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 148Pmm and 5-day 148Pmg produced by the irradiation of 2.6-year 147Pm 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 147Pm 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 148Pmg and 148Pmm activities respectively, in good agreement with the results of Fenner and Large, but significantly smaller than other recent measurements.