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dc.contributor.authorJones, Elizabeth Anne
dc.description.abstractA 700 keV Van de Graaff accelerator was used to accelerate protons onto solid targets of different light elements to produce ultrasoft, characteristic X-rays (< 5 keV). The proton energies were calibrated using the (p, y) resonances at 633 keV in Aluminium and at 340 and 483 keV in Fluorine. The X-ray emission characteristics of Aluminium, Carbon, Gold, Silicon/Carbon, Silicon/Nitrogen and Titanium/Boron were studied as a function of incident proton energy, angle of inclination of the target (30° - 60° to the proton beam) and angle of detection of the X-rays (40° - 130° to the beam). Detection of the X-rays was achieved using a gas-flow proportional counter directly coupled to a low-noise pre-amplifier. The resulting spectra, recorded on a multichannel analyser, were well fitted by linear combinations of single Gaussian curves to give peak position (X-ray energy), width and area (X-ray intensity). Carbon contamination of the target surface was studied in detail for the Aluminium target. A number of low beam currents onto the target (10 - 70 nA) were used for total irradiation times of up to 17 hours in order to establish the degree of overall X-ray energy mixing. The information gained from the study of both the Carbon contamination and the X-ray emission characteristics was used to propose practical optimum conditions for the production of ultrasoft X-rays by proton bombardment in their application to biological and biochemical irradiations. A computer code, capable of following the electron track histories resulting from ultrasoft X-ray interactions has been used to compare the details of such energy deposition with the results of mammalian cell irradiations made at the M. R. C. Radiobiology Unit for a number, of different ultrasoft X-ray energies. Such a-comparison has been used to try to identify the mechanisms of radiation action. Included in this work is the application of the computer code to a variety of. characteristic X-ray photon energies, thus extending the available, calculated data.en_US
dc.subjectMedical Physicsen_US
dc.titleThe Production and Use of Proton-Induced Ultrasoft X-raysen_US
dc.rights.holderThe copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consent of the author

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