Moments in the Life of a Proton
Before any collisions take place, the protons must go through multiple systems to increase their energy level from their initial energy to the final energy of 7 TeV. But first, physicists need to have protons to accelerate! How do they do this? Can they “make” protons out of nothing? No way! What actually happens is protons are separated from electrons in hydrogen atoms (which are made up of just that, one electron and one proton) and then sent through a combination of accelerators.
The picture below shows the routes of each particle, along with other apparatuses that are part of the CERN accelerator complex.
The first part of the procedure is the linear accelerator, LINAC2. This increases energy of the protons and sends them to the Proton Synchrotron Booster (PSB). Protons are then injected at 1.4 GeV into the Proton Synchrotron (PS) at 25 GeV. Next, the Super Proton Synchrotron (SPS) receives the protons from the PS and increases the energy of protons up to 450 GeV. And finally, the protons are directed to the main LHC tunnel where they circulate, the two separate proton beams circulating in opposite directions, for a certain amount of time. The particles reach speeds close to the speed of light (relativistic) and energies of about 7 TeV, then collide at each experiment site. When the collisions occur head on, a total energy of 14 TeV is obtained!
In special cases, the lead (Pb) ions come from a vaporized lead source and sent through LINAC3, another linear accelerator, to Low Energy Ion Ring (Leir) and then follows the same route as the protons.