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Tranferionization in fast collisions:
a direct access to the Helium ground state wave function.

The correlated Kinematical Transfer Ionization channel cKTI in fast 4-body (p + He -> H0 + He2+ + e) processes has been used to probe the highly correlated contributions to the asymptotic part of the He ground state wave function. In this reaction one electron with controlled initial momentum (2.5 to 7.5 a.u.) in the He ground state is kinematically captured by the proton at large impact parameters. The measured 3-particle final-state momentum distributions show features of a well-structured three-particle momentum wave function. We conclude that cKTI must almost exclusively proceed via the highly correlated and, virtually excited, non-s2 contributions in the He ground state.

Most of the electrons are emitted in the H0 scattering plane and in the backward direction. The final state momentum distributions show discrete structures very different from those expected for uncorrelated capture and ionization:

(a,b) recoil ion and (c-f) electron momentum distributions projected onto the H0 projectile scattering plane for different H0 scattering angles. kz is the direction of the incoming projectile momentum, kx the direction of the scattered H0 transverse momentum, ky the transverse momentum perpendicular to the scattering plane.

We are currently setting up a new COLTRIMS system to investigate this process with high resolution by measuring the electrons.

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