The scattering and absorption of heterogeneous x-radiation

Abstract

When a substance is traversed by a homogeneous X-radiation it is observed that the substance itself becomes a source of secondary radiations of two distinct types, one being a corpuscular radiation and the other an electromagnetic radiation similar in character to the original primary. If the primary radiation is not homogeneous similar secondary radiations are still observed) but in this case the effects are complicatef, by the fact that more than one wavelength is present in the primary beam. The secondary X-radiation is not in general of the same quality as the primary exciting it, but can be divided into two distinct parts. The first of these is a radiation characteristic of the element traversed by the primary beamT and) except for extremely slight variations observed with different chemical combinations of the element)) dependent on no other factor. This is the 'characteristic' or 'fluorescent' radiation of the element the conditions of excitation of which by a given primary radiation are well known.In the region of medium X-ray wavelengths, the other part of the secondary radiation never differs greatly in quality from the primary radiation exciting it, but depends, in varying degrees, on the scattering substance itself, on the wavelengths present in the primary beam, and on the direction of propagation of the secondary beam relative to the primary. It is with this radiation that we propose to deal, and which we may refer to as the X-radiation 'scattered° by the substance.