International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators
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SM/AE-05 Nuclear Microprobe Facility at iThemba LABS in Multidisciplinary Applications — W. Przybylowicz and J. Mesjasz-Przybylowicz Materials Research Group, iThemba LABS, Somerset West, South Africa Corresponding Author: przybylowicz@tlabs.ac.za Nuclear microprobe at Materials Research Group of iThemba LABS (earlier National Accelerator Centre) has been operational since 1991. Ion beams are provided by the 6 MV CN single-ended Van de Graaff accelerator (High Voltage Engineering USA) installed in 1963. Voltage range is between 0.6 and 6 MV. Several old components were replaced and the accelerator operation has been partly computerized in 2003 — 2006. The microprobe uses a standard magnetic quadrupole triplet (OM 150) and experimental chamber manufactured by Oxford Microbeams. Modifications including implementation of digital scanning system and computer-controlled changes of specimen position using stepper motors were made locally. The most often used techniques are PIXE and RBS. Other ion beam techniques (NRA, PIGE, STIM, IBIC) were also occasionally used. Protons and α particles were the only focused ion beams used. Since commissioning the microprobe has been serving the South African research community and industry, often hosting students and researchers from other African countries. It operates as a national and effectively regional facility, without fees charged for its usage by the academic community. Instead, rigorous collaboration protocols have been established and implemented with the goal of maximizing scientific outputs. Initially microbeams have been used in materials science and geological applications, which were typically forming part of M.Sc. or Ph.D. projects done in collaboration with local universities. An important factor in successful collaborations was the availability of auxiliary equipment for on-site specimen preparation, in particular the establishment of specialized cryo-preparation laboratory, with some equipment unique in Africa and skilled personnel being part of our research group. At present this is the only microprobe worldwide with analytical capabilities of biological specimens in frozen-hydrated state. This has been the key of success, especially in research projects related to plant physiology, ecophysiology, agriculture and environmental studies. Selected applications of finalized research projects will be presented.
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