Stuttgart 2012 – wissenschaftliches Programm

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SYIB: Symposium Fast Ion Beams in Nuclear, Atomic and Molecular Physics Research

SYIB 1: Fast Ion Beams in Nuclear, Atomic and Molecular Physics Research I

SYIB 1.4: Hauptvortrag

Dienstag, 13. März 2012, 12:00–12:30, V55.22

Low-Temperature Molecular Recombination from fast Electron and Ion Beams — •Oldrich Novotny — Columbia Astrophysics Laboratory, New York, USA — Max-Planck-Institute for Nuclear Physics, Heidelberg, Germany

Dissociative recombination (DR) of molecular ions plays a key role in controlling the composition and charge density of cold interstellar clouds. Experimental DR data are required in order to understand the chemical network in clouds and related processes such as star formation in the clouds. Needed data include reaction cross sections and also the chemical composition and excitation states of the neutral products. With the TSR storage ring in Heidelberg, Germany, we are measuring DR for astrophysically important molecular ions. We use a merged electron-ion beams technique to generate high-quality phase-space cooled, stored ion beams. This is combined with event-by-event fragment counting and fragment imaging. The neutral product count rate yields the absolute DR rate coefficient. Imaging the distribution of fragment separations provides information on the kinetic energy released and the states of both the initial molecule and the final products. Fragmentation channels are identified from the fragment-mass combination within each dissociation event. Such information is essential for studies on DR of polyatomic ions with multi-channel multi-fragment breakup. In this talk we will demonstrate these experimental capabilities on the recent DR results. Future experiments on the new cryogenic electrostatic storage ring CSR will be discussed.