Measurement of absolute gamma-ray emission probabilities from decay of 138Xe

• The activity of 138Xe was obtained by the decay relationship between 138Xe and 138Cs.
• The full-energy peak efficiencies of gamma-ray for 138Xe and 138Cs were accurately calibrated.
• The absolute gamma-ray probabilities from decay of 138Xe were determined.

The fission gaseous 138Xe products play an important role in the research of nuclear-reaction products and radioisotope applications. Therefore, precise data for emission probabilities of gamma-ray from decay of 138Xe are highly desired. However, a high precision is not achievable with a sufficient accuracy due to the limitations of the usual experimental techniques. In this paper, after the homogeneous sources of 138Xe–138Cs were prepared, the activity of 138Xe was obtained by the decay relationship between 138Xe and 138Cs using a HPGe detector. The full-energy peak efficiencies of gamma-ray for 138Xe and 138Cs were accurately calibrated using many activity standard sources and self-absorption was corrected. As a result, the absolute emission probabilities of the 258.4, 434.6 and 1768.3 keV gamma-ray from decay of 138Xe were determined to be 34.9(10)%, 22.2(6)% and 18.8(5)%, respectively.