The WA105-3x1x1 m3 dual phase LAr-TPC demonstrator

Abstract

The dual phase Liquid Argon Time Projection Chamber (LAr TPC) is the state-of-art technology for neutrino detection thanks to its superb 3D tracking and calorimetry performance. Its main feature is the charge amplification in gas argon which provides excellent signal-to-noise ratio. Electrons produced in the liquid argon are extracted in the gas phase. Here, a readout plane based on Large Electron Multiplier detectors provides amplification of the charges before its collection onto an anode with strip readout. The charge amplification enables constructing fully homogenous giant LAr-TPCs with tuneable gain, excellent charge imaging performance and increased sensitivity to low energy events. Following a staged approach the WA105 collaboration is constructing a dual phase LAr-TPC with an active volume of 3 × 1 × 1m 3 that will soon be tested with cosmic rays. Its construction and operation aims to test scalable solutions for the crucial aspects of this technology: ultra high argon purity in non-evacuable tank, large area dual phase charge readout system in several square meter scale, and accessible cold front-end electronics. A milestone was achieved last year in the completion of the 24 m 3 cryostat that hosts the TPC. This is the first cryostat based on membrane technology to be constructed at CERN and is therefore also an important step towards the realisation of the upcoming protoDUNE detectors. The 3 × 1 × 1m 3 dual phase LAr-TPC will be described in and we will report on the latest construction progress.

Review of Liquid Argon Detector Technologies in the Neutrino Sector

“…Constructed in 2016, the WA105 experiment (so called due to its location at CERN's "West Area") is the first of two detectors dedicated to assessing the scalability of the dualphase LArTPC concept-that is, if a DUNE far detector based on this design could be assembled and operated successfully. To that end, WA105 features a 3 × 1 × 1 m TPC [78] enclosed by a 1 m thick membrane cryostat constructed from layers of glass-reinforced polyurethane foam (for thermal insulation) and plywood (for pressure distribution). The TPC field cage, containing ≈4.2 tonnes of LAr, is suspended from the 1.2 m thick top-cap of the cryostat, as shown in Figure 40.…”

“…The TPC field cage, containing ≈4.2 tonnes of LAr, is suspended from the 1.2 m thick top-cap of the cryostat, as shown in Figure 40. At the bottom of the WA105 field cage is the cathode-a metallic grid nominally biased at −50 kV via a dedicated HV feedthrough [78]. This feedthrough has also been successfully operated at −300 kV, in order to test the design for eventual use in the larger ProtoDUNE-DP detector.…”

Gaseous and dual-phase time projection chambers for imaging rare processes

“…As we will see throughout the text, and in particular in section 6, there are numerous hints that future TPCs will be able to do more than 'just' that (e.g., [45,[55][56][57][58][59][60]. [61]; b) LUX, the dual-phase (optically read) xenon TPC for dark matter searches at the Sanford Underground Research Facility (SURF) [62]; c) NEW, the high pressure xenon TPC (optically read) developed for phase-I of the ββ0ν experiment NEXT, at Laboratorio Subterráneo de Canfranc (LSC) [12,63]; d) phase-I of the (Micromegas-based) Active Target TPC (AT-TPC), at the Facility for Rare Isotope Beams (FRIB) in Michigan [34]; e) 3 × 1 × 1 m 3 dual-phase argon prototype based on LEMs/thick GEMs for the far detector of the neutrino oscillation experiment DUNE [64]; f) The DarkSide-50 dual-phase argon detector for dark matter searches at Laboratori Nazionali del Gran Sasso (LNGS) [43].…”

“…Pictures of the membrane cryostats installed at CERN. Left, middle: internal and external views of the cryostat hosting a 3 × 1 × 1 m 3 dual-phase TPC prototype[64]. Right: the cryostat of the proto-DUNE 6 × 6 × 6 m 3 dual-phase demonstrator under construction in the CERN test beam area[269].…”

“…The WA105 dual-phase argon TPC prototypes at CERN. Left: the 3×1×1 m 3 (5 ton) active volume detector[64] being inserted into the cryostat. Right: cut view of the 6×6×6 m 3 (300 ton) prototype[269] already inside the cryostat.…”