Casting Light on Antimatter: Fundamental Physics with Bottled Antihydrogen Atoms with Project ALPHA at CERN – Makoto Fujiwara

Our second talk this week was from Makoto Fujiwara, who was visiting from TRIUMF in Canada. Prof. Fujiwara talked to us about the work he and his collaborators have been doing to create and trap atoms of anti-hydrogen at CERN.

After telling us a little about TRIUMF, Prof. Fujiwara moved on to discussing anti-hydrogen. As one might expect, anti-H atoms are made from an anti-proton and a positron. Although, anti-matter has been observed for decades, anti-H atoms were first observed quite recently, in 1996 at CERN. These were relativistic atoms, cold atoms (i.e. atoms whose kinetic energy was much less than their mass) were not observed until 2002.

Prof. Fujiwara explained that the ALPHA experiment at CERN that he is part of has been working to not only produce anti-H, but also to trap it. With trapped anti-H it will be possible to do precision spectroscopy and therefore probe the properties of anti-matter with great precision. This, in turn, may give insight into some of the foundations of modern physics, including the CPT theorem of quantum field theory and the equivalence principle of general relativity.

Next, Prof. Fujiwara explained how a combination of electric and magnetic fields could be used to trap charged particles and how more complicated magnetic field is needed to trap neutral particles. While the end result is neutral, and constituents of anti-H are charged, so both techniques are used.

After explaining some of the challenges inherent in trapping and cooling the charged particles, we then heard about the results. The collaboration succeeded in trapping anti-H in 2010, and later that same year managed to extend the trapping time to 1000 seconds. Prof. Fujiwara explained to us that the long trapping time was especially important for the precision spectroscopy experiments they wish to carry out.

The talk concluded with an outline of the future extensions of the ALPHA experiment and the various challenges they face.

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