Microscopic description of the pygmy dipole resonance in neutron-rich Ca isotopes

N.N Arsenyev,A.P Severyukhin,V.V Voronov,N.V Giai,N Arsenyev,A Bezbakh,I Rogov,A Vdovin,T Shneidman

doi:10.1051/epjconf/201819404002

N.N Arsenyev, A.P Severyukhin + Show 7 more

Open Access

https://doi.org/10.1051/epjconf/201819404002

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Abstract

We study the effects of the phonon-phonon coupling on the low-energy electric dipole response within a microscopic model based on an effective Skyrme interaction. The finite rank separable approach for the quasiparticle random phase approximation is used. Choosing as an example the isotopic chain of Calcium, we show the ability of the method to describe the low-energy E1 strength distribution. With one and the same set of parameters we describe available experimental data for 48Ca and predict the electric dipole strength function for 50Ca.

Highlights

With the fast development of radioactive beam techniques over the past several decades, experiments focused on the exotic short-lived nuclei were performed extensively
The pygmy dipole resonance (PDR) leads to the enhancement of dipole strength well below the region of the giant dipole resonance (GDR)
The total sum of the measured energyweighted sum rule (EWSR) of this E1 distributions is less than 1÷2% of the Thomas-Reiche-Kuhn (TRK) sum rule value for stable nuclei and less than 5÷6% for unstable neutron-rich nuclei [1]

Summary

Introduction

With the fast development of radioactive beam techniques over the past several decades, experiments focused on the exotic short-lived nuclei were performed extensively. The study of new exotic nuclei (or/and modes of excitation) stimulates the development of nuclear models to describe properties of nuclei away from the stability valley. The quasiparticle random phase approximation (QRPA) with a self-consistent mean-field derived from Skyrme energy density functionals (EDF) is one of the most successful methods for studying the low-energy dipole strength, see e.g., Refs. We illustrate our approach with the stable isotope 48Ca having the closed neutron shell N=28, in comparison with the unstable isotope 50Ca with N=30. These nuclides from the Ca chain are suitable candidates to follow the PDR evolution. Our results for neutron-rich Ca and Sn isotopes were reported in Refs. [12,13,14]

Brief outline of the FRSA model

Results and discussion

Summary