Grid-Controlled Photomultipliers as Elements of Fast Coincidence Circuits

Photomultipliers offering the possibility of rapid control of their sensitivity have been investigated with a view to improving the time analysis of transient processes. The time resolution of photomultipliers with a control grid in the dynode system (FEU-36), with one control grid in the cathode space (61 PK 412), and two control grids in the cathode space (SKP-1), have been tested by controlling with a frequency of 150 Mc/s. When two such controlled photomultipliers are used as elements for the selection of pulses in a coincidence system and they are excited by short light pulses, one obtains a half width of the coincidence curve of τ50: 0.9...0.7 ns and a base width at 0.1% of the maximum pulse rate of τ0,1 = 1.5...2.1 ns. (author)