Computer Controlled Energy Spread Measurement at the CERN PS Linac

A new method of energy spread measurement is described which permits a quick evaluation of the percentage of the PS Linac beam inside the acceptance range of energy spread for the PS Synchrotron. The execution of the measurement, for which a minimum of two beam pulses is lost, is under control of the PS Control Computer, IBM 1800, and makes use of two beam slits, a triplet lens and a beam deflecting magnet. The result of the measurement is simply obtained as the ratio of two beam current transformer readings. These are read near the beginning and near the end of the beam pulse and the computed results together with other Linac machine parameter readings of interest, such as RF tank levels, are displayed on TV-screens at the Linac and in the PS Main Control Room. On request, a print-out of the results can also be obtained. Before executing the measurement, the computer program checks the status and levels of important parameters and in case of malfunctioning warns the operator with a diagnostic message on the TV-screen.