The 2002 IAEA test spectra for low-level γ-ray spectrometry software

Test spectra for low-level γ-ray spectrometry were acquired and made available to the general public at www.iri.tudelft.nl/~rc/fmr/iaea2002. As opposed to the 1995 test spectra, where reference values were made available only for the peak energies and areas, the new set of test spectra was acquired with certified sources, so that the reference values are radionuclide activities. Two well-defined detection geometries were employed: a 500 ml Marinelli beaker on a 33% relative efficiency HPGe detector; and a 100 ml pillbox on a 96% HPGe detector. The complete set addresses various issues that are especially important in low-level gamma-ray spectrometry, i.e. determination of efficiency curves in the presence of coincidence summing, differences in source geometry and density between standard and sample, poor statistics, shielding of background by the sample, use of low X- or γ-ray energies and the assumption of secular equilibrium of the natural radionuclides. The set was used in an IAEA intercomparison of software packages in December, 2002, reported on in a separate paper.