Analysis of the triplet production by the circularly polarized photon at high energies

The possibility in principle of the determining high energy photon circular polarization by the measurement of the created electron polarization in the process of triplet photoproduction $\gamma +e^-\rightarrow e^+e^- +e^-$ is investigated. The respective event number which depend on polarization states of photon and created electron does not decrease with the growth of the photon energy, and this circumstance can ensure the high efficiency in such kind of experiments. We study different double and single distributions of the created electron (or positron), which allow to probe the photon circular polarization and to measure its magnitude (the Stock's parameter $\xi_2$), using the technique of the Sudakov's variables. Some experimental setups with different rules for event selection are studied and corresponding numerical estimations are presented.