Slow beams of atomic hydrogen by multistage Zeeman deceleration

Hydrogen atoms seeded in a supersonic expansion of Kr have been decelerated from an initial velocity of 435 m s(-1) to 107 m s(-1) in a multistage Zeeman decelerator. The operation of the decelerator has been fully quantified by numerical particle trajectory simulations and independent measurements of the velocity distribution by ion time-of-flight mass spectrometry following photoionization of the decelerated atoms. The velocity distributions of the decelerated atom clouds have a half-width at half-maximum of 25 +/- 12 m s(-1) corresponding to a temperature of similar to 30 mK. These velocities and temperatures are sufficiently low that magnetic trapping of the atoms can be envisaged.