First operation and drift field performance of a large area double phase LAr Electron Multiplier Time Projection Chamber with an immersed Greinacher high-voltage multiplier

• Published in: Journal of instrumentation 2012-08, Vol.7 (8), p.1-25
• Main Authors: Badertscher, A, Curioni, A, Degunda, U, Epprecht, L, Gendotti, A, Horikawa, S, Knecht, L, Lussi, D, Marchionni, A, Natterer, G, Nguyen, K, Resnati, F, Rubbia, A, Viant, T
• Format: Article
• Language: English
• Subjects: Chambers; Drift; Electric potential; Instrumentation; Multipliers; Recording; Three dimensional; Voltage
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/7/08/P08026

We have operated a liquid-argon large-electron-multiplier time-projection chamber (LAr LEM-TPC) with a large active area of 76 x 40 cm super(2) and a drift length of 60 cm. This setup represents the largest chamber ever achieved with this novel detector concept. The chamber is equipped with an immersed built-in cryogenic Greinacher multi-stage high-voltage (HV) multiplier, which, when subjected to an external AC HV of similar to 1 kV sub(pp), statically charges up to a voltage a factor of similar to 30 higher inside the LAr vessel, creating a uniform drift field of similar to 0.5 kV/cm over the full drift length. This large LAr LEM-TPC was brought into successful operation in the double-phase (liquid-vapor) operation mode and tested during a period of similar to 1 month, recording impressive three-dimensional images of very high-quality from cosmic particles traversing or interacting in the sensitive volume. The double phase readout and HV systems achieved stable operation in cryogenic conditions demonstrating their good characteristics, which particularly suit applications for next-generation giant-scale LAr-TPCs.