NUCLEAR RADII OF NA AND MG ISOTOPES

The effective root-mean-square (rms) matter radii of Na-A (A = 20-23,2 5-32) and Mg-A (A = 20,22,23,27,29-32) have been deduced from the meas ured interaction cross sections using a Glauber-type calculation. It w as found that the increase of rms matter radii in Na isotopes is prima rily a consequence of the increase of rms neutron radii. A correlation between the radii, corrected for quadrupole deformation, and the Ferm i-energy difference was observed for both Na and Mg isotopes. This cor relation can be explained by a model that assumes the valence nucleons are responsible for the changes in nuclear radii. The presence of a n eutron skin is suggested for neutron-rich Na and Mg isotopes. An appli cation to the nuclear equation of state (EOS) is discussed. (C) 1998 P ublished by Elsevier Science B.V.