1.2 GeV electron radiation spectra in thick tungsten single crystals and total radiation losses in tungsten, germanium and silicon single crystals

'True' radiation spectra of 1.2 GeV electrons in thick single tungsten crystals (0.34 and 0.91 radiation length) have been measured with a new technique permitting one to exclude the spectra distortion through the multiplicity of gamma-quantum creation. It is shown that the dependence of radiation brightness on initial electron energy Eo, obtained in the tungsten crystal of 0.3 radiation length thickness at the collimation angle of about mc(2)/E-0, is fitted by the law E-0(3) in the energy interval 0.9-1.2 GeV. The radiation brightness at E-0 = 1.2 GeV in tungsten and silicon crystals of 'optimal' thickness has been compared with that in tungsten and germanium crystals of various thicknesses. The radiation brightness in the angle mc(2)/E-0 proves to be maximum for the silicon crystal. This confirms the conclusion that silicon crystals are more preferable for application in gamma converter. (C) 1998 Elsevier Science B.V. All rights reserved.