An automatic ratio readout system for a double collection mass spectrometer

An improved isotope ratio readout system for a six-inch ratio mass spectrometer has been developed that offers the advantages of automatic operation. precision equivalent to or somewhat better than other systems, and low cost. A pair of solid-state vibrating reed electrometers are used to measure the ion currents from two isotopes. These are interfaced to a frequency counter, operated in ratio mode, through two voltage-to-frequency converters. A digital programer is used for automatic operation.