Equivalent effects of a lattice translation and rotation on planar channeled MeV protons

A lattice translation and rotation are shown to produce equivalent effects on the trajectories of planar channeled MeV protons. Both types of lattice disruption produce enhanced channeling and dechanneling compared with a perfect lattice, with a quarter channeling oscillation wavelength difference in their depth dependence. This behavior is characterized using Monte Carlo simulations and explained using a phase space model of planar channeling. The predicted depth-dependent enhanced channeling and dechanneling are observed experimentally in measurements of the average energy of MeV protons transmitted through thin layers containing a lattice rotation and translation. [S0031-9007(98)07866-1].