Résumé / Abstract Seminaire_GReCO
SÉMINAIRE DU GRECO

"GBAR: accurate verification of the weak equivalence principle with antimatter."

Paul Indelicato
Laboratoire Kastler Brossel (Paris, France)

With the discovery of gravitational waves, one of the last fundamental tests of general relativity, which requires direct a measurement, is the effect of gravitation on antimatter. The GBAR experiment (Gravitational Behavior of Antihydrogen at Rest), is based on a proposal by J. Waz and T. Hänsch. The idea is to make ultracold antihydrogen (10 µK), and to measure accurately its free fall time over a known distance. The originality of the GBAR proposal, which has been accepted by CERN in 2012, lies in the cooling procedure. Direct laser cooling of (anti)-hydrogen does not allow reaching temperatures below 2 mK (Doppler limit). To go below this temperature, Walz and Hänsch proposed to cool the \bar{H}+ (anti-H-) ion by sympathetic cooling with Be+. This \bar{H}+ ion would be the first three-body antimatter atomic system. It must be obtained by interaction of low-energy antiprotons with laser-excited positronium. Thanks to this very cold system, and with the help of quantum reflection, GBAR has the potential to reach an accuracy of 10-5 on the gravitational constant for antimatter.

In this seminar, I will describe the theoretical motivations, which justify doing such an experiment, as well as a description of the present status of the experiment.

lundi 12 juin 2017 - 11:00
Salle des séminaires Évry Schatzman,
Institut d'Astrophysique de Paris

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