INTERFERENTIAL MONOCHROMATOR FOR NEUTRAL ATOMS

When a so called “co-moving” magnetic field – i.e. a field moving at a velocity close to the atom ones – is used as a phase shifter in a Stern-Gerlach atom interferometer the resulting accumulated phase shift takes non negligible values for only those atomic velocities which are close to that of the field. The interferometer is then an adjustable interferential velocity filter. This effect has been demonstrated by means of a time-of-flight measurement on a metastable hydrogen atom beam the velocity distribution of which is wide (δv/v = 1). By scanning the field velocity, the velocity distribution of a continuous H* beam is readily obtained. Extension to accelerated magnetic fields and their application to gravimetry are proposed.