Measurements of scattering of 60Co gamma emission in broad-beam geometry - under presence and absence of a lead shield around a source and a detector - have been carried out. In such geometry from a shield to a detector only scattered emission is arrived. Growing of intensity of 1332 keV line comparing to 1332 keV line intensity has been discovered in case of a shield presence. The discovered effect is connected with receiving by detector an emission, which is coherently scattered in the big shield volume, which surrounds a detector. The effect's value is growing with growing of gamma-rays energy. That fact, that the effect is observed for energies above the pairs creation threshold, permits to tie it either with consequences of pairs creation, or with Delbr?ck scattering. The discovered effect is condi-tioned by scattering in big angles (backward scattering), for which cross sections of the known mechanisms of coherent scattering (Rayleigh, Thomson) are considered to be small. Therefore it seems that in the given geometry of the experi-ment it is possible to investigate the coherent scattering mechanism, which causes this effect, in a pure form, neglecting by Rayleigh and Thomson ones.
Keywords: gamma rays scattering, 60Со, broad-beam geometry, lead.
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