A micromechanical detector for molecular beams

We demonstrate the detection of a molecular beam by means of a micromechanical momentum transfer detector operated in vibrational resonance. With a sensitive surface area of 0.5×0.3 mm2 the small paddle allows us to detect a beam with 6.5×107 He atoms hitting the surface per second. The detector response time equals the damping time of the paddle oscillation of about 1 s. The detector is sensitive enough to measure intensities in molecular beam scattering experiments. The novel detection scheme has the potential to allow the development of a position sensitive molecular beam detector.