Séminaire / Seminar GReCO |
| « GBAR: accurate verification of the weak equivalence principle with antimatter. » |
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Paul Indelicato |
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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. |
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lundi 12 juin 2017 - 11:00 Salle des séminaires Évry Schatzman Institut d'Astrophysique de Paris |
| Pages web du séminaire / Seminar's webpage |