Possible Experimental Evidence of a Moderate Proton Halo in ²⁹S

The total reaction cross sections (TRCSs) of ²⁹S+²⁸Si have been measured at intermediate energies. An obvious enhancement in TRCS of ²⁹S is observed as compared with its neighbouring nuclei. The TRCSs of ²⁹S+²⁸Si are calculated with the modified Glauber theory in the optical limit and few-body approaches. The different factor d as a possible measure of halo appearance is deduced from the experimental and theoretical data. It is well accepted that ²⁷P is a proton halo nucleus. Although not as anomalous as ²⁷P, the different factor d of ²⁹S is obviously larger than that of its neighbouring isotones of N=13. This result indicates that a moderate proton halo may exist in ²⁹S nucleus. We calculate the total reaction cross sections for ²⁹S with the modified Glauber theory as a function of incident energy and compare the results with those for ²⁷Si which is a core nucleus of ²⁹S. The measured TRCSs of ²⁷Si+²⁸Si can be described to be satisfactory by the modified Glauber theory of the optical limit approach. Although a diffused nuclear density distribution is used, the theories still inadequately predict the experimental TRCSs of ²⁹S+²⁸Si, which further indicates the possibility of proton halo in²⁹S.