Use of the precision gamma-spectrometry and the method of normales at experimental evaluation of the reactions cross sections under the action of fast neutrons

The procedure of experimental estimate of cross sections using standard cross sections (normales) is described. The main attention is paid to the precision of determination of efficiencies of registering analytical line γ-quanta in measurements whose unfavourable features are: source extension; measurement geometry with no respect to the assumption of geometry ''point nature''; effects of γ-quanta self-absorption in a sample. It is shown that the unfavourable effect of the above factors on the precision of experiments can be excluded and the resulting precision of cross section determination equalling ∼ 3-5% obtained due to the measurement procedure suggested, in this case the absence of systematic errors is guaranteed