Cross section measurements of 27Al(n,.ALPHA.)21Na and 56Fe(n,p)56Mn reactions for neutron energies between 14.0 and 19.9MeV.

Abstract

Cross sections of the 27Al(n, α)24Na and 56Fe(n, p)56Mn reactions were measured precisely by foil activation in the energy range of 14.0 ∼ 19.9 MeV. For the lower energies of 14.0 ∼ 14.8 MeV, the neutron fluence rate was determined by associated α-particle counting, while the proton-recoil telescope was used for the higher energies of 15.2 ∼ 19.9 MeV. Correction was applied to account for the additional radioactivity brought by d + D neutrons from deuteron implantation in tritium target. The 24Na and 56Mn activities generated by the reactions of interest were determined using 4πβ-γ coincidence counter. In respect of the 27Al(n, α)24Na reaction, the present results agree well with the latest evaluations of Asami and Vonach and with Ryves' measurements, except in the higher energy regions, and in respect of the 56Fe(n, p)56Mn cross section, with Ryves' measurements. On the other hand, the ENDF/B-V evaluations deviate appreciably from the present results in respect of both reactions, and this applies also to...