Bremsstrahlung and pair production at ultrahigh energies in condensed amorphous matter

The article gives a review of the current state of the theory of bremsstrahlung by electrons of ultrahigh energy and pair production by photons of ultrahigh energy in condensed matter in the case in which the effective coherence length of the processes discussed is so large that the effect of competing processes is possible. Qualitative reasoning is considered which permits correct estimation of the effects, and the results of a quantitative discussion are presented.