Recoil-ion momentum distribution for and He(e,3e)He + +-reactions He(e,2e)He +

Using Recoil-Ion Momentum Spectroscopy (RIMS) we have measured the momenta of recoiling tar- get ions in He(e,2e)He +- and He(e,3e)He++-reactions at impact energies between 270 ev and 3200 eV. The recoil- ion momentum reflecting the sum momentum of all out- going electrons was determined for the first time in all three spatial dimensions separately for single and double ionization by electron impact. The data are compared to results of a nCTMC-calculation.