Particle accelerator: beam speed and the particles a collision can make
After 99.9% the speed of light, you stop getting faster
A particle accelerator is a microscope made of energy: electric fields kick charged particles faster each lap, magnetic fields steer them in a ring, and the collision energy becomes new matter by E = mc². As particles near light speed, relativity wins - energy climbs while speed flatlines. Raise the collision energy to slam beams together and watch which particles the energy can afford to create.
Accelerator ring
Lap 0 • 10 GeV
Log energy scale. Speed is for a proton beam carrying half the collision energy; the ladder lights each particle once the collision can pay its mass-energy (E = mc²).
bottom threshold reached
Collision energy
0.1 GeV10 GeV1 TeV14 TeV
Beam speed
0.988c
Heaviest particle
bottom
Electric fields accelerate - each pass through an RF cavity adds energy. The particle crosses a gap where the electric field oscillates at radio frequency; if it arrives at the right phase, the field kicks it forward and it leaves faster than it entered. Lap after lap, the energy compounds. The field does work on the particle, converting electrical potential energy into kinetic energy, and the particle gains speed - until relativity takes over and most of the added energy becomes mass-energy instead of velocity. Magnetic fields cannot do this: they deflect but never accelerate, because the Lorentz force is always perpendicular to motion.
Know This
Electric fields accelerate - each pass through an RF cavity adds energy; magnetic fields steer and focus but add none, while collision energy converts to mass through E = mc² run forward.