Complementary optical-potential analysis of -particle elastic scattering and induced reactions at low energies

Abstract

A previously derived semi-microscopic analysis based on the Double Folding Model, for α-particle elastic scattering on A ∼100 nuclei at energies below 32 MeV, is extended to medium mass A ∼50-120 nuclei and energies from ∼13 to 50 MeV. The energy-dependent phenomenological imaginary part for this semi-microscopic optical model potential was obtained including the dispersive correction to the microscopic real potential, and used within a concurrent phenomenological analysis of the same data basis. A regional parameter set for low-energy α-particles entirely based on elastic-scattering data analysis was also obtained for nuclei within the above-mentioned mass and energy ranges. Then, an ultimate assessment of (α, γ), (α, n) and (α, p) reaction cross sections concerned target nuclei from 45 Sc to 118 Sn and incident energies below ∼12 MeV. The former diffuseness of the real part of optical potential as well as the surface imaginary-potential depth have been found responsible for the actual difficulties in the description of these data, and modified in order to obtain an optical potential which describe equally well both the low energy elastic-scattering and induced-reaction data of α-particles.

α-particles optical potential for medium and heavy-mass nuclei around the Coulomb barrier

“…The analysis of α-induced reaction cross sections below the Coulomb barrier [6] has shown that the diffuseness a R of the OMP real part as well as the surface imaginary potential depth W D , established by the former analysis above B, are responsible for the difficulties encountered in the description of the reaction data at lower energies. Consequently, the modified energy dependence of these two parameters, for E c.m.…”

“…/B <0.9 (Table 3 of Ref. [6]) have provided an optical potential that describes equally well the low energy α-particle-induced reaction and elastic scattering data. This has been additionally proved [8] to be also the case of recent analysis of the (α,n) reactions on 92,94 Mo isotopes and α-capture on 112 Sn [3] and 117 Sn [4].…”

“…[7] (dotted curves), and the same parameters except the former depth [6] of the imaginary surface potential W D =4 MeV (dash-dotted curves), with the measured [11] and calculated (solid curves) cross sections of (α, γ) and (α, xn) reactions on 121 Sb and 127 I target nuclei. The short-dotted curves in the case of the reaction 127 I(α, n) 131 Cs reaction correspond to average s-wave radiative widths increased and decreased by 60 meV.…”

“…The same semi-microscopic analysis was then extended to A ∼50-120 nuclei and energies from ∼13 to 50 MeV [6]. The Double Folding Model (DFM) has been involved in order to obtain the real part of the optical potential while the energy-dependent phenomenological imaginary part was obtained including the dispersive correction to the DFM real potential.…”

Measurement and model analysis of(n,xα)cross sections for Cr, Fe,59Co, andKunieda1, Haight2, Kawano3 et al. 2012Phys. Rev. C25030View full textAdd to dashboardCite

“…For outgoing alpha-particles, we adopted the recent version of the global OMP of Avrigeanu et al [29,30]. Calculations are done using the ECIS code [31] assuming the spherical model.…”