Berlin 2001 – wissenschaftliches Programm
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A: Atomphysik
A 12: Posters Thursday (Ion/Atom/Molecule/Surface Scattering)
A 12.17: Poster
Donnerstag, 5. April 2001, 12:30–15:00, AT3
Recoil-ion momentum spectroscopy of 1-5 MeV H+-He collisions in CRYRING — •Henning Schmidt1, Jens Jensen2, Afshin Fardi1, Joachim Ullrich3, Horst Schmidt-Böcking4, Lew Cocke5, Reinhold Schuch1, and Henrik Cederquist1 — 1Stockholm University, Frecativägen 24, S-104 05 Stockholm, Sweden — 2Manne Siegbahn Laboratory, Stockholm, Sweden — 3Universität Freiburg, Fakultät für Physik, D-79104 Freiburg, Germany — 4Institut für Kernphysik Universität-Frankfurt, August Euler Strasse 6, D60486 Frankfurt, Germany — 5Department of Physics, Kansas State University, Manhattan, Kansas 66506, U.S.A.
We have measured the longitudinal and transverse momenta for singly and doubly ionized helium recoil ions produced in H+-He collisions. The proton beam was stored (1-5 MeV) in the ion-storage and cooler ring CRYRING at the Manne Siegbahn Laboratory. The beam current ranged from 10 to 50 µA and the storage time from a few hours to several days. The diameter of the helium-jet, intersecting the proton beam, was 1 mm. We use the pure single ionization and single electron capture processes to calibrate the longitudinal momentum scales. The transfer ionization processes are partly separated due to the uncorrelated and the correlated (Thomas) mechanisms. In the latter, the protons scatter on one of the electrons which in turn interacts with the other electron such that one is transferred to the projectile and one is released to the continuum. The preliminary analysis of the data shows that recoil ions from the Thomas process are emitted in the backwards direction (p//∼-1.6 a.u. at 3.2 MeV) rather than with the expected zero average longitudinal momentum.