MEASUREMENT AND ANALYSIS OF THE ECC CUSP STRUCTURE

We measured the electron capture to the continUUM (ECC) peak in the io nization of He atoms by the collision of 50, 100 and 200 keV H+ and 10 0 keV amu-1 He2+. We exhaustively scanned the double differential cros s section between the angles -1.5-degrees to 10-degrees and within the velocities (1 +/- 0.15)upsilon(i) where upsilon(i) is the impact velo city. We propose a new method for analysing the Ecc structure which is independent of the spectrometer transmission function modellization a nd enables a direct comparison with the available theories. Furthermor e, we distinguish two regimes for the ionization process, depending on whether the electron velocity is larger or smaller than the projectil e velocity.