Towards a liquid Argon TPC without evacuation: filling of a 6 m^3 vessel with argon gas from air to ppm impurities concentration through flushing

TL;DR

This paper demonstrates a method to fill a 6 m^3 vessel with argon gas from ambient air, reducing impurities to ppm levels without prior evacuation, by monitoring scintillation light to ensure purity.

Contribution

It introduces an effective filling procedure for large liquid argon TPCs without evacuation, using gas flushing and impurity monitoring via scintillation light.

Findings

Achieved impurity levels of a few ppm oxygen equivalent

Validated the flushing method for large-volume argon filling

Monitored impurity reduction through scintillation light analysis

Abstract

In this paper we present a successful experimental test of filling a volume of 6 m$^3$ with argon gas, starting from normal ambient air and reducing the impurities content down to few parts per million (ppm) oxygen equivalent. This level of contamination was directly monitored measuring the slow component of the scintillation light of the Ar gas, which is sensitive to {\it all} sources of impurities affecting directly the argon scintillation.