Speed determination of atomic gas under a supersonic expansion

Charged particles are recorded at the end of the spectrometer by a micro-channel-plate detector. A high-resolution vacuum-compatible chopper is employed to chop atomic beam pulses into a very thin slice. The speed distribution of the atomic beam is determined by analyzing the time synchronization between the laser ablation, the chopper, and the detector. Under our typical investigation, most of the atoms travel at a speed of 1650 m/s. The velocity-selected atoms can be controlled at an uncertainty of 1/1000, depending on conditions of atom formation.