Dominant g(9/2)^2 neutron configuration in the 4+1 state of 68Zn based on new g factor measurements

Abstract

The $g$ factor of the $4_1^{+}$ state in ${}^{68}$Zn has been remeasured with improved energy resolution of the detectors used. The value obtained is consistent with the previous result of a negative $g$ factor thus confirming the dominant $0g_{9/2}$ neutron nature of the $4_1^{+}$ state. In addition, the accuracy of the $g$ factors of the $2_1^{+}$, $2_2^{+}$ and $3_1^{-}$ states has been improved an d their lifetimes were well reproduced. New large-scale shell model calculations based on a ${}^{56}$Ni core and an $0f_{5/2}1p{g}_{9/2}$ model space yield a theoretical value, $g(4_1^{+})=+0.008$. Although the calculated value is small, it cannot fully explain the experimental value, $g(4_1^{+})=-0.37(17)$. The magnitude of the deduced B(E2) of the $4_1^{+}$ and $2_1^{+}$ transition is, however, rather well described. These results demonstrate again the importance of $g$ factor measurements for nuclear structure determination s due to their specific sensitivity to detailed proton and neutron components in the nuclear wave functions.

7 pages, 3 figs, submitted to PLB