[en] The authors discuss the results obtained by G.T. Adylov et al. (1977) and E.P. Dally et al. (1977) from pion-electron scattering at small angles. The authors show that the pion charge radii obtained in that work are incorrect because they are incompatible with world-averaged values of the rho meson mass and the coupling constant ratio fsub(rhoππ)/fsub(rho). (A.W.)

[en] The results of a pion-electron scattering experiment to measure the charge radius of the pion are reported. The experiment was performed in a 50 GeV/c negative, unseparated beam at the IHEP accelerator, Serpukhov. A magnetic spectrometer instrumented with wire spark chambers was used to record the incident pion trajectory and the angles and momenta of the scattered particles. Events are reconstructed by detailed trackfinding programs, and a set of kinematic and geometric cuts define the elastic sample. Electrons are identified both by kinematic criteria and pulse height information from total absorption lead glass Cerenkov counters. The final elastic sample consisted of 40 000 πe events in the region of four-momentum transfer squared 0.013 (GeV/c)² <= q² <= 0.036 (GeV/c)². A full error matrix fit to the form factors of the pion gave the r.m.s. charge radius of the pion: < rsub(π)²>sup(1/2) = (0.78sup(+0.09)sub(-0.10)) fm. (Auth.)