High spin yrast states in N = 126 isotones

?-Spectroscopy of 89 215 Ac126 and proton pairing inN=126 isotones

“…We therefore assign the spins of the lowest levels as 9/2-, 13/2% 17/2-, and 21/2-although the groundstate spin is not known. In the lighter isotones these states are firmly assigned to the h~/2-configuration [4,5]. Angular momentum algebra requires that the g-factors of all levels of the (h~/2)-configuration are equal.…”

Review of metastable states in heavy nuclei

“…Much of this programme of study began with the discovery of high-spin isomers in the N = 126 isotope 212 Rn [197,198]. At that time, the energy of the 8 + →6 + transition was uncertain, but it was later measured as 54.2 keV by Stuchbery et al [199].…”

“…[196], an extension of the study which identified a J π = 33 − isomer feeding the 30 + state via an enhanced E3 transition [163], the original assumptions of Refs. [197,198] have been vindicated, with the definition (through the energies of new crossover transitions) of the gap ∆ = 7.6 keV. The level scheme was also extended to excitation energies above 13 MeV, including six new isomers, the highest with J π = (38 + ) at 12.547 MeV, arising from triple neutron-core excitations.…”

Spectroscopy of excited states in216Ra

“…Another possibility is that instead of the promotion of a h9/2 proton to the i13/2 shell, a neutron jumps from the g9/2 to the J,s/2 shell, the energy differences between the neutron single-particle states being somewhat smaller than for the proton single-particle states [10]. The measured B(E2, 13-~11-)=90_+40e 2 fm a is however close to the B(E2) values between proton states (in 2a3Fr for example B(E2, 37/2 + +33/2 +)= 160e 2 fm 4 between 4 9 7rh9/2113/2 states [1]). …”

“…As an example, high spin isomers have recently been found in the N=126 isotones (212Rn, 213Fr, 2a4Ra) by Horn et al [1]. The appearance of such states has been explained in the framework of the spherical shell model with different residual interactions [-2] and in the independent particle model using a small oblate deformation [3].…”