Yrast decay schemes from heavy-ion +Ca48fusion-evaporation reactions. III.Fe57,58,Cr54,55, andMn57,58

Abstract

Fusion-evaporation reactions induced by beams of 25-65 MeV $^{13}\mathrm{C}$, $^{15}\mathrm{N}$, $^{11}\mathrm{B}$, and $^{9}\mathrm{Be}$ on an isotopically enriched $^{48}\mathrm{Ca}$ target have been used to populate high-spin yrast levels in $^{57,58}\mathrm{Fe}$, $^{54,55}\mathrm{Cr}$, and $^{57,58}\mathrm{Mn}$. Measurements consisted of $\ensuremath{\gamma}$-ray excitation functions, angular distributions, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences, and recoildistance and Doppler shift lifetime measurements, from which were deduced the energy levels, $\ensuremath{\gamma}$-ray branching ratios, most probable spin-parity assignments, and level lifetimes. Comparision is made with a large-basis shell-model calculation.NUCLEAR REACTIONS $^{48}\mathrm{Ca}(^{13}\mathrm{C},xn,yp,z\ensuremath{\alpha})^{57,58}\mathrm{Fe}$, $^{54,\phantom{\rule{0ex}{0ex}}55}\mathrm{Cr}$, and $^{57,\phantom{\rule{0ex}{0ex}}58}\mathrm{Mn}$; $^{48}\mathrm{Ca}(^{15}\mathrm{N},\ensuremath{\alpha}2n)^{57}\mathrm{Mn}$; $^{48}\mathrm{Ca}(^{11}\mathrm{B},pxn)^{54,55}\mathrm{Cr}$; and $^{48}\mathrm{Ca}(^{9}\mathrm{Be},3n)^{54}\mathrm{Cr}$. $E=25\ensuremath{-}65$ MeV; measured $\ensuremath{\sigma}(E,{E}_{\ensuremath{\gamma}})$ and coin; deduced levels; measured $\ensuremath{\sigma}({E}_{\ensuremath{\gamma}},\ensuremath{\theta})$; deduced ${J}^{\ensuremath{\pi}}$ for highspin levels; measured RDM and Doppler shifts; deduced ${t}_{m}$, ${|M(M1)|}^{2}$, and ${|M(E2)|}^{2}$. Enriched targets, Ge(Li) detectors.