First measurements of g factors in the even Kr isotopes

The g factors of the 2₁⁺ and 4₁⁺ states in ^{78,80,82,84,86}Kr have been measured for the first time, using Coulomb excitation of isotopic Kr beams and the transient field technique. The measured g factors of 2₁⁺ states in ^78,80,82Kr 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(2₁⁺)=1.12(14) value of ⁸⁶Kr, with its closed N=50 shell, is unequivocally dominated by specific proton configurations. The g factor of the 2₁⁺ state in ⁸⁴Kr, 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 2₁⁺ and 4₁⁺ states were remeasured by the Doppler shift attenuation method, yielding values which, in some cases, differ from those in the literature.