Opportunity to study the LPM effect in oriented crystal at GeV energy

The spectral distribution of electron-positron pair created by photon and the spectral distribution of photons radiated from high-energy electron in an oriented single crystal is calculated using the method which permits inseparable consideration both of the coherent and incoherent mechanisms of two relevant processes. The method includes the action of field of axis (or plane) as well as the multiple scattering of radiating electron or particles of the created pair (the Landau-Pomeranchuk-Migdal (LPM) effect). The influence of scattering on the coherent mechanism and the influence of field on the incoherent mechanism are analyzed. In tungsten, axis < 111 > for the pair creation process at temperature T= 100 K the LPM effect attains 8 % at photon energy 5 GeV and for the radiation process at T= 293 K the LPM effect reaches 6 % at electron energy 10 GeV.