Seminar “Nuclear Theory”

Date and Time: Monday, 29 June 2020, at 3:30 PM

Venue: Online conference in Zoom, Bogoliubov Laboratory of Theoretical Physics

Seminar topic: «Global calculations of the beta decay properties with the Fayans functional»

Speaker: I. N. Borzov (NRC ‘Kurchatov Institute” and BLTP JINR)

Abstract:

An effective approximation to fully self-consistent global calculations of the β-decay properties is presented. It is based on the self-consistent description of the ground states within the Fayans energy-density functional (DF3) and continuum quasiparticle random phase approximation (CQRPA). The accuracy of the DF3+CQRPA calculations is analyzed. For more than 200 (quasi) spherical nuclei with Z = 18 – 51 and T_1/2 < 5 s, the experimental lifetimes are described accurate up to factor of 2, and the probabilities of emission of delayed neutrons are up to factor of 3. A comparison with the current state-of-the-art self-consistent models: spherical relativistic HB+RQRPA with D3C* functional, deformed finite-amplitude method (FAM) and deformed HFB+QRPA with SkO’ and Sly4 Skyrme functionals, respectively, as well with Interacting Shell Model, is exemplified by studying the β-decay properties in the reference Ni isotopic chain.

The main mechanisms of the “sudden shortening” of the half-lives found in RIKEN for the isotopes heavier than doubly-magic ⁷⁸Ni are figured out. These are the contributions of the first-forbidden decays, many-particles–many holes configurations effects, possible deformation and ground-state spin inversion. The emphasis is made on extreme sensitivity of the effect to the balance of the Gamow–Teller and first-forbidden decays in the total β-decay rate. A change in their ratio before and beyond the neutron shell crossing at N = 50 is shown.

Link to the conference on Zoom