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Design and construction of a point-focusing Berreman type single crystal x-ray monochromator and its application to low-angle scattering studies of biological specimens

Citation

Dibble, William Edwin (1960) Design and construction of a point-focusing Berreman type single crystal x-ray monochromator and its application to low-angle scattering studies of biological specimens. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-02172006-154237

Abstract

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The design and construction of a point-focusing Berreman type, single quartz crystal X-ray monochromator is described. Monochromatization and point focusing of the copper [...] line are obtained by Bragg reflection from the surface of a 2 1/2 by 2 3/8 by 0.015 in. curved crystal lamina which has been subjected to two successive cylindrical bendings at right angles to each other. With a 0.0225 in. aperture defining the size of the X-ray source next to a General Electric CA-7 diffraction tube running at 45 KV and 18 ma, about 3 x 10(9) counts per minute as determined by Geiger tube measurements may be put into a 0.025 half width focus, with the beam in helium atmosphere. Parasitic scattering from the crystal had to be excluded by using a converging vane collimator, which required coating with lead chloride to prevent low-angle total reflection from the vanes. Sample-to-detector distances of up to 49 cm are obtainable. Both photographic and counter detection are used.

Scattering patterns obtained with the instrument on samples of rabbit reticulocyte ribosomes are interpreted to determine the radius of gyration of the particles of 105 A to 2 per cent and the molecular weight of 4.1 x 10(6) to about twenty per cent. No evidence of secondary scattering maxima was observed. The electron density of the sample is approximated by a Gaussian consistent with the data with a cutoff at 170 A, giving in connection with electron microscope data of Professor Hall a hydration of 2.7 g water per g ribosome.

Item Type:Thesis (Dissertation (Ph.D.))
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • DuMond, Jesse William Monroe
Thesis Committee:
  • Unknown, Unknown
Defense Date:1 January 1960
Record Number:CaltechETD:etd-02172006-154237
Persistent URL:http://resolver.caltech.edu/CaltechETD:etd-02172006-154237
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:666
Collection:CaltechTHESIS
Deposited By: Imported from ETD-db
Deposited On:01 Mar 2006
Last Modified:26 Dec 2012 02:31

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