SYSTEM DEVELOPMENT OF A TIME-OF-FLIGHT SPECTROMETER FOR SURFACE ANALYSIS OF MATERIALS

This is original study on design the time-of-flight Rutherford backscattering spectrometry (TOF-RBS) tech-nique for nano-material surface analysis with high resolu-tion. At Fast Neutron Research Facility, FNRF, upgrad-ing of the existing pulsed-beam accelerator from 150-keV of D+ to 280 keV of He+ was proposed to use for the most powerful method of a near-surface characterization of materials utilizing TOF-RBS. The beam transport was re-designed based on the new multicusp ion source which was designed the extraction and focusing system for optimiza-tion by the computer program KOBRA, and the existing beam pulsing system to provide He+ ion beam with a few nano-second width and 280-keV acceleration energy. Sim-ulation was done by the computer program Beam Optics, resulting in the beam size at the target position of 1 mm in diameter. The measured beam size was 6 mm in diame-ter. The optimization of the target position was done by the PARMELA program, to be at 3.14 m from the middle point of the buncher. Components, beam transport characteris-tics, beam optic simulation, and role of quadrupole magnet were explained with technical data listed. Design and test of the scattering chamber for TOF-RBS were shown with He-ion scattered spectra which were measured by the MCP detector. The quadrupole triplet was designed and con-structed at FNRF. Development of TOF-RBS system was implemented in this study. Designing component, fabrica-tion and installation to the accelerator system were com-pleted. Beam extraction and He-scattering tests were done