The N-dependence of Cd mean square charge radii (54 ⩽ N ⩽72) and the nuclear moments of 103Cd

Abstract

The isotope shift of the radioactive Cd isotopes 102Cd, 103Cd, 104Cd, 105Cd, 107Cd, 111Cd, 113Cd, 115Cd, 117Cd, 118Cd, 119Cd, 120Cd and the hyperfine structure Splitting of 103Cd are determined in the CdI 5s 2 1S 0-5s5p 3P 1, λ = 326.1 nm line by fluorescence laser spectroscopy using a pulsed laser system and frequency doubling. The unstable Cd isotopes are produced at the ISOLDE mass separator at CERN and are investigated on-line in a resonance vessel. Changes of mean square charge radii are derived from the isotope shift data. The curve of the radii as a function of the mass number, shows on top of the regular A 1 3 expansion a collective contribution of parabolic shape which peaks at N = 66 in the middle of the shell. This contribution is considerably stronger than calculated from the B(E2 + 1) values solely. Isotonic and isobaric shifts between Z = 37 and Z = 56 are obtained in a combined analysis of isotope shifts ( δ〈 r 2〉), muonic 〈 r 2〉 values and B(E2 + 1) values. The shifts agree with the predictions of the droplet model showing the buildup of a neutron skin along isobaric chains. The nuclear moments of 103Cd have been determined as μ I , = −0.81(3) μ n and Q s = −0.79(66)b.