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Design and technique of operation of a double crystal spectrometer

DuMond, Jesse W. M. and Hoyt, Archer (1930) Design and technique of operation of a double crystal spectrometer. Physical Review, 36 (12). pp. 1702-1720. ISSN 0031-899X. http://resolver.caltech.edu/CaltechAUTHORS:DUMpr30d

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Abstract

The double crystal x-ray spectrometer is distinctly different in principle from the single crystal spectrometer and calls therefore for a completely new design rather than an adaptation of single spectrometer design. One such new design is described in this paper. Emphasis is laid on the fact that the wave-length selected by the process of two successive crystal reflections in any prescribed orders depends solely on the dihedral angle between the crystals. The advantages of rotating both crystals in equal and opposite directions with respect to a plane through their axes of rotation are pointed out and a spectrometer designed to accomplish this is described. In this spectrometer the turning of a single shaft drives the two crystals, the spectrometer as a whole and the x-ray tube, at the proper angular rates about the proper centers to insure that the x-ray beam will at all times remain centered on the crystal faces and the window of the stationary ion chamber. It is pointed out that spurious fluctuations may be introduced in spectral curves by the x-ray beam migrating across small steps in the cleavage surface reflecting the radiation. Description of design covers design of spectrometer and turning mechanisms, the tube housing, lead shields, the detecting system consisting of an ion chamber with internal grid of special design to minimize natural leak and a Hoffmann vacuum electrometer connected to it through a short evacuated shield. Description of operating technique covers optical method of accurately orienting the crystal faces, methods of aligning the tube, precautions to eliminate background.


Item Type:Article
Additional Information:©1930 The American Physical Society. Received 8 November 1930.
Record Number:CaltechAUTHORS:DUMpr30d
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:DUMpr30d
Alternative URL:http://dx.doi.org/10.1103/PhysRev.36.1702
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:2598
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:12 Apr 2006
Last Modified:26 Dec 2012 08:49

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