Nuclear resonance fluorescence in 136Ba

The resonant scattering of electron bremsstrahlung by an enriched sample of 136Ba has been studied for photon energies of up to 5 MeV. It provided estimates of the radiative widths for 10 levels. Based on the relative yields at scattering angles of 960 and 1260, unambiguous spin assignments were made to 5 of these levels. Where feasible, the yield measurements were supplemented by self-absorption data and by linear polarization studies. For the strongest excitation in 136Ba, at 3.436 MeV, the resonance fluorescence experiments led to a 1- assignment and a value GAMMA0 = 88 +- 22 meV for the partial width of the ground state transition. The corresponding E1 strength is approximately 1/3 of the E1 strengths observed for the strongest low-lying E1 transitions in the even-even N = 82 nuclei. When combined with previous observations for N > 82, the result obtained for 136Ba (N = 80) indicates that the strengths of the ground state transitions from the lowest 1- states peak at N = 82. Yield information on a few levels in 137Ba and 138Ba was also obtained