Nuclear spectroscopy with lithium beams. I. High-spin states inFe55,Mn55, andCr53

Abstract

The $^{7}\mathrm{Li}$ bombardment of $^{51}\mathrm{V}$ has been used in conjuction with recoil distance lifetime (RDM), $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence, angular distribution, and Doppler shift attenuation lifetime (DSAM) measurements to gain information on the properties of high-spin states in the nuclei $^{55}\mathrm{Fe}$, $^{55}\mathrm{Mn}$, and $^{53}\mathrm{Cr}$. Mean lifetimes ($\ensuremath{\tau}$) determined by RDM were as follows---in $^{55}\mathrm{Fe}$: 1409-keV level ($\ensuremath{\tau}=57.8\ifmmode\pm\else\textpm\fi{}3.5$ psec), 2813 (14.5\ifmmode\pm\else\textpm\fi{}3.1 psec), 5099 (32.3\ifmmode\pm\else\textpm\fi{}1.1 psec); in $^{55}\mathrm{Mn}$: 126-keV level ($\ensuremath{\tau}=382\ifmmode\pm\else\textpm\fi{}16$ psec); in $^{53}\mathrm{Cr}$: 2173-keV level ($\ensuremath{\tau}=47\ifmmode\pm\else\textpm\fi{}15$ psec); 3084 ($\ensuremath{\tau}=43\ifmmode\pm\else\textpm\fi{}15$ psec). Tentative spin assignments were made as follows---in $^{55}\mathrm{Fe}$: 5099-keV level $J=(\frac{19}{2})$, 6528, $J=(\frac{21}{2})$, in $^{55}\mathrm{Mn}$: 3056-keV level $J=(\frac{15}{2})$. Lifetimes (or limits) were also established from DSAM measurements for a number of other levels in the above nuclei. The results are compared to shell model calculations.NUCLEAR REACTIONS $^{51}\mathrm{V}(^{7}\mathrm{Li}, 3n)$, $^{51}\mathrm{V}(^{7}\mathrm{Li}, p2n)$, $^{51}\mathrm{V}(^{7}\mathrm{Li}, \ensuremath{\alpha}n)$ $E=25$ MeV; measured $\ensuremath{\gamma}\ensuremath{\gamma}$ coin.; deduced levels in $^{55}\mathrm{Fe}$, $^{55}\mathrm{Mn}$, $^{53}\mathrm{Cr}$; measured $\ensuremath{\sigma}({E}_{\ensuremath{\gamma}}, \ensuremath{\theta})$; deduced ${J}^{\ensuremath{\pi}}$ for high spin states; measured recoil distance; deduced ${T}_{\frac{1}{2}}$, $B(E2)$, effective charges. Natural target, Ge(Li) detectors.