$\alpha$ decay of ${}_{97}^{249}$Bk and levels in ${}_{95}^{245}$Am

$\alpha$ decay of ${}^{249}$Bk has been investigated by measuring its $\alpha$ and $\gamma$-ray spectra, both in singles and in coincidence modes. The $\alpha$ spectrum of a freshly purified ${}^{249}$Bk sample was measured with a high-resolution, double-focusing magnetic spectrometer. $\gamma$ singles, $\gamma$-$\gamma$ coincidence, and $\gamma$-$\alpha$ coincidence spectra were also recorded. The absolute intensity of the 327.45-keV $\gamma$ ray has been determined to be ($1.44\pm 0.08)\times {10}^{-5}$% per ${}^{249}$Bk decay. Assignments of previously known single-particle states were confirmed. A new rotational band was identified in the $\alpha$ singles spectrum and Am K x rays have been observed in its decay. This single-particle state, with an energy of 154 keV, has been assigned to the 3/2${}^{-}$[521] Nilsson state. This is the lowest excitation energy for this orbital in any Am nucleus. More precise energies and intensities of the ${}^{249}$Bk $\alpha$ groups and $\gamma$-ray transitions are provided.