Cross Section Measurements of ²⁷ Al(n, α)²⁴Na and ⁵⁶Fe(n, p)⁵⁶Reactions for Neutron Energies between 14.0 and 19.9 MeV

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 the JENDL-2 evaluations in respect of the ⁵⁶Fe(n,p)⁵⁶Mn cross section.