In situ measurements of Krypton in Xenon gas with a quadrupole mass spectrometer following a cold-trap at a temporarily reduced pumping speed

TL;DR

This paper introduces a novel in situ measurement technique for detecting trace krypton in xenon gas using a cold trap and residual gas analyzer, achieving high sensitivity with minimal xenon loss.

Contribution

The paper presents a new method that enhances krypton detection sensitivity by temporarily reducing pumping speed with a custom valve, enabling precise in situ measurements.

Findings

Sensitivity of 40 ppt achieved

Measured krypton concentration of 330 ± 200 ppt in sample

Method requires minimal xenon consumption

Abstract

A new method for measuring trace amounts of krypton in xenon using a cold trap with a residual gas analyzer has been developed, which achieves an increased sensitivity by temporarily reducing the pumping speed while expending a minimal amount of xenon. By partially closing a custom built butterfly valve between the measurement chamber and the turbomolecular pump, a sensitivity of 40 ppt has been reached. This method has been tested on an ultra-pure gas sample from Air Liquide with an unknown intrinsic krypton concentration, yielding a krypton concentration of $330 \pm 200$ ppt.