Measurement of Cross Sections for the ¹⁰B(n,α)⁷Li Reaction at 4.0 and 5.0MeV Using an Asymmetrical Twin Gridded Ionization Chamber

Cross sections of the ¹⁰B(n,α)⁷Li reaction (including the total, the “leaking” alpha, forward alpha and backward alpha parts) at E_n =4.0 and 5.0 MeV were measured using an asymmetrical twin gridded ionization chamber and two back−to-back ¹⁰B samples. Measurements were performed at the 4.5 MV Van de Graaff accelerator of Peking University. Monoenergetic neutrons were produced through the ²H(d,n)³He reaction with a deuterium gas target. Absolute neutron flux was determined by a ²³⁸U sample set inside the gridded ionization chamber and a BF₃ long counter was employed as a neutron flux monitor and for normalization. The present results are compared with previous measurements and evaluations.