In large-scale liquid argon time projection chambers (LArTPC), such as those to be used in DUNE far detector, measuring and maintaining the purity of the liquid argon is crucial for obtaining a high signal-to-noise ratio. ProtoDUNE-SP is a prototype of the modules for the DUNE far detector with full-scale components. The purity monitors in ProtoDUNE-SP (and the future DUNE) are mini TPCs that make use of the photoelectric effect to create electrons and measure their lifetime within the LArTPC which is used to measure the purity of the argon, all while keeping them electrically isolated from the rest of the detector. This poster will give an introduction to the design and performance of these monitors within ProtoDUNE-SP during its test beam run at CERN in late 2018
The design and operation of the purity monitors for the largest liquid-argon TPC with single phase.