Programme

O.16 -- Oral, VCTP-49

Date: Friday, 2 August 2024

Time: 17:05 - 17:30

Odd-even mass differences of well and rigidly deformed nuclei in the rare earth region: A test of a newly proposed fit of pairing matrix elements

T. V. Nhan Hao (1), N. N. Bao Nguyen (1), and D. Quang Tam (1,2), P. Quentin (3), L. Bonneau (3), Meng-Hock Koh (4)

(1) Faculty of Physics, University of Education, Hue University, 34 Le Loi Street, Hue City, Vietnam and Center for Theoretical and Computational Physics, University of Education, Hue University, 34 Le Loi Street, Hue City, Vietnam (2) Faculty of Basic Sciences, University of Medicine and Pharmacy, Hue University, Hue City 52000, Vietnam (3) LP2I, UMR 5797, Universit´e de Bordeaux, CNRS, F-33170, Gradignan, France (4) Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia. and UTM Centre for Industrial and Applied Mathematics, 81310 Johor Bahru, Johor, Malaysia

We discuss a test of a recently proposed approach to determine average pairing matrix elements within a given interval of sp states around the Fermi level λ as obtained in the so-called uniform gap method (UGM). It takes stock of the crucial role played by the averaged single particle (sp) level density ˜ρ(e). These matrix elements are deduced within the UGM approach, from microscopically calculated ˜ρ(e) and gaps obtained from analytical formulae of a semi-classical nature. Two effects generally ignored in similar fits have been taken care of. They are: a) the correction for a systematic bias in choosing to fit pairing gaps corresponding to equilibrium deformation solutions as discussed by Moller and Nix [Nucl. Phys. A 476, 1 (1992)] and b) the correction for a systematic spurious enhancement of ρ(e) for protons in the vicinity of λ, due to the use of the local Slater approximation for the treatment of the Coulomb exchange terms in most calculations (see e.g. [Phys. Rev C 84, 014310 (2011)]). This approach has been deemed to be very efficient upon performing Hartree-Fock + BCS (with seniority force and self-consistent blocking when dealing with odd nuclei) calculations of a large sample of well and rigidly deformed even-even rare-earth nuclei. The reproduction of their experimental moments of inertia has been found to be at least of the same quality as what has been obtained in a direct fit of these data [Phys. Rev C 99, 064306 (2019)]. We extend here the test of our approach to the reproduction, in the same region, of three point odd-even mass differences centered on odd-N or odd-Z nuclei. The agreement with the data is again roughly of the same quality as what has been obtained in a direct fit, as performed in the above reference.

Presenter: Tran Viet Nhan Hao