The HERMES polarized atomic beam source

The HERMES atomic beam source is used to provide nuclear polarized hydrogen or deuterium atoms for the HERMES target. The setup including the dissociator, the sextupole magnet system and the high-frequency transitions is described. Measurements of the hydrogen intensity of up to 6.4 x 10^(16) atoms/s in two hyperfine substates and of the deuterium intensity of up to 5.8 x 10^(16) atoms/s in three hyperfine substates are presented. A degree of dissociation of 92.8% for H (94.5% for D) at the entrance of the storage cell and a nuclear polarization of around 0.97 (H) and 0.92 (D) have been found constant within a couple of percent over the whole running period of the HERMES experiment.