Erice Lecture, 1986
Recently we mentioned the possibility which we have been studying for some time, of using a nested pair of Penning traps to simultaneously capture positrons and antiprotons. ... Low [production] rates might might be sufficient to observe antihydrogen for the first time. When antihydrogen is formed in an ion trap, the neutral atoms will no longer be confined and will thus quickly strike the trap electrodes. Resulting annihilations of the positron and antiprotons could be monitored. However, it is clear that the very low rate will make further experiments with antihydrogen to be very different than experiments with copious amounts of hydrogen, and much more difficult.
For me, the most attractive way around this difficulty would be to capture the antihydrogen in a neutral particle trap as has been used for neutrons and neutral atoms. The objective would be to then study the properties of a small number of atoms confined in the neutral trap for a long time.
G. Gabrielse, "Penning Traps Masses and Antiprotons",
in the book Fundamental Symmetries, edited by P. Bloch, P. Pavlopoulos and R. Klapisch,
(Plenum Publishing, 1987)