Saturation analysis as a test of statistical fission in heavy ion reactions

Abstract

Evaporation residue and binary (fissionlike) cross sections are reported for $^{56}\mathrm{Fe}$+$^{120,122}\mathrm{Sn}$ at incident $^{56}\mathrm{Fe}$ energies between 330 and 456 MeV. The ${\ensuremath{\sigma}}_{\mathrm{ER}}$ are compared with results for the two additional entrance channels $^{35}\mathrm{Cl}$+ $^{141}\mathrm{Pr}$ and $^{86}\mathrm{Kr}$+ $^{90}\mathrm{Zr}$ producing similar compound nuclei. Comparisons of $\frac{{\ensuremath{\sigma}}_{\mathrm{ER}}}{\ensuremath{\pi}{\ensuremath{\lambda}}^{2}}$ versus excitation energy (which tests the Bohr independence hypothesis) support the conclusion that the yields are limited by statistical fission decay. Similar results are shown for the entrance channels $^{84,86}\mathrm{Kr}$+ $^{65}\mathrm{Cu}$ and $^{40}\mathrm{Ar}$+ $^{109}\mathrm{Ag}$. It is shown that evaporation residue data of this type (where yields are limited by saturation in the fission channel) provide a good means of determining statistical fission parameters.NUCLEAR REACTIONS Illustrate consistency of evaporation residue excitation functions formed in heavy ion reactions with Bohr independence hypothesis; illustrate that statistical parameters deduced should be valid.