... alkali photocathode Diameter of 28.5mm(1.12 inch), nine stage, side-on photomultiplier tubes, borosilicate glass, double-alkali photocathode ... Features: Diameter of 28.5mm(1.12 inch), nine stage, side-on photomultiplier tubes, borosilicate glass,double-alkali photocathode, ... time4ns Diameter of 28.5mm(1.12 inch), nine stage, side-on photomultiplier tubes, borosilicate glass, double-alkali ...