A study of low-energy incomplete fusion was done by the measurements of excitation functions of evaporation residues produced in the ${}^{16}\mathrm{O}+{}^{148}\mathrm{Nd}$ system at energies $\approx 4–7$ MeV/nucleon. The stacked foil activation technique using offline $\gamma$-ray spectrometry was employed. Significant enhancements were found in the measured cross sections from the theoretical predictions of pace-4 for the evaporation residues populated through $\alpha$-emission channels. This enhancement is attributed to incomplete fusion (ICF) of ${}^{16}\mathrm{O}$ with ${}^{148}\mathrm{Nd}$. The comparison of present work with literature data shows that the ICF probability increases exponentially with existing entrance channel parameters. The dependence of ICF dynamics on target deformation was investigated using deformation parameter (${\beta }_2^T$), deformation length (${\beta }_2^T{R}^T$) and neutron excess ${(N-Z)}^T$ of the target. The present analysis indicates that the ICF fraction rises exponentially with ${\beta }_2^T$, ${\beta }_2^T{R}^T$, and ${(N-Z)}^T$. These results show that the ICF fraction follows a systematic exponential pattern rather than a simple linear growth with various entrance channel parameters reported in the literature. However, this study also suggests that the ICF dynamics is strongly influenced by the structure of projectile along with that of the target. Further, the role of deformation parameters on incomplete-fusion dynamics was also investigated through the method of universal fusion function. Analysis of the present data indicates that the experimental fusion functions are suppressed with different factors depending on deformation of the target nuclei. These suppressions are removed by including incomplete-fusion cross sections in the fusion function calculations. The average value of experimental fusion functions deviates from the universal fusion function for deformed targets. However, the average value of the total fusion function for deformed targets shifts towards the average value of the universal fusion function. The present study shows that the effect of target deformation plays an important role in affecting the ICF dynamics, along with various entrance channel parameters for different systems.

• Received 27 January 2019
• Revised 20 June 2019

DOI:https://doi.org/10.1103/PhysRevC.100.024621