Measurements of g(4+/1 , 2+/2) in 70,72,74,76Ge: Systematics of low-lying structures in 30 < Z < 40 and 30 < N < 50 nuclei

Background: The interplay between single-particle and collective excitations in the 30 <= Z <= 40 and 30 <= N <= 50 even-even isotopes has been examined in light of recent new measurements of magnetic moments of 4(1)(+), 2(2)(+), and 2(1)(+) states. Purpose: The g factors of the 4(1)(+) and 2(2)(+) states in the Ge-72,Ge-74,Ge-76 isotopes have been measured for the first time and the g(2(1)(+)) values have been remeasured. Methods: The transient field (TF) technique in inverse kinematics with a variety of targets has been applied, following Coulomb excitation of the relevant states. The data have been analyzed within the framework of the IBA-II model. Large-scale shell-model calculations have been performed within the p(3/2), p(1/2), f(5/2), g(9/2) orbital space for both protons and neutrons with the JUN45 and JJ4B interactions. Results: The measured Ge g factors were compared to the g factors of the low-lying states of the neighboring Zn, Ge, Se, Kr, and Sr isotopes. The results were evaluated in the context of the systematics of g factors in the A similar to 80 region. Conclusions: The predictions based on the classic collective model and the interacting boson model IBA-II agree with the experimental results. No evidence for shell closure was found for neutrons at N = 38 or N = 40.