Mass-Yield Curve of First-Chance Fission from Proton- and Deuteron-Induced Fission ofRa226

Abstract

Information has been obtained on the mass distribution and kinetic energy release for fission of $^{226}\mathrm{Ra}$ induced by protons and deuterons at moderate bombarding energies (20 MeV). The mass distribution, which is triple peaked, has previously been interpreted in terms of two separate fission modes: a single symmetric peak, characteristic of symmetric fission, associated with higher excitation energies; and a double-peaked distribution, characteristic of asymmetric fission, associated with lower excitation energies. It is shown that by a proper choice of proton and deuteron bombarding energies, and by a proper weighting of their respective mass-yield curves, the mass distribution for the fission of a single species, $^{228}\mathrm{Ac}$, can be determined for a single excitation energy. At excitation energies near 25 MeV this mass distribution for $^{228}\mathrm{Ac}$ is shown to be a single symmetric peak, in agreement with the hypothesis of two fission components. It is shown further that the measured kinetic energy distributions can also be interpreted in terms of the two-component hypothesis.