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

The proton-rich nucleus Formula: see textSm 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 EFormula: see text = 4 MeV and up to IFormula: see text = (16Formula: 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 hFormula: see text proton pair. A negative-parity structure with its bandhead at EFormula: see text = 2061 keV and IFormula: see text = (7Formula: see text) has been identified and is attributed to the excitation of protons in the hFormula: see text and gFormula: 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.