Discrete deexcitations in 235U below 3 MeV from nuclear resonance fluorescence

Gamma-ray transitions in U-235 were measured using the (gamma,gamma') reaction below 3 MeV. The nuclear-resonance-fluorescence experiment was carried out at the High-Intensity gamma-ray Source facility using nearly monoenergetic and circularly polarized photon beams. More than 20 transitions corresponding to deexcitations to the ground state and low-lying levels in U-235 were observed. The integrated cross sections to the excited levels and intensities of branching transitions were deduced. The experimental results are compared with predictions from a quasiparticle random-phase approximation in a deformed basis.