Searching for an Octupole Rotational Band in⁷¹Ga

Recently, a rotational band with static octupole deformation (pearlike shapes) was observed in ⁷¹Ge, the first odd-mass isotope in the mass A ≈ 70 region to show evidence of this behavior. Systematic experimental and theoretical studies of nuclei in this region indicate that octupole deformation might be enhanced for isotopes with N = 40. The goal of this work was thus to search for an octupole rotational band in the N = 40 isotope of gallium (⁷¹Ga) while enhancing the existing level scheme. A ⁶²Ni (¹⁴C, αp) reaction at 50 MeV was performed at Florida State University to populate high-spin states in ⁷¹Ga, and their decays were measured in coincidence using a Compton suppressed array of Ge detectors, including 3 Clover detectors and 7 single-crystal detectors. Using gating to filter out isotopes more strongly produced in this reaction, recently observed transitions and their placement within the level scheme were confirmed, and their intensities were measured. No conclusive evidence was found for a possible octupole rotational band, however. Cranked shell model calculations were performed to make a systematic comparison of the kinematic moments of inertia in the lowest positive- and negative-parity bands across a range of odd-A Ga isotopes, which all show very similar behavior for A > 67. The aligned angular momentum for these isotopes behave similarly as well. Total Routhian surface (TRS) calculations show a competition between single-particle and collective behavior as angular frequency increases.