The quasielastic scattering (QES) excitation function for the systems ${}^{16}\mathrm{O}+{}^{176}\mathrm{Yb}$ and ${}^{16}\mathrm{O}+{}^{178}\mathrm{Hf}$ are measured by detecting projectile like ions at the back angle using a scattering chamber at Inter-University Accelerator Centre (IUAC), New Delhi. The measurements were performed with energy range from $0.78V_B\text{−}1.10V_B, V_B$ is the Coulomb barrier. The experimental fusion barrier distributions (BD) were derived from the measured data using the point difference formula. The excitation function and the BD are subjected to coupled channel (CC) calculations using a scattering version of the CC code ccfull K. Hagino, et al., Comput. Phys. Commun. 123, 143 (1999), where Woods-Saxon potential parametrization is used. The best fitted optical model parameters are extracted for the real and the imaginary parts. For ${}^{16}\mathrm{O}+{}^{176}\mathrm{Yb}$, considering the coupling of two rotational states $(2^{+},4^{+})$ of the ${}^{176}\mathrm{Yb}$ nucleus along with a pair of neutron transfer $(Q=–0.5\mathrm{MeV})$ both the excitation function and the BD are well reproduced. In case of ${}^{16}\mathrm{O}+{}^{178}\mathrm{Hf}$ too, incorporating the coupling of two rotational states $(2^{+},4^{+})$ of the ${}^{178}\mathrm{Hf}$ nucleus and one pair of neutron transfer $(Q=–1.82\mathrm{MeV})$, both the excitation function and the BD are fairly reproduced. Technique of ${\chi }^2/f$ minimization was used to determine a new set of hexadecapole deformation. The values are found to be ${\beta }_4=-0.019\pm 0.014$ and ${\beta }_4=-0.032\pm 0.017$ for ${}^{176}\mathrm{Yb}$ and ${}^{178}\mathrm{Hf}$ respectively. The excitation functions and the BDs of the two systems are also compared with available experimental data by other groups to better understand the reaction dynamics around the barrier.

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• Elastic scattering reactions
• Inelastic scattering reactions
• Nuclear reactions
• Nuclear shapes and moments
• Nucleon distribution
• 150 ≤ A ≤ 189
• Optical, coupled-channel & distorted wave models