Statut  Confirmé 
Série  IPNTHEO 
Domaines  nuclth 
Date  Mercredi 6 Décembre 2017 
Heure  11:30 
Institut  IPN 
Salle  Bâtiment 100, Salle A015 
Nom de l'orateur  Arsenyev 
Prenom de l'orateur  N. N. 
Addresse email de l'orateur  
Institution de l'orateur  Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna, Russia 
Titre  Microscopic Description of Pygmy Dipole Resonances in Neutronrich Ca Isotopes 
Résumé  The structure of exotic neutronrich nuclei is one of the main fields of interest in contemporary nuclear physics research. Much attention has been devoted to the ef fects of varying the ratio between the proton Z and neutron N numbers on different nuclear structure characteristics of nuclei away from their valley of &#946;stability. One of the phenomena associated with the change in N/Z ratios is the pygmy dipole res onance (PDR). One of the successful tools for describing the PDR is the quasiparticle random phase approximation (QRPA) with the selfconsistent meanfield derived from Skyrme energy density functionals (EDF). Such an approach can describe the properties of the lowlying states reasonably well by using existing Skyrme inter actions. Due to the anharmonicity of the vibrations there is a coupling between onephonon state and more complex configurations. The main difficulty is that the complexity of calculations beyond standard QRPA increases rapidly with the size of the configuration space, and one has to work within limited spaces. Using a finite rank separable approximation for the residual particlehole interaction derived from the Skyrme forces one can overcome this numerical problem. As an illustration, we study the properties of the lowlying dipole states in the even even nuclei 40 &#8722; 58 Ca. Using the same set of the EDF parameters we describe available experimental data for 40,44,48 Ca and give predictions for 50 &#8722; 58 Ca. In particular, we examine the impact of the coupling between one and twophonon states on the low energy E1 strength of 40,44,48 Ca. We predict a strong increase of the summed E1 strength below 10 MeV with increasing neutron number from 48 Ca. 
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