Fe 56,54 (n,α) Cr 53,51 cross sections in the MeV region

Abstract

Fe56,54(n,α)Cr53,51 cross sections were measured in the neutron energy region of 5-11 MeV using three neutron sources based on accelerators, a twin gridded ionization chamber, and highly enriched Fe56 and Fe54 foil samples. The U238(n,f) reaction was used to monitor the neutron fluence, and the interferences from the low-energy neutrons were corrected according to the neutron energy spectra obtained through unfolding the pulse height spectra measured by a liquid scintillator. Both the measured cross sections show a "shoulder" structure in the 8-11 MeV region which may be caused by the level structure of the residual nuclei. The present paper aims to improve constraint of the Fe56,54(n,α)Cr53,51 excitation functions in the MeV region where their neutron energy dependences are significant, while related measurements are nonexistent or scarce and the deviations among existing measurements and evaluations are significant. To obtain more precise excitation functions of the Fe56,54(n,α)Cr53,51 reactions, further measurements and improved evaluations are required.