sources in an energy range from 30 keV to 3.5 MeV (the range depends on detector and geometry) while the silicon-drifted detector is used for sources emitting low-energy gamma-rays between 5 keV and 130 keV. This system requires constant updates and maintenance of the detectors and associated electronics. Efficiency measurements are routinely updated and checked for different source geometries including point sources, Marinelli beakers, gas spheres and glass ampoules.