CHANNELING RADIATION FROM 72 MEV ELECTRONS IN SILICON - TRANSITION FROM PLANAR TO AXIAL CHANNELING

Channeling radiation from 72 MeV electrons was measured using the new superconducting electron accelerator at Darmstadt (S-DALINAC). Radiation spectra were obtained for electrons channeled along the main axes and planes in a 13-mu-m thick silicon crystal. Good agreement between theory, i.e. many-beam calculations, and experiment can be reported for planar channeling radiation. The radiation at the transition from planar channeling in the (110) plane and the (111) plane to channeling along the [110] axis was also investigated. The spectra show a continuous change from pure planar radiation to the more intense axial channeling radiation, with new lines occurring in the (110) spectra for angles between the electron direction and the [110] axis smaller than about 10 mrad. The line energies depend on the angle to the axis and range from about 50 to several hundred keV.