Berlin 2005 – scientific programme
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Q: Quantenoptik und Photonik
Q 20: Poster Fallen & Kühlung
Q 20.13: Poster
Monday, March 7, 2005, 11:00–12:30, Poster HU
Sympathetic Cooling of Helium and Molecular Hydrogen Ions — •Bernhard Roth, Peter Blythe, Ulf Fröhlich, Helmut Wenz, and Stephan Schiller — Heinrich-Heine-Universität Düsseldorf
Few-body Coulomb systems belong to the most
fundamental in physics, and have been central in the development
of quantum mechanics, relativistic quantum mechanics, QED and
nuclear physics. Helium and molecular hydrogen ions are
interesting systems, e.g. for precision tests of QED and
measurement of fundamental constants. As one of the simplest
molecules, HD+ is particularly suitable to test theories of
molecular structure. One important aspect in future precision
experiments will be the availability of trapped ultracold helium
and molecular hydrogen ions, in order to minimize the influence of
Doppler broadening and allow a precise study of systematic effects.
We have generated ultracold ensembles of 3He+, 4He+,
and of various molecular hydrogen isotopes, by sympathetic cooling
using laser-cooled 9Be+ in a linear rf-trap. Stable ion
plasmas in an ordered state (Coulomb crystal) containing several
100 localized sympathetic particles and up to 6.000 Be+
ions at temperatures of <20 mK were obtained. We have studied
the properties of these mixed-species ion plasmas, both for
spheroidal and ellipsoidal symmetry, as well as chemical reactions
between the atomic coolants and neutral light molecules. The
experimental results are compared to molecular dynamics
simulations. The present work also indicates the feasibility of
cooling and trapping highly charged atomic ions using 9Be+
as coolant.