On the determination of the true dead-time of a pulse-counting system in isotope ratio mass spectrometry

Abstract

The dead-time of a pulse-counting system used in isotope ratio mass spectrometry has been investigated. The dead-time was determined via a ratio measurement approach, and also with an electronic method. The electronic method gives the true dead-time, which should ideally be the same as the one determined with the ratio measurement. A discrepancy between the two methods indicates a problem within the pulse-counting system. Furthermore, a lack of understanding of the measurement system will limit the possibility of performing reliable measurements. Pulse-counting systems showing abnormal dead-times in mass spectrometry have been reported in the literature. The combination of the two methods presented in this work can be used to evaluate the performance of the pulse-counting system.