Building of a ton-scale liquid argon prototype detector

Background Based on the unique PSD characteristic which essentially relies on the detector light yield, liquid argon detector is widely used for dark matter searching experiment. The experimental study of how to get larger light yield for a ton-scale liquid argon detector is worth to be carried out. Purpose A ton-scale liquid argon prototype detector is built to check the detector implementation as well as the light collection efficiency. Methods A ton-scale single-phase liquid argon prototype detector is built in the surface laboratory for scalable detector construction experience. The detector adopts the classical spherical arrangement mode to obtain a large PMT photocathode coverage. Forty-two PMTs are immersed in the liquid argon, and polymer materials are used to construct the PMT supporting structures. Totally about 2.2 tons of liquid argon is used, of which about 160 kg is the active volume. In this paper the details of the experiment as well as the detector performance are introduced. Results Experiment results show that the light yield reaches 6.3 PE/keV, with an effective photon collection efficiency of 74.3% achieved.