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An experimental investigation of dechanneling in copper single crystals

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dc.contributor.author Tulonen, Paul V. G. en_US
dc.date.accessioned 2009-07-09T17:31:15Z
dc.date.available 2009-07-09T17:31:15Z
dc.date.issued 1984-07-09T17:31:15Z
dc.identifier.uri http://hdl.handle.net/10464/1737
dc.description.abstract This investigation comprises a comparison of experimental and theoretical dechanneling of MeV protons in copper single crystals. Dechanneling results when an ion's transverse energy increases to the value where the ion can undergo small impact parameter collisions with individual atoms. Depth dependent dechanneling rates were determined as functions of lattice temperature, ion beam energy and crystal axis orientation. Ion beam energies were IMeV and 2MeV,temperatures ranged from 35 K to 280 K and the experiment was carried out along both the (lOa) and <110) axes. Experimental data took the form of aligned and random Rutherford backscattered energy spectra. Dechanneling rates were extracted from these spectra using a single scattering theory that took explicit account of the different stopping powers experienced by channeled and dechanneled ions and also included a correction factor to take into account multiple scattering effects along the ion's trajectory. The assumption of statistical equilibrium and small angle scattering of the channeled ions allows a description of dechanneling in terms of the solution of a diffusion like equation which contains a so called diffusion function. The diffusion function is shown to be related to the increase in average transverse energy. Theoretical treatments of increase in average transverse energy due to collisions of projectiles with channel electrons and thermal perturbations in the lattice potential are reviewed. Using the diffusion equation and the electron density in the channel centre as a fitting parameter dechanneling rates are extracted. Excellent agreement between theory and experiment has been demonstrated. Electron densities determined in the fitting procedure appear to be realistic. The surface parameters show themselves to be good indicators of the quality of the crystal. en_US
dc.language.iso eng en_US
dc.publisher Brock University en_US
dc.subject Copper crystals. en_US
dc.subject Channeling (Physics) en_US
dc.title An experimental investigation of dechanneling in copper single crystals en_US
dc.type Electronic Thesis or Dissertation en_US
dc.degree.name M.Sc. Physics en_US
dc.degree.level Masters en_US
dc.contributor.department Department of Physics en_US
dc.degree.discipline Faculty of Mathematics and Science en_US


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