LXXV International Conference «NUCLEUS – 2025. Nuclear physics, elementary particle physics and nuclear technologies»

Ground state and beta-decay properties of heavy isotopes near N=126

Not scheduled

20m

70(2013) (Санкт-Петербургский Государственный Университет )

Oral Section 1. Experimental and theoretical studies of nuclei. 1. Experimental and theoretical studies of nuclei

Speaker

IVAN BORZOV (National Research Centre "Kurchatov Institute")

Description

The precision laser spectroscopy data for exotic neutron-rich nuclei obtained at the RIB facilities call for unified description of the charge radii, magnetic moments and β decay half-lives. Our calculations in the long chains of spherical isotopes near the magic neutron shell Nmag =126 use the self-consistent Finite Fermi System Theory (FFST) and new version of Fayans energy density functional DF3-a with modified volume isovector part [1].
The isotopic behavior of the charge radii and magnetic moments is sensitive to the spin-parity of the orbital occupied by the valence neutron. A delicate competition of the Gamov-Teller (GT) and high energy first-forbidden (FF) decays at N>Nmag, increases sensitivity of the total rate to the ordering of neutron orbitals.
The Fayans-type functionals complies with the experimental single-particle neutron spectra above N =126 (for the reference 208Pb nucleus Δε (n2g9/2 - n1i11/2 ) = - 780 keV). The present calculations, as the ones by [2, 3] show that reproducing the normal ordering of the quasi-particle neutron spectra at N >Nmag is crucial for simultaneous self-consistent description of the charge radii, magnetic moments and β decay half-lives. For comparison, relativistic Hartree-Bogoliubov (RHB) model with covariant functionals [4] which gives an inversed order of these neutron states reproduces the kink in the charge radii at N=126. At the same time, global RQRPA calculation [5] typically overshoot available experimental β decay rates of the isotopes near N =126.
Simultaneous description of the experimental data on nuclear geometric properties and spin-isospin response is indispensable for fine calibration of the energy density functionals and reliable prediction of the β decay rates for the waiting-point nuclei important for the astrophysical r-process nucleosynthesis.

1. I.N. Borzov, S.V. Tolokonnikov. Physics of Atomic Nuclei. 86, 304 (2023).

2. Z. Yue, A.N. Andreyev, A.E. Barzakh, Borzov I.N., et. al. for CERN IDS Collaboration (I219). Phys.Rev. C110, 034315 (2024); Phys. Lett. B849, 138452 (2024).

3. . Borzov I.N., Tolokonnikov S.V. Physics of Atomic Nuclei 87, 423 (2024).

4. U. C. Perera, A. V. Afanasjev and P.Ring. Phys. Rev. C104, 064313 (2023).

5. T. Marketin, L. Huther and G. Martı ́nez-Pinedo. Phys. Rev. C93, 025805 (2016).