Nature of the pygmy dipole resonance in 140Ce studied in (alpha, alpha' gamma) experiments.
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').
Savran
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Institut für Kernphysik, TU Darmstadt, Schlossgartenstrasse 9, D-64289 Darmstadt, Germany. savran@ikp.tu-darmstadt.de
Babilon
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van den Berg
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Harakeh
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Hasper
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Matic
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Wörtche
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Zilges
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