ALPHA published a paper in the journal Nature this week that reports the first ever measurement of the optical spectrum of an antimatter atom. The team behind the paper says that this is the result of over 20 years of work by the CERN antimatter community. The measurements are of the antihydrogen spectrum and were performed with high-precision according to the team.
“Using a laser to observe a transition in antihydrogen and comparing it to hydrogen to see if they obey the same laws of physics has always been a key goal of antimatter research,” said Jeffrey Hangst, Spokesperson of the ALPHA collaboration.
The team says that when the electrons of an atom move from one orbit to another, they absorb or emit light at specific wavelengths. Which element has its own unique spectrum and that light is able to be observed using spectroscopy and the tool is commonly used in physics, astronomy, and chemistry. Hydrogen is the most abundant and well understood atom in the universe and has a spectrum that has been measured to very high degrees of accuracy.
Antihydrogen atoms in the other hand are poorly understood. Part of the challenge for the team was that the components inside the antihydrogen atom, antiprotons and positrons, had to be assembled before the spectrum could be measured. The team put the effort in because studying antihydrogen could help understand the matter-antimatter imbalance in the universe.
The measurements resulting from the team’s efforts allowed the light spectrum from matter and antimatter to be compared for the first time. The team reports that within experimental limits, there was no difference in the spectral line between hydrogen and antihydrogen. This observation is consistent with the Standard Model that predicts hydrogen and antihydrogen should have identical spectroscopic characteristics.