Observation of Anisotropy in the Fission Decay of Nuclei with Vanishing Fission Barrier

Abstract

Fission angular distributions for nuclei formed by fusion of ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$, ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$, ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$, ${}_{}{}^{248}{}_{}{}^{}\mathrm{Cm}$ show an appreciable anisotropy although spherical saddle-point configurations are predicted for these systems by the rotating-liquid-drop model. The analysis of the data in terms of the statistical model indicate that composite systems of $Z=106, 108, \mathrm{and} 112$ have been formed with deformations $\beta <~0.35$.