Special features of the isospin splitting of the giant dipole resonance in the 90Zr nucleus

Data on the proton and neutron channels of the 90Zr photodisintegration were analyzed in detail, basic parameters of the isospin splitting of the giant dipole resonance in 90Zr being determined by the properties of these channels. New data concerning the cross sections for the partial photoneutron reactions 90Zr(γ, n)89Zr and 90Zr(γ, 2n)88Zr and resulting from a simultaneous correction of data from experiments performed in Livermore (USA) and Saclay (France) by using beams of quasimonoenergetic annihilation photons were invoked. Use was made of information about the positions on the energy scale of states characterized by different isospin values in the 90Zr nucleus and nuclei neighboring it, which are members of the respective isospin multiplet. New data on the parameters of the isospin splitting of the giant dipole resonance in the 90Zr nucleus were obtained on the basis of a global analysis of data on the giant-dipole-resonance states of the 90Zr nucleus, which are manifested in the respective photoneutron and photoproton cross sections and in their decay channels involving states of different isospin in neighboring nuclei.