Phenomena associated with the anomalous absorption of high energy gamma radiation.—II

Abstract

In a previous paper we gave an account of an investigation of the secondary radiation produced when different elements are irradiated with the high energy γ-rays of thorium C". The present paper describes an extension of this investigation. It will be reduced that confusion with the ordinary scattered radiation was almost entirely eliminated by examining the secondary radiation in a direction making a large angle with the primary beam, since under these conditions not only is the Compton radiation relatively very much weaker, but in addition it is comparatively soft and is easily absorbed in the radiator itself, or in a very small thickness of absorber, owing to the large increase in wave-length at this large angle of scattering.