  ARIADNE is a 1-ton (330 kg fiducial mass) dual-phase liquid argon (LAr) time
projection chamber (TPC) featuring a novel optical readout. Four
electron-multiplying charge-coupled device (EMCCD) cameras are mounted
externally, and these capture the secondary scintillation light produced in the
holes of a thick electron gas multiplier (THGEM). Track reconstruction using
this novel readout approach is demonstrated. Optical readout has the potential
to be a cost effective alternative to charge readout in future LArTPCs. In this
paper, the technical design of the detector is detailed. Results of mixed
particle detection using a secondary beam from the CERN PS (representing the
first ever optical images of argon interactions in a dual-phase LArTPC at a
beamline) and cosmic muon detection at the University of Liverpool are also
presented.
