Xenon purity analysis for EXO-200 via mass spectrometry

TL;DR

This paper presents a highly sensitive mass spectrometry method with a cold trap for analyzing xenon purity in the EXO-200 experiment, enabling detection of impurities at parts-per-billion levels, which is crucial for the experiment's success.

Contribution

It introduces the first application of cold trap mass spectrometry to an operating physics experiment for precise xenon purity analysis.

Findings

Detection of impurities at one part-per-billion levels.

Effective screening of xenon before, during, and after use.

Enhanced sensitivity achieved by liquid nitrogen cold trap.

Abstract

We describe purity measurements of the natural and enriched xenon stockpiles used by the EXO-200 double beta decay experiment based on a mass spectrometry technique. The sensitivity of the spectrometer is enhanced by several orders of magnitude by the presence of a liquid nitrogen cold trap, and many impurity species of interest can be detected at the level of one part-per-billion or better. We have used the technique to screen the EXO-200 xenon before, during, and after its use in our detector, and these measurements have proven useful. This is the first application of the cold trap mass spectrometry technique to an operating physics experiment.