Speaker
Description
The successful operation of noble fluid particle detectors relies on adhering to stringent purity constraints. To take full advantage of the scintillation performance of liquid argon, sub-ppm levels of impurity concentrations must be achieved. Commercial providers do not reliably meet these requirements, thus creating the need for on-site purification. We designed and constructed a liquid-phase purification system to remove contaminants commonly present in liquid argon. A molecular sieve extracts water, whereas activated copper removes oxygen. A limited amount of nitrogen is retained in the system as well, although it is not optimized for that. The purifier is used in-line to fill the shallow-underground SCARF cryostat with 1 ton of high-purity liquid argon. To demonstrate the purification performance, LLAMA measures in-situ the liquid argon scintillation and optical properties. In addition to in-line purification while filling, the system purifies liquid argon also in circulation mode using a cryogenic submersion pump. Here, we present the design of SCARF's liquid argon purification system as well as its performance during initial filling and recirculation.
