Experimental study of the F17+C12 fusion reaction and its implications for fusion of proton-halo systems

Le résumé fourni par la source

The total fusion cross section for the $^{17}\mathrm{F}+^{12}\mathrm{C}$ system at incident energies near the top of the Coulomb barrier was studied using the newly developed Encore active-target detector at Florida State University. The $^{17}\mathrm{F}$ nucleus exhibits interesting nuclear structure properties in that although it has a low threshold against $^{17}\mathrm{F}\ensuremath{\rightarrow}^{16}\mathrm{O}+p$ breakup $({S}_{p}=600\phantom{\rule{0.28em}{0ex}}\mathrm{keV})$, the valence proton is in the $1{d}_{5/2}$ shell in the ground state so that the nuclear matter radius is predicted to be similar to that of the $^{16}\mathrm{O}$ core. By contrast, the low-lying $1/{2}^{+}$ first excited state (bounded by 105 keV) with the valence proton in the $2{\phantom{\rule{4pt}{0ex}}s}_{1/2}$ shell is considered to be a proton halo. In this paper possible influences of both the weak binding and the halo nature of the excited state on the total fusion cross section were investigated. The new data reported here complement existing measurements for the total fusion of $^{17}\mathrm{F}$ with heavy $(^{208}\mathrm{Pb})$ and medium mass ($^{58}\mathrm{Ni}$) targets by extending the range of systems studied to one where Coulomb effects should be minimal. Total fusion cross sections for the stable counterpart systems $^{16}\mathrm{O}+^{12}\mathrm{C}$ and $^{19}\mathrm{F}+^{12}\mathrm{C}$ were also measured to enable a systematic comparison. No significant influence of either the weak binding or the halo nature of the $^{17}\mathrm{F}\phantom{\rule{0.28em}{0ex}}1/{2}^{+}$ first excited state on the above barrier total fusion excitation function was observed when compared with the stable counterpart systems.

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