| ELENA | Extra low energy antiproton ring – further decelerates antiprotons coming from AD |
|---|---|
| AD experiments | |
| ATHENA | AD-1 Antihydrogen production and precision experiments |
| ATRAP | AD-2 Cold antihydrogen for precise laser spectroscopy |
| ASACUSA | AD-3 Atomic spectroscopy and collisions with antiprotons |
| ACE | AD-4 Antiproton cell experiment |
| ALPHA | AD-5 Antihydrogen laser physics apparatus |
| AEgIS | AD-6 Antihydrogen experiment gravity interferometry spectroscopy |
| GBAR | AD-7 Gravitational behaviour of anti-hydrogen at rest |
| BASE | AD-8 Baryon antibaryon symmetry experiment |
| PUMA | AD-9 Antiproton unstable matter annihilation |
GBAR (Gravitational Behaviour of Anti hydrogen at Rest), AD-7 experiment, is a multinational collaboration at the Antiproton Decelerator of CERN.
The GBAR project aims to measure the free-fall acceleration of ultra-cold neutral anti-hydrogen atoms in the terrestrial gravitational field. By measuring the free fall acceleration of anti-hydrogen and comparing it with acceleration of normal hydrogen, GBAR is testing the equivalence principle proposed by Albert Einstein. The equivalence principle says that the gravitational force on a particle is independent of its internal structure and composition.[1]