Abstract
We present two applications of the use, in Stern-Gerlach interferometry with metastable hydrogen atoms, of comoving magnetic fields, i.e. fields travelling at atomic velocites, which could allow us to reach the slow-atom domain. In the first application, atoms interact with a single extended zone of comoving B-field. A velocity coherent filtering effect is demonstrated and characterized. In the second one, atoms interact with a double zone of comoving B-field. This Ramsey's type configuration takes advantage of the fact that the sensitivity of the apparatus with respect to velocity changes is significantly enhanced.