"Studies of shape coexistence using Coulomb excitation of light Hg isotopes" K. Rezynkina
In the neutron-deficient 182-186Hg isotopes the so-called intruder states come down in excitation energy to the vicinity of the spherical states, yielding the low-lying non-yrast energy levels [1]. The mixing between the states of the coexisting configurations gives rise to transitions with a strong electric monopole component, often referred to as a fingerprint of shape coexistence.
Coulomb excitation studies have been performed at the ISOLDE facility on even mass mercury isotopes and reveal the coexistence of the prolate and the weakly-deformed oblate configurations in these nuclei [2].
Recent data from decay spectroscopy at ISOLDE indicates very high internal conversion coefficients (ICC) for the 2+-2+ transitions [3], suggesting the strong mixing between the two shape configurations. These new spectroscopic data (i.e. the ICC and the branching ratios) are used in a re-analysis of the Coulomb excitation yields from REX- ISOLDE, providing a unique opportunity to extract the transitional matrix elements, the spectroscopic quadrupole moments QS and the electric monopole transition strengths ρ(E0).
The new results from the GOSIA calculations for 182Hg and 184Hg will be presented, compared with the Interacting Boson Model, General Bohr Hamiltonian and Beyond Mean-Field predictions and interpreted in terms of a two-state mixing model. The monopole transition strengths of the 2+-2+ transitions in mercury isotopes will also be presented and compared with theory. The future Coulomb excitation and decay spectroscopy experiments at ISOLDE will be discussed.
[1] K. Heyde, J. L. Wood, Rev. Mod. Phys. 83, (2011) 1467
[2] N. Bree et al., Phys. Rev. Le . 112, 16 (2014), 162701
[3] E. Rapisarda et al., J. Phys. G: Nucl. Part. Phys. 44 (2017) 074001