Mass-Energy Relations in the Fission of Highly Excited Heavy Nuclei

Mass-energy relations in the fission of the compound nucleus ${\mathrm{Fm}}^{254}$ have been studied at excitation energies in the range from 58 to 116 MeV. This compound nucleus was produced by bombardments of ${\mathrm{Th}}^{232}$, ${\mathrm{U}}^{238}$, and ${\mathrm{Pu}}^{242}$ with the heavy ions ${\mathrm{Ne}}^{22}$, ${\mathrm{O}}^{16}$, and ${\mathrm{C}}^{12}$, respectively. The kinetic energies of the two fission fragments from each event were measured by using semiconductor detectors. From these energies the masses and total kinetic energies were calculated.