First measurements of g factors in the even Kr isotopes -: art. no. 024314

The g factors of the 2(1)(+) and 4(1)(+) states in Kr-78,Kr-80,Kr-82,Kr-84,Kr-86 have been measured for the first time, using Coulomb excitation of isotopic Kr beams and the transient field technique. The measured g factors of 2(1)(+) states in Kr-78,Kr-80,Kr-82 are well described, in both magnitude and progression with neutron number, by the IBA-II model. Whereas the lighter isotopes show a dominant collective structure with g factor values close to Z/A, the large g(2(1)(+)) = 1.12(14) value of Kr-86, with its closed N = 50 shell, is unequivocally dominated by specific proton configurations. The g factor of the 2(1)(+) state in Kr-84, with two holes in the 1g(9/2) neutron orbit, reflects both proton and neutron components in the wave function. In addition, the lifetimes of several 2(1)(+) and 4(1)(+) states were remeasured by the Doppler shift attenuation method, yielding values which, in some cases, differ from those in the literature.