Reconfigurable positron annihilation lifetime spectrometer utilizing a multi-channel digitizer

Positron annihilation lifetime (PAL) spectroscopy is a powerful tool to study atomic-scaled microstructure of materials. But PAL spectra can be easily distorted, then one will get wrong conclusions. Conventional PAL spectrometers have been widely used but the data processing capability is limited. In order to deal with the generally existed problems related to spectra distortion, and find an economic way to let conventional PAL spectrometers have better performance, we design a reconfigurable PAL spectrometer based on conventional electronic system, multi-channel digitizer card, and LaBr${}_3$ scintillator. By using several data processing methods, analysis results of PAL spectra show significant improvements. We discuss the reasons that cause PAL spectra distortion, and try to figure out how our methods can bring changes. Related works including PAL spectra simulation and Geant4 energy deposition simulation have been done. Several other functions such as time walk offset have been developed to improve the performance of whole system. The spectrometer is still capable to add more functions if needed.