The SLAC high-energy spectrometer data acquisition and analysis system

One of the experimental stations for the Stanford two-mile Linear Accelerator is equipped with three large magnetic spectrometers for scattered electron analysis. To maximize data collection rates for these, an SDS 9300 computer with a sizable I/O multiplexing capacity has been programmed for fast real-time data acquisition and on-line analysis. The system is structured to permit the experimenter to specify his experimental configurations and program requirements in terms of strings of subprograms which can be triggered either by external interrupts, teletype commands, or programmed clocks. The subprograms are symbolically identified and may be either resident or loaded at execution time. A control language for teletype dialog permits flexibility in the description of the desired configuration and mid-experiment editing of the strings of analysis procedures. The paper describes the data-gathering configuration, the program structure, and the control language of the system.