On the Performance of Grid-Controlled Photomultipliers in the Nanosecond Region

Controlled photomultipliers may be used for analysing modulation frequencies and other time parameters of radiation, which lie beyond the bandwidth or the time parameters of secondary emission systems. On the basis of the electron-optical characteristics of a control system for photomultipliers with two control grids, the properties to be expected are investigated for quasi-stationary operation and under consideration of transit-time effects. Due to the electron-optical properties of the control system, disturbing residual pulses are nearly made ineffective. It is experimentally shown that when using two controlled photomultipliers of the Type SKP-1 as coincidence elements at a distance of 1.5 ns of the gating intervals, the pulse rate decreases to less than 0.1 % (Fig. 12) compared with the rate at a time coincidence of the gating intervals. These values do not only depend on the photomultiplier, but also on the length of the light pulses and the period of the control voltage. The half-width of the coincidence between a light pulse and an electrical control pulse is smaller than 0.5 ns.