Skip to Main content Skip to Navigation
Journal articles

Collectivity in the light radon nuclei measured directly via Coulomb excitation

Abstract : Background: Shape coexistence in heavy nuclei poses a strong challenge to state-of-the-art nuclear models, where several competing shape minima are found close to the ground state. A classic region for investigating this phenomenon is in the region around Z=82 and the neutron mid-shell at N=104. Purpose: Evidence for shape coexistence has been inferred from α-decay measurements, laser spectroscopy and in-beam measurements. While the latter allow the pattern of excited states and rotational band structures to be mapped out, a detailed understanding of shape coexistence can only come from measurements of electromagnetic matrix elements. Method: Secondary, radioactive ion beams of 202Rn and 204Rn were studied by means of low-energy Coulomb excitation at the REX-ISOLDE facility in CERN. Results: The electric-quadrupole (E2) matrix element connecting the ground state and first-excited 2+1 state was extracted for both 202Rn and 204Rn, corresponding to B(E2;2+1→2+1)=29+8−8 W.u. and 43+17−12 W.u., respectively. Additionally, E2 matrix elements connecting the 2+1 state with the 4+1 and 2+2 states were determined in 202Rn. No excited 0+ states were observed in the current data set, possibly due to a limited population of second-order processes at the currently-available beam energies. Conclusions: The results are discussed in terms of collectivity and the deformation of both nuclei studied is deduced to be weak, as expected from the low-lying level-energy schemes. Comparisons are also made to state-of-the-art beyond-mean-field model calculations and the magnitude of the transitional quadrupole moments are well reproduced.
Document type :
Journal articles
Complete list of metadatas
Contributor : Fanny Cadou <>
Submitted on : Wednesday, March 9, 2016 - 3:14:42 PM
Last modification on : Thursday, December 3, 2020 - 9:40:03 PM

Links full text



L. P. Gaffney, A. P. Robinson, D. G. Jenkins, A. N. Andreyev, M. Bender, et al.. Collectivity in the light radon nuclei measured directly via Coulomb excitation. Physical Review C, American Physical Society, 2015, 91, pp.064313. ⟨10.1103/PhysRevC.91.064313⟩. ⟨in2p3-01285636⟩



Record views