Formation of heavy neutron-deficient nuclides in 3He-induced reactions

Abstract

Reactions of 3He with actinide nuclei are a promising tool for the production of heavy neutrondeficient nuclei, which are of great interest as tracers in environmental studies. In this work, highly enriched 235U targets 1 mg cm–2 thick were irradiated using 3He ions with energies of 20.4–42.0 MeV at the Accelerator Laboratory of University of Jyvaskyla, Finland. The irradiated targets were analyzed with gamma and alpha spectrometers and then dissolved in order to chemically separate Pu and Np from the fission products and the target material. The chemical yields of 234Np and 236Pu were determined by measuring their activities prior to and after chemical separation. Previously unknown excitation functions of the nuclides 234, 236, 237Pu and 234, 235, 236m Np were thus found. The obtained experimental data were analyzed using the direct reaction theory for a model with nuclear friction included in the fission channel and due consideration of the preequilibrium processes.