Towards a spin polarized antihydrogen beam

The ASACUSA collaboration has developed a cusp trap scheme to realize an in-flight high precision microwave spectroscopy of ground-state hyperfine splitting of antihydrogen ( H) for a stringent test of CPT symmetry. Cold H atoms were successfullysynthesized by employing a cusp trap which consisted of a superconducting anti-Helmholtz coil and a stack of ring electrodes. This was achieved with an antiproton ( p) accumulator, MUSASHI, and a positron ( e+) accumulator. The principal quantum number and the time evolution of H synthesis were investigated. The latest progress was also presented.