Date of Award

1-1-2010

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Physics

Content Description

1 online resource (vii, 95 pages) : illustrations (some color)

Dissertation/Thesis Chair

Carolyn A MacDonald

Committee Members

Mark Anastasio, Ariel Caticha, John Kimball, Kevin Knuth, Carolyn MacDonald

Keywords

breast cancer, coherent scatter, diffraction, mammography, polycapillary optics, x ray, X-rays, Diagnostic imaging, Breast, X-ray microanalysis

Subject Categories

Nuclear | Optics | Radiology

Abstract

Powder diffraction is commonly used to determine the structures of both inorganic and organic materials. The angle and intensity of the diffraction (also called coherent scatter) peak depends on the nanostructure of the material. When no x-ray optic is used, the peak width broadens, and hence the resolution worsens, as the sample area is increased. However, a small sample area gives low diffracted signal intensity, particularly for thin films and for organic materials, which have low diffraction cross sections. X-ray optics can be used in x-ray powder diffraction to increase the diffraction intensity, thus decreasing exposure times. For a small sample area, highly focused beams will provide the greatest intensity increase, but focused beams will also broaden the diffraction peaks. For some kinds of optics, this again degrades the resolution. However, because of the clean, symmetric, near-Gaussian peaks produced by polycapillary optics, the location of the center of the diffraction peak can be obtained with high precision even with broad peak widths.

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