Multiparticle configurations in N=84 isotones located at the proton drip line

Excited states in the proton-rich N=84 isotones 72¹⁵⁶Hf₈₄,¹⁵⁷₇₃Ta₈₄, and 74¹⁵⁸W₈₄ were observed using ¹⁰²Pd(⁵⁸Ni,xp2n) 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 ¹⁵⁶Hf, the h_11/2 state in ¹⁵⁷Ta, and the 8⁺ isomeric state in ¹⁵⁸W. The level schemes constructed for ¹⁵⁶Hf,¹⁵⁷Ta, and ¹⁵⁸W are compared with these of lighter N=84 isotones and are discussed within the framework of the shell model.