Noble Gas Laboratory

The University of Lausanne Noble Gas Laboratory is focussed on the determination of high-quality ⁴⁰Ar/³⁹Ar and (U-Th)/He ages of geological samples. The laboratory is well-equipped and houses two separate, custom built, extraction systems capable of determining high-precision ⁴⁰Ar/³⁹Ar and (U-Th)/He ages. ⁴⁰Ar/³⁹Ar extraction system is designed such that ⁴⁰Ar/³⁹Ar ages can be determined by incrementally heating separated grains with either a resistance furnace or infrared laser. In addition, high spatial resolution ⁴⁰Ar/³⁹Ar ages can be determined in situ by ultraviolet laser ablation of thin sections or chips. The laboratory is equipped with a Nu Instruments© Noblesse gas mass spectrometer fitted with one faraday and two ion counting multipliers. The mass spectrometer is on line to a custom built, low-blank stainless steel extraction system. The entire system is computer controlled and argon is progressively expanded through the extraction system and into the mass spectrometer by a series of pneumatically actuated valves.

A second system has been custom built for the determination of (U-Th)/He ages and is modelled after Ken Farley's laboratory at Caltech. This system consists of a CO2 laser, quantitatively calibrated ³He spike, a variable temperature cryogenic cold trap built by Janis Research^©, and a Pfeiffer-Balzers Prisma^© quadrupole mass spectrometer. The entire system is controlled by custom software created with Labview^©. Uranium and thorium concentrations in samples are measured on isotopically spiked samples using a Perkin Elmer^© ICP-MS. All data are stored in a custom made interactive database facilitating data transfer and calculations.

Contact: Dr. Mike Cosca

Ar/Ar mass spectrometer

Laser ablation system