Multiphonon states in _{56}^{136}Ba_{80}

Low-lying multiphonon states in Ba-136 have been populated with the inelastic neutron scattering reaction. Excitation functions were performed at neutron energies from 2.2 to 3.9 MeV, and gamma-ray angular distributions were measured at 2.5, 3.0, and 3.5 MeV. Lifetimes have been determined using the Doppler-shift attenuation method, and electromagnetic transition rates have been deduced. The previously assigned 2(1,ms)(+) mixed-symmetry state at 2128.9 keV has been confirmed and is not greatly fragmented. For the first time in the N = 80 isotones, a 3(2,ms)(+) two-phonon mixed-symmetry state is proposed. In addition, the 2(5)(+) and the 4(3)(+) levels at 2222.7 and 2356.4 keV, respectively, decay with large B(M1) values to the two-phonon 2(2)(+) and 4(1)(+) states, respectively, which suggests two-phonon mixed-symmetric character. Their excitation energies, however, are not consistent with this interpretation.