New final focus concepts at 5 TeV and beyond

At multi-TeV energies, the length of conventional beam-delivery systems becomes excessive, raising doubts about the value of a compact, high-gradient accelerator to future high-energy physics. In this paper, the reasons for the unfavorable length scaling are discussed, and alternative design concepts are described, for which final focus and collimation systems are orders of magnitude shorter and which produce higher luminosity at lower beam power than conventional approaches. These concepts include a sextupole free final focus, linac energy-spread compensation, bunch combination and laser collimation. They are compatible with novel acceleration techniques, such as an active matrix linac. A consistent parameter set for a 5 TeV collider is presented.