The Reflection of the X-Rays.

Abstract

MESSRS. LAUE, Friedrich, and Knipping's remarkable photographs taken through a crystal with X-rays have opened a new field of research. Mr. W. L. Bragg has shown that much stronger photographs are produced by a grazing reflection from mica. We have recently used the latter discovery to study the reflected beam electrically. We find that it resembles ordinary X-rays. Just like the primary rays it ionises air and helium and produces a soft radiation when it strikes metals. The variation of its ionisation in air with pressure is also similar. We have so far obtained effects as great as 1 or 2 per cent, of the primary beam. In some cases the measurements in helium were magnified by ionisation by collision.