Fission Of Nuclei And Metal Clusters

The fission process is very revealing in the way it illustrates the interplay between average (i.e., bulk) properties of the fissioning medium and specific quantum-size effects. In the nuclear quantum liquid, the charge (i.e., proton) density is everywhere confined to be about one-half of the total nucleon density, and the polarizability is extremely small. In metals, on the other hand, the net charge-to-mass ratio is virtually a free parameter and the excess charge resides on the surface, where it is easily polarized by external fields. Because of this, there is a very wide scope for fission studies with metal clusters. So far, such fission experiments have relied on thermally activated fission in competition with the evaporation of neutral atoms. The high polarizability and the sensitivity to initial- and final-state quantum effects is brought to light in this way. On the other hand, fission of large and highly charged clusters, which should be truly symmetric and proceed through a relatively compact transition configuration, remains to be explored.