Changes of the Nuclear Charge Distribution of Nd, Sm, Gd and Dy from Optical Isotope Shifts

Abstract

Isotope shifts and hyperfine structures in 28 optical transitions for 28 stable isotopes of Nd, Sm, Gd and Dy were measured by means of the atomic-beam laser-spectroscopy. The nuclear parameter λ was obtained from the isotope shift measurement for all the stable nuclei with the improved accuracy. The λ values were analyzed by using the Fermi distribution for the nuclear charge density. As a result, the diffuseness at the nuclear surface or the hollow depth near the center of nucleus in the charge distribution depends on the neutron number. The values of δ⟨r²⟩ and also δ⟨r⁴⟩ were determined. It is shown that λ is a good probe into the systematic change of the nuclear charge distribution.