D0 experiment

The DØ experiment (sometimes written D0 experiment, or DZero experiment) consists of a worldwide collaboration of scientists conducting research on the fundamental nature of matter. DØ was one of two major experiments (the other was the CDF experiment) located at the Tevatron Collider at Fermilab in Batavia, Illinois, USA. The Tevatron was the world's highest-energy accelerator from 1983 until 2009, when its energy was surpassed by the Large Hadron Collider. The DØ experiment stopped taking data in 2011, when the Tevatron shut down, but data analysis is still ongoing. The DØ detector is preserved in Fermilab's DØ Assembly Building as part of a historical exhibit for public tours. The DØ experiment (sometimes written D0 experiment, or DZero experiment) consists of a worldwide collaboration of scientists conducting research on the fundamental nature of matter. DØ was one of two major experiments (the other was the CDF experiment) located at the Tevatron Collider at Fermilab in Batavia, Illinois, USA. The Tevatron was the world's highest-energy accelerator from 1983 until 2009, when its energy was surpassed by the Large Hadron Collider. The DØ experiment stopped taking data in 2011, when the Tevatron shut down, but data analysis is still ongoing. The DØ detector is preserved in Fermilab's DØ Assembly Building as part of a historical exhibit for public tours. DØ research is focused on precise studies of interactions of protons and antiprotons at the highest available energies. These collisions result in 'events' containing many new particles created through the transformation of energy into mass according to the relation E=mc2. The research involves an intense search for subatomic clues that reveal the character of the building blocks of the universe. In 1981, Fermilab director Leon M. Lederman asked for preliminary proposals for a 'modest detector built by a modestly sized group' that would be located at the 'DØ' interaction region in the Tevatron ring and complement the planned Collider Detector at Fermilab. More than fifteen groups submitted proposals. Three of these proposals were merged into one effort under the leadership of Paul Grannis, which officially began on September 1, 1983. The group produced a design report in November 1984. The detector was completed in 1991, it was placed in the Tevatron in February 1992, and observed its first collision in May 1992. It recorded data from 1992 until 1996, when it was shut down for major upgrades. Its second run began in 2001 and lasted until September 2011. As of 2019, data analysis is still ongoing. The DØ experiment is an international collaboration that, at its peak, included about 650 physicists from 88 universities and national laboratories from 19 countries. It studied the collisions between the protons and antiprotons circulating in the Tevatron to test many aspects of the Standard Model of particle physics. The DØ detector consisted of several nested subdetector groups surrounding the region where the beam protons and antiprotons collided. The subdetectors provided over a million channels of electronics that were collected, digitized and logged for off-line analyses. About 1.7 million collisions of the proton and antiproton beams were inspected every second, and about 100 collisions per second were recorded for further studies. DØ conducted its scientific studies within six physics groups: Higgs, Top, Electroweak, New Phenomena, QCD, and B Physics. Significant advances were made in each of them. One of the early goals of the DØ experiment was to discover the top quark, the last of the six constituents of matter predicted by the Standard Model of particle physics. The DØ and CDF experiments both collected data for the search, but they used different observation and analysis techniques that allowed independent confirmation of one another's findings. On February 24, 1995, DØ and CDF submitted research papers to Physical Review Letters describing the observation of top and antitop quark pairs produced via the strong interaction. On March 2, 1995, the two collaborations jointly reported the discovery of the top quark at a mass of about 175 GeV/c2 (nearly that of a gold nucleus). On March 4, 2009, the DØ and CDF collaborations both announced the discovery of the production of single top quarks via the weak interaction. This process occurs at about half the rate as the production of top quark pairs but is much more difficult to observe since it is more difficult to distinguish from background processes that can create false signals. The single top quark studies were used to measure the top quark lifetime of about 5 × 10-25 seconds, measure the last unknown element of the CKM matrix of quark inter-generational mixing, and to search for new physics beyond the Standard Model.