Drift compensation in dual start/stop data acquisition positron lifetime measurements

Abstract

When analyzing positron annihilation lifetime spectra with multiple components using an exponential function with a single component, there is a difference between the experimental data and the fitted spectrum. Compensating for this difference causes a shift in the starting time (T0) in the fitted spectrum. Previously, we applied single-component analysis to the positron lifetime spectrum of a defect-containing metal and confirmed the effectiveness of the shift in T0 (ΔT0) for defect analysis. To optimally use the T0 variation for defect analysis, however, it is necessary to minimize the drift in the positron lifetime spectrum due to the temporal instability of the photomultiplier tube and high-voltage power supply. In this study, we report significant suppression of the drift by using dual start/stop data acquisition (dual acquisition), which employs each of the two γ-ray detectors to acquire start and stop signals.