Halo Generation and Beam Cleaning by Resonance Trapping

One of the mechanisms of halo generation occurs when particles are trapped by a nonlinear resonance ν ∼ m/p as the tune ν is being modulated. This note is intended to renew some attention to this mechanism, and hopefully to trigger new study to understand it more quantitatively. This same mechanism used in reverse could serve to clean beam halos and to relax requirements on the collimators