Excited states in the proton-rich $N=84$ isotones ${}_{72}^{156}{\mathrm{Hf}}_{84},{}_{73}^{157}{\mathrm{Ta}}_{84}$, and ${}_{74}^{158}{W}_{84}$ were observed using ${}^{102}\mathrm{Pd}({}^{58}\mathrm{Ni},\mathit{xp}2n)$ reactions at 270 MeV. γ rays were detected with the Gammasphere array of Compton-suppressed Ge detectors coupled with the Argonne fragment mass analyzer and were assigned to individual reaction channels using the recoil-decay tagging method. Prompt γ-ray cascades were associated with the α decay of both the ground state and the $8^{+}$ isomeric state in ${}^{156}\mathrm{Hf}$, the $h_{11/2}$ state in ${}^{157}\mathrm{Ta}$, and the $8^{+}$ isomeric state in ${}^{158}\mathrm{W}$. The level schemes constructed for ${}^{156}\mathrm{Hf},{}^{157}\mathrm{Ta}$, and ${}^{158}\mathrm{W}$ are compared with these of lighter $N=84$ isotones and are discussed within the framework of the shell model.

• Received 11 February 2005

DOI:https://doi.org/10.1103/PhysRevC.71.054319