Overview of collimation in the Next Linear Collider

Abstract

The Next Linear Collider (NLC) requires a substantial system of beam collimators to minimize the halo-related backgrounds at the interaction point, provide machine protection against errant pulses, and limit radiation doses throughout the accelerator. In particular, the NLC design contains a complete 5-dimensional (x,x',y,y',energy) collimation system at the entrance and exit of the main linac; transverse collimators at the electron and positron sources, at the 250 MeV point in the injector linac, and immediately upstream of the damping rings; a series of collimators at points with substantial z-energy correlation for longitudinal collimation; and a final set of transverse and energy collimators in the final focus, a few hundred meters from the IP. We describe the systems above and estimate the intensity of the halo at each point, as well as the efficiency with which the halo is removed by the collimators.