Development of spin-polarized positronium time-of-flight measurement

スピン偏極ポジトロニウムの飛行時間測定法の開発

前川 雅樹; Zhou, K.*; 深谷 有喜   ; Zhang, H.; Li, H.; 河裾 厚男

Maekawa, Masaki; Zhou, K.*; Fukaya, Yuki; Zhang, H.; Li, H.; Kawasuso, Atsuo

For the application of the positron annihilation spectroscopy method to the study of magnetic substances, we have developed a spin-polarized positron beam. Using this, the spin-polarization at the first surface layer was estimated from the 3- annihilation of positronium. The energy distribution of the emitted positronium is concerned with the electron density of state (DOS). This means that spin-polarized DOS at the first surface layer could be obtained by measuring the energy distribution of the spin-polarized positronium (SP-Ps). For this purpose, we are constructing a SP-Ps time-of-flight (TOF) apparatus. Time-of-flight of emitted Ps is determined by a time difference of a start and a stop signal, which are triggered by secondary electrons obtained by passing through a carbon thin film and annihilation ray of the 3- annihilation of the emitted Ps, respectively.