Ion detector of time-of-flight mass spectrometer with registration of leading and trailing edges.

Abstract

The accuracy of the ion flight time measurement in the time-of-flight mass spectrometer is critical to achieving high resolution. The pulse amplitude variation of the detector pulses leads to the registration time spread at a given pulse detection threshold. This time spread can be eliminated by determining the position of the pulse apex. To determine the position of the pulse apex, the output of the ion detector is fed simultaneously to the two channels of the time-to-digital converter. In this case, the first channel is set to register the leading edge, and the second channel is set to register the trailing edge of the pulse. Using a simple processing of the received data, the position of the pulse tip is determined. Thus, the dependence of the temporal position of the peak on the pulse amplitude is largely eliminated. Examples are given, and the efficiency of using this algorithm to increase the resolution of time-of-flight mass spectral peak registration is demonstrated.