Gamma radiation spectra of 1200 MeV electrons in the single crystals of the beryllium 1.2 mm thick, silicon 1.5 mm and 15.0 mm thick and tungsten 1.18 mm thick along of the crystallographic axes were measured. Also spectral-angular distributions of gamma radiation in the silicon single crystals 1.5 mm thick along of the crystallographic axes <100>, <110> and <111> were measured. On the basis of these measurements the radiation spectra for the different solid angles up to 6.97*10-6 sr were obtained. Gamma radiation spectra of the electrons with energy 1200, 600 and 300 MeV in the Si single crystals 15.0 mm thick and the W thick 3.0 mm also were measured. The above results complement the previously obtained experimental and theoretical data and can be used to create a source of intense gamma-ray beams for radiation technologies.

In this work, the possibility of different techniques to measure real spectral-angular distributions of radiation under conditions of multiple photon generation is analyzed in dependence of experimental requirements. The technique based on Compton scattering, on narrow collimation of direct gamma-quanta beams, on pair magnetic spectrometer use and on measured opening angles of electron–positron pairs are examined. It is shown that for the measurement of photon spectral-angular distributions and photon multiplicity one can employ the narrow collimation technique. The real photon spectra within the limited emission angle may be measured with a pair magnetic spectrometer. An estimate of the multiplicity of the photons, which are registered by a total absorption spectrometer as one photon and the average energy of these photons may be obtained by measuring the opening angle of the electron–positron pairs generated by the photons in a thin converter.