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The Athena experiment, an “antimatter factory” is fitted out at Cern,
in Geneva and it produced for the first time in 2002 an antimatter “cloud”,
formed of some thousands of anti-hydrogen atoms. The result was
published by Nature review. Nevertheless, researchers pointed out a
strange structure that appeared in the distribution of annihilation
positions of the antimatter. “Athena stopped taking data at the end of
2004, but the analysis of the data gathered up that moment went on and
the research published today is one of the result of this activity. It
explains exactly that, at that time, “mysterious” structure, says
Evandro Lodi Rizzini, who coordinated this analysis and who belongs to
Infn associated group of Brescia.
Atoms of anti-hydrogen in Athena were created making come in contact
anti-protons and anti-electrons in a high vacuum environment. In these
conditions about 10.000-100.000 hydrogen molecules per a cube
centimetre remain, versus the many thousands milliard and milliard
molecules that would be present in a no vacuum environment. “Probably,
exactly these remaining molecules are responsible for the observed
phenomenon. We believe in fact that the anti-electrons, which were put
in the vacuum room, caused the ionization of some hydrogen molecules,
by removing an electron from them. These ionized molecules (H2+) have
been then attracted by the antiprotons, which can be considered in
this case anti-hydrogen ions. The chemical reaction that produced the
protonium derived exactly from this process” goes on Evandro Lodi
Rizzini.
Production of protonium was in the past already observed, but in
different conditions. This is the first time that this simple and
symmetric structure of matter and anti-matter - that looks like a
hydrogen atom and an anti-hydrogen one - is produced through a
chemical reaction. This result opens a course for the realization of
high-efficiency protonium sources. We will be able to study in details
fundamental characteristics of this structure, in particular the
energy levels, in order to compare them with the theoretical models.
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