Updating of beam dynamics in the CLIC main linac

For the Compact Linear Collider (CLIC) study, the beam dynamics has been revisited in order to search for consistent beam parameters that simultaneously satisfy the emittance requirements and the experimental conditions. In the main linac, emphasis was put on the minimization of the energy-spread for limiting losses in the telescope acceptance, on the increase in the ratio between the bunch intensity and the vertical beam-size for improving luminosity, and on the preservation of the very small vertical emittance, in the presence of strong wakefields. Simultaneously, the emittance ratio and beam-size aspect ratio were adjusted in order to keep the average energy loss in the collisions low and boost the fraction of luminosity contained to within two percent of the centre-of-mass energy. The conclusions directly apply to single-bunch mode and can be extended to multibunch mode after adequate adjustments.