RARE-EARTH NUCLEI - RADII, ISOTOPE-SHIFTS AND DEFORMATION PROPERTIES IN THE RELATIVISTIC MEAN-FIELD THEORY

A systematic study of the ground-state properties of even-even rare ea rth nuclei has been performed in the framework of the Relativistic Mea n-Field (RMF) theory using the parameter set NL-SH. Nuclear radii, iso tope shifts and deformation properties of the heavier rare-earth nucle i have been obtained, which encompass atomic numbers ranging from Z = 60 to Z = 70 and include a large range of isospin. It is shown that RM F theory is able to provide a good and comprehensive description of th e empirical binding energies of the isotopic chains. At the same time the quadrupole deformations beta(2) Obtained in the RMF theory are fou nd to be in good agreement with the available empirical values, The th eory predicts a shape transition from prolate to oblate for nuclei at neutron number N = 78 in all the chains. A further addition of neutron s up to the magic number 82 brings about the spherical shape. For nucl ei above N = 82, the RMF theory predicts the well-known onset of prola te deformation at about N = 88, which saturates at about N = 102. The deformation properties display an identical behaviour for all the nucl ear chains. A good description of the above deformation transitions in the RMF theory in all the isotopic chains leads to a successful repro duction of the anomalous behaviour of the empirical isotopic shifts of the rare-earth nuclei. The RMF theory exhibits a remarkable success i n providing a unified and microscopic description of various empirical data.