Lifetime of the $6_1^{+}$ state in ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ti}$

The mean lifetime of the 3041-keV ($6_1^{+}$) state in ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ti}$ has been measured to be $\tau =4.5\mathrm{}\pm 0.3$ nsec. This value represents an improvement by a factor of 6 from previous measurements. States in ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ti}$ were populated by the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}({}_{}{}^3{}_{}{}^{}\mathrm{He},n\gamma )$ reaction with $E_{3_{\mathrm{He}}}=10\mathrm{} \mathrm{and} 12$ MeV. The experimental value of $B\left(E2\mathrm{}\right)=27.6\mathrm{}\pm 1.8e^2$ ${\mathrm{fm}}^4$ for the ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ti}$ $6^{+}$ →$4^{+}$ transition together with the ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$ $6^{+}$ →$4^{+}$ $B\left(E2\mathrm{}\right)\mathrm{}$ value provides a measure of the importance of the isovector giant quadrupole state on the effective $E2\mathrm{}$ operator which is used in shell-model calculations.

[NUCLEAR REACTIONS ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}({}_{}{}^3{}_{}{}^{}\mathrm{He},n\gamma )$, $E=10,12\mathrm{}$ MeV; measured pulsed beam electronic timing; deduced $T_{\frac{1}{2}}$, $B\left(E2\mathrm{}\right)\mathrm{}$, effective charge. Natural target, Ge(Li) detectors.]