Development of a gaseous PMT with micro-pattern gas detectors

Gaseous photomultiplier tubes with micro-pattern gas detectors sensitive to visible light are under development. Long term stability of a bi-alkali photocathode is examined for more than 500 days. A micro-pattern gas detector of Kapton GEM is found to be incompatible with bi-alkali photocathode, while a glass capillary plate has no problem. A new production method for a Pyrex glass GEM has been developed. Some studies on ion-feedback suppression are presented.