Caltech Noble Gas Lab

My laboratory consists of a MAP 215-50 noble gas mass spectrometer and associated vacuum systems for the analysis of the abundance and isotopic composition of helium, neon, argon, krypton, and xenon. A second system, based on a Pfeiffer-Balzers Prisma quadrupole mass spectrometer, is used for high precision noble gas abundance determinations using isotope dilution. Both instruments are fully automated for high sample throughput and improved reproducibility. We can extract noble gases from a variety of geological materials including water and gas samples, for example as collected from volcanic hotsprings. We can also release noble gases from rocks, minerals and sediments using vacuum crushing, conventional vacuum fusion, and heating with a Q-switched Nd-YAG laser. After extraction the noble gases are purified of contaminants such as CO2 and N2 using SAES getters, and adsorbed on a variable temperature (8 - 450 kelvin) cryogenic cold trap built by Janis Research. The individual noble gases are then thermally desorbed and analyzed with the mass spectrometers. The laboratory automation system is run by custom software created with Labview.

In 2005 I received a newly designed split-tube noble gas mass spectrometer (Helix SFT) manufactured by GV instruments. This instrument is specifically designed for simultaneous detection of 4He (on a Faraday collector) and 3He (on an electron multiplier). The split tube design and a secondary electrostatic filter in front of the multiplier will provide very high abundance sensitivity for measuring extremely low 3He/4He ratios and 3He concentrations. This instrument is performing extremely well.

In addition to commercial instrumentation my group is collaborating with Dr. Ara Chutjian at JPL to design and test a static-vacuum-mode Paul ion trap mass spectrometer for noble gases. The goal of this project is to assess the sensitivity and resolution of the instrument.