Liquid argon purification and purity monitoring: apparatus and first results

TL;DR

This paper presents a liquid argon purification system and initial results demonstrating impurity levels and electron lifetime, supporting future detector R&D for large-scale LArTPCs.

Contribution

It introduces a 13-liter liquid argon test stand with a purification system and purity monitor, providing initial performance data for detector R&D.

Findings

Impurity concentration of 0.25 ppb O$_2$-equivalent measured.

Electron lifetime of 1.5 ms at 500 V/cm drift field.

Supports development of large-scale LArTPC technologies.

Abstract

We report results from a 13-liter purified liquid argon test stand at Wellesley College. The system includes a single-pass liquid-phase purification column, a double-gridded purity monitor to assess the electron lifetime, and a slow control and data acquisition system. Initial measurements demonstrate an O$_2$-equivalent impurity concentration of 0.25 ppb, corresponding to an electron lifetime of 1.5 ms at a drift field of 500 V/cm. This test stand supports ongoing detector R&D on charge and light readout technologies for future large-scale liquid argon time projection chambers, such as Q-Pix and other cold electronics systems, as part of a facility at Wellesley College for fundamental studies of LArTPC readouts.