Abstract

A fast multichannel scaler has been developed with a resolution of 12.5 ns and and a channel memory of 2^{1 5} (32 768), yielding a timing range of 410 μs. The maximum cycle time of the instrument is 30 starts/s. Fast timing is achieved by the use of multiplexing and parallelism in data collection and transfer. When operating at the highest resolution, each channel is a 1‐bit counter (flip‐flop). The scaler is intimately interfaced to an 8‐bit Z80 microcomputer. The characteristics of the scaler are ideal for ion time‐of‐flight measurements in multiphoton ionization experiments. The time resolution is illustrated with a photoelectron–photoion coincidence time‐of‐flight mass spectrum. In addition, the MCS is compared to a time‐to‐pulse‐height converter/multichannel analyzer system by collecting random stop signals.