Evaluated cross sections of the σ(γ, nX) and σ(γ, 2nX) reactions on 112, 114, 116, 117, 118, 119, 120, 122, 124Sn isotopes

Abstract

A combined analysis of experimental data on total and partial photoneutron reaction cross sections, obtained using bremsstrahlung γ-radiation and quasi-monoenergetic annihilation photon beams, was performed for nine Sn isotopes. The partial reactions σeval(γ, nX) and σeval(γ, 2nX) cross sections were evaluated using an approach free of the shortcomings of experimental neutron multiplicity sorting methods. This approach involves calculations within the photonuclear reaction model, based on Fermi gas densities and considering the effects of nucleus deformation, the isospin splitting of its giant dipole resonance (GDR), and experimental data on the total photoneutron cross sections σexp(γ, xn) = σexp(γ, nX) + 2σexp(γ, 2nX) = σexp(γ, n) + σexp(γ, np) + … + 2σexp(γ, 2n) + 2σexp(γ, 2np) + …. The evaluated σeval(γ, nX) and σeval(γ, 2nX) reactions cross sections were obtained using the introduced transition multiplicity functions Ftheor = σtheor(γ, 2nX)/σtheor(γ, xn) = σtheor(γ, 2nX)/[σtheor(γ, nX) + 2σtheor(γ, 2nX) + …]; and σeval.(γ, 2nX) = Ftheor.σexp.(γ, xn) = σeval(γ, nX) = (1 − 2Ftheor)σexp(γ, xn). The evaluated partial reaction cross sections were used to assess the total photoneutron reaction cross sections σeval(γ, sn) = σeval(γ, nX) + σeval(γ, 2nX) + … as functions of the mass number A. The GDR features of 112, 114, 116, 117, 118, 119, 120, 122, 124Sn isotopes were studied and are discussed here.