Capture Cross Sections for Thermal Energy Neutrons

Cross sections for capture of thermal energy neutrons were measured for several elements. The method consisted in comparing, by a B${\mathrm{F}}_3$ ionization chamber, the density of thermal neutrons in water and in a solution of the element investigated. In order to avoid corrections for geometry, the effect of the substance was compared with that of boron solutions of different concentrations, and consequently the measurements directly give the ratio of the cross sections of the elements investigated to the cross section of boron. Data are given for N, F, Na, P, Cl, K, V, Mn, Co, As, Se, Br, Cd, I, Ba.