Proposal for enhancement of antihydrogen ion production in the GBAR experiment

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.