Differential cross sections for the reactions e- + p --> e- + p + pi0 and e- + p --> e- + n + pi+ have been measured near the Delta (1236) resonance at four-momentum transfers of 0.05, 0.13, 0.25, and 0.4 (GeV/c)^2. A few measurements of the pi+ angular distribution have been obtained at a four-momentum transfer of 0.6 (GeV/c)^2. Cross sections for the pi0 reaction are compared with dispersion-theory predictions at several pion-nucleon c.m. energies for each four-momentum transfer. A phenomenological analysis of the pi0 results leads to the determination of the magnetic dipole and electric quadrupole partial-wave amplitudes and the gamma N Delta transition form factor. Evidence is found for the existence of a significant scaler-transverse interference term in the cross section, which is tentatively associated with the resonant scaler quadrupole interaction. Cross sections for pi + electroproduction are compared with dispersion theories using the pion form factor as a free parameter. The results suggest a form factor similar to that of the proton. A fit to the form-factor results, using the rho -dominance model, requires m rho =560±80 MeV. The rms pion charge radius is estimated to be 0.86±0.14 F.
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