Recent Developments in Multiplier Phototubes

A number of developments on multiplier phototubes have taken place in these laboratories since the last scintillation counter symposium. The most important of these developments are discussed and detailed operating data on various tubes are presented. One development of interest has been the large area multiplier phototubes. These tubes have been constructed with usable cathode diameters of ll inches, 142 inches, and 20 inches. On the other extreme, ten stage multiplier phototubes with an over-all outside diameter of 3/4 inches have been developed and the characteristics of these tubes will be presented. A program of ruggedization of multiplier phototubes has been carried out on all standard tubes and the results of this program have led to tubes with better mechanical stability in the field. Work is also described on cathode surfaces, on secondary emission surfaces, and on improvements of the dark current characteristics of multiplier phototubes.