The Korean Physical Society 06130 22, Teheran-ro 7-gil, Gangnam-gu, Seoul, Republic of Korea 610 Representation : Tae Won NOH TEL: 02-556-4737 FAX: 02-554-1643 E-mail : webmaster@kps.or.kr Copyright(C) KPS, All rights reserved.
30 May 2022 to 4 June 2022
Virtual Seoul
Asia/Seoul timezone

Filling and purification of large volume of liquid argon for LEGEND-200.

Not scheduled
20m
Virtual Seoul

Virtual Seoul

Poster Neutrinoless double beta decay Poster

Description

Thanks to its scintillation properties, Liquid Argon (LAr) is a commonly used detector material in neutrino physics and other rare event searches. The chemical purity of LAr is critical, as it directly correlates with its light emission properties. In the LEGEND experiment, LAr serves as a cooling medium for the germanium detectors and an instrumented shield. The LAr was purified during the LEGEND-200 cryostat's initial filling to achieve optimal detector performance.
The LEGEND LAr purification System (LLArS) performance was monitored in real-time during purification and filling. The monitoring was done by probing the argon scintillation properties by triplet state lifetime measurements. Simultaneously, a direct measurement of the concentrations of impurities, such as water, oxygen, and nitrogen, with a sensitivity of 0.1 ppm was performed. Additionally, the purity and light-emitting properties of argon inside the cryostat are constantly monitored and studied by the LEGEND Liquid Argon Monitoring Apparatus (LLAMA) device. The achieved argon triplet lifetime (τ3) measured inside the 70%-filled LEGEND-200 cryostat was 1.3 μs. It dropped to 1.1 μs after filling some hundred liters of LAr of worse quality; the delivered LAr had high nitrogen content, which was not fully removed by LLArS. For the fully filled cryostat, τ3 has been kept at 1.15 μs since September 2021. 
Here, the design, construction, and performance of the LLArS system capable of purifying 65 $m^3$ of liquid argon to a sub-ppm level for the LEGEND-200 experiment will be presented.

Collaboration LEGEND

Primary author

Malgorzata Haranczyk (Jagiellonian University)

Co-authors

Nina Burlac (University and INFN of Roma Tre) Natalia DiMarco Patrick Krause (TUM) Tomasz Mroz (Jagiellonian University) Laszlo Papp (TUM) Giuseppe Salamanna (Roma Tre) Mario Schwarz (Physics Department, TUM) Stefan Schönert Diego Tagnani Stefan Tombinski (Jagiellonian University) Christoph Vogl Grzegorz Zuzel (Jagiellonian University)

Presentation Materials