Is hydrogen as magnetic as anti-hydrogen

First step to check the fundamental symmetries of the standard model: At CERN, anti-hydrogen atoms were captured

ALPHA experiment

Geneva (Switzerland) - At the European nuclear and particle research center Cern, anti-hydrogen atoms have been captured for the first time and released again in a controlled manner. As part of the ALPHA experiment, a total of 38 anti-hydrogen atoms could be held in a magnetic trap for 0.17 seconds, reports the research team in an online publication in the journal "Nature". According to the scientists, this opens the door to an investigation of the properties of anti-hydrogen - and the examination of fundamental symmetries in the so-called standard model of particle physics.

The absence of antimatter in the cosmos is one of the great puzzles in physics. Because symmetries of the laws of nature ensure - at least that's what the Standard Model says - that particles and antiparticles behave in the same way. The Big Bang should therefore have created as much antimatter as matter - why did this antimatter disappear? The cause could be a violation of the fundamental symmetries. Such a symmetry violation could be noticeable, for example, by differences in the radiation spectrum of hydrogen and anti-hydrogen.

The production of anti-hydrogen has been routine at Cern for several years. But the anti-matter is short-lived and is destroyed again in a very short time by contact with normal matter. In order to be able to study the properties of anti-hydrogen, physicists have to capture the atoms and prevent them from being destroyed. This has now been achieved within the framework of the ALPHA experiment.

The researchers used a special magnetic trap that interacts with the magnetic moment of the atoms. But this trap can only hold atoms at a temperature of 0.5 degrees above absolute zero. "The extreme experimental challenge was to synthesize such cold atoms from plasmas of charged particles with a temperature of 10 to the power of 5 Kelvin", according to the ALPHA researchers, "and to clearly differentiate the rare occurrence of such an atom from background processes". After the interaction of ten million antiprotons and 700 million positrons, only 38 anti-hydrogen atoms landed in the trap - but for more than a tenth of a second. Long enough, according to the scientists, to be able to examine anti-hydrogen in detail in the future. With further improvements to the experiment, the ALPHA team also hopes to increase both the yield of trapped atoms and the retention time of the atoms in the trap.