A measurement of the 6Li( n, α) cross-section

Abstract

The relative shape of the 6 Li(n,α) 235 U(n,f) cross-section ratio has been determined in the range of incident neutron energy from 2 to 800 keV. The measurements were made by the time-of-flight method using the Harwell 45 MeV linac to provide the pulsed source of neutrons. A thin 6Li-glass scintillator was used to register the ( n, α) events, and the ( n, f) events (in a metallic sample of 235U) were registered with fission neutron detectors. The shape of the 6Li( n, α) cross-section was obtained by combining the measured 6 Li(n,α) 235 U(tn,f) cross-section ratio with an evaluation of the 235U( n, f) cross-section. The cross-section so derived was placed on an absolute scale by normalization in the neutron energy interval 2–10 keV, where the 6Li( n, α) cross-section is accurately known. The cross-section at the peak of the prominent p-wave resonance near 240 keV is found to be 3.29 ± 0.12 b. The results are compared with other measurements and also with a recent theoretical calculation of the cross-section.