“…Bohr (1941Bohr ( , 1948 argues that a calculation of the energy loss of fission fragments requires that a certain effective charge, q eff / which characterizes the ionic charge of the fragments, must be known for all velocities during the slowing-down process. Then, in its simplest interpretation, the stopping cross section, S, of a partially stripped heavy ion is related to the stopping cross section, S , of protons at the same velocity and in the same stopping material been applied, for example, by Steigert (1960a, 1960b), Northcliffe (1960), Martin and Northcliffe (1962), Teplova et al (1962), and Bethge et al (1966) and Grant (1965), Cumming and Crespo (1967), Pierce and Blann (1968), Kalish et al (1969), and Brown and Moak (1972 (5.13). Roll and Steigert (1960a) report no significant differences in q ff for ions with Z < 10 when stopped in gaseous and solid media, but in a more careful analysis of more extensive data, Roll and Steigert (1960b) find for fluorine ions that solid stopping materials lead to distinctly higher values of q f £ than gaseous ones.…”