Acquisition of a multicollector mass spectrometer for 40Ar/39Ar geochronology

This project provides a new mass spectrometer for 40Ar/39Ar dating of geologic materials such as rocks and minerals. This instrument will be used to provide fundamental time constraints on the evolution of Earth and its biota, including humans. Among other applications, specific topics to be addressed include the tempo and history of climate change, which is needed to evaluate the extent of anthropogenic effects; the causes of mass extinctions manifest in the geologic record; and the timescales of volcanism, which is critical to evaluating volcanic hazards.

The instrument will be extensively used by students who will gain invaluable hands-on experience in furtherance of sustaining the STEM educational pipeline. The Berkeley Geochronology Center laboratory is an important training ground for the next generations of 40Ar/39Ar geochronologists, who will benefit from experience using the most modern available instrument.

The new instrument replaces obsolete and failing mass spectrometers with multi-collector, high sensitivity, high resolution capabilities which serve to improve the precision and accuracy of 40Ar/39Ar dates. The multicollection feature enables a five-fold increase in throughput. The instrument uses novel capacitive discharge ion beam detection, enabling the use of highly stable Faraday collectors, thus reducing the precision and accuracy sacrificed by the intercalibration of ion-counting multipliers.

The ion Ar beam is produced by a novel cathode source that operates at substantially lower temperatures than conventional filament sources, enabling higher sensitivity and greater source lifetime. The new instrument will be mated to a highly flexible, fully automated extraction line with dual sample chambers to exploit the increased throughput, and reference gas reservoirs to monitor mass discrimination and sensitivity.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.