Population of Fission Isomers inU236by the (d,p) Reaction

Measurements have been made of the ratio of the cross section for producing a fission isomer by the ($d,p$) reaction to the cross section for the ($d,pf$) reaction as a function of a discriminator setting on the energy of the outgoing proton. For the ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}\mathrm{}(d,p)\mathrm{}{}_{}{}^{236m}{}_{}{}^{}\mathrm{U}$ reaction the results give isomer/prompt ratios of (0.87 ± 0.13) × ${10}^{-4\mathrm{}}$ for all excitation energies less than 7.5 MeV and (2.05 ± 0.25) × ${10}^{-4\mathrm{}}$ for excitation energies less than 6.0 MeV. The value obtained for the half-life of the ${}_{}{}^{236m}{}_{}{}^{}\mathrm{U}$ isomer is $T_{\frac{1}{2}}=130\mathrm{}\pm 15$ nsec.