The production cross sections of 23 fission fragments in the mass range $71\le A\le 141$ have been measured in the ${}^{12}\mathrm{C}+{}^{193}\mathrm{Ir}$ reaction at $E_{\mathrm{lab}}=83.99\pm 0.013, 80.99\pm 0.007$, and $74.82\pm 0.026\mathrm{MeV}$ using the recoil-catcher activation technique followed by offline $\gamma$-ray spectroscopy. The mass and charge distributions of the fission fragments have been analyzed to study the isotopic and isobaric yield distributions. The mass dispersion parameter (${\sigma }_A^2$) for iodine isotopes is found to be $4.66\pm 0.82, 4.04\pm 0.52$, and $3.13\pm 0.39$ at $E_{\mathrm{lab}}=83.99\pm 0.013, 80.99\pm 0.007$, and $74.82\pm 0.026\mathrm{MeV}$, respectively. The charge dispersion parameter (${\sigma }_Z$) for iodine isotopes is estimated to be 0.862, 0.799, and 0.709 at the respective energies. It has been observed that the fission fragment mass distribution displays well-described Gaussian functions, consistent with compound-nucleus fission. The variance of the fission-fragment mass distribution has been analyzed as a function of compound-nucleus temperature and found to increase exponentially with it. The variance is strongly influenced by entrance-channel mass asymmetry, highlighting the role of entrance-channel parameters. The present study also explores a linear dependence of mass variance on the deformation parameter (${\beta }_2$) of the target nuclei at the same excitation energy for ${}^{12}\mathrm{C}+{}^{193}\mathrm{Ir}$ and ${}^{12}\mathrm{C}+{}^{169}\mathrm{Tm}$ systems.

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• Fission
• Low & intermediate energy heavy-ion reactions
• Nuclear reactions