Measuring the antihydrogen fall

TheAEg ̄ISexperiment(AntimatterExperiment:Gravity,Interferometry, Spectroscopy (Drobychev et al., 2007)), aims at directly measuring the gravitational acceleration g on a beam of cold antihydrogen (H). After production, the H atoms will be driven to fly horizontally with a velocity of a few 100 m/s for a path length of about 1 meter. The small deflection, few tens of μm, will be measured using two material gratings coupled to a position-sensitive detector working as a Moiré deflectometer similarly to what has been done with atoms (Oberthaler et al., Phys Rev A 54:3165, 1996). Details about the detection of the H annihilation point at the end of the flight path with a position-sensitive microstrip detector and a silicon tracker system will be discussed.