Antimatter and the Large Hadron Collider

Adriana Noemi Santiago Miranda 

During the course of high school and during my first years of college, I remembered being told that the atomic model was composed by electrons, neutrons and protons, and therefore I assumed that besides these particles and the photons, there were no other subatomic particles. For my surprise, just a few months ago, I discovered that this was not true. The discovery of the first subatomic particle, the electron, was achieved by in 1897 by J. J. Thomson. Then in 1905, Albert Einstein demonstrated the physical reality of the photons, hypothesized by Max Planck in 1900, in order to solve the problem of black body radiation. The proton was discovered in 1918 and the neutron in 1932. That same year the first antiparticle, the positron, was discovered by Carl D. Anderson. To the date 25 different kind of subatomic particles had been discovered: six types of quarks, six types of leptons and thirteen gauge bosons. 

Antiparticles or antimatter are the corresponding part of usual particles; they have the same mass but opposite charge. Curiously an antiproton and a positron can make an antihydrogen atom which has similar properties than a regular hydrogen atom. From this fact raises the question of why the universe is conformed primarily by matter instead of half antimatter and half matter. The CP violation, a postulate of particle physics, tries to explain the dominancy of matter over antimatter and why such symmetry doesn’t exist. Nevertheless, this is one of the most controversial unanswered questions of the physics world. 

When matter collides with antimatter annihilation occurs. In this process the two particles collide to create new particles, for example, during low energy annihilation photons are created. Particle accelerators use colliding positrons (antielectrons) and electros at relativistic speeds to create annihilation that by consequence, create diverse subatomic particles. Physicists study the results of these collisions to test theoretical predictions and to search for new kinds of subatomic particles. Specifically, the Large Hadron Collider was created to address some of the most fundamental questions of physics and laws of nature.

It has a circumference of 16.8 miles and is 328 feet underground and use 9,600 magnets that are cooled to 1.9 degrees Kelvin, very close to the absolute temperature. It uses magnets of several tons that propel particles at 99.99% the speed of light! Some of the main questions that are hope to be answered using this equipment are: the existence of extra dimensions as predicted by models based on the String Theory, the nature of dark matter and why are there apparent violations of the symmetry between matter and antimatter. In September 2011 the Large Hadron Collider claimed to have measured neutrinos faster than the speed of light, putting Einstein's theory into question. A huge controversy raised but then, this was proved false when it was found that the departure time was miscalculated.