High sensitivity S-option upgrade for an inductively coupled plasma mass spectrometer system

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The inductively coupled plasma (ICP) source with a quadrupole mass filter is the most cost effective instrument for measuring isotopes with moderate precision and high throughput. Combined with a laser ablation source, this is used for dating large numbers of zircon grains to moderate precision. These ages are a powerful tool for understanding ancient geologic events and processes. Although plasmas produce close to 100% ionization, the transmission efficiency of ions into the high vacuum of the mass analyzer is low, placing a limitation on sensitivity. The equipment requested consists of a 75 litre/sec rotary pump connected to the Ion Sampling Interface where ions pass from the atmospheric pressure of the plasma to the ion focusing region. By reducing the pressure in this region there is less probability of collision and neutralization of ions with other molecules, giving an estimated increase in sensitivity of a factor of 3 to 6. This will greatly extend the ability of the instrument to accurately analyze relatively young and high quality zircon as well as low-U phases used for dating meteorites. The improved age data will be of benefit to the many geologists with whom we collaborate as well as to students who are dating events associated with the formation of the solar system.