SPECTRAL-ANGULAR AND POLARIZATION PROPERTIES OF NEAR-AXIS CHANNELING RADIATION OF 31 MEV ELECTRONS IN SILICON

The spectral-angular and the linear polarization properties of channel ing radiation emitted by 30.8 MeV electrons incident on a 13 mu m thic k silicon crystal at small angles with respect to various major crysta l axes have been investigated. The transition from axial to planar cha nneling radiation properties is well described by a two-dimensional ma ny-beam calculation based on a periodic string potential. At energies above the strongest planar channeling radiation lines coherent bremsst rahlung linearly polarized perpendicular to the polarization of the co rresponding planar channeling radiation is observed and found to be we ll reproduced by the model calculations. Axial channeling radiation of the [1 1 0] axis shows a small amount of linear polarization due to t he 'double-well' potential in agreement with the calculations. (C) 199 8 Elsevier Science B.V. All rights reserved.