Speaker
Description
Here I will present our new experimental and theoretical work on nuclear shapes based on electric quadrupole (E2) matrix elements. New beam development and experimental facilities funded through the GAMKA project have allowed the precise determination of E2 matrix elements at iThemba LABS [1,2]. The large oblate deformation determined in 60Ni is is inconsistent with the near-zero quadrupole moment expected for simple harmonic surface vibrations around the Z=28 shell closure. Instead, we show stable triaxial rotations about the three axis as the main mode of collective excitation near magic numbers, assuming the gamma dependence is provided by the irrotational flow [3]. The empirically determined triaxial deformation gamma is consistent with collective wave functions calculated using the projected generator coordinate method with the D1S nuclear interaction. We will further generalize these findings for nuclei typically considered as surface vibrators at or close to shell closures as well as propose new ideas for a new research program aimed at the empirical determination of triaxiality for unstable nuclei at HIE-ISOLDE.
[1] Mehl CV, Orce JN, et al., Phys. Rev. C. 111(5), 054318 (2025).
[2] Orce JN, Zulu A et al., submitted to Phys. Rev. Lett. (2025).
[3] E. A. Lawrie, E. A. and Orce, J. N. At. Data Nucl. Data Tables 164, 101730 (2025).
