  Colossal two-phase Liquid Argon Time Projection Chambers (LAr TPCs) are a
proposed option for future long-baseline neutrino experiments. This study
illustrates the feasibility of using an EMCCD camera to capture light induced
by single cosmic events in a two-phase LAr TPC employing a THGEM. An Andor iXon
Ultra 897 EMCCD camera was externally mounted via a borosilicate glass viewport
on the Liverpool two-phase LAr TPC. The camera successfully captured the
secondary scintillation light produced at the THGEM holes that had been induced
by cosmic events. The light collection capability of the camera for various
EMCCD gains was assessed. For a THGEM gain of 64 and an EMCCD gain of 1000,
clear images were captured with an average signal-to-noise ratio of 6.
Preliminary 3D reconstruction of straight cosmic muon tracks has been performed
by combining the camera images, PMT signals and THGEM charge data.
Reconstructed cosmic muon tracks were used to determine THGEM gain and to
calibrate the intensity levels of the EMCCD image.
