Design and construction of high-frequency transition units for polarized deuterium internal targets

Abstract

Radio-frequency transition units have been developed in order to produce vector and tensor polarized atomic deuterium beams. Transitions between various hyperfine states were generated using both a medium field transition unit and a resonant cavity structure as a strong field transition unit. Tests were carried out to determine the transition efficiencies of these units as function of radio frequency power, strength of the magnetic holding field, magnetic field gradient, and for the strong field unit, also as function of the position of the atomic beam in the cavity structure. A Stern—Gerlach source equipped with a medium and a strong field unit will provide a tensor polarized deuterium beam with the highest figure of merit at the minimum number of transition units. This polarization scheme allows for rapid reversal of tensor polarization while keeping the vector polarization fixed, and vice versa. The performance of the high-frequency transition units is described well by the results of a quantum-mechanical calculation. We will demonstrate that in a realistic internal target environment the efficiencies for the transitions between the 1–4, 2–6, and 3–5 hyperfine states exceeded in all cases 90% of the theoretical maximum polarization.