Expected performance in the injectors at 25 ns without and with Linac4

The quality of the 25ns beams that can be delivered at the LHC injection is determined by the injection process into the PSB, as well as by space charge, collective interactions, electron cloud and RF power limitations in the PS and SPS. Using the information available from our present experience, the main goal of this paper is twofold: (1) to assess the intensity and brightness reach of the 25ns beams produced by the LHC injector chain with the two main schemes, before and after the connection of the PSB to Linac 4; and (2) to identify which bottlenecks will be likely to limit the performance with Linac 4. A few options to maximize the potential of the increased brightness provided by Linac 4, based on flattened bunch profiles at the PS injection or the use of alternative optics configurations, will be included in the analysis.