Neutron-resonance capture gamma rays inBa136

Earlier experiments have reported an anomalous $M1\mathrm{}$ strength for the ground-state radiative transition in ${}_{}{}^{136}{}_{}{}^{}\mathrm{Ba}$ following neutron capture. Barium has been restudied in discrete resonance and average resonance capture. The $\gamma$-ray widths are measured and tabulated. We find a $\gamma$-ray strength function for $M1\mathrm{}$ transitions of (20 ± 7) × ${10}^{-9\mathrm{}}$ Me${\mathrm{V}}^{-3\mathrm{}}$ from a study of capture in discrete resonances below 500 eV. From a study of neutron capture in an energy band 2 keV wide at 24.5 keV we find comparable values. These values are near the mean value (18 × ${10}^{-9\mathrm{}}$) Me${\mathrm{V}}^{-3\mathrm{}}$ observed for all nuclei; hence we conclude that the average $M1\mathrm{}$ strength in ${}_{}{}^{136}{}_{}{}^{}\mathrm{Ba}$ is quite normal. Additional widths for primary $E1\mathrm{}$ and $M1\mathrm{}$ transitions are also reported. A detailed multilevel analysis of the partial ($n,\gamma$) cross sections below the first ${}_{}{}^{135}{}_{}{}^{}\mathrm{Ba}$ resonance at 24 eV shows a negligible direct $M1\mathrm{}$ component.