The Dynamics of Nuclear Coalescence or Reseparation
Аннотация
A qualitative theory of the macroscopic dynamics of nucleus-nucleus collisions is presented. Attention is focused on three degrees of freedom: asymmetry, fragment separation, and neck size. The physical ingredients are a macroscopic (liquid-drop) potential energy [1], a macroscopic dissipation (in the form of the Wall- and Wall-plus-Window formulae [2, 3]) and a simplified treatment of the inertial force. These ingredients are distilled into algebraic equations of motion that can often be solved in closed form. The applications include the calculation of the normal modes of motion around the saddle-point shapes, and the division of nuclear reactions into: (a) dinucleus (deep-inelastic) reactions, (b) mononucleus or composite nucleus (quasi-fission) reactions, and (c) compound-nucleus reactions. Static and dynamic scaling rules are deduced for comparing different dinuclear reactions in a systematic way. Estimates are given for the critical curve in the space of target and projectile mass above which deep-inelastic reactions ought to make their appearance. The extra push over the interaction barrier needed to make two nuclei form a composite nucleus or else to fuse into a compound nucleus is also estimated.