Pygmy dipole strength in {sup 90}Zr

Journal Article · Mon Dec 15 00:00:00 EST 2008 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.78.064314· OSTI ID:21199425

Schwengner, R; Rusev, G; Benouaret, N; Beyer, R; Erhard, M; Junghans, A R; Klug, J; Kosev, K; Nair, C; Schilling, K D; Wagner, A ^[1]; Tsoneva, N ^[2]; Grosse, E ^[1]; Lenske, H ^[2]

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1. Institut fuer Strahlenphysik, Forschungszentrum Dresden-Rossendorf, D-01314 Dresden (Germany)
2. Institut fuer Theoretische Physik, Universitaet Giessen, D-35392 Giessen (Germany)

The dipole response of the N=50 nucleus {sup 90}Zr was studied in photon-scattering experiments at the electron linear accelerator ELBE with bremsstrahlung produced at kinetic electron energies of 7.9, 9.0, and 13.2 MeV. We identified 189 levels up to an excitation energy of 12.9 MeV. Statistical methods were applied to estimate intensities of inelastic transitions and to correct the intensities of the ground-state transitions for their branching ratios. In this way we derived the photoabsorption cross section up to the neutron-separation energy. This cross section matches well the photoabsorption cross section obtained from ({gamma}, n) data and thus provides information about the extension of the dipole-strength distribution toward energies below the neutron-separation energy. An enhancement of E1 strength has been found in the range of 6 to 11 MeV. Calculations within the framework of the quasiparticle-phonon model ascribe this strength to a vibration of the excessive neutrons against the N=Z neutron-proton core, giving rise to a pygmy dipole resonance.

• OSTI ID: 21199425
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 78, Issue 6; Other Information: DOI: 10.1103/PhysRevC.78.064314; (c) 2008 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2813
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
BRANCHING RATIO
BREMSSTRAHLUNG
CROSS SECTIONS
DIPOLES
E1-TRANSITIONS
ELECTRONS
EXCITATION
GROUND STATES
LINEAR ACCELERATORS
MEV RANGE 01-10
MEV RANGE 10-100
NEUTRON SEPARATION ENERGY
NEUTRONS
PHOTONS
PROTONS
QUASIPARTICLE-PHONON MODEL
SCATTERING
SIMULATION
STATISTICAL MODELS
ZIRCONIUM 90