Digital measurement of positron lifetime

Abstract

A prototype of a digital positron lifetime apparatus is presented. We demonstrate that direct digitizing of detector pulses and subsequent simple analysis with software, can be used to replace the conventional analog electronics chain (constant-fraction discriminators, time-to-amplitude converter and multichannel analyzer). In this work, we use a fast digital oscilloscope. The quality of the lifetime data is shown to be as good as with a usual apparatus. For a pulsed positron lifetime beam the digital system is particularly suitable as no coincidence detection is needed and only one analog pulse has to be analyzed. #

Defect identification in semiconductors with positron annihilation: Experiment and theory

“…Typical time intervals for each MCA channel are of the order of 25 ps. The modern and considerably cheaper way of doing the same is through direct digitization (fast analog-to-digital conversion) of the detector pulses and performing the signal analysis by software (Rytsölä et the digitized measurement is that it also allows for novel functionalities such as postmeasurement signal analysis (Rytsölä et al, 2002;Becvar, Cizek, and Prochazka, 2008) and, e.g., efficient pump-probe measurements with high frequencies Mäki et al, 2012). Figure 2 shows a typical lifetime spectrum collected with a positron lifetime spectrometer, containing roughly 2 Â 10 6 detected emission-annihilation (lifetime) events.…”

Morphology of Free‐Volume Holes in Amorphous Polymers by Means of Positron Annihilation Lifetime Spectroscopy

“…Linearity of the apparatus guarantees constancy of the ratio ∆t/∆v, which can be confirmed easily through a calibration procedure. Certain of the electronic units (CFD and TAC) have now been replaced by their digital counterparts [Rytsölä et al, 2002;Saito et al, 2002]; signals from the PMT are digitized by means of ultrafast modules. Digitized pulses are stored in a personal computer and analyzed off-line by software; digital filters select pulses of suitable shape and amplitude.…”

Digitized detection of gamma-ray signals concentrated in narrow time windows for transient positron annihilation lifetime spectroscopy

“…For this reason, positron storage devices were essential to convert pulsed beams to quasi-continuous beams. 4,5 Instead of the analog circuits, digital circuits such as digital storage oscilloscopes 6,7 and waveform digitizers 8 have been recently introduced to improve time resolutions as well as to simplify detection systems. In principle, the digital circuits in the previous studies handled gamma-ray signals in the same manner as the conventional analog circuits.…”