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An Automated Two-Crystal Spectrometer Employing Direct Angular Positioning and Readout

Published online by Cambridge University Press:  06 March 2019

T. K. Gregory
Affiliation:
Physics Department and Institute of Materials Science University of Connecticut, Storrs, Connecticut 06268
P. E. Best
Affiliation:
Physics Department and Institute of Materials Science University of Connecticut, Storrs, Connecticut 06268
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Abstract

A unique approach has been used in the construction of a vacuum-two-crystal spectrometer. The instrument uses digital shaft encoders directly coupled to the analysing crystal axes to give accurate absolute angular measurement over a 360° revolution of each crystal. Each axis is driven directly by a torque motor tachometer combination which allows precise speed and position control. The complete two-crystal carriage assembly rotates about the first crystal axis, thus permitting the x-ray tube to be fixed to the vacuum chamber. The carriage and detector rotations are driven through antibacklash gearing by smaller shaft encoder, torque motor, tachometer assemblies. Because the complete unit is housed within the vacuum chamber, there are no alignment changes on system pump-down. The spectrometer is part of a completely automated computer controlled system. The computer is used for data acquisition and analysis as well as for controlling the angular position of the analyzing crystals, detector, and carriage.

Type
Research Article
Copyright
Copyright © International Centre for Diffraction Data 1971

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