DENSITY AND COMPOSITION ANALYSIS USING FOCUSED MEV ION MICROBEAM TECHNIQUES

Nuclear microscopy uses focused MeV ion microbeams to non-destructivel y characterize materials and components with micron scale spatial reso lution. Although a number of accelerator-based microbeam methods are a vailable for materials analysis, this paper centers on the techniques of Ion Microtomography (IMT) and Particle-Induced X-ray Emission (PIXE ). IMT provides quantitative three-dimensional density information wit h micron-scale spatial resolution and 1% density variation sensitivity . Recently, IMT has become more versatile because greater emphasis has been placed on understanding the effects of reconstruction artifacts, beam spatial broadening, and limited projection data sets. PIXE provi des quantitative elemental information with detection sensitivities to 1 mu g/g or below in some instances. By scanning the beam, two-dimens ional maps of elemental concentration can also be recorded. However, s ince X-rays are produced along the entire path of the ion beam as it p enetrates the sample, these measurements only give depth-averaged info rmation in general. PIXE tomography (PIXET) is the natural extension f rom conventional PIXE analysis to the full three-dimensional measureme nt and forms the bridge linking the complementary techniques of PIXE a nd IMT. This paper presents recent developments and applications of th ese ion beam techniques in a diverse range of fields including charact erizing metal-matrix composites, biological specimens and inertial con finement fusion targets.