Spin dependence ofKmixing, strong configuration mixing, and electromagnetic properties ofHf178

Abstract

The combined data of two Coulomb excitation experiments has verified the purely electromagnetic population of the ${K}^{\ensuremath{\pi}}={4}^{+},{6}^{+},{8}^{\ensuremath{-}}$, and ${16}^{+}$ rotational bands in $^{178}\mathrm{Hf}$ via $2\ensuremath{\le}\ensuremath{\nu}\ensuremath{\le}14$ $K$-forbidden transitions, quantifying the breakdown of the $K$-selection rule with increasing spin in the low-$K$ bands. The \ensuremath{\gamma}-, ${4}^{+}$, and ${6}^{+}$ bands were extended, and four new states in a rotational band were tentatively assigned to a previously known ${K}^{\ensuremath{\pi}}={0}^{+}$ band. The quasiparticle structure of the ${6}^{+}$ (${t}_{\frac{1}{2}}=77$ ns) and ${8}^{\ensuremath{-}}$ (${t}_{\frac{1}{2}}=4$ s) isomer bands were evaluated, showing that the gyromagnetic ratios of the ${6}^{+}$ isomer band are consistent with a pure $\ensuremath{\pi}{\frac{7}{2}}^{+}[404],\ensuremath{\pi}{\frac{5}{2}}^{+}[402]$ structure. The ${8}^{\ensuremath{-}}$ isomer band at 1147 keV and the second ${8}^{\ensuremath{-}}$ band at 1479 keV, thought to be predominantly $\ensuremath{\nu}{\frac{7}{2}}^{\ensuremath{-}}[514],\ensuremath{\nu}{\frac{9}{2}}^{+}[624]$ and $\ensuremath{\pi}{\frac{9}{2}}^{\ensuremath{-}}[514],\ensuremath{\pi}{\frac{7}{2}}^{+}[404]$, respectively, are mixed to a degree approaching the strong-mixing limit. Based on measured $\ensuremath{\langle}{K}^{\ensuremath{\pi}}={16}^{+}\ensuremath{\Vert}E2\ensuremath{\Vert}{K}^{\ensuremath{\pi}}={0}^{+}\ensuremath{\rangle}$ matrix elements, it was shown that heavy-ion bombardment could depopulate the ${16}^{+}$ isomer at the $~1$% level, although no states were found that would mediate photodeexcitation of the isomer via low-energy x-ray absorption.

Spin dependence ofKmixing, strong configuration mixing, and electromagnetic properties ofHf178

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Abstract

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