Symmetric multi-fragmentation barriers and their temperature dependence in medium and heavy mass nuclei

Shapes consisting of a series of pear-like bodies surrounding an inner joined sphere are assumed to be those associated with symmetric fission or fragmentation into two or more fragments. The shapes evolve smoothly from that of an initial spherical nucleus to the scission point. The shapes are calculated using a generalization of the cassinian ovaloid shape parameterization, which has been demonstrated to be a good approximation for binary fission. Using this parameterization, fission barriers have been calculated for 2-, 3-, 4-, 6- and 8-fold multi-fragment final states. Proximity effects are included. The temperature dependence of these fission barriers is also calculated. The importance of nuclear dynamics in determining the range in which static barriers are sampled is discussed. (orig.)