A number of innovative experiments dedicated to neutrino oscillations and rare event physics, such as direct searches for dark matter particles or neutrinoless double beta decays, are using liquefied noble-gases, particularly Liquid Argon (LAr), as detection media. Among many advantages of noble liquids, from the detection point of view, the most important ones are high scintillation and ionisation yields, possible long drift paths of ionisation electrons and feasible large detector masses. LAr is sufficiently dense and relatively cheap and therefore is the only adequate noble liquid for huge volumes. This paper describes a particle detection system that exploits the prompt signals from the scintillation light produced by ionising particles in LAr. The detector has been exposed to cosmic rays. The system performance in terms of trigger efficiency and timing resolution, with a view to its application in neutrino detectors, is presented. •Particle detection system that exploits the LAr scintillation light has been set up.•The system enables studies of PMTs, DAQ and trigger electronic performances.•The study involves temperature stability, electronic noise and timing synchronisation.•The tests within this system are an important input for a future large LAr detector.