Energy levels ofCm247populated in theαdecay ofCf98251

Abstract

$\ensuremath{\alpha}$-Particle, conversion-electron, and $\ensuremath{\gamma}$-ray singles spectra of $^{251}\mathrm{Cf}$ sources containing few Bq activities were measured with high-resolution semiconductor detectors. $\ensuremath{\alpha}\text{\ensuremath{-}}\ensuremath{\gamma}$ coincidence and level half-life measurements were also performed. On the basis of these measurements the following single-particle states have been identified in $^{247}\mathrm{Cm}$: $9∕{2}^{\ensuremath{-}}[734]$, 0 keV; $5∕{2}^{+}[622]$, 227.4 keV; $7∕{2}^{+}[624]$, 285.4 keV; $1∕{2}^{+}[620]$, 404.9 keV; $1∕{2}^{+}[631]$, $518.6\phantom{\rule{0.3em}{0ex}}\text{keV}$. The measured single-particle energies are in good agreement with energies calculated with a Woods-Saxon single-particle potential. From the measured half-life of the $227.4\text{\ensuremath{-}}\text{keV}$ level and the $E3$ branching ratio, a $B(E3)$ value of $5\phantom{\rule{0.3em}{0ex}}\text{W.u.}$ has been deduced between the $5∕{2}^{+}[622]$ and $9∕{2}^{\ensuremath{-}}[734]$ bands. The large $B(E3)$ value is an indication of octupole mixing in the $227.4\text{\ensuremath{-}}\text{keV}$ level.