Measurement of the average 6Li absorption cross section relative to the average 235U fission cross section

The ratios of the average Li 6 absorption cross section (A6) and U-235 fission cross section (F25) were measured on critical assemblies with different neutron spectra. The average cross sections were measured with the aid of a Li 6 counter on semiconductor detectors. For the detection of neutrons absorbed in lithium, the authors used the reaction Li 6 (n, a) H 3, where Q = 4.78 MeV. The reaction products were recorded with two surface-barrier detectors. The noncollinearity of the separation of secondary particles is discussed and the results of measurements are presented