New Information on Nuclear Structure in the Cd-In-Sn Region from Laser Spectroscopy and the Question of Core Polarization Contribution to Nuclear Radii

Abstract

Nuclear spin, moments and isotope shifts of charge radii have been measured by laser spectroscopy for about 70 nuclear states in the range 48 ≦ Z ≦ 50, 54 ≦ N ≦ 78. 1/2^--states in heavy In-isotopes cross the Schmidt line, indicating complex nuclear structure. Magnetic as well as spectroscopic quadrupole moments of most of the odd odd In-isotopes can be reproduced satisfactorily by coupling the respective experimental moments of odd even and even odd neighbouring nuclei. The isotope shift of all three elements exhibits a parabolic shape, which is superimposed to the almost linear droplet model expectation. The shape can be fitted quantitatively to Talmis core polarization model. The curvature of the parabola which peaks in the middle of the neutron shell is a direct measure of the collective contribution to the charge radius. It corresponds to deformation parameters 〈β²〉 twice as large as observed from B(E2, 0⁺→2 ⁺₁ ) values. One suggests, therefore, that the latter one does not exhaust the full collectivity of the nuclear ground state. By comparing to charge radii in the Rb and Cs region one derives isotonic and isobaric shifts in accordance with the droplet model. The isobaric shifts may be interpreted as a build up of a neutron skin in a simple way.