With the time-differential angular-distribution method the $g$ factor of the lowest ($\nu f_{\frac{7}{2}}^{}{}_{}{}^2$) $6^{+}$ state in ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$ has been determined to be ${-0.50\mathrm{}}_{-0.03\mathrm{}}^{+0.02\mathrm{}}$, which is closer to the Schmidt value for the $0f_{\frac{7}{2}}$ neutron than is that of the ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$ ground state. Strong violation of the additivity of the effective magnetic moment for these states is interpreted by a larger mixing of the core-excited deformed states into the ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$ ground state.

• Received 10 May 1971

DOI:https://doi.org/10.1103/PhysRevLett.27.523