Precise Solid-Angle Counting

The principle of solid-angle counting is described and the corrections are reviewed which must be applied to the measured counting rates to calculate the disintegration rates. The main correction is that for the solid angle subtended by the diaphragm. All other corrections are due to scattering or absorption effects,- which depend on the kind and energy of the counted radiations. Some theoretical estimations of these effects are presented. The efficiency of different kinds of detectors, transmission through, and scattering at, the diaphragm, absorption and scattering between source and detector, and absorption and scattering inside the source and the backing are discussed with respect to the different radiations and energies. The investigation of the errors connected with these corrections makes it possible to find out for which radiations and which energy intervals the method is the most promising. For these cases all the considered sources of error have also been investigated experimentally. The results confirm the theoretical estimations and permit precise deduction of the obtainable accuracies. Some recent examples of high-precision solid-angle counting on suitable radiations are described in detail. (author)