Depth and Temperature Dependence of the Channeling Effect in Diatomic Crystals

The depth and temperature dependence of the channeling effect have been studied in diatomic single crystals of CaF 2 and BaF 2 . The interactions between fast protons and the two sublattices have been studied separately by using Rutherford scattering and by detecting gamma-rays from the nuclear reaction F 19 (p,αγ)O 16 . The experimental values of the critical angle at the surface are found to vary with temperature in agreement with calculations. Comparison in absolute values between calculations from an analytical formula given by Barrett and the experimental values shows the experimental values to be slightly larger than those predicted by Barrett for the direction ⟨111⟩ with mixed rows. For the directions ⟨110⟩ and ⟨100⟩, which consist of pure rows, the interaction between the protons and the "heavy element rows" also gave slightly larger values than those predicted. On the other hand smaller values than those predicted were obtained for the interaction with the pure fluorine rows.