Pulse-To Pulse Modulation of the Beam Characteristics and Utilization in the CERN PS Accelerator Complex

The CERN PS complex (comprising the 50 MeV Linac, the 800 MeV Booster, the 28 GeV PS and the 3.5 GeV/c Antiproton Accumulator) must deliver beams of various characteristics (e.g. energy, intensity, emittances, ejection mode) to several users, with a repetition time as low as 0.65 s. The SPS accelerator, ISR and LEAR storage rings and the 25 GeV physics experiments receive beams in a repetitive sequence, called a supercycle. The coordination is achieved by the Program Lines Sequencer (PLS) which sends to the equipment concerned (before every machine cycle) a serial message, describing the user and the characteristics of the beam. This message is created by an on-line computer using (i) previously-entered information through a series of application programs and (ii) external conditions coming from the process or the users: these signals in turn can modify the information (i) accordingly.