Fission-fragment angular correlations and fission probabilities have been measured for a series of odd-$A$ uranium and plutonium isotopes excited by ($d,p$), ($t,d$), and ($t,p$) reactions. The following fissioning nuclei have been studied: (1) ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$ from ($d,pf$), ($t,pf$); (2) ${}_{}{}^{237}{}_{}{}^{}\mathrm{U}$ from ($d,pf$), ($t,df$), ($t,pf$); (3) ${}_{}{}^{239}{}_{}{}^{}\mathrm{U}$ from ($d,pf$); (4) ${}_{}{}^{241}{}_{}{}^{}\mathrm{Pu}$ from ($d,pf$), ($t,df$), ($t,pf$); and (5) ${}_{}{}^{243}{}_{}{}^{}\mathrm{Pu}$ from ($d,pf$), ($t,df$). Fission probabilities and angular-correlation coefficients for each case are compared with previously reported ($n,f$) results. The direct-reaction experiments show fission thresholds at excitation energies equal to or less than threshold energies observed in ($n,f$) experiments. Some qualitative characteristics of the transition-state spectrum for the nuclei studied are determined from comparisons of the direct-reaction and ($n,f$) results.

• Received 19 January 1970

DOI:https://doi.org/10.1103/PhysRevC.2.1758