A 10 kilo-tonne dual-phase liquid argon TPC is one of the detector options considered for the Deep Underground Neutrino Experiment (DUNE). The detector technology relies on amplification of the ionisation charge in ultra-pure argon vapour and offers several advantages compared to the traditional single-phase liquid argon TPCs. A 4.2 tonne dual-phase liquid argon TPC prototype, the largest of its kind, with an active volume of 3 × 1 × 1 m 3 has been constructed and operated at CERN. In this paper we describe in detail the experimental setup and detector components as well as report on the operation experience. We also present the first results on the achieved charge amplification, prompt scintillation and electroluminescence detection, and purity of the liquid argon from analyses of a collected sample of cosmic ray muons.

The 3×1×1 m3 demonstrator is a dual phase liquid argon time projection chamber that has recorded cosmic rays events in 2017 at CERN. The light signal in these detectors is crucial to provide precise timing capabilities. The performance of the photon detection system, composed of five PMTs, are discussed. The collected scintillation and electroluminescence light created by passing particles has been studied in various detector conditions. In particular, the scintillation light production and propagation processes have been analyzed and compared to simulations, improving the understanding of some liquid argon properties.

A: We report the results of the analyses of the cosmic ray data collected with a 4 tonne (3×1×1 m 3 ) active mass (volume) Liquid Argon Time-Projection Chamber (TPC) operated in a dual-phase mode. We present a detailed study of the TPC's response, its main detector parameters and performance. The results are important for the understanding and further developments of the dual-phase technology, thanks to the verification of key aspects, such as the extraction of electrons from liquid to gas and their amplification through the entire one square metre readout plain, gain stability, purity and charge sharing between readout views.

Cosmic-ray muons have been studied at IFIN-HH for more than 20 years. Starting as fundamental physics research, the muon flux measurements bring new directions of study regarding muography. Two new directions have been recently developed: underground muon scanning of old mining sites in order to detect the possible presence of unknown cavities and underwater scanning of ships in commercial harbours in order to prevent the illegal traffic of radioactive materials. The main goal of the first direction of study is to improve the security of underground civilian and industrial infrastructures, by starting the development of a new, innovative detection system that can be used to identify potentially dangerous conditions using a non-invasive, totally safe method. The method proposed uses information provided by a device placed underground that measures directional cosmic muon flux and identifies anomalies produced by irregularities in the geological layers above. For the second direction of study, the method proposed is based on the detection and analysis of the cosmic muon flux. The high-density materials (uranium, lead—used for radiation shielding, etc.) cause a decrease in the directional muon flux. The detection system will be submerged underneath the ship that will be scanned, being able to locate illegal radioactive materials without exposing any personnel to radiation or contamination. Correlated with simulations based on the known configuration of the ship scanned, the data provided by the detection system will provide the location and dimensions of the undeclared material transported. This article is part of the Theo Murphy meeting issue ‘Cosmic-ray muography’.

The possibility to build a SiPM-readout muon detector (SiRO), using plastic scintillators with optical fibers as sensitive volume and readout by SiPM photodiodes, is investigated. SiRO shall be used for tracking cosmic muons based on amplitude discrimination. The detector concept foresees a stack of 6 active