Year: 2010
Type: article
Abstract: A key feature for the success of the liquid Argon imaging TPC (LAr-TPC) technology is the industrial purification against electro-negative impurities, especially Oxygen and Nitrogen remnants, which have to be continuously kept at an exceptionally low level by filtering and recirculating liquid Argon. Improved purification techniques have been applied to a 120 liters LAr-TPC test facility in the INFN-LNL laboratory. Through-going muon tracks have been used to determine the free electron lifetime in liquid Argon against electro-negative impurities. The short path length here observed (30 cm) is compensated by the high accuracy in the observation of the specific ionization of cosmic ray muons at sea level as a function of the drift distance. A free electron lifetime of τ ∼ (21.4 +7.3 −4.3 ) ms, namely > 15.8 ms at 90% C.L. has been observed over several weeks under stable conditions, corresponding to a residual Oxygen equivalent of ≈ 15 ppt (part per trillion). At 500 V/cm, the free electron speed is 1.5 mm/μs. In a LAr-TPC a free electron lifetime in excess of 15 ms corresponds for instance to an attenuation of less than 20% after a drift path of 5 m, opening the way to the operation of the LAr-TPC with exceptionally long drift distances.
Source: Journal of Instrumentation
Institutions: Istituto Nazionale di Fisica Nucleare, Sezione di Padova, University of Padua, Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, Institute of Nuclear Physics, Polish Academy of Sciences, Istituto Nazionale di Fisica Nucleare, Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Gran Sasso, European Organization for Nuclear Research
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2067364177