Proposal for enhancement of antihydrogen ion production in the GBAR experiment

D.A Cooke,D Lunney,P Crivelli,A Husson,P Bühler

doi:10.1051/epjconf/201818101002

Abstract

The production of antihydrogen ions (H̅+) in the GBAR experiment will occur via a two step charge exchange process. In a first reaction, the antiprotons(P̅) from the ELENA ring will capture a positron from a positronium(Ps) target producing antihydrogen (H̅) atoms. Those interacting in the same Ps target will produce in a second step H̅+. This results in a dependence for the H̅+ production rate which is roughly proportional to the Ps density squared. Wepresent a scheme to increase the anti-ion production rate in the GBAR experiment by tailoring the antiproton to the positron pulse in order to maximise thetemporal overlap of Ps and p̅. Detailed simulations show that an order of magnitude could be gained by bunching the antiprotons from ELENA. In order to avoid losses in their capture in the Paul trap due to the energy spread introducedby the bunching, debunching with a symmetrical inverted pulse can be appliedto the H̅+ ions.

Highlights

Its goal is to measure the gravitational acceleration gimparted to freely falling Hatoms, in order to perform a direct experimental test of the Weak Equivalence Principle with antimatter
Different theoretical explanations have been put forward and experimental efforts are ongoing to try to address the origin of the Baryon Asymmetry observed in our Universe
No compelling theoretical argument seems to support that a difference between the gravitational behaviour of matter and antimatter should be expected [1], some attempts have been made to show the contrary [2,3,4,5] and it would be allowed in the context of the Standard Model Extension (SME) [6, 7]

Summary

Introduction

Its goal is to measure the gravitational acceleration gimparted to freely falling Hatoms, in order to perform a direct experimental test of the Weak Equivalence Principle with antimatter. We propose to first bunch the antiprotons in order to increase the H + formation probability, followed by time debunching (bunching in energy) the H + to keep the energy spread below 100 eV in order not to affect the capturing efficiency in the Paul trap.

Results

Conclusion