Transfer reaction cross sections from the interactions ofNe20andNe22withTh232

Abstract

A target of $^{232}\mathrm{Th}$ has been bombarded with 114 MeV and $^{22}\mathrm{Ne}$ and with 114 MeV and 129 MeV $^{20}\mathrm{Ne}$ beams. Recoiling reaction products were chemically isolated and the cross sections for protactinium, uranium, and neptunium isotopes were determined. The width of the cross section distributions for a given $Z$ and their neutron-richness are the same as those for similar transfers in Ne+$^{248}\mathrm{Cm}$ reactions. Population of low spin isomeric states is favored in these reactions over population of high spin states. As was seen in reactions with heavier targets, an increase in reaction energy does little to shift the evaporation residues toward neutron deficiency. The implications are that only primary products with little or no excitation energy and angular momentum survive the fission process to become evaporation residues in these systems, and that the production of these nuclides is more controlled by the change in the identity of the projectile than by the corresponding change in the target.