Pattison, Philip (1975) X-ray and gamma-ray Compton scattering. PhD thesis, University of Warwick.

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Abstract

The Compton profile which can be obtained from the energy loss spectrum of inelastically scattered photons provides a measure of the momentum distribution of electrons in matter. The use of a solid state detector to analyze the spectrum of scattered gamma-rays has many advantages over the earlier system which employed an x-ray tube and crystal spectrometer. A description of the experimental arrangement and data processing procedures is given for both techniques, with emphasis on the newer gamma-ray method.

It is shown that the presence of multiple photon scattering has led to serious systematic errors in almost every experimental profile published up to the present time. A theoretical treatment, with the use of approximate analytical formulae, is found to be too limited. Instead a Monte Carlo approach is adopted; this provides a general method for calculating the contribution from multiple scattering in most experimental conditions.

The predictions of the Monte Carlo procedure are tested by removing multiple scattering effects from experimental profiles, and the resulting corrected curves are found to be independent of the sample geometry. Moreover, a corrected Compton profile of water shows very good agreement with a recent near Hartree-Fock calculation. Further confirmation came from a measurement of the ratio of total elastic and Compton cross sections, which provides an experimental figure for the total amount of multiple scattering.

Several experimental profiles are reported, and in each case multiple scattering is important. An x-ray profile of aluminium shows marked disagreement with theoretical profiles, whereas a corrected profile measured with 60 keV gamma-rays is in excellent agreement with an interacting electron gas model. Gamma-ray profiles are also obtained for several molecular systems (formamide, p-benzoquinone and decaborane) and the data is used to assess the reliability of localised molecular orbital and semi-empirical descriptions of these complex systems.

Item Type:	Thesis (PhD)
Subjects:	Q Science > QA Mathematics Q Science > QC Physics
Library of Congress Subject Headings (LCSH):	Compton effect, Scattering (Physics), Photons -- Scattering, Gamma rays -- Scattering, X-rays -- Scattering, Monte Carlo method
Official Date:	April 1975
Dates:	Date Event April 1975 Submitted
Institution:	University of Warwick
Theses Department:	Department of Physics
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Cooper, Malcolm
Sponsors:	Science Research Council (Great Britain)
Extent:	135 leaves : illustrations, charts
Language:	eng

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