Quenching of the Octupole Rotational Band in ⁷¹Ge

Static octupole deformation, having pearlike shapes, has been observed in several even-even nuclei in the mass A ≈ 70 region (⁷⁴Se, ⁷⁶Kr, ⁷⁸Kr, and ⁸²Sr). Recently, experimental evidence for an octupole rotational band was observed for the first time in an odd-A isotope (⁷¹Ge). However, only very limited experimental information about this band is currently available. The goal of this study was to enhance the knowledge of the properties of this band and to investigate whether the band persists to even higher spin. An experiment at Florida State University using the ⁶²Ni (¹⁴C, αn) reaction at 50 MeV was used to produce ⁷¹Ge at high spin. An array of 10 Compton-suppressed Ge detectors, consisting of 3 Clover detectors and 7 single-crystal detectors, was used to measure the gamma decays in coincidence. An analysis of the resulting coincidence spectra resulted in the placement of six additional transitions in the ⁷¹Ge level scheme, one of which (1092 keV) extends the octupole band to a (35/2^-) state at 8208 keV. Calculations of the kinematic moment of inertia and aligned angular momentum for the octupole band show that the 1092-keV transition disrupts the smooth rotational pattern and may point to a band crossing, potentially quenching the octupole deformation. Comparisons between the octupole band in ⁷¹Ge and those of other neighboring even-even nuclei show similar behaviors.