Endres J, Litvinova E, Savran D, Butler PA, Harakeh MN, Harissopulos S, Herzberg RD, Krücken R, Lagoyannis A, Pietralla N, Ponomarev VY, Popescu L, Ring P, Scheck M, Sonnabend K, Stoica VI, Wörtche HJ, Zilges A. Isospin character of the pygmy dipole resonance in 124Sn.
PHYSICAL REVIEW LETTERS 2010;
105:212503. [PMID:
21231295 DOI:
10.1103/physrevlett.105.212503]
[Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Indexed: 05/30/2023]
Abstract
The pygmy dipole resonance has been studied in the proton-magic nucleus 124Sn with the (α, α'γ) coincidence method at Eα=136 MeV. The comparison with results of photon-scattering experiments reveals a splitting into two components with different structure: one group of states which is excited in (α, α'γ) as well as in (γ, γ') reactions and a group of states at higher energies which is only excited in (γ, γ') reactions. Calculations with the self-consistent relativistic quasiparticle time-blocking approximation and the quasiparticle phonon model are in qualitative agreement with the experimental results and predict a low-lying isoscalar component dominated by neutron-skin oscillations and a higher-lying more isovector component on the tail of the giant dipole resonance.
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