Experimental observation of the M1 scissors mode in <SUP>254</SUP>No



Garrote, FL Bello, Lopez-Martens, A, Larsen, AC, Deloncle, I, Peru, S, Zeiser, F, Greenlees, PT, Kheswa, BV, Auranen, K, Bleuel, DL
et al (show 29 more authors) (2022) Experimental observation of the M1 scissors mode in <SUP>254</SUP>No. PHYSICS LETTERS B, 834. p. 137479.

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Abstract

We present the first experimental evidence of the scissors mode in the superheavy nucleus 254No produced in the 208Pb(48Ca, 2nγ))254No reaction. The spectrum of γ rays emitted by the excited 254No nuclei shows an enhanced γ-ray yield for transition energies of ≈2.5 MeV. By measuring the linear polarization properties of the emitted γ rays, we confirm that the transitions in the enhancement region are predominantly of magnetic-dipole character, characteristic for the scissors mode. To further characterize the enhanced γ-ray yield, simulations of the electromagnetic decay of 254No were performed. The observed enhancement is reproduced by including an M1 component in the γ strength function with total strength B(M1↑)=11.8(19)μN2. This is in good agreement with the integrated M1 strength from sum-rule estimates and new calculations within the quasi-particle random-phase approximation presented here. Our results provide a stringent test of phenomenological formulae for the scissors mode currently used in stellar nucleosynthesis calculations. We find that those formulae are not satisfactory, and we recommend using sum-rule estimates assuming a rigid-body moment of inertia instead for describing the scissors mode in superheavy nuclei.

Item Type: Article
Uncontrolled Keywords: Scissors mode, ?-strength function, Transfermium nuclides
Depositing User: Symplectic Admin
Date Deposited: 07 Oct 2022 15:15
Last Modified: 18 Oct 2023 15:17
DOI: 10.1016/j.physletb.2022.137479
Open Access URL: https://doi.org/10.1016/j.physletb.2022.137479
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3165271