Hyperfine anomaly in Be isotopes in the cluster model and the neutron   spatial distribution
  The study of the hyperfine anomaly of neutron rich nuclei, in particular, neutron halo nuclei, can give a very specific and unique way to measure their neutron distribution and confirm a halo structure. The hyperfine structure anomaly in Be+ ions is calculated with a realistic electronic wave function, obtained as a solution of the Dirac equation. In the calculations, the Coulomb potential modified by the charge distribution of the clustered nucleus and three electrons in the 1s^2 2s configuration is used. The nuclear wave function is obtained in the core+nucleon model of 9,11Be. The aim of this study is to test whether the hyperfine structure anomaly reflects a halo structure in 11Be. 
Y. L. Parfenova and Ch. Leclercq-Willain