The GBar - Experiment
Prof. Patrice Perez (CEA / Saclay, France)

The equivalence principle is one of the cornerstones of general relativity. It states that the trajectory of a particle does not depend on its nature or composition. However, this principle has never been tested directly with antimatter. The GBAR project at CERN aims at performing a free fall experiment with ultra cold antihydrogen atoms, measuring their gravitational acceleration with better than 1% precision. Its originality is to produce anti-ions that can be cooled to very low temperatures and subsequently neutralised in order to obtain neutral antiatoms with velocities of order 1 m/s. I will describe the different parts of the project, how we will produce the ingredients to form the anti-ions, their formation and cooling processes and the free fall measurement itself. The experiment is planned to start installing in 2015 and take the first data using the ELENA antiproton decelerator with first beams available in 2017.