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  • Experimental observation of...
    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.; Cox, D.M.; Crespo Campo, L.; Giacoppo, F.; Görgen, A.; Grahn, T.; Guttormsen, M.; Hagen, T.W.; Harkness-Brennan, L.; Hauschild, K.; Henning, G.; Herzberg, R.-D.; Julin, R.; Juutinen, S.; Laplace, T.A.; Leino, M.; Midtbø, J.E.; Modamio, V.; Pakarinen, J.; Papadakis, P.; Partanen, J.; Renstrøm, T.; Rezynkina, K.; Sandzelius, M.; Sarén, J.; Scholey, C.; Siem, S.; Sorri, J.; Stolze, S.; Uusitalo, J.

    Physics letters. B, 11/2022, Letnik: 834
    Journal Article

    We present the first experimental evidence of the scissors mode in the superheavy nucleus 254No produced in the 208Pb(48Ca, ))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 . 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. (Elsevier B.V.)