Fertile-to-Fissile and Fission Measurements for Depleted Uranium and Thorium Bombarded by 800-MeV Protons

Axial distributions of fissions and of fertile-to-fissile conversions in thick depleted uranium and thorium targets bombarded by 800-MeV protons have been measured. The amounts of ²³⁹Pu and ²³³ U produced were determined by measuring the yields of ²³⁹Np and ²³³Pa, respectively. The number of fissions was deduced from fission product mass-yield curves. Integration of the axial distributions gave the total number of conversions and fissions occurring in the targets. For the uranium target, experimental results were 5.90 ± 0.25 fissions and 3.81 ± 0.01 atoms of²³⁹Pu produced per incident proton. Corresponding calculated results were 6.14 ± 0.04 and 3.88 ± 0.03. In the thorium target, 1.56 ± 0.25 fissions and 1.25 ± 0.01 atoms of ²³³U per incident proton were measured; the calculated values were 1.54 ±0 0.01 fissions and 1.27 ± 0.01 atom/proton.