(n,n'γ) study and structure of the N=82 nuclei /sup 138/Ba and /sup 140/Ce

Low spin levels in /sup 138/Ba and /sup 140/Ce have been studied by means of the (n.n' γ) reactions using reactor fast neutrons. Excited states up to an excitation energy of 3.5 MeV and with spin values up to 6 were populated. Energies, intensities and angular distributions of γ-rays have been measured. In addition to the confirmation of known level characteristics, several unambiguous spin assignments and spin restrictions have been proposed. Multipole mixing ratios have been extracted for the most intense γ-transitions. The experimental level energies and several electromagnetic properties were compared with shell model predictions. The comparison of the experimental and theoretical results demonstrate that the shell model description of excited even parity states of the N=82 nuclei /sup 138/Ba and /sup 140/Ce reflects the essential aspects of their structure