磁界レンズを用いたエネルギー選別型β<SUP>+</SUP>-γ同時計測陽電子寿命測定装置

Abstract

A β+-γ coincidence positron lifetime spectrometer equipped with two electromagnetic lenses was constructed. The electromagnetic lens was used to have energy-selected positron beam. It accomplished a time resolution of 385 ps (FWHM) for the total system with a Pilot U plastic scintillator. By using a silicon avalanche diode instead of Pilot U plastic scintillator to initiate start timing signals, the time resolution was improved to 345 ps (FWHM). With this method, in-situ positron lifetime measurements at high temperatures or under high stresses can be attained easily.