A1 Journal article (refereed)
Experimental observation of the M1 scissors mode in 254No (2022)

Bello, G. F., Lopez-Martens, A., Larsen, A.C., Deloncle, I., Péru, S., Zeiser, F., Greenlees, P.T., Kheswa, B.V., Auranen, K., Bleuel, D.L., Cox, D.M., Crespo, C. L., Giacoppo, F., Görgen, A., Grahn, T., Guttormsen, M., Hagen, T.W., Harkness-Brennan, L., Hauschild, K., . . . Uusitalo, J. (2022). Experimental observation of the M1 scissors mode in 254No. Physics Letters B, 834, Article 137479. https://doi.org/10.1016/j.physletb.2022.137479

JYU authors or editors

Publication details

All authors or editors: Bello, Garrote F.L.; Lopez-Martens, A.; Larsen, A.C.; Deloncle, I.; Péru, S.; Zeiser, F.; Greenlees, P.T.; Kheswa, B.V.; Auranen, K.; Bleuel, D.L.; et al.

Journal or series: Physics Letters B

ISSN: 0370-2693

eISSN: 1873-2445

Publication year: 2022

Volume: 834

Article number: 137479

Publisher: Elsevier

Publication country: Netherlands

Publication language: English

DOI: https://doi.org/10.1016/j.physletb.2022.137479

Publication open access: Openly available

Publication channel open access: Open Access channel

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/83504

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.

Keywords: nuclear physics

Free keywords: scissors mode; γ-strength function; transfermium nuclides

Contributing organizations

Ministry reporting: Yes

Reporting Year: 2022

JUFO rating: 2