Large shape staggering in neutron-deficient Bi isotopes

Barzakh, A.*; Andreyev, A. N.; Raison, C.*; Cubiss, J. G.*; 53 of others*

The changes in the mean-square charge radius (relative to Bi, magnetic moments and quadrupole moments of the neutron-deficient bismuth isotopes Bi were measured at ISOLDE (CERN). In the experiment, the in-source resonance-ionization spectroscopy technique was employed, which permits to study isotopes produced with rates as low as 0.1/sec. The radii of Bi manifest a large staggering, corresponding to a sudden increase of the radius of Bi relative to its Bi neighbors. This staggering effect occurs at neutron number =105, where shape staggering was also observed in the mercury isotopes. Experimental results were compared with state-of-the-art mean-field calculations, which permit to identify the quasiparticle configurations compatible with the observed spin, parity and magnetic moment of the newly observed states.