The AEgIS experiment

The goal of the AEgIS experiment is a first direct measurement of the earth's gravitational acceleration with the simplest form of electrically neutral antimatter, namely antihydrogen. In the first phase a measurement of the gravity force with 1% precision will be carried out by sending an antihydrogen beam lauched horizontally in a vacuum tube and by measuring the gravitational sag with a Moiré deflectometer and a position sensitive detector.

Principle of the AEgIS experiment Sketch of the setup

Moiré deflectomer (D = annihilation detector)

The essential steps leading to the production of anti-hydrogen and the measurement of g with AEgIS are the following
(for details see the experimental proposal):

– Production of positrons (e+) from a Na (Surko-type) source and accumulator;

– Capture and accumulation of antiprotons from CERN's antiproton decelerator in a cylindrical Penning trap;

– Production of positronium (Ps) by bombardment of a nanoporous material with an intense e+ pulse;

– Excitation of the Ps to a Rydberg state with principal quantum number n = 30 . . . 40;

– Recombination of antihydrogen by resonant charge exchange between Rydberg Ps and cold antiprotons:

Ps + antiproton -> e- + antihydrogen;

– Formation of an antihydrogen beam by Stark acceleration with inhomogeneous electric fields;

– Determination of g in a two-grating moiré deflectometer coupled to a position-sensitive
annihilation detector made of nuclear emulsions.