From phys.org,
“In a paper published today in the journal Nature, the ALPHA collaboration reports the first ever measurement on the optical spectrum of an antimatter atom.”
“Today’s ALPHA result is the first observation of a spectral line in an antihydrogen atom, allowing the light spectrum of matter and antimatter to be compared for the first time. Within experimental limits, the result shows no difference compared to the equivalent spectral line in hydrogen. This is consistent with the Standard Model of particle physics, the theory that best describes particles and the forces at work between them, which predicts that hydrogen and antihydrogen should have identical spectroscopic characteristics.”
ALPHA observes light spectrum of antimatter for first time
CERN experiment produces first beam of antihydrogen atoms for
hyperfine study