Two recent studies of high-spin fission from compound nuclei near ${}_{}{}^{200}{}_{}{}^{}\mathrm{Pb}$, formed in three different entrance channels (${}_{}{}^6{}_{}{}^{}\mathrm{Li}$+${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$, ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$+${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$, and ${}_{}{}^{30}{}_{}{}^{}\mathrm{Si}$+${}_{}{}^{170}{}_{}{}^{}\mathrm{Er}$), have led to differing conclusions concerning the need to modify rotating liquid-drop model fission barrier heights to reproduce observed decay properties. In order to investigate possible origins of the differences, we have performed consistent statistical model calculations for all three systems. We obtain satisfactory agreement with the measured fission cross sections for the three systems with a level density treatment incorporating collective enhancements which fade with increasing temperature, and input structure parameters fixed to predictions of the rotating liquid-drop model and the noninteracting Fermi-gas model. We thus find no evidence for any significant inadequacy of the rotating-liquid-drop-noninteracting-Fermi-gas structure predictions for high excitation and $A\simeq 200$.

• Received 9 June 1983

DOI:https://doi.org/10.1103/PhysRevC.29.872