Proton electron elastic scattering and the proton charge radius
  It is suggested that proton elastic scattering on atomic electrons allows a precise measurement of the proton charge radius. Very small values of transferred momenta (up to four order of magnitude smaller than the ones presently available) can be reached with high probability. 
G.I. Gakh, A. Dbeyssi, E.Tomasi-Gustafsson, D. Marchand, V.V. Bytev
nucl-th hep-ph