Nuclear spectroscopy with lithium beams. II. High-spin states in Cr 52 , <mml:mi mathvariant…
1974; American Institute of Physics; Volume: 10; Issue: 6 Linguagem: Inglês
10.1103/physrevc.10.2329
ISSN1538-4497
AutoresA. R. Poletti, B. A. Brown, D. B. Fossan, E. K. Warburton,
Tópico(s)Radioactive element chemistry and processing
ResumoThe nuclei $^{52}\mathrm{Cr}$, $^{54}\mathrm{Mn}$, and $^{56}\mathrm{Fe}$ have been investigated using $^{7}\mathrm{Li}$ bombardment of $^{51}\mathrm{V}$ at about 25 MeV bombarding energy. Further information has been obtained on the nuclei $^{54}\mathrm{Mn}$ and $^{54}\mathrm{Fe}$ from the $^{6}\mathrm{Li}$ bombardment of $^{51}\mathrm{V}$ at the same energy. Experimental methods used included recoil distance lifetime measurements (RDM), $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidence measurements, angular distribution measurements, and Doppler shift attenuation lifetime measurements (DSAM) on $\ensuremath{\gamma}$ rays from high spin states in the various nuclei. Mean lifetimes determined by RDM were as follows: in $^{52}\mathrm{Cr}$, 3114-keV level ($\ensuremath{\tau}=60.0\ifmmode\pm\else\textpm\fi{}2.6$ psec); in $^{54}\mathrm{Mn}$, 156-keV level ($\ensuremath{\tau}={278}_{\ensuremath{-}120}^{+40}$ psec); 368 keV (10.4 \ifmmode\pm\else\textpm\fi{} 1.6 psec); 1073 keV (292 \ifmmode\pm\else\textpm\fi{} 50 psec); in $^{56}\mathrm{Fe}$, 847-keV level ($\ensuremath{\tau}=7.9\ifmmode\pm\else\textpm\fi{}1.2$ psec). Tentative spin assignments were made as follows: in $^{52}\mathrm{Cr}$, 4751-keV level, $J=(8)$ (this state can be identified with the seniority 4, ${J}^{\ensuremath{\pi}}={8}^{+}$ state predicted in this region); in $^{54}\mathrm{Mn}$, 1073-keV level $J=(6)$; in $^{56}\mathrm{Fe}$, 3389-keV level $J=(6)$. Decay schemes observed in these nuclei are presented. Lifetimes (or limits) were also established from DSAM measurements for a number of other levels in these nuclei. Recent shell model calculations for these nuclei are discussed.NUCLEAR REACTIONS $^{51}\mathrm{V}(^{7}\mathrm{Li}, \ensuremath{\alpha}2n)^{52}\mathrm{Cr}$, $^{51}\mathrm{V}(^{7}\mathrm{Li}, p3n)^{54}\mathrm{Mn}$, $^{51}\mathrm{V}(^{7}\mathrm{Li}, 4n)^{54}\mathrm{Fe}$, $^{51}\mathrm{V}(^{7}\mathrm{Li}, 2n)^{56}\mathrm{Fe}$, $^{51}\mathrm{V}(^{6}\mathrm{Li}, p2n)^{54}\mathrm{Mn}$, $^{51}\mathrm{V}(^{6}\mathrm{Li}, 3n)^{54}\mathrm{Fe}$ $E=25$ MeV; measured $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coin.; deduced levels in $^{52}\mathrm{Cr}$, $^{54}\mathrm{Mn}$, $^{54}\mathrm{Fe}$, $^{56}\mathrm{Fe}$; measured $\ensuremath{\sigma}({E}_{\ensuremath{\gamma}}, \ensuremath{\theta})$; deduced ${J}^{\ensuremath{\pi}}$ for high-spin states; measured recoil distance; deduced ${T}_{\frac{1}{2}}$, $B(E2)$. Natural target, Ge(Li) detectors.
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