All matter consists of atoms combined in different proportions. Physicists that study matter tell us that atoms consist of electrons circling a nucleus. Protons and neutrons make up the the nucleus, and have their own building blocks called quarks. Quarks are believed to be the ultimate building blocks of matter.
The Nature of Quarks
There are six types of quarks and they come in three pairs: up and down, charm and strange, and top and bottom. Quarks are also identified by their mass, charge and spin. Mass tells you how heavy it is, spin tells you how it will react to a magnetic field, and charge describes how it will behave in an electric field. The entire behavior of quarks is described in what is called the "standard model" of particles.
Up and Down
Quarks were first discovered in 1968 when the proton was split at the Stanford Linear Accelerator Center (SLAC). Originally named partons, they were soon identified as the quarks predicted in 1964 by Murray Gell-Mann and George Zweig. The up quark has a mass approximately half that of the down quark. The up quark has a fractional charge of two-thirds. The down quark has a charge of negative one-third.
Charm and Strange Flavors
In 1970 and 1995, particle experiments at SLAC and Fermilab discovered the charm and strange flavors of quarks. Mass is measured in million of electrons volts (Mev) and billions of election volts (Gev). The charm has a much bigger mass (1.22Gev) than the Strange (104Mev). The charm's charge is negative one-third; the strange's charge is two-thirds.
Top and Bottom Flavors
The top quark weighs more than the bottom quark. The top has a mass of about 180 Gev while the bottom has just 4.2 Gev. The charge is two-thirds for the top and negative one-third for the bottom. A group of scientists from Columbia University, Fermilab and the State University of New York at Stony Brook, led by Leon Lederman of Columbia, discovered the bottom quark in August 1978. The top quark was discovered in February 1995 at Fermilab's Tevatron proton anti-proton collider.
Particles, Quarks and Nobels
The search for fundamental particles such as quarks has resulted in many Nobel prizes in physics. For example, Murray Gell-Mann won the Nobel in 1969 for his "classification of elementary particles and their interactions" and correct prediction of quarks. In 1988, Leon Ledermann, Melvin Schwartz and Jack Steinberger won the Nobel for their discovery of the muon neutrino particle. In 1990, Jerome Friedman, Henry Kendall and Richard Taylor won the Nobel for discovering the structure of quarks.
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