HE2+ ON HE - STATE-SELECTIVE, SCATTERING-ANGLE-DEPENDENT CAPTURE CROSS-SECTIONS MEASURED BY COLD TARGET RECOIL ION MOMENTUM SPECTROSCOPY (COLTRIMS)

We present the first state-selective, scattering-angle-dependent cross sections for the reaction 0.25-1 MeV He2+ + He --> He1+ + He1+. The experiment was performed, using a new generation of recoil ion momentum spectroscopy, which enabled us to determine the three momentum components and the charge state of the recoil ion simultaneously. An absolute momentum resolution of +/-0.13 a.u, for the longitudinal and +/-0.02 a.u. for the transverse momentum component has been achieved, which is equivalent to a resolution in projectile energy loss of +/-5.6 eV and an uncertainty of the projectile scattering angle of better than +/-1 mu rad.