How to produce polarized Hydrogen/Deuterium Molecules in single Hyperfine Substates

Polarized atomic beam sources (ABS’s), modified versions of the Rabi apparatus, are used in nuclear physics either to produce nuclear polarized protons/deuterons to be accelerated further or to feed polarized targets. Thus, the spin dependence of the nuclear forces can be investigated directly. Due to the relatively small flux of about 10^17 atoms/s the density of the gas jet is less than 10^12 atoms/cm^2. To increase this density up to 10^14 polarized atoms/cm^2 T-shape storage cells are an important tool and used since many years at different accelerators.One problem of this technique is the reactivity of the hydrogen radicals, because during chemical reactions normally a large fraction of the polarization will be lost. To investigate this processes and how to avoid them, especially the recombination into molecules, a dedicated apparatus was built at the research center Jülich. The exchangeable cells are mounted inside a superconducting solenoid to produce a magnetic field up to 1 T and to cool the cell to temperatures down to 100 - 40 K. After the recombination of the polarized atoms on different surface materials the molecules are ionized and electrostatically accelerated to 1-2 keV. The ions in the beam are then filtered by a Wien filter before they reach the Lamb-shift polarimeter where the occupation numbers of the nucleons with different spin orientations are determined. In this way it was possible to produce H2, D2 and even HD molecules and their ions in dedicated hyperfine-substates with polarization values up to P=0.8. In parallel, it is possible to measure the coupling constants between the nuclear spins and the rotational magnetic moment or the shift of the rotation axis between H2/D2 and HD. Possible future projects might be the collection of the polarized molecules as ice for further use as polarized fuel in fusion reactors or the measurement of the Breit-Rabi diagram of H2+, D2+ or HD+ ions