DIFFERENTIAL ELECTRON-EMISSION FOR ISOTACTIC H-2+ IMPACT ON HELIUM( AND HE)

Experimental data are presented for differential electron emission fro m helium induced by isotachic H+ and He-2+ impact. Electron emission a t 15-degrees was studied in order to investigate maxima in the d2sigma /dupsilon(e)dOMEGA spectra. These maxima were previously observed to s hift to lower electron velocities as the projectile charge state incre ased and the shifts were interpreted as evidence of an independent sad dle-point-ionization mechanism. The present data for H+ and He2+ impac t do not confirm any such shifts and indicate that previous He-2+ meas urements, where shifts were observed, are in error.