Effect of air-scattered β particles on instrument and dosimeter response

Air-scattered β particles are responsible for many of the inaccuracies encountered when readings are obtained with many types of β survey instrument and personnel dosimeters. The ratio of β particles scattered at various angles to β's coming directly from the source increases as the distance from the source increases. This ratio, at a given distance from the source, is also a function of the β energy, becoming larger for lower-energy β sources. Changes in this ratio cause the response of β instruments to have an apparent change in the directional response. Air-scattered β's also cause personnel dosimeters, which are not properly designed to detect them, to have responses that are low. The authors give experimental results to confirm the above effects. Design changes to survey instruments and dosimeters are suggested that would eliminate the errors created by the failure of the instruments to detect these air-scattered β particles