Year: 2026
Type: preprint
Abstract: Stable isotopes of mercury, with two fewer protons than magic lead, are found experimentally to exhibit oblate deformation, similar to neighbouring platinum isotopes. These isotopes are of special interest due to the use of $^{199}$Hg as an experimental laboratory for electric dipole moment searches, which are a powerful test of charge-parity ($CP$) violation and the interpretation of which depends critically on the quadrupole and octopule shapes of the underlying nucleus. It is observed that the ratio between experimental quadrupole moments and electric quadrupole transition strengths exceed physical limits, placing uncertainty on this underlying shape. In an effort to resolve this situation, a Coulomb excitation experiment was performed to remeasure the spectroscopic quadrupole moment ($Q_s(2^+_1)$) of $^{200}$Hg and $^{202}$Hg utilising $^{48}$Ti and $^{120}$Sn targets. The values obtained were $Q_s(2^+_1)$ $^{200,202}$Hg = $0.52(14)$, $0.63(10)$ eb, lying within physical limits defined by $B(E2)$ values but still consistent with near axially-symmetric oblate deformation. A systematic study of nuclei indicates that, as with neighbouring Pt isotopes, $^{200,202}$Hg are strongly oblate deformed, albeit without fully developing into an axial rotor.
Source: arXiv (Cornell University)
Authors: Willmott, G., Heery, J., Henderson, J., Stevenson, P., Cousins, C., Doherty, D. T., Ertoprak, A., Kay, B. P., Morrison, L., Mueller-Gatermann, C., O'Shea, C., Regan, P. H., Reviol, W., Rhodes, D. M., Russell, R., Sensharma, N., Seweryniak, D., Siciliano, M., Sidhu, R. S., Tolstukhin, I. A., Wu, C. Y.
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G102163711, G107546177, G1092422733, G1313983767, G1356433355, G14554683, G1664757510, G1760870335, G2023430102, G2145270357, G2287611682, G254035773, G262962599, G2732101764, G2812149348, G2896472831, G3075337988, G3669113783, G498139845, G574795485, G6750061500, G6918803902, G6960589894, G8342505454, G8707073667, G895790057, G991281326, G993149817
OpenAlex ID: W7223122813