A Diffusion-deposition Tracer System

A dual'tracer technique has been developed for use in experiments in low-level atmospheric dispersion and deposition. The system is considered unique in two respects. First, it permits definition of thc airborne concentrations of a cloud of small particles representative of a true aerosol and simultaneously the deposition of larger particles on the soil and vegetation beneath. Second, the deposition tracer consisting of Cu64 particles in the 1 to 10-micron range can be detected directly on the surface without the intervention of any artificial collecting mechanism or the necessity of inferring deposition by mass balance techniques. Techniques, instruments, and facilities for the I.".eparation, activation, emission, sampling, and measurement of both tracers are described in sufficient detail to permit reproduction. The report is also intended as a background reference for future analytical studies resulting from field experiments. A DIFFUSION-DEPOSITION TRACER SYSTEM