Rare decay modes by cluster emission from nuclei

A new interpretation of cluster preformation probability is given as the penetrability of the prescission part of the barrier, within a fission theory. It is shown that the preformed cluster model is equivalent to the fission model. A universal curve of cluster radioactivities is derived. The parameter Z²/A is only applicable to symmetric fission. A similar quantity for asymmetric fission may be borrowed from the theory of heavy ion fusion reactions. The logarithm of symmetric fission half-lives calculated in the framework of the liquid drop model is linearly decreasing function of fissility, but a different dependence is obtained for asymmetric fission.