Tevatron
Encyclopedia
The Tevatron is a circular particle accelerator
in the United States
, at the Fermi National Accelerator Laboratory
(also known as Fermilab), just east of Batavia, Illinois
, and is the second highest energy particle collider in the world after the Large Hadron Collider
(LHC). The Tevatron is a synchrotron
that accelerates proton
s and antiproton
s in a 6.28 km (3.9 mi) ring to energies of up to 1 TeV
, hence its name. The Tevatron was completed in 1983 at a cost of $120 million ($ today) and significant upgrade investments were made in 1983-2011. (The 'Energy Doubler', as it was known then, produced its first accelerated beam — 512 GeV — on July 3, 1983.) The Main Injector was the most substantial addition, built over five years from 1994 at a cost of $290 million ($ today).
The Tevatron ceased operations on 30 September, 2011, due to budget cuts; it is not as powerful as the LHC, which began operations in early 2010. The main ring of the Tevatron will probably be reused in future experiments, and its components may be transferred to other particle accelerators.
Cockcroft-Walton
pre-accelerator, which ionizes hydrogen
gas and accelerates the negative ions created using a positive voltage
. The ions then pass into the 150 meter long linear accelerator (linac) which uses oscillating electrical fields to accelerate the ions to 400 MeV
. The ions then pass through a carbon foil, to remove the electron
s, and the charged proton
s then move into the Booster.
The Booster is a small circular synchrotron, around which the protons pass up to 20,000 times to attain an energy of around 8 GeV
. From the Booster the particles pass into the Main Injector, which was completed in 1999 to perform a number of tasks. It can accelerate protons up to 150 GeV; it can produce 120 GeV protons for antiproton creation; it can increase antiproton energy to 120 GeV and it can inject protons or antiprotons into the Tevatron. The antiprotons are created by the Antiproton Source. 120 GeV protons are collided with a nickel target producing a range of particles including antiprotons which can be collected and stored in the accumulator ring. The ring can then pass the antiprotons to the Main Injector.
The Tevatron can accelerate the particles from the Main Injector up to 980 GeV. The protons and antiprotons are accelerated in opposite directions, crossing paths in the CDF
and DØ
detectors to collide at 1.96 TeV. To hold the particles on track the Tevatron uses 774 niobium-titanium
superconducting dipole
magnet
s cooled in liquid helium
producing 4.2 tesla
s. The field ramps over about 20 seconds as the particles are accelerated. Another 240 NbTi quadrupole
magnets are used to focus the beam.
The initial design luminosity of the Tevatron was 1030 cm−2 s−1, however the accelerator has following upgrades been able to deliver luminosities up to 3x1032 cm−2 s−1.
On September 27, 1993 the cryogenic cooling system of the Tevatron Accelerator was named an International Historic Landmark by the American Society of Mechanical Engineers
. The system, which provides cryogenic liquid helium to the Tevatron's superconducting magnets, was the largest low-temperature system in existence upon its completion in 1978. It keeps the coils of the magnets, which bend and focus the particle beam, in a superconducting state so that they consume only 1/3 of the power they would require at normal temperatures.
, the 2005 Sumatra earthquake
, New Zealand's 2007 Gisborne earthquake
, the 2010 Haiti earthquake
and the 2010 Chile earthquake
.
and DØ
collaborations announced the discovery of the top quark
, and by 2007 they measured its mass to a precision of nearly 1%.
In 2006, CDF made the first measurement of Bs oscillations
, and observed two types of sigma baryon
.
In 2007, the DØ and CDF experiments reported direct observation of the "Cascade B" Xi baryon.
In September 2008, the DØ experiment reported detection of the , a "double strange
" Omega baryon
with the measured mass significantly higher than the quark model prediction. In May 2009 the CDF
collaboration made public their results on search for based on analysis of data sample roughly four times larger than the one used by DZero experiment. CDF
measured mass to be in excellent agreement with Standard Model prediction. No signal has been observed at DZero reported value. The two results differ by or by 6.2 standard deviations and therefore are inconsistent. Excellent agreement between CDF measured mass and theoretical expectations is a strong indication that the particle discovered by CDF is indeed the . It is anticipated that new data from LHC
experiments will clarify the situation in the near future.
On April 7, 2011, the CDF team at Fermilab announced the discovery of a possible new particle after a new non-Higgs particle appeared in their data. However, an independent analysis of data from trillions of particle collisions by the DØ team was not able to reproduce the detection of the new particle, thus suggesting that the initial observation was a statistical fluke and that, in fact, no new particle had been discovered. Although disappointed that the data did not yield a new discovery, scientists were quick to point out that this is exactly how science is supposed to work - data and discoveries must be independently replicated and verified by numerous measurements and teams. In this case, the scientific process worked perfectly.
Particle accelerator
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, at the Fermi National Accelerator Laboratory
Fermilab
Fermi National Accelerator Laboratory , located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics...
(also known as Fermilab), just east of Batavia, Illinois
Batavia, Illinois
Batavia was founded in 1833, and is the oldest city in Kane County, Illinois, with a small portion in DuPage County. During the Industrial Revolution, Batavia became known as ‘The Windmill City’ for being the largest windmill producer of the time...
, and is the second highest energy particle collider in the world after the Large Hadron Collider
Large Hadron Collider
The Large Hadron Collider is the world's largest and highest-energy particle accelerator. It is expected to address some of the most fundamental questions of physics, advancing the understanding of the deepest laws of nature....
(LHC). The Tevatron is a synchrotron
Synchrotron
A synchrotron is a particular type of cyclic particle accelerator in which the magnetic field and the electric field are carefully synchronised with the travelling particle beam. The proton synchrotron was originally conceived by Sir Marcus Oliphant...
that accelerates proton
Proton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
s and antiproton
Antiproton
The antiproton is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived since any collision with a proton will cause both particles to be annihilated in a burst of energy....
s in a 6.28 km (3.9 mi) ring to energies of up to 1 TeV
TEV
TEV may refer to:* TeV, or teraelectronvolt, a measure of energy* Total Enterprise Value, a financial measure* Total Economic Value, an economic measure* Tobacco etch virus, a plant pathogenic virus of the family Potyviridae....
, hence its name. The Tevatron was completed in 1983 at a cost of $120 million ($ today) and significant upgrade investments were made in 1983-2011. (The 'Energy Doubler', as it was known then, produced its first accelerated beam — 512 GeV — on July 3, 1983.) The Main Injector was the most substantial addition, built over five years from 1994 at a cost of $290 million ($ today).
The Tevatron ceased operations on 30 September, 2011, due to budget cuts; it is not as powerful as the LHC, which began operations in early 2010. The main ring of the Tevatron will probably be reused in future experiments, and its components may be transferred to other particle accelerators.
Mechanics
The acceleration occurs in a number of stages. The first stage is the 750 keVKev
Kev can refer to:*Kev Hawkins, a fictional character.*Kevin, a given name occasionally shortened to "Kev".*Kiloelectronvolt, a unit of energy who symbol is "KeV".* Krefelder Eislauf-VereinKEV can refer to:...
Cockcroft-Walton
Cockcroft-Walton generator
The Cockcroft–Walton generator, or multiplier, is an electric circuit which generates a high DC voltage from a low voltage AC or pulsing DC input...
pre-accelerator, which ionizes hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
gas and accelerates the negative ions created using a positive voltage
Voltage
Voltage, otherwise known as electrical potential difference or electric tension is the difference in electric potential between two points — or the difference in electric potential energy per unit charge between two points...
. The ions then pass into the 150 meter long linear accelerator (linac) which uses oscillating electrical fields to accelerate the ions to 400 MeV
MEV
MeV and meV are multiples and submultiples of the electron volt unit referring to 1,000,000 eV and 0.001 eV, respectively.Mev or MEV may refer to:In entertainment:* Musica Elettronica Viva, an Italian musical group...
. The ions then pass through a carbon foil, to remove the electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s, and the charged proton
Proton
The proton is a subatomic particle with the symbol or and a positive electric charge of 1 elementary charge. One or more protons are present in the nucleus of each atom, along with neutrons. The number of protons in each atom is its atomic number....
s then move into the Booster.
The Booster is a small circular synchrotron, around which the protons pass up to 20,000 times to attain an energy of around 8 GeV
GEV
GEV or GeV may stand for:*GeV or gigaelectronvolt, a unit of energy equal to billion electron volts*GEV or Grid Enabled Vehicle that is fully or partially powered by the electric grid, see plug-in electric vehicle...
. From the Booster the particles pass into the Main Injector, which was completed in 1999 to perform a number of tasks. It can accelerate protons up to 150 GeV; it can produce 120 GeV protons for antiproton creation; it can increase antiproton energy to 120 GeV and it can inject protons or antiprotons into the Tevatron. The antiprotons are created by the Antiproton Source. 120 GeV protons are collided with a nickel target producing a range of particles including antiprotons which can be collected and stored in the accumulator ring. The ring can then pass the antiprotons to the Main Injector.
The Tevatron can accelerate the particles from the Main Injector up to 980 GeV. The protons and antiprotons are accelerated in opposite directions, crossing paths in the CDF
Collider Detector at Fermilab
The Collider Detector at Fermilab experimental collaboration studies high energy particle collisions at the Tevatron,the world's former highest-energy particle accelerator...
and DØ
D0 experiment
The DØ experiment consists of a worldwide collaboration of scientists conducting research on the fundamental nature of matter...
detectors to collide at 1.96 TeV. To hold the particles on track the Tevatron uses 774 niobium-titanium
Niobium-titanium
Niobium-titanium is an alloy of niobium and titanium, used industrially as a type II superconductor wire for superconducting magnets...
superconducting dipole
Dipole magnet
A dipole magnet, in particle accelerators, is a magnet constructed to create a homogeneous magnetic field over some distance. Particle motion in that field will be circular in a plane perpendicular to the field and collinear to the direction of particle motion and free in the direction orthogonal...
magnet
Magnet
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.A permanent magnet is an object...
s cooled in liquid helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
producing 4.2 tesla
Tesla (unit)
The tesla is the SI derived unit of magnetic field B . One tesla is equal to one weber per square meter, and it was defined in 1960 in honour of the inventor, physicist, and electrical engineer Nikola Tesla...
s. The field ramps over about 20 seconds as the particles are accelerated. Another 240 NbTi quadrupole
Quadrupole
A quadrupole or quadrapole is one of a sequence of configurations of—for example—electric charge or current, or gravitational mass that can exist in ideal form, but it is usually just part of a multipole expansion of a more complex structure reflecting various orders of complexity.-Mathematical...
magnets are used to focus the beam.
The initial design luminosity of the Tevatron was 1030 cm−2 s−1, however the accelerator has following upgrades been able to deliver luminosities up to 3x1032 cm−2 s−1.
On September 27, 1993 the cryogenic cooling system of the Tevatron Accelerator was named an International Historic Landmark by the American Society of Mechanical Engineers
American Society of Mechanical Engineers
The American Society of Mechanical Engineers is a professional body, specifically an engineering society, focused on mechanical engineering....
. The system, which provides cryogenic liquid helium to the Tevatron's superconducting magnets, was the largest low-temperature system in existence upon its completion in 1978. It keeps the coils of the magnets, which bend and focus the particle beam, in a superconducting state so that they consume only 1/3 of the power they would require at normal temperatures.
Earthquake detection
Sensors on underground magnets in the Tevatron are capable of detecting minute seismic vibrations from earthquakes thousands of miles away. The Tevatron recorded vibration spikes emanating from the 2004 Indian Ocean earthquake2004 Indian Ocean earthquake
The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on Sunday, December 26, 2004, with an epicentre off the west coast of Sumatra, Indonesia. The quake itself is known by the scientific community as the Sumatra-Andaman earthquake...
, the 2005 Sumatra earthquake
2005 Sumatra earthquake
The 2005 Sumatra earthquake, referred to as the Nias Earthquake by the scientific community, was a major earthquake on 28 March 2005, located off the west coast of northern Sumatra, Indonesia. Approximately 1300 people were killed by the earthquake, mostly on the island of Nias...
, New Zealand's 2007 Gisborne earthquake
2007 Gisborne earthquake
The 2007 Gisborne earthquake was an earthquake of magnitude 6.8 on the Richter scale which struck in the Pacific Ocean, 50 km off the eastern coast of New Zealand's North Island at 8.55 pm NZDT on 20 December 2007...
, the 2010 Haiti earthquake
2010 Haiti earthquake
The 2010 Haiti earthquake was a catastrophic magnitude 7.0 Mw earthquake, with an epicentre near the town of Léogâne, approximately west of Port-au-Prince, Haiti's capital. The earthquake occurred at 16:53 local time on Tuesday, 12 January 2010.By 24 January, at least 52 aftershocks...
and the 2010 Chile earthquake
2010 Chile earthquake
The 2010 Chile earthquake occurred off the coast of central Chile on Saturday, 27 February 2010, at 03:34 local time , having a magnitude of 8.8 on the moment magnitude scale, with intense shaking lasting for about three minutes. It ranks as the sixth largest earthquake ever to be recorded by a...
.
Discoveries
In 1995, the CDFCollider Detector at Fermilab
The Collider Detector at Fermilab experimental collaboration studies high energy particle collisions at the Tevatron,the world's former highest-energy particle accelerator...
and DØ
D0 experiment
The DØ experiment consists of a worldwide collaboration of scientists conducting research on the fundamental nature of matter...
collaborations announced the discovery of the top quark
Top quark
The top quark, also known as the t quark or truth quark, is an elementary particle and a fundamental constituent of matter. Like all quarks, the top quark is an elementary fermion with spin-, and experiences all four fundamental interactions: gravitation, electromagnetism, weak interactions, and...
, and by 2007 they measured its mass to a precision of nearly 1%.
In 2006, CDF made the first measurement of Bs oscillations
B-Bbar oscillation
Neutral B meson oscillations is one of the manifestations of the neutral particle oscillation, a fundamental prediction of the Standard Model of particle physics. It is the phenomenon of B mesons changing between their matter and antimatter forms before their decay...
, and observed two types of sigma baryon
Sigma baryon
The Sigma baryons are a family of subatomic hadron particles which have a +2, +1 or -1 elementary charge or are neutral. They are baryons containing three quarks: two up and/or down quarks, and one third quark, which can be either a strange , a charm , a bottom or a top quark...
.
In 2007, the DØ and CDF experiments reported direct observation of the "Cascade B" Xi baryon.
In September 2008, the DØ experiment reported detection of the , a "double strange
Strangeness
In particle physics, strangeness S is a property of particles, expressed as a quantum number, for describing decay of particles in strong and electromagnetic reactions, which occur in a short period of time...
" Omega baryon
with the measured mass significantly higher than the quark model prediction. In May 2009 the CDF
Collider Detector at Fermilab
The Collider Detector at Fermilab experimental collaboration studies high energy particle collisions at the Tevatron,the world's former highest-energy particle accelerator...
collaboration made public their results on search for based on analysis of data sample roughly four times larger than the one used by DZero experiment. CDF
Collider Detector at Fermilab
The Collider Detector at Fermilab experimental collaboration studies high energy particle collisions at the Tevatron,the world's former highest-energy particle accelerator...
measured mass to be in excellent agreement with Standard Model prediction. No signal has been observed at DZero reported value. The two results differ by or by 6.2 standard deviations and therefore are inconsistent. Excellent agreement between CDF measured mass and theoretical expectations is a strong indication that the particle discovered by CDF is indeed the . It is anticipated that new data from LHC
Large Hadron Collider
The Large Hadron Collider is the world's largest and highest-energy particle accelerator. It is expected to address some of the most fundamental questions of physics, advancing the understanding of the deepest laws of nature....
experiments will clarify the situation in the near future.
On April 7, 2011, the CDF team at Fermilab announced the discovery of a possible new particle after a new non-Higgs particle appeared in their data. However, an independent analysis of data from trillions of particle collisions by the DØ team was not able to reproduce the detection of the new particle, thus suggesting that the initial observation was a statistical fluke and that, in fact, no new particle had been discovered. Although disappointed that the data did not yield a new discovery, scientists were quick to point out that this is exactly how science is supposed to work - data and discoveries must be independently replicated and verified by numerous measurements and teams. In this case, the scientific process worked perfectly.