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How is particle energy measured in electron volts?

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Diagram of a linear proton resonance accelerator, or linac, showing protons entering from a source, passing through a series of labeled drift tubes powered by a radio-frequency source, and exiting as a beam through a cavity. — particle accelerator The accelerator is a large-diameter tube within which an electric field oscillates at a high radio frequency. Within the accelerator tube are smaller diameter metallic drift tubes, which are carefully sized and spaced to shield the protons from decelerating oscillations of the electric field. In the spaces between the drift tubes, the electric field is oriented properly to accelerate the protons in their direction of travel.

In the context of a particle accelerator, particle energy is measured in electron volts (eV), which represents the amount of energy an electron gains when it travels through an electric potential difference of one volt.12

Because an electron carries a unit electronic charge, the potential difference it traverses directly determines the energy it acquires. In a vacuum, as particles move toward a positive potential, they are accelerated by the electric field, increasing their velocity and energy.12

For higher energy levels, scientists use prefixes to denote larger scales:
* keV (kiloelectron volts): $10^{3}$ eV2
* MeV (megaelectron volts): $10^{6}$ eV12
* GeV (gigaelectron volts): $10^{9}$ eV12
* TeV (teraelectron volts): $10^{12}$ eV12

Modern accelerators, such as linear accelerators and synchrotrons, achieve these high energies by using alternating electric fields to provide cumulative pushes to the particles, rather than relying on a single, massive static voltage.2