Little Story of Infinity : Cyclotron!
Each month, Gwenhaël W. De Wasseige tells us through her Little Story of Infinity the latest news about the universe and the domain of the infinitely small.
Cyclotron! Memorable curse of Captain Haddock?!
Not only! The cyclotron is actually a particle accelerator invented at Berkeley university in 1930.
A cyclotron accelerates charged particles, such as protons or electrons for example. How?! It makes them circulating in a cavity crossed perpendicularly by a constant magnetic field. The particles follow a circular path and are accelerated at each turn by a variable electric field, making the radius of their trajectory increasing up to leave the cavity. This machine is able to accelerate particles up to a few dozens of MeV.
"Particle accelerator" rings a bell? Something related to CERN? Indeed, the largest particle accelerator to date, the Large Hadron Collider or LHC, is at CERN.
The LHC works a bit differently from a cyclotron as it keeps particles on a circular trajectory with a fixed radius because of a variable magnetic field. This leads to particles with an energy up to 7 TeV, 1 000 000 more energetic than the cyclotron’s ones, all due to its 27km circonférence and its superconducting electromagnets.
You may think that writing about an invention from 1930 is not really what you called news… However, what is definitely in the news is the European Physical Society commemorating a modern version of this amazing machine located at Louvain-la-Neuve, Belgium!
The UCLouvain cyclotron was already a symbol, as it is at the very same place that the Belgian king Baudouin put the first stone of the university 50 years ago this year. The cyclotron enters a bit more the legend, joining two other Belgian places in the list of EPS historical sites:
- The Hotel Metropole in Brussels, where the first Solvay Conference was held in 1911. Marie Curie, Albert Einstein, Max Planck, and other leading physicists of the time were invited to discuss "The Theory of Radiation and the Quanta".
- The Heilige Heestcollege in Leuven where Georges Lemaître, catholic priest, mathematician, and astronomer, has developed what we commonly call "the Big Bang Theory".
The cyclotron can be proud, without blushing, to be listed among all these prestigious European sites. The place was selected for being the place of an innovative experiment mixing nuclear physics and astrophysics in the 1990s.
Researchers from the UCLouvain, ULB, and KULeuven have indeed managed to create a beam of unstable nitrogen, i.e. a radioactive product. They then made it collide with Hydrogen to obtain Oxygen and a flash of light, reproducing a similar reaction than that happening in stellar cores. In fact, it has recently been confirmed by the Borexino neutrino detector that the very same reaction happens in the core of our Sun. But that is another story…
Historical site = museum? Quite the opposite!
The cyclotron from the Centre des Ressources du Cyclotron keeps its status of cutting-edge technological platform. It is today used to carry out projects from the European Space Agency and the CERN. The cyclotron’S products are also used in biomedicine and biotechnology. And it does not intend to stop its incredible story and is now aiming at developing new tools for the space industry and radiobiology.
About the author :
Gwenhaël W. De Wasseige is assistant professor at UCLouvain in astroparticle physics. Members of the IceCube and KM3NeT collaborations, she leads the neutrino hunt both at the South Pole and in the Mediterranean Sea. Each month, Gwenhaël will tell us through her Little Story of Infinity the latest news about the universe and the domain of the infinitely small.

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