Kπ=6+and8−isomer decays inHf172and ΔK=8E1 transition rates

A recoil-shadow measurement of isomer decays in $^{172}\mathrm{Hf}$ has revealed many weak \ensuremath{\gamma}-ray transitions. One of these is a sevenfold K-forbidden E1 transition from the ${\mathit{K}}^{\mathrm{\ensuremath{\pi}}}$=${8}^{\mathrm{\ensuremath{-}}}$ isomer (${\mathit{T}}_{1/2}$=163 ns) to the ${\mathit{K}}^{\mathrm{\ensuremath{\pi}}}$=${0}^{+}$ ground-state band. The low hindrance factor for this transition in $^{172}\mathrm{Hf}$ is compared with the hindrance factors for other \ensuremath{\Delta}K=8 E1 transitions.