Search for beyond-mean-field signatures in heavy-ion fusion reactions

Examination of high-resolution, experimental fusion excitation functions for ${}^{16,17,18}\mathrm{O}+{}^{12}\mathrm{C}$ reveals a remarkable irregular behavior that is rooted in the structure of both the colliding nuclei and the quasimolecular composite system. The impact of the $\ell$-dependent fusion barriers is assessed using a time-dependent Hartree-Fock model, viewed as a mean-field reference. Barrier penetrabilities, taken directly from a density-constrained calculation, provide a significantly improved description of the experimental data as compared to the standard Hill-Wheeler approach. The remaining deviations between the parameter-free theoretical mean-field predictions and experimental fusion cross sections are exposed and discussed.

Figure 1

Experimental fusion excitation functions for the reactions of ${}^{16}\mathrm{O}$ (black triangles) [13], ${}^{17}\mathrm{O}$ (red dots) [14], and ${}^{18}\mathrm{O}$ (open squares) [15, 16] impinged on a ${}^{12}\mathrm{C}$ target. The inset shows the results of ${\mathrm{TDHF}}^{*}$. See text for details.

Figure 2

Comparison of experiment with theory for the fusion excitation function for the ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$ reaction. Experimental data are taken from Refs. [18] (blue circles), [5] (green squares), [13] (orange diamonds), and [19] (red upside-down triangles). Raw TDHF results are shown with a light dotted line and modified DC-TDHF/TDHF hybrid results are shown with a solid black line. The difference between TDHF and ${\mathrm{TDHF}}^{*}$ is highlighted by shading. The values of $\ell \left(E_{\mathrm{c}.\mathrm{m}.}\right)$ computed in TDHF are marked.

Figure 3

Similar as in Fig. 2 but for the ${}^{17}\mathrm{O}+{}^{12}\mathrm{C}$ reaction. Experimental data are taken from Refs. [18] (blue circles), [45] (green squares), [14] (orange diamonds), [44] (red upside-down triangles), and [20] (purple triangles).

Figure 4

Similar as in Fig. 2 but for the ${}^{18}\mathrm{O}+{}^{12}\mathrm{C}$ reaction. Experimental data are taken from Refs. [18] (blue circles), [49] (green squares), [15] (orange diamonds), [5] (red upside-down triangles), and [16] (purple triangles).