Systematical studies of theE1photon strength functions combining the Skyrme-Hartree-Fock-Bogoliubov plus quasiparticle random-phase approximation model and experimental giant dipole resonance properties

Abstract

Valuable theoretical predictions of nuclear dipole excitations in the whole nuclear chart are of great interest for different applications, including in particular nuclear astrophysics. We present here the systematic study of the electric-dipole (E 1) photon strength functions combining the microscopic Hartree-Fock-Bogoliubov plus quasiparticle random-phase approximation (HFB + QRPA) model and the parametrizations constrained by the available experimental giant dipole resonance (GDR) data. For about 10 000 nuclei with 8 Z 124 lying between the proton and the neutron drip-lines on nuclear chart, the particle-hole (ph) strength distributions are computed using the HFB + QRPA model under the assumption of spherical symmetry and making use of the BSk27 Skyrme effective interaction derived from the most accurate HFB mass model (HFB-27) so far achieved. Large-scale calculations of the BSk27 + QRPA E 1 photon strength functions are performed in the framework of a specific folding procedure describing the damping of nuclear collective motion empirically. In particular, three phenomenological improvements are considered in this folding procedure. First, two interference factors are introduced and adjusted to reproduce at best the available experimental GDR data. Second, an empirical expression accounting for the deformation effect is applied to describe the peak splitting of the strength function. Third, the width of the strength function is corrected by a temperature-dependent term, which effectively increases the deexcitation photon strength function at low energy. The theoretical E 1 photon strength functions as well as the extracted GDR peaks and widths are comprehensively compared with available experimental data. A relatively good agreement with data indicates the reliability of the present calculations. Eventually, the astrophysical rates of (n, γ ) reactions for all the 10 000 nuclei with 8 Z 124 lying between the proton and the neutron drip lines are estimated using the present E 1 photon strength functions. The resulting reaction rates are compared with the previous BSk7 + QRPA results as well as the Gogny-HFB + QRPA predictions based on the D1M interaction.

Systematic study of the radiative proton capture including the compound, pre-equilibrium, and direct mechanisms

“…Large-scale derivations of the γ -ray strength function have been conducted with the use of the HFB plus quasiparticle random phase approximation (QRPA) models [46][47][48][49]. The HFB + QRPA model is known to be an accurate tool to estimate the γ -ray strength function in both closedand open-shell nuclei.…”

“…The experimental data are taken from Refs. [67,68] for 48 Ca(p, γ ) 49 Sc, [69,70] for 50 Cr(p, γ ) 51 Mn, [69,[71][72][73][74] for 58 Ni(p, γ ) 59 Cu, [69] for 77 Se(p, γ ) 78 Br, [75] for 89 Y(p, γ ) 90 Zr, [76,77] for 92 Mo(p, γ ) 93 Tc, [78,79] for 102 Pd(p, γ ) 103 Ag, [80] for 119 Sn(p,γ ) 120 Sb, and [75] for 123 Sb(p, γ ) 124 Te.…”

Effectiveness of the TGI-QRPA approach for studying the electric dipole response

“…The advantage of QRPA-based approaches is that they can in principle be applied to all nuclei other than a few very light systems, and they are successful and accurate at reproducing observed quantities. Among QRPA-based approaches we could mention translational and Galilean invariant (TGI)-QRPA [1][2][3][4][5][6][7][8][9][10], the self-consistent QRPA approach based on Skyrme [11][12][13][14][15][16][17][18], and the relativistic density functional QRPA [19][20][21][22][23][24] and QRPA on Gogny force [25][26][27][28], to name but a few. As a rule, these models often employed phenomenological potentials (e.g., oscillator, Nilsson, Woods-Saxon, etc).…”