Developments of the cusp trap to synthesize antihydrogen atoms for high precision spectroscopy of ground state hyperfine splitting

We have been developing a so-called cusp trap to synthesize antihydrogen atoms, and to make high precision microwave spectroscopy. The cusp trap consists of an anti-Helmholtz coil and a multi-ring trap, which yield axially symmetric magnetic and electric fields. This axial symmetry is quite important to realize stable confinements of antiproton and positron plasmas, which guarantees stable operation during the antihydrogen synthesis.