Effectiveness of slit collimation of radiometric detectors

The article investigates theoretically and experimentally the effectiveness of slit collimation of detectors. Formulas are obtained approximating the dependence of the instrument build-up factor on the parameters of the slit collimator for different radiative energies and materials of the product. The experiment was carried out on a laboratory installation with radiation source type 137Cs with an activity of 1.5 g-eq of radium. Conversion of the radiation to an electric signal was effected by a scintillation detector consisting of a single crystal of cesium iodide and a photomultiplier operating in the regime of stable anodic current. For recording the defectorgrams a rapid automatic recorder was used. The obtained dependences of the instrument build-up factor for unidirectional and isotropic radiation sources make it possible to evaluate fairly simply the expected contribution of scattered radiation to the total signal at the output of the slit collimator or to choose the parameters of the collimator by proceeding from the maximally permissible ratio of the contributions of scattered and unscattered radiation to the total signal