Channeling studies in single crystals of calcium fluoride

The channeling characteristics of protons and helium ions in a di-atomic single crystal (CaF2) have been studied in the energy range 0.67 to 4.00 MeV. The steering properties of each sublattice have been measured independently by detecting Rutherford back-scattered ions and gamma-rays from the nuclear reaction F19(p,αγ)O16. The critical angle for channeling (ψ1/2) and the minimum yield (χmin) have been measured and compared to theory. The value of ψ1/2 for axial channeling has a functional dependence which agrees well with calculations based on the average potential along the row. The measured critical angles are, however, lower in absolute magnitude than calculated.