Polarization induced by Radiation in ‘Perspex’

Abstract

IF, after irradiation of a thick piece of ‘Perspex’ with a sufficient number of electrons of a few MeV., the specimen is knocked with a sharp tool, a rather intense ‘lightning flash’ is seen and a tree-like crack pattern occurs. The foot of the stem is situated at the point which was struck. Sometimes the discharge occurs spontaneously towards any disturbance at the surface of the ‘Perspex’ block.