Neutron skin thickness of 208Pb, 116,120,124Sn, and 40Ca determined from reaction cross sections of 4He scattering

Background: We constructed the Kyushu chiral g matrix and confirmed its reliability at 30 < Ein < 100 MeV and 250 < Ein < 400 MeV for 12C scattering. Reaction cross-section data of 4He scattering are available for some nuclides including 208Pb. The PREX II collaboration reported a thick neutron skin for 208Pb. Purpose: Our purpose is to deduce neutron skin thicknesses of 208Pb and some other nuclides from reaction cross sections calculated in terms of the double folding model with the g matrix. Methods: We fold the g matrix and densities given by mean-field calculations. To remedy the weaker constraint of the neutron sector, we renormalize densities so as to reproduce the observed cross sections. Results: We found that a 3.4% renormalization is necessary for 208Pb. The neutron density obtained from renormalization results in Rskin = 0.416 +/- 0.146 fm by confronting the precision proton radius. Conclusions: Our result is consistent with PREX II and therefore supports larger slope parameter L. Results for 40Ca and 124Sn are also consistent with Rskin deduced from other experiments. For 116,120Sn the present method gives thicker skins.