Phototubes capable of high current output

Reports progress achieved and anticipated in the development of phototubes for measurement of high intensity short-duration gamma radiation using co-axially designed tubes comprising concentric and cylindrical anode and cathode members having a frac122.25 dimension ratio with impedance characteristic of 50 Omega. The latest form consists of a multi-alkali metallic disc cathode mounted on a central support and the anode is an electroformed nickel mesh of 80% light transmission. When energized at 10 KU, the phototube gave 55.5 A before departure from linearity as compared with the theoretical value of 92 A. Dark current does not exceed 10-9 A at 10 kV compared with specified 10-8 A at 8 kV. A much smaller tube gave 25 Amp at 10 kV.