Transition-State Theory for Fission Angular Distributions: A Flexible-Rotor Model

Current studies of heavy-ion reactions make extensive use of fission-fragment angular distributions to prove the limits of statistical equilibrium. The "standard" theory was derived for a rigid-rotor, transition-state nucleus. Here a more complete theory is developed by inclusion of the dependence of transition-state shape on orientation of the symmetry axis. It is concluded that even this improved application of the liquid-drop model cannot give an adequate prediction of the $\frac{Z^2}{A}$ dependence of fission-fragment anisotropies.