Mass spectrometry system for determining a measure of a rate of decay

A mass spectrometry system comprising:

• a mass analyser arranged in a vacuum region pumped by a turbomolecular pump;
• and
• a controller configured to perform a method for determining a measure of a rate of decay of an ion sample undergoing mass analysis in the mass analyser with image current detection, the method comprising:
• receiving a detection signal for the ion sample from a transient detection of the ion sample obtained using the mass analyser, the detection signal for the ion sample having a rate of decay over time;
• and
• determining the measure of the rate of decay of the ion sample based on an extrapolated resolution for the ion sample, the extrapolated resolution being an expected resolution of the detection signal in conditions in which the rate of decay over time of the detection signal for the ion sample is dominated by collisional effects;
• wherein the controller is configured to control the pressure within the mass analyser to control the rate of decay over time of the detection signal for the ion sample by:
• controlling a pumping speed of the turbomolecular pump.

A mass spectrometry system comprising:

• a mass analyser arranged in a vacuum region pumped by a turbomolecular pump;
• and
• a controller configured to perform a method for determining a measure of a rate of decay of an ion sample undergoing mass analysis in the mass analyser with image current detection, the method comprising:
• receiving a detection signal for the ion sample from a transient detection of the ion sample obtained using the mass analyser, the detection signal for the ion sample having a rate of decay over time;
• determining an adjustment function for the ion sample, based on:
• a measure of intensity and/or a measure of mass-to-charge ratio of the detection signal for the ion sample;
• and
• a measure of intensity and/or a measure of mass-to-charge ratio of a detection signal previously obtained for a calibrant using the mass analyser;
• and
• determining the measure of the rate of decay of the ion sample, by adjusting a measure of the rate of decay over time of the detection signal for the ion sample using the adjustment function;
• wherein the controller is configured to control the pressure within the mass analyser to control the rate of decay over time of the detection signal for the ion sample by:
• controlling a pumping speed of the turbomolecular pump.