Effect of the atomic nucleus Coulomb field on the ratio of charged photopion yields

Energy spectra of charged pions outcoming under the angle THETAsub(lab)=90 deg during photon interaction at Esub(γ)sup(max)=400 MeV with 6Li, 12C, 24Mg, 28Si and 40Ca atomic nuclei are determined. Pions have been detected by means of a freon bubble chamber within Esub(π)=40-110 MeV energy range. The ratio of π-/π+-meson yield is stated to smoothly decrease with the growth of particle energy and the distance between the maxima in the spectra of π+- and π--mesons increases with the growth of the nucleus mass number. Shift of π+- and π--meson energy spectra relatively to each other at a doubled value of the Coulomb barrier on the atomic nucleus interface is exercised. The spectrum maxima are shown to coincide in this case, and the ratio of π-/π+ yields is independent from pion energy