Isospin mixing in the 4 + doublet of 54 Co

Abstract

The T = 1 admixture into the T = 0 member of a recently discovered $J^\pi = 4^{ + }$ isospin-doublet in 54Co is obtained from the measured electromagnetic E2/M1 multipole mixing ratio, $\delta = 0.12(4)$ of the $T = 0, 4^{ + } \rightarrow T = 0, 3^{ + }$ transition. Combining these data with shell model calculations for strong isovector M1 and isoscalar E2 electromagnetic matrix elements one obtains a value for the T = 1 admixture into the T = 0, 4 + state of $0.23_{-0.10}^{ + 0.29}\%$ . The corresponding mixing matrix element in the 4 + doublet is $V_{\rm mix} = 10$ keV.