New method for high counting rate of positron annihilation age-momentum correlation (AMOC) measurement

Hirade, Tetsuya  ; Ando, Hirokazu*; Manabe, Kensuke*; Ueda, Daisuke*

Although positron annihilation ray age-momentum correlation (AMOC) measurements can give information that cannot be obtained by other methods, it takes a long time to measure. The time resolution and the counting rate are in a trade-off relationship. We tried to improve the counting rate by increasing detectors. If the position of the detector deviates by 1 mm, it shifts 3 ps on the time axis. Even if multiple detectors are introduced, it is very difficult to match the time information obtained by each detector. Therefore, we have introduced each characteristic waveform to the signal from every detector. It was possible to identify a detector by use of a characteristic shape of waveforms, i.e. every spectrum for each detectors can be obtained. Afterward, every time shift for each spectrum can be calculated and then finally all of the events can be analyzed by correcting time shifts to construct one spectrum. Hence we succeeded to perform high count rate AMOC measurements.