Original scientific paper

Investigation of dipole excitations below the giant dipole resonance in 89y using the ELBE facility

N. Benouaret ; Faculté de physique, Université des Sciences et de la Technologie d'Alger, Algerie; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany
R. Schwengner ; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany
G. Rusev ; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany; Present address: Department of Physics, Duke University, Triangle Universities Nuclear Laboratory, Durham, NC 27708, U. S. A.
F. Dönau ; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany
R. Beyer ; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany
M. Erhard ; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany
E. Grosse ; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany; Institut für Kern-und Teilchenphysik, Technische Universität Dresden, Dresden, Germany
A. R. Junghans ; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany
K. Kosev ; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany
C. Nair ; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany
K. D. Schilling ; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany
A. Wagner ; Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Dresden, Germany

Abstract

We have investigated the dipole response of the stable N = 50 nucleus 89Y up to the excitation energy of the giant dipole resonance (GDR) using the bremsstrahlung facility at the ELBE accelerator at the research center Helmholtz-Zentrum DresdenRossendorf. After eliminating background radiation from atomic processes as well as inelastic transitions in the spectra by using statistical methods, the photoabsorption cross section could be deduced from the photon-scattering data. This cross section was combined with that known from (γ, n) experiments. An excess of the cross section relative to a simple Lorentz approximation of the tail of the GDR is found in the energy range from about 6 MeV up to 11 MeV. The comparison with predictions of a quasiparticle-random-phase approximation (QRPA) showed that the corresponding excitations may be caused by an oscillation of the excessive neutrons forming a so-called pygmy dipole resonance (PDR) as it was found for the neighbouring isotones 88Sr and 90Zr.

Keywords

photon scattering; dipole resonances in 89Y; up to giant dipole resonance; quasiparticle-random-phase approximation; pygmy dipole resonances

Hrčak ID:

304718

URI

https://hrcak.srce.hr/304718

Publication date:

1.9.2011.

Article data in other languages: croatian

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