A simple high-sensitivity technique for purity analysis of xenon gas

摘要

We report on the development and performance of a high-sensitivity purity-analysis technique for gaseous xenon. The gas is sampled at macroscopic pressure from the system of interest using a UHV leak valve. The xenon present in the sample is removed with a liquid-nitrogen cold trap, and the remaining impurities are observed with a standard vacuum mass-spectroscopy device. Using calibrated samples of xenon gas spiked with known levels of impurities, we find that the minimum detectable levels of N_2, O_2, and methane are 1 × 10~(-9), 160×10~(-12), and 60 ×10~(-12)g/g, respectively. This represents an improvement of about a factor of 10000 compared to measurements performed without a cold trap.