Dropping Antimatter: Measuring the Gravitational Free-fall of Antihydrogen as a Test of Einstein’s Equivalence Principle with the ALPHA-g Experiment at CERN*

ALPHA-g is a new initiative by the ALPHA Collaboration at CERN. Its goal is to investigate the gravitational behaviour of antihydrogen, the simplest neutral antimatter atoms. Studying gravity in any system is challenging because of its extreme weakness, compared to other fundamental forces in Nature. Gravitational studies of antimatter are particularly challenging, due to its scarcity, and it has prevented thus far any direct measurement of antimatter gravity; no one has ever seen antimatter fall. However, dramatic developments in the past two decades in our ability to synthesize, confine and control antihydrogen, have now made it conceivable to devise an experiment to make a precision measurement of gravity with antimatter. In this talk, I will give an over view of ALPHA-g, and discuss the status of the experiment which is currently under construction with aggressive schedule, aiming at performing first commissioning measurements this fall at CERN.