Energy Loss and Range of Fission Fragments in Solid Media

Energy losses and ranges in Mylar have been measured for some representative fission fragments; these data and existing stopping-power measurements for bromine and iodine ions in media from carbon to gold are shown to be consistent with a semiempirical theory which treats electronic stopping processes in terms of an effective charge Z₁* which depends on the velocity of the ion. The fractional effective charge Z₁*Z₁ is shown to be a universal function of the variable vv₀Z₁2/3, where v₀ is the Bohr velocity and Z₁ is the nuclear charge of the fragment. This semiempirical treatment, when combined with existing theoretical estimates for nuclear stopping powers, correctly predicts ranges of fission-fragment-like ions.