Development of minute test piece evaluation technique using positron annihilation lifetime spectroscopy

Ando, Hirokazu*; Yamawaki, Masato*; Hirade, Tetsuya  ; Akiyoshi, Masafumi*

Positron annihilation lifetime spectroscopy (PALS) is very strong tool to investigate sab-nanometer scale defects in metals and semiconductors. PALS is based on the -ray measurement techniques and it is difficult to measure radioactive samples such as Neutron irradiated samples. Therefore we are creating a method by which you can measure PALS for one very small radioactive sample. It is needed to reject events that positrons annihilate at outside of the sample. We placed the sample at a small space between scintillators and used signals from the scintillators for the anti-coincidence method to reject the events. We succeeded to reject 20% of the events.