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The ion-atom merged-beam apparatus at Oak Ridge National Laboratory in Oak Ridge, Tennessee has been successful in measuring absolute cross sections of charge transfer between atomic ions and hydrogen atoms for many years. Moreover, the first molecular ion measurements with the current version of the apparatus, performed for D2+ + H, are used to benchmark theory between 0.5 - 2 keV/u including vibrationally specific adiabatic theory for the (H2–H)+ complex, the most fundamental ion-molecule two-electron system. The absolute cross section of direct charge transfer in D2+ + H was measured with the merged-beam apparatus between 2.0 keV/u - 10 keV/u, and is presented here. The new measurements agree with McGrath et al. measurements at their lowest energy of 10 keV/u. These new measurements show that, besides the local maximum at 0.1 keV/u observed in our previous measurements, the absolute cross section also has a maximum around 2.2 keV/u, delineating an oscillation-like structure. [ABSTRACT FROM AUTHOR]

A cryogenic electrostatic ion storage ring CSR is under development at the Max-Planck Institute for Nuclear Physics in Heidelberg, Germany. Cooling of the ultrahigh vacuum chamber is envisaged to lead to extremely low pressures as demonstrated by cryogenic ion traps. The ring will apply electron cooling with electron beams of a few eV up to 200 eV. Through long storage times of 1000 s as well as through the low wall temperature, internal cooling of infrared-active molecular ions to their rotational ground state will be possible and their collisions with merged collinear beams of electrons and neutral atoms can be detected with high energy resolution. In addition storage of slow highly charged ions is foreseen. Using a fixed in-ring gas target and a reaction microscope, collisions of the stored ions at a spead of the order of the atomic unit can be kinematically reconstructed. The layout and the cryogenic concept are introduced. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]