The limit of nuclear deformation and fission properties of heavy and superheavy elements

The degrees of the deformation of nuclei at the scission points in the symmetric and asymmetric fission are experimentally determined. They are found to be constant, respectively, in a wide range of Af among the asymmetric fission and among the asymmetric fission of highly excited nuclei although in the latter for the spontaneous fission and low energy induced fission, the degree of deformation decreases gradually for Af>245 until Af∼260. The constancy of the degree of the scission deformation in each fission mode leads to a TKE systematic formula for each fission mode which is comparable to Viola's TKE formula. Based on the new TKE formulas derived from the deformation parameter of the fissioning nucleus, the extension of the present knowledge to predict the fission properties of the superheavy elements is addressed. It is pointed out that the symmetric and asymmetric fission valleys may merge into one for the superheavy elements around the A=280-290 region