Generation and Stability of Intense Long Flat Bunches

This report surveys possible schemes for producing long, “flat”, intense bunches of about 5×1011 protons spaced by 50 ns, as are required by one of the proposed LHC upgrade scenarios. It also examines potential intensity limitations and instability thresholds for such beams. THE ISSUE The “large Piwinski angle ” (LPA) scenario of the LHC upgrade [1] requires bunches of 5 × 1011 protons, spaced by 50 ns, with a flat longitudinal profile. For demonstrating the feasibility of such upgrade path, the following questions must be addressed: • How and where can such intense bunches be gener-ated? • How and where can they be made flat