Abstract
Fission-fragment mass and total-kinetic-energy (TKE) distributions following fission of even-even nuclides in the region 74 le Z le 126 and 92 le N le 230, comprising 896 nuclides have been calculated using the Brownian shape-motion method. The emphasis is the region of superheavy nuclei. To show compatibility with earlier results the calculations are extended to include earlier studied regions. An island of asymmetric fission is obtained in the superheavy region, 106le Zle 114 and 162le Nle 176, where the heavy fragment is found to be close to ^{208}Pb and the light fragment adjusts accordingly. Most experimentally observed alpha -decay chains of superheavy nuclei with Z > 113 terminate by spontaneous fission in our predicted region of asymmetric fission. In these cases, the pronounced large asymmetry is accompanied by a low TKE value compatible with measurements.
Highlights
The first step is to calculate the potential-energy surfaces as functions of five shape parameters
We use the same set of levels to calculate the shell corrections for several neighbouring nuclei, which still leads to satisfactory accuracy
The total available energy in the fission process is given by the initial excitation energy, Eexc, with respect to the ground state of the fissioning nucleus and the Q value, The available energy is divided between the total kinetic energy and the total excitation energy of the fragments, i.e., Q∗ = ETKE + ETXE
Summary
The first step is to calculate the potential-energy surfaces as functions of five shape parameters. In previous publications [3,4,6,7,8,9] potential-energy surfaces calculated in Ref. Where BS is the ratio of the surface area of the current shape to that of a spherical shape. This is important for nuclei in the vicinity of fermium (Fm) as discussed in great detail in Refs. Once the levels are determined, the time needed to calculate the shell and pairing corrections and macroscopic contributions to the potential energy is almost negligible. We use the same set of levels to calculate the shell corrections for several neighbouring nuclei, which still leads to satisfactory accuracy.
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