Coulomb Fission by Very Heavy Ions

Abstract

It is proposed that very heavy ions (including uranium) be utilized to induce fission through the Coulomb interaction only. Because the projectile moves slowly, the process is expected to be nearly adiabatic (no intrinsic excitation). Dynamical-model calculations have been performed at zero impact parameter to determine the threshold energy, cross section, and fragment angular distribution. Differential cross sections of hundreds of millibarns are calculated, and fission fragments are found to emerge preferentially at 90\ifmmode^\circ\else\textdegree\fi{} in the pair frame. The calculations incorporate reasonable model data, but the equilibrium-to-saddle distance $\ensuremath{\Delta}\ensuremath{\beta}$ is unknown. In order for fission to occur below the Coulomb barrier, $\ensuremath{\Delta}\ensuremath{\beta}$ must be greater than 0.15 in the case of Cf, for example. Rotational and vibrational excitation is discussed for energies below the fission threshold. A primary objective of the experiments would be to determine $\ensuremath{\Delta}\ensuremath{\beta}$ (and the shape of the energy-deformation curve). This would provide a severe test of various nuclear-model theories.