Emission brightness,photon yield,and radiation losses of ultrarelativistic electrons in oriented thick crystals

The brightness E_rad/ of -radiation produced in oriented single crystals and amorphous targets of various thicknesses by electrons with E₀=900 MeV has been measured experimentally. Comparison with theoretical calculations reveals that the radiation channeled in the axial direction in diamond has the maximum brightness. The measured angular distributions and spectral composition of the radiation have been used to determine the photon yield in the cone with angle _c=0.6 mrad and it is shown that diamond has no competitors in this respect. It is concluded that the use of targets made of single crystals with Z as small as possible (diamond and beryllium) is preferable.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 8–20, June, 1991.We wish to express our sincere gratitude to Professor E. Uggeroi for providing a perfect tungsten single crystal.