Cern scientists have succeeded, for the first time in history, in producing a beam of antihydrogen atoms. They reported the unambiguous detection of 80 antihydrogen atoms 2.7 metres downstream of their production, where the perturbing influence of the magnetic fields used initially to produce the antiatoms is small. This result is a significant step towards precise hyperfine spectroscopy of antihydrogen atoms.
Primordial antimatter has so far never been observed in the universe, and its absence remains a major scientific enigma.
Italian researchers of the Nuclear Physics Italian Institute work in the Asacusa project of Geneve Cern Laboratory which has recently discovered the Higgs Bosom and is now studying, for the first time, the anti-matter.
“Around us we see only matter. We have never found an anti-atom: where the anti-matter is in the universe, it is a mystery”, said Luca Venturelli, researcher of the Istituto Nazionale di Fisica Nucleare of Brescia and of the University of Brescia, who coordinates the Italian group which collaborates with the Asacusa.
The new data could finally give an answer to the question: why don’t we see the antimatter if, immediately after the Big Bang, it was present in a quantity equal to that of the matter?
Matter and antimatter annihilate immediately when they meet so, aside from creating antihydrogen, one of the key challenges for physicists is to keep antiatoms away from ordinary matter. To do so, experiments take advantage of antihydrogen’s magnetic properties (which are similar to hydrogen’s) and use very strong non-uniform magnetic fields to trap antiatoms long enough to study them.
The Asacusa collaboration developed an innovative set-up to transfer antihydrogen atoms to a region where they can be studied in flight, far from the strong magnetic field.
The next step for the Asacusa experiment will be to optimize the intensity and kinetic energy of antihydrogen beams, and to understand better their quantum state.
“Our results are very promising for high-precision studies of antihydrogen atoms, particularly the hyperfine structure, one of the two best known spectroscopic properties of hydrogen. Its measurement in antihydrogen will allow the most sensitive test of matter/antimatter symmetry. We are looking forward to re-starting this summer with an even more improved set-up” said Yasunori Yamazaki, team leader of the Asacusa collaboration.
Progress with antimatter experiments at Cern has been accelerating in recent years. In 2011, the Alpha experiment announced trapping of antihydrogen atoms for 1000 seconds and reported observation of hyperfine transitions of trapped antiatoms in 2012. In 2013, the Atrap experiment announced the first direct measurement of the antiproton’s magnetic moment with a fractional precision of 4.4 parts in a million.
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