Recoil-distance lifetime measurements of ${}_{}{}^{48}{}_{}{}^{}\mathrm{V}$ levels

Lifetimes for a number of levels in ${}_{}{}^{48}{}_{}{}^{}\mathrm{V}$ have been measured using the recoil-distance technique. The experimental results for the mean lifetimes are 8.8±1.4 psec for the 428-keV $5^{+}$ level, 21.6±1.1 psec for the 613-keV $4^{+}$ level, 111±9 psec for the 627-keV $6^{+}$ level, 6.7±1.8 psec for the 1056-keV $3^{-}$ level, and 6.5±0.5 psec for the 1099-keV $4^{\mathrm{}(-)\mathrm{}}$ level. Lifetime limits were measured for other levels. The electromagnetic transition strengths for the positive and negative parity bands are discussed. For the positive parity levels, shell model calculations are carried out assuming wave functions of the form ${\left(\pi f_{\frac{7}{2}}\right)}^n{\left(\nu f_{\frac{7}{2}}\right)}^{-n}$. Many properties of ${}_{}{}^{48}{}_{}{}^{}\mathrm{V}$ and surrounding nuclei, particularly for the high-spin states, can be described using the ${}_{}{}^{42}{}_{}{}^{}\mathrm{Sc}$ effective interaction with effective operators $e_p+e_n=2\mathrm{}$ and $g_p-g_n=1.29\mathrm{}$. For some aspects, however, the effective operator approach within this limited $1f_{\frac{7}{2}}$ model space is not adequate.

NUCLEAR REACTIONS ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}(\alpha , n)$ $E=9.5\mathrm{}$ MeV; measured $n-\gamma$ coin, deduced levels in ${}_{}{}^{48}{}_{}{}^{}\mathrm{V}$; measured recoil distance, deduced $T_{\frac{1}{2}}$, $B\left(L\right)\mathrm{}$, $\pi$ assignments. Natural target, Ge(Li) detectors.