Investigation of radiation from channeled electrons and positrons. Final report, September 1, 1978-August 31, 1981

Theoretical and experimental studies have been performed on the radiation emitted by electrons and positrons channeled by planes and axes in crystals. The theoretical work consisted primarily of the determination of the properties of the radiation (photon energy, linewidth, direction, polarization and intensity) using appropriate crystal potential functions in the relativistic wave equation. Excellent agreement between theory and experiment was achieved using a many-beam analysis based upon theHartree-Fock model of the atom. Experimental work was done with the linear accelerator at the Lawrence Livermore National Laboratory. Electrons and positrons were channeled in both silicon, germanium, and diamond crystals (most of the effort was with Si) at energies of 28 and 54 to 56 MeV. The crystal was mounted on a three-axis gomiometer with 60 μrad resolution. With the particle beam deflected by a dump magnet, forward directed x-ray radiation was observed with a Ge:Li detector. This research has demonstrated that it is possible to study both crystal properties and the channeling phenomenon by means of channeling radiation. In addition, an interestig new source of hard x-rays has been produced that is well collimated, linearly polarized, of picosecond duration, relatively narrow bandwidth, and tuneable