Spallation-Fission Competition in Heavy-Element Reactions: Th232+He4 and U233+d

Abstract

Cross sections and excitation functions have been determined for spallation and fission products from bombardments of ${\mathrm{Th}}^{232}$ with helium ions (15 to 46 Mev) and ${\mathrm{U}}^{233}$ with deuterons (9 to 24 Mev). This work extends a series of investigations of charged particle ($\alpha$, $d$, and $p$) induced reactions in heavy elements ($Z\ge 88$). Radiochemical methods were employed to isolate products corresponding to the following spallation reactions: neutron emission, ($\alpha , 4n$), ($\alpha , 5n$), ($d, n$), ($d, 2n$), and ($d, 3n$); emission of one proton and neutrons ($\alpha , p$), ($\alpha , \mathrm{pn}$), ($\alpha , p2n$), and ($\alpha , p3n$); and emission of two protons and neutrons, ($\alpha , 2p$), ($\alpha , 2pn$), and ($\alpha , \alpha n$), and ($d, \alpha n$). In addition, the following fission products were isolated from one or more bombardments: ${\mathrm{Zn}}^{72}$, ${\mathrm{Ge}}^{77}$, ${\mathrm{As}}^{77}$, ${\mathrm{Br}}^{82,83}$, ${\mathrm{Rb}}^{86}$, ${\mathrm{Sr}}^{89,91}$, ${\mathrm{Y}}^{93}$, ${\mathrm{Zr}}^{95,97}$, ${\mathrm{Nb}}^{96}$, ${\mathrm{Mo}}^{99}$, ${\mathrm{Ru}}^{103,105,106}$, ${\mathrm{Pd}}^{109,112}$, ${\mathrm{Ag}}^{111}$, ${\mathrm{Cd}}^{115,115m,117}$, ${\mathrm{I}}^{131,133}$, ${\mathrm{Cs}}^{136}$, ${\mathrm{Ba}}^{139,140}$, ${\mathrm{La}}^{140}$, ${\mathrm{Ce}}^{141,143,144}$, ${\mathrm{Nd}}^{147}$, ${\mathrm{Eu}}^{157}$, and ${\mathrm{Gd}}^{159}$.