Comprehensive Test of the Brink-Axel Hypothesis in the Energy Region of the Pygmy Dipole Resonance

We investigate isovector pygmy dipole resonance (IVPDR) for the case of neutron-rich nuclei 68 Ni , 130 Sn and 134 Sn using effective nucleon–nucleon Skyrme interaction. We use the Hartree–Fock–Bogoliubov (HFB) theory and employ the (quasiparticle) random phase approximation (Q)RPA. We calculate and compare the PDR strength in the PDR energy region for the case of density dependent central and full interaction modes for RPA and QRPA calculations. We observe that the results for the pygmy dipole resonance for neutron-rich soft nuclei 68 Ni that we consider are in reasonable agreement with their experimental results in both interactions and calculations. We also study the PDR for highly neutron-rich heavy nuclei, such as 130 Sn and 134 Sn . We see that only the QRPA calculation with full interaction is in good agreement with the experimental results for these nuclei and with a recent study in the literature. We find that the PDR strength distribution sensitively depends on the chosen interaction modes, especially for the neutron-rich heavy nuclei 134 Sn .

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Pygmy Dipole Resonance: Status of the Theory and Unsolved issues

10.1063/1.3087104 ◽

2009 ◽

Author(s):

A. Avdeyenkov ◽

F. Gruemmer ◽

S. Kamerdzhiev ◽

S. Krewald ◽

N. Lyutorovich ◽

...

Keyword(s):

Dipole Resonance ◽

Pygmy Dipole Resonance

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Investigation of pygmy dipole resonance in 154Sm

10.1063/1.4976416 ◽

2017 ◽

Cited By ~ 1

Author(s):

Huseynqulu Quliyev ◽

Zemine Zenginerler ◽

Ekber Guliyev ◽

Ali Akbar Kuliev

Keyword(s):

Dipole Resonance ◽

Pygmy Dipole Resonance

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The electric dipole response of even-even 154-164Dy isotopes

Physica Scripta ◽

10.1088/1402-4896/ac4863 ◽

2022 ◽

Author(s):

Huseynqulu Quliyev ◽

Nilufer Demirci Saygı ◽

Ekber Guliyev ◽

Ali Akbar Kuliev

Keyword(s):

Cross Sections ◽

Random Phase Approximation ◽

Random Phase ◽

Electric Response ◽

Quasiparticle Random Phase Approximation ◽

Effective Interactions ◽

Dipole Resonance ◽

Pygmy Dipole Resonance ◽

Strength Functions ◽

Dipole Response

Abstract The excitation of pygmy dipole resonance (PDR) and giant dipole resonance (GDR) in even-even 154-164Dy isotopes is examined through quasiparticle random-phase approximation (QRPA) with the effective interactions that restores the broken translational and Galilean invariances. In each isotope, an electric response emerges by showing ample distribution at energies below and above 10 MeV. We, therefore, study the transition cross sections and probabilities, photon strength functions, transition strengths, isospin character, and collectivity of the predicted E1 responses.

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Gamma Strength Functions and Level Densities from High-Resolution Proton Scattering under 0°

EPJ Web of Conferences ◽

10.1051/epjconf/201817806002 ◽

2018 ◽

Vol 178 ◽

pp. 06002

Author(s):

Peter von Neumann-Cosel ◽

Sergej Bassauer ◽

Dirk Martin ◽

Atsushi Tamii

Keyword(s):

High Resolution ◽

Energy Region ◽

Level Density ◽

Experimental Information ◽

Fluctuation Analysis ◽

Proton Scattering ◽

Heavy Nuclei ◽

High Resolution Data ◽

Dipole Resonance ◽

Strength Functions

Inelastic proton scattering at energies of a few 100 MeV and forward angles including 0° provides a novel method to measure gamma strength functions (GSF) in nuclei in an energy range of about 5 – 20 MeV. The experiments provide not only the E1 but also the M1 part of the GSF. The latter is poorly known in heavy nuclei. Comparison with gamma decay data (e.g. from the Oslo method) allows to test the generalised Brink-Axel (BA) hypothesis in the energy region of the pygmy dipole resonance (PDR) crucial for the modelling of (n,γ) and (γ,n) reactions in astrophysical reaction networks. From the two test cases studied, 208Pb remains inconclusive in the energy region of the PDR because of large Porter-Thomas fluctuations due to the small level density (LD), while the BA hypothesis seems to hold in case of 96Mo. A fluctuation analysis of the high-resolution data also provides a direct measure of the LD in the energy region of the isovector giant dipole resonance (IVGDR) well above the neutron threshold, where hardly any experimental information is available. This permits an independent test of the decomposition of GSF and LD in Oslo-type experiments.

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