The 41 and 35 MeV helium ion-induced fission of 185Re and 187Re

Abstract

Extension of the particle induced fission of elements of atomic number less than 84 has produced a pattern for the characteristics of the observed symmetric fission fragment mass distribution curves. The enriched isotopes 185Re and 187Re were bombarded with 41 and 35 MeV helium ions and produced fission fragment curves which have widths at half maximum, W 1 2 , of the order of 9±2 a.m.u. for each species. The results are somewhat uncertain due to what appears to be a residual low level contamination in the Re powder targets. This yields a rather broad based mass distribution curve out of which rises the apparent fission fragment distribution curve of the 185Re and 187Re. These determinations are further complicated by the fact that the total fission cross sections, σ f , for these two species are of the order of 10μbarn. The pseudo fission fragment cross sections for the suspected contamination are of the order of ·01 μbarn or more. The total cross sections for fission of 185Re and 187Re were 12·7 and 9·6 μbarn respectively at 41 MeV and 5·1 and 5·8 μbarn respectively at 35 MeV with an error of approximately ±20 per cent in all cases.