The Overview and Status of the GBAR Experiment

The GBAR (Gravitational Behaviour of Anti-hydrogen at Rest) experiment aims to perform a free-fall experiment of an ultra-cold anti-hydrogen at the terrestrial gravitational field. An anti-hydrogen ion which is trapped and cooled is neutralized and kicked by photo-detachment laser and free-falls in a vacuum chamber. By measuring secondary particles from anti-hydrogen annihilation after the free-fall motion, the gravitational acceleration of the anti-hydrogen atom can be measured within 1% precision. The GBAR experiment plans to produce anti-hydrogen atom and ion as a first goal. In here, the experimental technique with some detail and the current status of the experiment will be shown.