Development and testing of a positron accumulator for antihydrogen production

A positron accumulator based on a modified Penning-Malmberg trap has been constructed and undergone preliminary testing prior to being shipped to CERN in Geneva where it will be a part of an experiment to synthesize low-energy antihydrogen. It utilises nitrogen buffer gas to cool and trap a continuous beam of positrons emanating from a ${}^{\mathrm{22}}\mathrm{Na}$ radioactive source. A solid neon moderator slows the positrons from the source down to epithermal energies of a few eV before being injected into the trap. It is estimated that around ${10}^8$ positrons can be trapped and cooled to ambient temperature within 5 minutes in this scheme using a 10 mCi source.