New techniques for tailoring longitudinal density in a proton synchrotron

The characteristics of the beam required for the Large Hadron Collider (LHC) impose stringent requirements on the CERN complex of injectors. A completely new scheme of operation, notably from the longitudinal standpoint, is foreseen for the Proton Synchrotron (PS) machine and its Booster (PSB) and has been tested in December 1993. It includes the original processes of “bunch flattening” and “bunch splitting”. The first of these is applied in the PSB to reduce the space-charge induced transverse tune shift at injection in the PS. The second is employed in the PS to facilitate acceleration and debunching at high energy. Both techniques are described and the results achieved in December are presented and discussed.