Penning-trap type pulsed positron sources using radioisotopes for the elemental analysis of metallic materials

A variety of metallic materials are subjected to investigation of compositional analysis by using beam techniques such as XPS, EPMA, and SIMS, while of morphological or structural analysis by SEM, TEM, and LEED. This work specifically aims at positron annihilation analysis of microscopic defects in carbon steels S10C fatigued under extreme conditions for advanced research, observing the spatial and size distribution of defects by measuring the emitted γ-ray energy, emission angle and the annihilation lifetime. The authors prepared the positron source which is an acrylic block deposited with drops of Na 22 solution, and surrounded by solid Ne as a moderator, operated in DC mode. This year they obtained the relationship between the nature of defects in the specimen and positron lifetime observed. (S. Ohno)