ELASTIC DIFFERENTIAL CROSS-SECTIONS OF 1500 EV ELECTRON-SCATTERING FROM HELIUM

Detailed experimental and theoretical studies of electron scattering f rom helium at an impact energy of 1500 eV and scattering angles betwee n 3 degrees and 11.5 degrees have been made. Absolute differential cro ss sections are obtained after the correction of certain small solid a ngles of the detector. The experimental correction factors are checked by means of an approximate calculation. Finally, the experimental dif ferential cross sections are compared with calculations based on the e ikonal Born series, the first Born approximation and the relativistic static and non-local exchange estimation. Only the eikonal Born series shows satisfactory agreement with the present measurement.