During the last 60 years, Sona transition devices have been used to invert the occupation numbers of pure states by a rapidly changing magnetic field across a zero crossing point. The inversion of the magnetic quantisation axis changes fast enough in this case the Lamor precession cannot follow. In addition, spectroscopic measurements of the hyperfine splitting are possible. In the present setup hydrogen atoms move at a constant velocity through the Sona unit. Therefore, the Sona unit provides the region where the beam passes a static magnetic field with a gradient. It has the shape of a sine-function in z- and a cosine-function in radial direction. Thus the hydrogen atom experiences a time-varying electromagnetic field, which leads to transitions between the hyperfine states in the Breit-Rabi diagram. The beam velocity is directly proportional to the “photon” energy necessary to achieve a transition. Finally, the big advantage is that low beam energies (0.5 keV) are already enough to induce the transitions at $E\approx5$ neV and its odd multiples, which gives the possibility to have a precession high enough to even observe the QED-corrections.