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Physics at Fermilab
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Discoveries at Fermilab

Paving the way to the 21st century

Fermilab produced its first high-energy particle beam on March 1, 1972. Since then hundreds of experiments have used Fermilab's accelerators to study matter at ever smaller scales. Here an overview of the top ten achievements so far.

Discovery of the top quark
On March 2, 1995, physicists at Fermilab's CDF and DZero experiments announced the discovery of the top quark, the last undiscovered quark of the six predicted to exist by current scientific theory. Scientists worldwide had sought the top quark since the discovery of the bottom quark at Fermilab in 1977. Physicists discovered the top, as heavy as an entire gold atom but much smaller than a single proton, using particle beams from the Tevatron, the world's highest energy particle accelerator. Details

Discovery of the bottom quark and subsequent studies of its properties
Physicists at Fermilab's E288 collaboration, led by Nobel laureate Leon Lederman, announced the discovery of a new particle named the upsilon on June 30, 1977. The experimenters showed that the upsilon particle contains a bottom quark and an anti-bottom quark: Thus, the third generation of quarks was revealed. Details

Determination of top quark and W boson masses to high precision
Particle physicists measure particle masses to verify the correctness and accuracy of their particle models. Knowing the value of the top quark mass to high precision has allowed physicists to zero in on the mass of the undiscovered Higgs boson, a crucial component of the theoretical framework of particle physics.

Observation of direct CP violation in kaon decays
On February 24, 1999, physicists from Fermilab's KTeV collaboration announced results establishing the existence of direct CP violation in the decay of kaons (particles containing a strange quark). The observation is a significant step in understanding why the universe displays an abundance of matter, while antimatter disappeared at an early stage in the evolution of the universe. Details

Precise measurement of the lifetimes of charm particles
The charm quark, the fourth quark of the Standard Model, is much heavier than the first three quarks. Studying the production and decay mechanisms of charm particles when produced in proton-antiproton collisions proved to be crucial in understanding the forces between quarks and how quarks combine to form composite particles. Details

First direct evidence for the tau neutrino
On July 21, 2000, scientists at Fermilab announced the first direct evidence for the tau neutrino, the third kind of neutrino known to particle physicists. Although earlier experiments had produced convincing indirect evidence for the particle's existence, no one had directly observed the interaction of a tau neutrino with matter. Tau neutrinos are massless or almost massless particles that carry no electric charge and barely interact with surrounding matter, making an observation extremely difficult. With the tau neutrino observation, three of the four particles of the third generation of the Standard Model were discovered at Fermilab: the bottom quark, the top quark and then the tau neutrino. Details

Mapping the structure of protons and neutrons using neutrino beams
Using neutrino beams has proved a unique and fruitful method of studying the structure of matter at the smallest scales possible. Since neutrinos have no electric charge, they can probe quarks, the building blocks of protons and neutrons, via weak interactions, complementing decades of studies based on electromagnetic interactions. A long series of experiments at Fermilab and other high-energy laboratories has carefully mapped the composition of protons, antiprotons and neutrons. Details

Measurement of the magnetic moments of particles containing strange quarks
Hyperons, subatomic relatives of the proton, are like tiny magnets that live less than a billionth of a second. From 1975 to 1985, precision experiments at Fermilab measured their magnetic strengths and clearly showed that hyperons are made of quarks, a major contribution to formulating the theoretical framework called the Standard Model. Details

Discovery of a quasar at a distance of 27 billion light years
On April 13, 2000, scientists of the Sloan Digital Sky Survey announced the observation of the most distant object ever observed, a quasar at a red shift of 5.8, a distance of 27 billion light years from Earth. The SDSS collaboration will ultimately survey 10,000 square degrees, or one quarter of the sky, and 200 million celestial objects. Fermilab scientists are involved in managing and analyzing this large amount of data. These astrophysical studies complement Fermilab's quest to understand the structure and evolution of the universe. Details

Calculation of the strong coupling constant using supercomputers
Quarks interact via the strong force. Many properties of this short-range force are calculable only with the aid of the large-scale numerical calculations of lattice gauge theory. Using powerful supercomputers, the Fermilab lattice gauge theory group performed the first accurate determination of the "strong coupling constant," the characteristic strength describing this force. The calculation presented one of the first accurate lattice determinations of any fundamental parameter of the standard model.

last modified 2/23/2001   email Fermilab