Nonlinear resonant collimation for future linear colliders

We present a scheme for collimating large amplitude particles in the main linacs of a linear collider, by adding octupoles to the FODO lattice of the linac. With this scheme the requirements on downstream collimation can be greatly reduced or perhaps even eliminated. An analytic estimate of the amplitude at which particles are lost is made by calculating the separatrix of the fourth order resonance, and is in good agreement with the results of simulations. Simulations of particle distributions in the beam core and halo are presented, as well as alignment tolerances for the octupoles