### Session M5: New Directions in Coincidence Studies of Atomic Few Body Systems (Followed by Business Meeting)

 Sunday, April 17, 2005 3:15PM - 3:51PM M5.00001: Transfer Ionization Studies for Proton on He - new Inside into the World of Correlation Invited Speaker: Horst Schmidt-B\"ocking Correlated many-particle dynamics in Coulombic systems, which is one of the unsolved fundamental problems in AMO-physics, can now be experimentally approached with so far unprecedented completeness and precision. The recent development of the COLTRIMS technique (COLd Target Recoil Ion Momentum Spectroscopy) provides a coincident multi-fragment imaging technique for eV and sub-eV fragment detection. In its completeness it is as powerful as the bubble chamber in high energy physics. In recent benchmark experiments quasi snapshots (duration as short an atto-sec) of the correlated dynamics between electrons and nuclei has been made for atomic and molecular objects. This new imaging technique has opened a powerful observation window into the hidden world of many-particle dynamics. Recent transfer ionization studies will be presented and the direct observation of correlated electron pairs will be discussed. Sunday, April 17, 2005 3:51PM - 4:27PM M5.00002: What do electrons dance before the break-up in transfer-ionization? Invited Speaker: Alexander Godunov The transfer-ionization process offers a unique opportunity to reveal tiny details of radial and angular electron correlation in the ground states of atomic systems. We report a theoretical analysis and calculations for fully differential cross sections for the transfer ionization process. $${\rm Z^{q+} + He \rightarrow Z^{(q-1)+} + He^{2+} + e^-}.$$ The theoretical model includes both the first and second order terms on projectile-target interaction. The wavefunction for the ground state of helium was calculated in the multiconfigurational Hartree-Fock approximation (MCHF). Results of our calculations for different collision geometries demonstrate a clear target dependency and we thus conclude that the two- electron processes in fast transfer ionization reactions occur mainly due initial state correlations and post collision electron correlations have only a minor influence on the final- state momentum pattern. It terms of a Hartree-Fock description of the helium ground state we have shown that terms other than the (ns$^2$) give the dominant contributions to the transfer ionization fully differential cross section. We have, we believe, demonstrated conclusively that the mechanism proposed by Schmidt-Bocking does indeed give the dominant contribution to the transfer-ionization process. Both theory and experiment are now in good accord and indicate that transfer ionization in fast collisions at small scattering angles is very sensitive to high-level target correlation effects. \\ 1. A.L. Godunov, Colm T. Whelan and H.R.J. Walters, {\it J. Phys. B:} {\bf 37}, L201 (2004)\\ 2. A.L. Godunov, Colm T. Whelan and H.R.J. Walters et al, {\it Phys. Rev.} A (2005) (submitted)\\ 3. M. Sch\"offler, A.L. Godunov, Colm T. Whelan, et al {\it J. Phys. B:} (2005) (submitted)