Upgrade of the positron system of the ASACUSA-Cusp experiment

TL;DR

The paper describes an upgrade to the ASACUSA-Cusp positron system, reducing vacuum contamination and increasing positron production efficiency for antihydrogen experiments.

Contribution

Introduction of a new positron accumulator and a rare gas moderator to improve positron yield and vacuum conditions in antihydrogen production.

Findings

Vacuum contamination was reduced.

Positron yield was comparable to previous system.

Potential for faster antihydrogen production cycles.

Abstract

The ASACUSA-Cusp collaboration has recently upgraded the positron system to improve the production of antihydrogen. Previously, the experiment suffered from contamination of the vacuum in the antihydrogen production trap due to the transfer of positrons from the high pressure region of a buffer gas trap. This contamination reduced the lifetime of antiprotons. By adding a new positron accumulator and therefore decreasing the number of transfer cycles, the contamination of the vacuum has been reduced. Further to this, a new rare gas moderator and buffer gas trap, previously used at the Aarhus University, were installed. Measurements from Aarhus suggested that the number of positrons could be increased by a factor of four in comparison to the old system used at CERN. This would mean a reduction of the time needed for accumulating a sufficient number of positrons (of the order of a few million) for an antihydrogen production cycle. Initial tests have shown that the new system yields a comparable number of positrons to the old system.