Isotope shift in the Ca I resonance line and changes in mean-square nuclear charge radii of the stable Ca isotopes

The isotope shift of all stable Ca isotopes was studied in the Ca I resonance line. Enriched isotopes were used in an atomic beam, passing through the center of a spherical Fabry-Perot interferometer. The measured isotope shifts were separated into mass shift and field shift by comparing the optical isotope shift with δ〈r ²〉 values derived from recent muonic x-ray measurements. The results are discussed together with known data on the isotope shift in the Ca I intercombination line and data from Hartree-Fock calculations. The following mean values are obtained for the change in nuclear charge distribution δ〈r ²〉 fm²]∶ 40, 42] 0.23(3); 40, 43] 0.13(3); 40, 44] 0.28(4); 40, 46] 0.14(7); 40, 48] 0.00(2).