Capture from random flux to channeling for protons transmitted through a Si foil

Flux redistribution and formation of channeling peaks have been observed in the geometry of initially wide-angle incidence for protons transmitted thr ough monocrystalline Si membranes. The channeling peaks are generated by th e crystalline medium as a result of multiple charge-exchange events due to the impact-parameter dependence of the electron capture and loss cross-sect ions. This explains successfully the detection of channeling peaks only at a low enough residual proton energy: E-p(f) less than or equal to 0.6 MeV, after the transmission. (C) 2000 Elsevier Science B.V. All rights reserved.