The existence of antihydrogen was verified by the observations of hot, fast antihydrogen atoms. The hot antihydrogen atoms are moving much too fast to allow measurements to be carried out at an interesting level of accuracy. Properties of the fast atoms cannot be measured accurately in the much too short time it takes to pass through an apparatus. It also seems unlikely that large numbers of fast atoms will ever be made. Calculation suggests the possibility to observe hot, fast antihydrogen at existing accelerators.
Improved calculation predicts production rates that are much lower.