Excitation of octupole, beta- and gamma-vibration band levels of 238U by inelastic neutron scattering

Abstract

Experimental data on inelastic neutron scattering are analyzed in a Hauser–Feshbach–Moldauer approach with a coupled-channel estimates of the direct reaction contribution. For the direct excitation of the ground state rotational band levels with J π = 0 + , 2 + , 4 + , 6 + , 8 + the rigid rotator model was used, whereas for the direct excitation of members of the β-, γ- ( K π = 0 2 + , 0 3 + , 2 + ) and first octupole band ( K π = 0 − ) a soft-deformable rotator model was used. Quadrupole, octupole, hexadecapole and gamma-deformation parameters are defined by consistent analysis of excited rotational–vibrational band structures and excitation cross sections of the relevant levels. Structures evident in measured neutron emission spectra for E n ∼ 1 – 6 MeV are correlated with excitation of levels of K π = 0 − and K π = 0 2 + , 0 3 + , 2 + bands.