The ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$${(}^{117}$Sn, ${}_{}{}^{118}{}_{}{}^{}\mathrm{Sn}$${)}^{238}$Pu reaction at a beam energy of 630 MeV has been used to attempt populating the 0.5 ns fission isomer in ${}_{}{}^{238}{}_{}{}^{}\mathrm{Pu}$. The measured cross section for prompt fission of ${}_{}{}^{238}{}_{}{}^{}\mathrm{Pu}$ populated by neutron transfer is (6±2) mb while the cross section for prompt fission of ${}_{}{}^{239}{}_{}{}^{}\mathrm{Pu}$ excited by inelastic scattering is (1.7±1.0) mb. A single candidate delayed fission event was observed, corresponding to the population of a fission isomer, most probably in ${}_{}{}^{238}{}_{}{}^{}\mathrm{Pu}$, with a cross section of (80±80) nb. The heavy-ion induced transfer reaction shows no enhancement of the ratio of delayed to prompt fission, compared to light-ion induced reactions.

• Received 16 May 1994

DOI:https://doi.org/10.1103/PhysRevC.51.1025