Isospin and Z1/3 Dependence of the Nuclear Charge Radii

摘要: Based on the systematic investigation of the data available for A ≥ 40, a Z1/3 dependence for the nuclear charge radii is shown to be superior to the generally accepted A1/3 law. A delicate scattering of data around Rc/Z1/3 is infered as owing to the isospin effect and a linear dependence of Rc/Z1/3 on N/Z ( or (N − Z)/2 ) is found. This inference is well supported by the microscopic Relativistic Continuum Hartree-Bogoliubov (RCHB) calculation conducted for the proton magic Ca, Ni, Zr, Sn and Pb isotopes including the exotic nuclei close to the neutron drip line. With the linear isospin dependence provided by the data and RCHB theory, a new isospin dependent Z1/3 formula for the nuclear charge radii is proposed.