AC-227 - A SUGGESTED LONG-LIVED MULTIPLE-LINE GAMMA-RAY CALIBRATION STANDARD

x-Ray and gamma-ray lines following the decay of Ac-227 in transient e quilibrium with its daughters were assayed via high-purity germanium-c rystal (HPGe) spectrometry of a chemically purified Ac-227 gamma-ray s ource. Relative emission probabilities were determined for 120 lines ( I(gamma) greater-than-or-equal-to 0.003%), and conversion to absolute emission probabilities was achieved via normalization to the known int ensity of the well-characterized 351-keV gamma-ray line of Bi-211, a d aughter of Ac-227. Special emphasis was paid to the stronger lines, wh ich can be used for energy and/or efficiency calibrations of germanium detectors.