Fission-fragment angular distributions for 230Th(n,f) in the vicinity of the 715 keV resonance

Fission-fragment angular distributions have been measured for the neutron-induced fission of ²³⁰Th in the vicinity of the 715 keV resonance with a 2.5 keV (FWHM) neutron energy resolution. An analysis was performed to find a set of fission barrier characteristics that reproduce simultaneously the present angular distribution data and the fission cross-section data of Blons et al. The analysis results show that the data for the 715 keV resonance could be fitted only if allowance is made for the existence of two rotational bands with opposite parities but with the same K quantum number. The moment of inertia parameter $\text{kh}{}^2\text{2}\text{I}$ extracted from the analysis has a value of 1.9 keV, which is compatible with the existence of a third minimum in the fission barrier at a quadrupole deformation of ε₂ = 0.85.