DOUBLE-ELECTRON CAPTURE BY FAST BARE IONS IN HELIUM-ATOMS - PRODUCTION OF SINGLY AND DOUBLY-EXCITED STATES

Double electron capture by fast bare ions in helium is studied in the framework of the Four-Body Continuum Distorted Wave theory. It is show n that experimental data is well reproduced when the theoretical total cross-section include both contributions from the ground state and fr om the first singly excited states. In addition, cross-sections for th e production of the first doubly excited states are also calculated. P resent results call for additional experimental data at higher impact energies than presently available.