The Beam Control System for the CERN PS Booster

The purpose of the CPS booster (PSB) and the characteristics of its RF system are discussed elsewhere. Because of the tight tolerances on longitudinal beam dilution each ring of the PSB is provided with an independent beam control. Among the different possible solutions we chose a phase-lock that includes the accelerating cavity in the loop (Fig. 1), as used in the CPS. This system provides a rapid correction of any non adiabatic error (induced in the electronics). The static and low frequency errors (such as those arising from errors in the magnetic field) of the phase lock are corrected by a beam radial position servo. At full energy the bunches of the four rings are synchronized in phase for injection into the CPS. For this the magnetic guide fields of the four rings will be made equal to within ΔB/B = ± 2 × 10-4 , which corresponds to an energy error of ± 50 keV and a longitudinal dilution in the CPS of about 10%. The whole system is described and performance figures given.