Splitting of the Pygmy Dipole Resonance

Endres J, Butler P, Harakeh M.N., Harissopulos S, Herzberg R.-D., Kruecken R., Lagoyannis A, Litvinova E., Pietralla N., Tonomarev V.Yu., Lucia Popescu, Ring P, Savran D., Scheck M., Sonnabend K., Stoica V.I., Woertche H.J., Zilges A., Dieter Pauwels

    Research outputpeer-review


    In recent years investigations have been made to study the electric Pygmy Dipole Resonance (PDR) systematically, mainly in semi-magic nuclei. For this purpose the well understood high resolution (γ ,γ ') photon scattering method is used. In complementary (α,α'γ ) coincidence experiments at Eα = 136 MeV a similar γ -energy resolution and a high selectivity to E1 transitions can be obtained at the Big-Bite Spectrometer (BBS) at KVI, Groningen. In comparison to the (γ ,γ') method a structural splitting of the PDR is observed in the N=82 nuclei 138Ba and 140Ce and in the Z=50 nucleus 124Sn. The low energy part is excited in (γ ,γ') as well as in (α,α'γ ) while the high energy part is observed in (γ ,γ') only. The experimental results together with theoretical QPM and RQTBA calculations on 124Sn which are able to reproduce the splitting of the PDR qualitatively are presented. The low-lying group of 1− states seem to represent the more isoscalar neutron-skin oscillation of the PDR while the energetically higher-lying states seemingly belong to the transitional region between the PDR and the isovector Giant Dipole Resonance (IVGDR).
    Original languageEnglish
    Title of host publicationFrontiers in Nuclear Structure, Astrophysics, and Reactions: FINUSTAR 3
    Place of PublicationUnited States
    StatePublished - 28 Oct 2011
    EventFrontiers in Nuclear Structure, Astrophysics, and Reactions: FINUSTAR 3 - Rhodes
    Duration: 23 Aug 201027 Aug 2010

    Publication series

    NameAIP Conference Proceedings


    ConferenceFrontiers in Nuclear Structure, Astrophysics, and Reactions: FINUSTAR 3

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