Reaction cross-sections and reduced strong absorption radii of nuclei in the vicinity of closed shells N = 20 and N = 28.

Energy integrated reaction cross-section measurements of around sixty neutron-rich nuclei covering the region of closed shells N = 20 and N = 28 were performed at intermediate energy (30-65 A ^. MeV) using direct method. In this experiment, silicon detectors were used as active targets. The reduced strong absorption radii, r₀², for 19 new nuclei (²⁷F, ^27,30Ne, ³³Na, ^{28, 34-35}Mg, ^36-38Al, ^38-40Si, ^41-42P, ^42-44S and ⁴⁵Cl) are deduced for the first time. An additional 60 radii, also measured in this experiment, are compared to results from literature. A new quadratic parametrization is proposed for the nuclear radius as a function of the isospin in the region of closed shells N = 8 and N = 28. According to this parametrization, the skin effect is well reproduced and anomalous behaviour on the radii are observed in ²³N, ²⁹Ne, ³³Na, ³⁵Mg, ⁴⁴S, ⁴⁵Cl and ⁴⁵Ar nuclei. [ABSTRACT FROM AUTHOR]