Disagreement between capture probabilities extracted from capture and quasi-elastic backscattering excitation functions

Experimental quasi-elastic backscattering and capture (fusion) excitation functions are usually used to extract the s -wave capture probabilities for the heavy-ion reactions. We investigated the ¹⁶O + ¹²⁰Sn , ¹⁴⁴Sm , ²⁰⁸Pb systems at energies near and below the corresponding interaction barriers and concluded that the probabilities extracted from quasi-elastic data are much larger than the ones extracted from fusion excitation functions at sub and deep-sub barrier energies. This seems to be a reasonable explanation for the known disagreement observed in the literature for the nuclear potential diffuseness derived from both methods.