Energy levelsin98251Cf populated in the α decayof100255Fm

Gamma-ray spectra of a 20-h ${}^{255}\mathrm{Fm}$ source containing $\sim 1$ mCi activity were measured with a 25% Ge detector and a low-energy photon spectrometer (LEPS). Gamma lines with intensities as low as $1.0\times {10}^{-6}\%$ per ${}^{255}\mathrm{Fm}$ $\alpha$ decay were observed. Gamma-gamma coincidence spectra of a ${}^{255}\mathrm{Fm}$ sample were measured with the GAMMASPHERE array. A comparison of the $\gamma$-ray spectrum gated by the Cf $K_{\alpha }$ x-ray peak with the $\gamma$-singles spectrum provided spins of the excited states in ${}^{251}\mathrm{Cf}.$ The $\gamma$-ray data, in conjunction with previously measured ${}^{250}\mathrm{Cf}\mathrm{}(d,p)\mathrm{}$ reaction data, allowed us to characterize several single-particle and vibrational states above the $N=152\mathrm{}$ subshell gap.