Rapid three-dimensional imaging of defect distributions using a high-intensity positron microbeam

Abstract

An intense positron microbeam generated by an electron accelerator has been developed for obtaining three-dimensional positron lifetime mappings in a sample to permit visual evaluation of defect distributions. The beam diameter at the sample was 80–100 μm. The counting rate of the positron annihilation γ rays used to measure positron lifetime was as large as 3×103 s−1. Three-dimensional imaging was demonstrated of positron lifetimes in a SiO2 sample, which was irradiated with ion beams through a mesh mask. The time to obtain a single image (3500 pixels for an area of 2.5×3.5 mm2) was 0.5–1 h.