Cross sections for thermal neutron capture by 180 W and 184 W.

Based on activation measurements with W targets of natural isotopic abundance, the cross sections for thermal neutron capture by 180 W and 184 W have been determined by comparing the activities of 181 W and 185 W after activation with that of 187 W. Relative to the known cross sections for capture by 186 W, after correction of the latter for changes in the recommended γ-ray branching intensities, the values of the thermal cross sections have been determined to be 22.7(16) b for capture by 180 W and 1.60(11) b for 184 W. The half-life of 187 W was re-determined to be 23.80(3) h.