Top Quark Is Discovered
The discovery of the top quark marks a significant milestone in particle physics, occurring on April 23, 1994, at Fermilab, a premier research facility located in Batavia, Illinois. Quarks are fundamental constituents of matter, forming the building blocks of protons and neutrons within atoms. The top quark is unique as it is the heaviest of the six known quarks, which include up, down, strange, charm, bottom, and top. While the existence of these quarks was theorized in the 1970s, the top quark remained elusive for many years after the other five were identified by 1977. Researchers believe that all six quarks were formed shortly after the Big Bang, but top quarks decayed rapidly into lighter forms, making them difficult to observe in nature.
To study such particles, scientists utilize particle accelerators like Fermilab's Tevatron, which is the most powerful of its kind in the world. These accelerators collide high-energy particles, creating conditions that can produce short-lived particles like the top quark. The successful creation of the top quark at Fermilab not only confirmed theoretical predictions but also enhanced the understanding of the fundamental structure of matter and the forces governing it.
On this Page
Subject Terms
Top Quark Is Discovered
Top Quark Is Discovered
Quarks are the smallest particles of matter known to science. They are the elementary building blocks of such larger particles as protons and neutrons which are found in the atom. On April 23, 1994, scientists at the United States Department of Energy's Fermi National Accelerator Laboratory, or Fermilab, announced that they had created the elusive top quark, the heaviest of the six types of quarks.
The existence of these six basic quarks—up, down, strange, charm, bottom, and top—had been theorized by the 1970s in what was called the standard model, and by 1977 the first five types had been discovered in the laboratory. The sixth or “top” quark, however, was the heaviest of all and has yet to be found in nature. It is thought that all six types of quarks were created when the Big Bang began the universe, tens of billions of years ago, but that the top quarks (and probably the nearly-as-heavy bottom quarks too) decayed into lighter types almost immediately thereafter. Therefore, top quarks (if they could exist) would have to be created in a giant device known as a particle accelerator, such as the one found at Fermilab.
Fermilab is located at Batavia, Illinois, near the city of Chicago. It is named after Enrico Fermi (1901–54), the Italian scientist who moved to the United States and won the Nobel Prize in Physics in 1938 for his work in splitting the atom. The facility is operated by a consortium of universities from the United States, Canada, and Japan. Fermilab has the world's most powerful particle accelerator, the massive four-mile Tevatron, built in a circular underground tunnel. The object of particle accelerators is to direct high-energy particle beams into collision with stationary objects or with each other. Also known as atom smashers, particle accelerators thus produce subatomic particles such as quarks. With the assistance of the Main Ring, another accelerator which feeds into the Tevatron, particles can be accelerated to a strength of 1 trillion volts. It was in this manner that the top quark was discovered.