Newly developed gaseous photomultiplier

A new micromesh gas (Micromegas) detector has been developed for a gaseous photomultiplier tube (PMT) with a bialkali photocathode. A basic performance test of the Micromegas detector was carried out for a Ne (90%) + CF4 (10%) gas mixture using an X-ray beam. We constructed gaseous PMTs with a bialkali photocathode and Micromegas detectors. The photoelectron collection efficiencies in several gases and the suppression of ion feedback were investigated.