Can weakly absorbing surface transparent nucleus-nucleus interaction ensure orbiting?

Abstract

We find that in contrast to the large orbiting yield seen in $^{28}\mathrm{Si}$${+}^{12}$C, $^{24}\mathrm{Mg}$${+}^{16}$O, $^{24}\mathrm{Mg}$${+}^{12}$C, and $^{20}\mathrm{Ne}$${+}^{12}$C reactions, the back-angle, strongly damped binary yields from $^{4}\mathrm{He}$${+}^{27}$Al and $^{4}\mathrm{He}$${+}^{40}$Ca reactions are in agreement with the predictions of statistical compound nuclear reaction. These results disagree with the observation from heavy-ion reaction systematics that the orbiting yield will dominate whenever the number of open channels is small, and suggest that the weak absorption and surface transparency of nucleus-nucleus interaction are not sufficient conditions for the dominance of orbiting in back-angle, strongly damped reaction.