Measurement of enhanced electric dipole transition strengths at high spin in $^{100}$Ru: Possible observation of octupole deformation

TL;DR

This study measures high-spin electric dipole transition rates in $^{100}$Ru, suggesting it may be the first nucleus in the A≈100 region exhibiting static octupole deformation, indicated by enhanced transition strengths.

Contribution

The paper provides experimental evidence of enhanced electric dipole transitions in $^{100}$Ru, indicating possible static octupole deformation in this nucleus, a novel observation in the A≈100 mass region.

Findings

Enhanced electric dipole transition rates observed

$^{100}$Ru may be the first octupole deformed nucleus in its mass region

Experimental data supports reflection asymmetric shape in $^{100}$Ru

Abstract

The majority of atomic nuclei have deformed shapes and nearly all these shapes are symmetric with respect to reflection. There are only a few reflection asymmetric pear-shaped nuclei that have been found in actinide and lanthanide regions, which have static octupole deformation. These nuclei possess an intrinsic electric dipole moment due to the shift between the center of charge and the center of mass. This manifests in the enhancement of the electric dipole transition rates. In this article, we report on the measurement of the lifetimes of the high spin levels of the two alternate parity bands in $^{100}$Ru through the Doppler Shift Attenuation Method. The estimated electric dipole transition rates have been compared with the calculated transition rates using the triaxial projected shell model without octupole deformation, and are found to be an order of magnitude enhanced. Thus, the observation of seven inter-leaved electric dipole transitions with enhanced rates establish $^{100}$Ru as possibly the first octupole deformed nucleus reported in the A $\approx$ 100 mass region.