The excited states of ${}^{148}\mathrm{Ho}$ and ${}^{149}\mathrm{Ho}$ isotopes are studied using $\gamma$-ray and electron spectroscopy in off-beam and in-beam modes following ${}^{112,114}\mathrm{Sn}$(${}^{40}\mathrm{Ar}$,$\mathit{xnyp}$) reactions. Experiments include measurements of single $\gamma$-rays and conversion electron spectra as well as $\gamma$-$\gamma$, electron-$\gamma$, $\gamma -t$, and $\gamma -\gamma -t$ coincidences with the use of the OSIRIS-II 12-HPGe array and conversion electron spectrometer. Based on the present results, the level schemes of ${}^{148}\mathrm{Ho}$ and ${}^{149}\mathrm{Ho}$ are revised and significantly extended, up to about 4 and 5 MeV of excitation energy, respectively. Spin and parity of $5^{-}$ are assigned to the $9.59$-s isomer in ${}^{148}\mathrm{Ho}$ based on conversion electron results. Previously unobserved $\gamma$ rays feeding the ${10}^{+}$ isomer in ${}^{148}\mathrm{Ho}$ and the $27/2^{-}$ isomer in ${}^{149}\mathrm{Ho}$ nuclei are proposed. Shell-model calculations are performed. Possible core-excited states in ${}^{149}\mathrm{Ho}$ are discussed.

• Received 7 December 2009

DOI:https://doi.org/10.1103/PhysRevC.81.044305