Neutron number dependence of the energies of the γ-vibrational states in nuclei with Z ~ 100 and the manifestation of pseudospin symmetry.

Background: The symmetry-guided methods have shown their power over many years of nuclear physics research. It was found that the concept of the pseudospin symmetry is very helpful in providing a simple explanation of many features of heavy nuclei. Purpose: To show, based on the results of calculations of the energies of the γ-vibrational states in nuclei with Z ~ 100, that the experimental data on these energies will give us information indicating how well the pseudospin symmetry is realized in these exotic nuclei. Method: The quasiparticle-phonon model is used to calculate the energies of the γ-vibrational states. Results: It is shown that the energies of the γ--vibrational states in the Cm, Cf, Fm, No, and Rf isotopes considered as the functions of the number of neutrons N have a minimum at N = 156 when the neutron Fermi level lies just between the following neutron single particle levels: 3/2[622] and 1 /2[620] which belong to the pseudospin doublet. It is shown that the corresponding two-quasiparticle component gives the main contribution to the structure of the γ- phonon. Conclusion: The experimental information on the energies of the γ-vibrational states in nuclei with Z ~ 100 can be used to determine a splitting of the [521] pseudospin doublet. [ABSTRACT FROM AUTHOR]