Decay Schemes for the Isomers of ¹⁴⁸Pm and the Cross Sections for their Production by Neutron Capture in ¹⁴⁷Pm

Abstract

The γ-ray spectra arising from the decay of 41-day 148 Pm m and 5-day 148 Pm g produced by the irradiation of 2.6-year 147 Pm in a thermal reactor neutron flux have been measured with a Ge(Li) detector. The absolute probabilities for γ-ray emission were determined from an analysis of the spectra and used to construct an improved decay scheme for the two isomers and to obtain their production cross sections. The 147 Pm thermal neutron cross sections obtained after making a small correction for epithermal capture are 84 ± 10 b and 72.4 ± 3.0 b for the production of the 148 Pm g and 148 Pm m activities respectively, in good agreement with the results of Fenner and Large, but significantly smaller than other recent measurements.