Alignment in yrast structure and negative-parity sideband in the proton-rich nucleus ¹³⁴Sm

The proton-rich nucleus [Formula: see text]Sm has been studied up to high spin and the level scheme has been extended beyond the six transitions previously reported in the ground-state band. Levels beyond E[Formula: see text] = 4 MeV and up to I[Formula: see text] = (16[Formula: see text]) have been identified. The first nucleon alignment in the yrast positive-parity structure has been established at a rotational frequency of ≈ 0.30 MeV, and is attributed to the breaking of a h[Formula: see text] proton pair. A negative-parity structure with its bandhead at E[Formula: see text] = 2061 keV and I[Formula: see text] = (7[Formula: see text]) has been identified and is attributed to the excitation of protons in the h[Formula: see text] and g[Formula: see text] orbitals. Cranked shell model calculations using the Ultimate Cranker code with standard Nilsson parameters indicate a prolate deformed minimum which persists to high frequencies. The calculated proton alignment frequency is in good agreement with the experimental value, and the neutron crossing is expected at a significantly higher frequency on account of the N = 72 deformed subshell gap.