Evidence for rigid triaxial deformation at low energy in76Ge

Nuclear structure of Ge76 from inelastic neutron scattering measurements and shell model calculations

“…The value of δ for the 611.6-keV transition is reported to be 0.50 (8) in Ref. [5], which agrees well with our measured value of 0.59…”

“…The decay of the 6 + 1 state was observed by Toh et al [5]. The lifetime obtained in the present work, 0.38…”

“…• 2988.2-keV level: This level with 319.0-, 500.9-and 534.4-keV γ rays reported by Toh et al [5] was not observed, but this may reflect its higher spin.…”

“…The low-lying 0 + states in the stable Ge nuclei have been interpreted as evidence for shape coexistence [2], which was established in 72 Ge with multistep Coulomb excitation [3] and was recently extended to 80 Ge [4]. Moreover, Toh et al [5] proposed that 76 Ge may be a rare example of a nucleus exhibiting rigid triaxial deformation in its low-lying states, i.e., that it follows the rigid triaxial rotor model of Davydov and Filipov [6] with a well-defined potential minimum at a non-zero value of γ. The defining feature on which this claim is based is the energy staggering in the γ band.…”

“…However, the recent detailed in-beam γ-ray spectroscopic investigation with the Gammasphere array by Toh et al [5] contributed significantly to removing ambiguities in the literature and to establishing the ground, γ, and negative-parity bands in 76 Ge to moderate spins. In the work presented here, we have focused on describing the structure of this nucleus through the measurement of lifetimes, branching ratios, and multipole mixing ratios combined with a careful construction of a detailed level scheme, ultimately leading to the determination of transition probabilities, and resolving questions about the nuclear structure in the low-energy and low-spin regime.…”