Browsing by Author "Eisa, Mohamed Eltayeb M"

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    Optimisation of accelerator optics and the application of nuclear microscopy to the biomedical field
    (2005) Eisa, Mohamed Eltayeb M; Comrie, Craig; Conradie, Lowry; Pineda-Vargas, Carlos A
    With the aim of improving the reliability and stability of the beams delivered to the nuclear microprobe at IThemba LABS, as well as optimization of the beam characteristics along the Van de Graaf acceleratore beamlines in general, relevant modifications were implemented. The design and layout of the beamlines in general, relevant modifications were implemented. The design and layout of the beamlines were revised. The beam-optical characteristics through the accelerator, from the ion source up to the analysing magnet directly after the accelerator, were calculated and the design optimised, using the computer codes TRANSPORT, IGUN and TOSCA. The ion source characteristics and optimal operating conditions were determined on an ion source test bench. The measured optimal emittance for 90% of the beam intensity was bout 50π mm mrad for an extraction voltage of 6kV. These changes allow operation of the Nuclear Microprobe at proton energies in the range 1 MeV to 4 meV with beam intensities of tens of a pA at the target surface. The capabilities of the nuclear micropobe facility were evaluated in the improved beamline, with particular emphasis to the characertisation of hard human calcium-rich tissue materials. The process of demineralization in teeth erosion due to exposure to acidic media was investigated in a group of test and control healthy human molar teeth. Samples were cut in cubes of