Dependence of Isobaric Charge Distributions on Energy Loss and Mass Asymmetry in Damped Collisions

Yields for specific $Z$ and $A$ have been measured for projectilelike fragments produced in the reaction of 8.3-MeV/u ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ ions with targets of ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$, ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$, and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. Variances of the isobaric charge distributions ${{\sigma }_Z}^2\mathrm{}\left(A\right)\mathrm{}$ reveal a saturation value of ${{\sigma }_Z}^2\mathrm{}\left(A\right)\mathrm{}\approx 0.8$, reached within the first 30-50 MeV of energy loss depending on target. Variances of the isotopic mass distributions saturate at a value of ${{\sigma }_Z}^2\mathrm{}\left(A\right)\mathrm{}\approx 2-4$, which is reached after about 60-80 MeV of energy loss. The data are compared with $\frac{N}{Z}$ equilibration models.