A hydrogen beam to characterize the ASACUSA antihydrogen hyperfine spectrometer.

The antihydrogenprogramme of the ASACUSA collaboration at the antiproton deceleratorof CERN focuses on Rabi-type measurements of the ground-state hyperfine splitting of antihydrogenfor a test of the combined Charge-Parity-Time symmetry. The spectroscopyapparatus consists of a microwave cavityto drive hyperfine transitions and a superconducting sextupole magnet for quantum state analysis via Stern-Gerlach separation. However, the small production rates of antihydrogenforestall comprehensive performance studies on the spectroscopyapparatus. For this purpose a hydrogen source and detector have been developed which in conjunction with ASACUSA's hyperfine spectroscopyequipment form a complete Rabiexperiment. We report on the formation of a cooled, polarized, and time modulated beam of atomic hydrogen and its detection using a quadrupole mass spectrometer and a lock-in amplification scheme. In addition key features of ASACUSA's hyperfine spectroscopyapparatus are discussed.t