Construction and operation of a Double Phase LAr Large Electron Multiplier Time Projection Chamber

Understand

We successfully operated a novel kind of LAr Time Projection Chamber based on a Large Electron Multiplier (LEM) readout system.

• The prototype, of about 3 liters active volume, is operated in liquid-vapour (double) phase pure Ar.
• The ionization electrons, after drifting in the LAr volume, are extracted by a set of grids into the gas phase and driven into the holes of a double stage LEM, where charge amplification occurs.
• Each LEM is a thick macroscopic hole multiplier of 10x10 cm$^2$ manufactured with standard PCB techniques.