How do scientists know there are quarks?

Quarks are very small and are located inside other particles such as the proton. Since the forces that hold them inside the proton are really strong, it takes a lot of energy to break apart the proton to see them. The idea is that you take protons and smash them against other particles at very high speeds to try to break them apart to see the quarks. In order to get the protons moving at high speeds, you use a machine called an accelerator. There is an accelerator at Fermilab, near Chicago, that does this. Then you need a detector to watch the particles that fly out. There are two groups of people that have built detectors at Fermilab. One of these detectors, called the D0 detector, is shown with the people who helped to build it.

Particle Accelerators

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