PRODUCTION OF A QUASI-MONOCHROMATIC $gamma$-RAY BEAM FROM MULTI-Gev ELECTRON ACCELERATORS
Measurements of electron pair production and bremsstrahlung from high- energy photons in a silicon single crystal were made. A "fine structure" was discovered in the coherent bremsstrahlung from the crystal. The bremsstrahlung cross section was calculated taking into account the actual structure of the crystal lattice planes. Calculations of the "fine structure" agree with results. Consequences in experiments using multi-Bev electron accelerators are discussed. (L.N.N.)