Abstract : We use the Brownian shape-motion model, with its recent extensions, which allow modeling of
odd-even staggering, to calculate the evolution of fission-fragment charge distributions with neutron number
for the compound-system sequence 234U, 236U, 238U, and 240U. We compare to experimental data where
available, for neutron- and electromagnetic-induced fission over a compound-nucleus excitation energy
range from about 6 to 20MeV. A notable result of the study is that the evolution of the location of the
peak charge yield from Z = 54 in 234U towards Z = 52 in heavier isotopes, seen in the experimental data,
is present also in the calculated yields. We further show that to describe yields at higher compound-nucleus
excitation energies, then, already at 20MeV, it is necessary to take multi-chance fission into account.
