Exploring the multicollection approach for the 40Ar/39Ar dating technique

We present an original analytical system for 40Ar/39Ar dating. It makes use of a 180° sector multicollection mass spectrometer equipped with five Faraday cups, which renders peak switching unnecessary during argon isotopic analyses. Compared to the single‐collector approach commonly used for argon isotopic analyses, our system presents greater stability during data acquisition. Faraday cup efficiencies, which can be a limiting factor for the multicollection mass spectrometer, were highly reproducible. The analytical validity of the 40Ar/39Ar ages obtained using this new mass spectrometer has been preliminarily tested using geological standard minerals (MMhb‐1, FCT‐San, and HD‐B1) commonly used as neutron fluence monitors. Independent plateau age determinations of Ethiopian samples duplicated over a 1‐year interval demonstrated the reproducibility of the analyses. The results of these measurements highlight the good behavior of this new instrument for 40Ar/39Ar step heating dating. The age reproducibility of successive steps leads to analytical errors lower than 0.1% for well‐behaved samples. This system, still in its initial stage of development, represents an alternative solution that is worth exploring in order to improve absolute dating by the 40Ar/39Ar technique.