Symmetric analog positron lifetime spectrometer utilizing charge-to-digital converters

A symmetric positron annihilation lifetime (PAL) spectrometer using a charge-to-digital converters was designed. It is based on a coincidence circuit for the trigger and recording of the timing and the charge of the pulses of two scintillation detectors. The off-line data processing allows a detailed study of the spectrometer performance in function of the width of the digital charge discriminator windows for acceptance of the pulses as starts and stops. Some technical problems when working with BaF2 scintillators were solved. The parasitic effect of the pileup and backscattered γ-rays on the PAL spectrum is discussed.