Open AccessA camera for electron diffraction
Author(s) -
George Thomson,
C. G. Fraser
Publication year - 1930
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1930.0137
Subject(s) - diffraction , optics , cathode , reflection (computer programming) , electron , vacuum tube , cathode ray tube , cathode ray , electron diffraction , beam (structure) , tube (container) , electron gun , photographic plate , materials science , physics , computer science , electrical engineering , engineering , nuclear physics , composite material , programming language
The apparatus described in this paper, which will be called for shortness an electron camera, is intended to study the diffraction patterns formed by the reflection of cathode rays from crystalline surfaces. It differs from the original apparatus used by Davisson and Germer for this purpose in that the method of detection is photographic instead of electrical, and that the energy of the electrons is much greater, being at least 6000 volts (more usually 30,000) instead of about 300. In consequence of the much greater penetrating power of these fast rays it is not necessary to use an elaborate vacuum technique. The principle of the apparatus is that a narrow beam of cathode rays generated in a gas-filled discharge tube is selected by passing through two fine pin-holes and then strikes the crystalline target, where it is diffracted into divergent beams which ultimately strike a photographic plate.