We have laser cooled beryllium ions in a Penning-Malmberg trap dedicated for antihydrogen formation. This trap is combined with a magnetic minimum trap to confine antihydrogen.This can be used to assist in the studies of antihydrogen in two distinct ways. The first application of the cold ⁹Be⁺ is to sympathetically cool positrons, which are used for antihydrogen formation. With this assistance we expect to produce colder antihydrogen and ultimately enhance the trapping rates of antihydrogen inside a magnetic trap by at least an order of magnitude. This would greatly improve measurements of antihydrogen properties allowing for increased precision. Cold Be⁺ could also be used for in-situ measurements of magnetic fields in our antihydrogen traps. The method proposed in this work is to measure an electron spin-flip transition frequency in the ground state of Be⁺, which is highly sensitive to the external magnetic field strength. The electron spin-flip transition could be induced by microwave radiation and detected via fluorescence from laser-cooling transition. Magnetometry plays a crucial role in trapped antihydrogen research, especially for antimatter gravity measurement performed at high magnetic fields. Also, with increasing precision of the antihydrogen spectroscopy measurements, the uncertainty of the magnetic field will increase the contribution to the systematic errors. Additionally, the benefit of using electron spin-flip in Be+is that it could be used to characterise the strength of the microwaves inside theALPHA-2 trap. In this work, the feasibility of magnetometry using9Be+inside the ALPHA’s Penning trap was studied. The microwave induced electron spin-flip in Be+was observed for the first time within the ALPHA apparatus. The uncertainty of the external magnetic field derived from this proof-of-principle measurement was comparable to the currently used Electron Cyclotron Resonance method and there are prospects for significant improvement. The laser cooling procedure was improved, which should allow further study with sympathetic cooling of positrons and application of this technique to antihydrogen production sequence.

Joanna Peszka