Purification System and Purity Measurements of LiquidArgon for Liquid Argon Time Projection Chambers

Liquid Argon Time Projection Chambers (LArTPCs) serve as a high resolution and high sensitivity detectors that are used to conduct neutrino experiments and dark matter searches. In order to achieve long drift times for electrons that are produced as a result of charged particle (created by a neutrino interaction) ionizing our volume of argon, we need to achieve purity levels of liquid argon (LAr) at an order of a few parts per trillion (ppt). To achieve these high purity levels, our purification system system uses activated copper and molecular sieve granules to remove impurities such as oxygen and water, respectively, from LAr and by utilizing high powered resistors, it also boils the liquid furiously to recirculate argon in the system. We use the filter materials present to then regenerate the filter materials in situ by heating them at about 180oC and passing Ar-H mixture through them. In this work, we describe the construction and workings of a purification system and purity monitor used at The University of Texas at Arlington.