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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. This achievement features technological developments that open up a completely new era in high-precision antimatter research. It is the result of over 20 years of work by the CERN1 antimatter community.
"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.
[...] With its single proton and single electron, hydrogen is the most abundant, simple and well-understood atom in the Universe. Its spectrum has been measured to very high precision. Antihydrogen atoms, on the other hand are poorly understood. Because the Universe appears to consist entirely of matter, the constituents of antihydrogen atoms – antiprotons and positrons – have to be produced and assembled into atoms before the antihydrogen spectrum can be measured. It's a painstaking process, but well worth the effort since any measurable difference between the spectra of hydrogen and antihydrogen would break basic principles of physics and possibly help understand the puzzle of the matter-antimatter imbalance in the Universe.
Additional coverage from The New York Times and National Public Radio.
Observation of the 1S–2S transition in trapped antihydrogen (DOI: 10.1038/nature21040) (DX)
(Score: 3, Interesting) by MichaelDavidCrawford on Thursday December 22 2016, @11:53PM
one can create a short-lived hydroven-like bound state between an electron and a proton. But it doesn't have a nucleus, rather the two particles have symmetric orbitals.
There is also charmonium, whose spectrum was measured in the early 80s.
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(Score: 4, Interesting) by Immerman on Friday December 23 2016, @12:27AM
I assume that should read "electron and positron" rather than proton. I don't think I've ever heard it given a name before. Now I'm curious as to whether it has multiple excitation states and corresponding emission lines, or would just come apart. Not to mention whether such a thing can be created with more than two particles.
Hadn't heard of charmonium, but having looked it up that sounds like an entirely different class of thing, charm flavor of quarkonium, a rare kind of meson created by bonding a quark with it's own anti-quark. But since mesons are unstable outside a nucleus, it would seem like measuring their spectrum would mean something completely different than it does for atoms or electron-positron couplings, but that's about the point where I could no longer make sense out of the wikipedia article.
(Score: 0) by Anonymous Coward on Friday December 23 2016, @03:34AM
https://en.wikipedia.org/wiki/Positronium [wikipedia.org]
It is in general unstable and will decay into two gamma rays in about 10-10 second.