Dependence of Probability for Excitation on the Distance from the Crystal-Plane and Surface Derived by Using the Channeling of Hydrogens

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Concerning the experimental apparatus; the scattering chamber and the ion pump were replaced with somewhat large ones. The ultra-high vacuum of 10^<-10> Torr becomes easily available after baking of the chamber. An Ar-sputtering ion-gun was prepared and installed to the chamber putting a gate-valve between them. The rapid evacuation of the residual Ar gas after the sputtering was made possible.Concerning the sample; epitaxial foils of AI were prepared and observed by a transmission electron microscope. Some of them can be used in the following channeling experiment.Concerning the cleaning of the sample-surface; the sputtering of the surface by the Ar beam from the ion-gun was carried out. In order to maintain the vacuum, the oxide-layer of the AI was sputtered in a high vacuum. Thereafter, a few monolayer were sputtered in the ultra-high vacuum.Concerning the main experiment; a MeV H^+-ion beam from the accelerator of the Nara Women's University was impinged on the AI foil under a channeling condition. The foils were placed in the UHV chamber to be almost perpendicular to, and with the angle of 30° measured from, the incident beam direction. The measured neutral fractions for channeling through ions were decreased compared with those measured for random ions. The energy dependence of the channeling effect was also measured in addition to the exchanging foils. It was found that the energy dependence of the two angles of foils was different from each other.Concerning the theoretical calculation; the neutral fraction of the channeling-ions was calculated with the ion trajectories. By applying an effect of scattering at the atoms on the surface to the calculation, a good agreement with the experimental results was obtained.