Time stability characterization of quadrupole mass spectrometers

This study focuses on the time stability of different metrological characteristics of quadrupole mass spectrometers (QMSs). Investigated parameters were the sensitivity, when using a Faraday cup as a detector, the peak position, the peak width, the gain of a secondary electron multiplier, and the minimum detectable partial pressure. Eight different commercial QMSs were investigated at seven national metrology institutes under three different nominal calibration pressures of 5 x 10-6 Pa, 5 x 10-5 Pa, and 5 x 10-4 Pa Pa for N2 and He. The measurements were carried out using a periodicity of approximately 3 months for a total duration of 2 years. Sensitivity calibrations were conducted either through a comparison method using calibrated ionization gauges or by applying a primary vacuum calibration system. In the case of ionization gauges, they were periodically recalibrated to ensure their stability and traceability to a primary pressure standard.