Effects of thermal vlbrations and impurity atoms on channeling phenomena

The temperature dependence of minimum yield and dechanneling coefficient is studied for and axial channeling in germanium and silicon crystals. The observed minimum yield and the dechanneling coefficient are represented by linear relations of the mean square amplitude of thermal vibrations, and the results are compared with theory. For the minimum yield, the observed values are independent of energy and kind of particles and agree with theoretical values. The dechanneling coefficients show a poor agreement with theory. To find a reason for this discrepancy, the critical angle and the theoretical treatment are considered and discussed. A method to obtain the lattice disorder in a crystal doped with impurity atoms by measuring the dechanneling coefficient and minimum yield for protons and helium ions is presented. This method is applied to a silicon crystal containing arsenic atoms.