The Contraction of Nuclear Emulsions

Abstract

A technique for measuring the fractional change in thickness which occurs when a nuclear emulsion is processed, is described. The method involves the registration in the emulsion of the tracks of α-particles from a radiothorium source and this permanent record can be used to follow any subsequent thickness variations. Some observations on Ilford C2 emulsions, 50μ in thickness, have been made and these show considerable variations in thickness over a period of time. Tests indicated that some of the change is probably due to humidity variations. The application of this method to the monitoring of variations in k for emulsions, in which deuterons or other tracks have been registered, is described.