Plutonium particle size determination using an α-particle imaging system

This paper has discussed the use of an α-particle imaging system in estimating the particle size of Pu aerosols. The relation between the total α disintegration, A, and the spot diameter, d, can be expressed as log A = a + b·d. The sensitivity of the imaging system is about 30 times higher than ZnS(Ag) autoradiography system. The imaging system can detect α activity of about 0.5 dpm for an exposure time of 20 min. These results indicate that the imaging system is practically applicable to rapidly estimate the particle size of Pu aerosols. In the near future, the imaging system may be improved to record an image of the Pu particles on a video display. Furthermore, the particle size distribution may be automatically obtained by using a particle size analyzer.