I don't think they're presently operating the antiproton source, but for decades one could get them at Fermilab, too. https://www.fnal.gov/pub/tevatron/tevatro

I don't think they're presently operating the antiproton source, but for decades one could get them at Fermilab, too. https://www.fnal.gov/pub/tevatron/tevatron-operation.html https://www.fnal.gov/pub/tevatron/tevatron-operation.html