At CERN in Geneva begins the new era of physics – Il Sole 24 Ore

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This article was published on June 4, 2015 at 5:55.
The last change is the June 4, 2015 at 24:23.

Beginning of 1954, a few months before he died, Enrico Fermi imagined, during a conference, the particle accelerator “definitive”, a ring of 50 thousand kilometers in orbit around the Earth, which was to achieve amazing energy. Today, similar energies have become reality thanks to the most powerful accelerator in the world, the Large Hadron Collider (LHC) at CERN in Geneva, which has a circumference of “just” 27 km. What made it possible to realize the dream of Fermi was a new conception of the accelerators, proposed half a century ago by a brilliant physicist Italian-Austrian Bruno Touschek.

While in conventional accelerators, such as who thought Fermi, the particle beam is sent on a fixed target, in colliders Touschek invented by two beams of particles circulating in opposite directions and collide head, thus maximizing the useful energy. The LHC, which collide beams of protons, is the last heir to the tradition inaugurated by Touschek and collaborators in 1961, the laboratories of Frascati (the National Institute of Nuclear Physics), with a car and a meter in diameter that did collide electrons and positrons, the legendary AA (ring Accumulation).

From the sixties to the present day the energy of accelerators has increased by several orders of magnitude, and the last record was broken yesterday by the LHC, which, after two years of technological improvements, has resumed operation at ‘ energy of 13 TeV (thirteen billion electron volts), the highest ever, nearly twice that at which the LHC was discovered in 2012, the Higgs boson.

But why do we need higher and higher energies? The answer lies in the relativity and quantum mechanics. The first tells us that the energy of the colliding particles is converted into mass of the produced particles, and thus to produce heavier particles need more energy. The second tells us that the accelerators are a kind of microscopes infinitely small, because the particles act as probes, whose resolving power is proportional to the energy: the greater the energy of a particle, the smaller the region space that it allows us to explore.

The goal LHC is to produce heavier particles and explore smaller areas, in search of a “new physics”, ie of phenomena not covered by the Standard Model, the current theory particles and the fundamental forces. The focus is mainly on supersymmetry, a new symmetry of nature, which could occur through particles that are affordable LHC. In addition to various theoretical advantages (related to the unification of the forces of nature and to overcome some conceptual difficulties of the Standard Model), supersymmetry particles also provide the right to solve one of the most exciting puzzles of physics, that of dark matter – matter we do not see, because it does not emit or absorb light, but that is much more abundant than ordinary matter.

The LHC experiments (involving about 1,500 researchers and technicians INFN) then begin their second season. The hope of all is that, after the confirmation, come now the news and surprises.

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