High-resolution gamma-ray spectroscopy (HRGS) is used to confirm the presence of plutonium isotopes by detecting gamma-rays that are emitted when the isotopes decay. It uses the unique signature of gamma-ray quanta to identify radio nuclides and to determine their activity. A gamma-ray spectrum shows peaks for gamma-rays that completely deposited their energy in the detector. When the spectrometer is calibrated for the gamma-ray energy, the position of the peaks and corresponding energy can be used to identify the radionuclide responsible for the peak. Once radionuclides have been identified in the spectrum, their activity can be computed if information on the detection efficiency calibration is known. This technology collects proliferation sensitive information and requires the use of an information barrier.
Read more about HRGS in the following technology data sheet.