Performance of dual phase XeTPC with CsI photocathode and PMTs readout for the scintillation light

We have tested a dual phase xenon time projection chamber (TPC) consisting of a reflective cesium iodide photocathode and an array of seven PMTs for scintillation light readout. Present results show that 19% quantum efficiency (QE) of CsI photocathode can be achieved at 3 kV/cm. The dependence of quantum efficiency as a function of different electric field was measured and compared with the recent results obtained with a small chamber operated in parallel plate geometry.