Indexed on: 01 May '65Published on: 01 May '65Published in: Atomic Energy
The process in which black spots are produced in nuclear emulsions by β and ψ emitters with dimensions from 10μ down to hundredths of microns is discussed. A calibration curve is presented which relates activity to spot size for locally produced type XX film after 10-day exposures. By means of the technique which was developed; a spot size distribution was obtained for failout samples collected in the northern hemisphere in December 1962 and May 1963. It is shown that the distribution is of a hyberbolic type with a tendency toward increased slope with the passage of time after the instant of aerosol injection into the stratosphere.