First-excited state g factors in the stable, even Ge and Se isotopes FIRST-EXCITED STATE g FACTORS in the ... B. P. McCORMICK et al.

Transient-field g-factor measurements in inverse kinematics were performed for the first-excited states of the stable, even isotopes of Ge and Se. The g factors of Ge74 and Se74 were measured simultaneously using a cocktail beam, which eliminates most possible sources of systematic error in a relative g-factor measurement. The results are g(Se74)/g(Ge74)=1.34(7), g(Ge70)/g(Ge74)=1.16(15), g(Ge72)/g(Ge74)=0.92(13), g(Ge76)/g(Ge74)=0.88(5), g(Se76)/g(Se74)=0.96(7), g(Se78)/g(Se74)=0.82(5), g(Se80)/g(Se74)=0.99(7), and g(Se82)/g(Se74)=1.19(6). The measured g-factor ratios are in agreement with ratios from previous measurements, despite considerable variation in previous reported absolute values. The absolute values of the g factors remain uncertain, however, the Rutgers parametrization was used to set the transient-field strength and then compare the experimental g factors with shell-model calculations based on the JUN45 and jj44b interactions. Modest agreement was found between experiment and theory for both interactions. The shell-model calculations indicate that the g(21+) values and trends are determined largely by the balance of the spin carried by orbital motion of the protons.