Aerodynamic parameter determination in inlet orifice of CEA alpha dosimeter

Among the aerodynamic parameters critically affecting the efficiency of personal alpha dosimeters, intended for use in the open-pit mining of uranium, the geometry of the sampling head and the size and location of the aspiration zone in relation to the breathing zone of the worker were examined in the laboratory. The size of aspiration zone of a CEA dosimeter, worn at the waist, was not large enough to overlap with the breathing zone. A discrepancy of radioactivity count in the aspiration zone and breathing zone (true value) would create some problems in efficiency determination