Savran D, Babilon M, van den Berg AM, Harakeh MN, Hasper J, Matic A, Wörtche HJ, Zilges A. Nature of the pygmy dipole resonance in 140Ce studied in (alpha, alpha' gamma) experiments.
PHYSICAL REVIEW LETTERS 2006;
97:172502. [PMID:
17155468 DOI:
10.1103/physrevlett.97.172502]
[Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2006] [Indexed: 05/12/2023]
Abstract
A concentration of electric-dipole excitations below the particle threshold, which is frequently denoted as the pygmy dipole resonance, has been studied in the semimagic nucleus 140Ce in (alpha, alpha' gamma) experiments at E alpha = 136 MeV. The technique of alpha-gamma coincidence experiments allows the separation of E1 excitations from states of other multipolarities in the same energy region and provides an excellent energy resolution to allow a detailed analysis for each state. The experimental results show that the PDR splits into two parts with different nuclear structure: one part which is excited in (alpha, alpha' gamma) as well as (gamma, gamma') experiments and one part which is excited only in (gamma, gamma').
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