Determination of photon emission probabilities for the main gamma-rays of 223Ra in equilibrium with its progeny

•Measurements of photon emission probabilities of 223Ra in equilibrium with its progeny.•Use of high purity germanium detectors for gamma-ray spectrometry measurements.•Use of the primary activity determination of 223Ra sources.

The currently published 223Ra gamma-ray emission probabilities display a wide variation in the values depending on the source of the data. The National Institute of Standards and Technology performed activity measurements on a 223Ra solution that was used to prepare several sources that were used to determine the photon emission probabilities for the main gamma-rays of 223Ra in equilibrium with its progeny. Several high purity germanium (HPGe) detectors were used to perform the gamma-ray spectrometry measurements.