Argonne Tandem Linear Accelerator System
Encyclopedia
Argonne National Laboratory
Argonne National Laboratory is the first science and engineering research national laboratory in the United States, receiving this designation on July 1, 1946. It is the largest national laboratory by size and scope in the Midwest...
. ATLAS is the first superconducting
Superconductivity
Superconductivity is a phenomenon of exactly zero electrical resistance occurring in certain materials below a characteristic temperature. It was discovered by Heike Kamerlingh Onnes on April 8, 1911 in Leiden. Like ferromagnetism and atomic spectral lines, superconductivity is a quantum...
linear accelerator for heavy ion
Heavy ion
Heavy ion refers to an ionized atom which is usually heavier than helium. Heavy-ion physics is devoted to the study of extremely hot nuclear matter and the collective effects appearing in such systems, differing from particle physics, which studies the interactions between elementary particles...
s at energies in the vicinity of the Coulomb barrier
Coulomb barrier
The Coulomb barrier, named after Coulomb's law, which is named after physicist Charles-Augustin de Coulomb , is the energy barrier due to electrostatic interaction that two nuclei need to overcome so they can get close enough to undergo a nuclear reaction...
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The ATLAS accelerator at Argonne should not be confused with the ATLAS experiment
ATLAS experiment
ATLAS is one of the six particle detector experiments constructed at the Large Hadron Collider , a new particle accelerator at the European Organization for Nuclear Research in Switzerland...
at 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....
at CERN
CERN
The European Organization for Nuclear Research , known as CERN , is an international organization whose purpose is to operate the world's largest particle physics laboratory, which is situated in the northwest suburbs of Geneva on the Franco–Swiss border...
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How ATLAS works
Ions are generated from one of two sources: the 9-MV electrostatic tandem Van de GraffVan de Graaff generator
A Van de Graaff generator is an electrostatic generator which uses a moving belt to accumulate very high voltages on a hollow metal globe on the top of the stand. It was invented in 1929 by American physicist Robert J. Van de Graaff. The potential differences achieved in modern Van de Graaff...
accelerator or the Positive Ion Injector, a 12-MV low-velocity linac
Linear particle accelerator
A linear particle accelerator is a type of particle accelerator that greatly increases the velocity of charged subatomic particles or ions by subjecting the charged particles to a series of oscillating electric potentials along a linear beamline; this method of particle acceleration was invented...
and electron cyclotron resonance
Electron cyclotron resonance
Electron cyclotron resonance is a phenomenon observed both in plasma physics and condensed matter physics. An electron in a static and uniform magnetic field will move in a circle due to the Lorentz force...
(ECR) ion source. The ions are sent from one of these two into the 20-MV 'booster' linac, then to the 20-MV 'ATLAS' linac section.
The ATLAS linac section contains 62 resonators, each one of seven different type. Each type accelerates ions to a particular velocity. Each resonator is also tunable to allow for a wide range of velocities.
The ions in the ATLAS linac are aligned into a beam which exits the linac into one of three experimental areas. The experiment areas contain scattering chambers, spectrometers and spectrographs
Spectrometer
A spectrometer is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum, typically used in spectroscopic analysis to identify materials. The variable measured is most often the light's intensity but could also, for instance, be the polarization...
, beamline
Beamline
In particle physics, a beamline is the line in a linear accelerator along which a beam of particles travels. It may also refer to the line of travel within a bending section such as a storage ring or cyclotron, or an external beam extracted from a cyclic accelerator.In materials science, physics,...
s, a gamma-ray facility, and particle detector
Particle detector
In experimental and applied particle physics, nuclear physics, and nuclear engineering, a particle detector, also known as a radiation detector, is a device used to detect, track, and/or identify high-energy particles, such as those produced by nuclear decay, cosmic radiation, or reactions in a...
s.
What ATLAS is for
The energy levels of the ions produces by ATLAS are ideal to study the properties of the nucleusAtomic nucleus
The nucleus is the very dense region consisting of protons and neutrons at the center of an atom. It was discovered in 1911, as a result of Ernest Rutherford's interpretation of the famous 1909 Rutherford experiment performed by Hans Geiger and Ernest Marsden, under the direction of Rutherford. The...
. Specifically, understanding reactions between nuclei from very low energies (typically encountered in burning stars) to the very highest energies (encountered soon after the "Big Bang"). Nuclei with specific properties can be studied to understand fundamental interactions.
What is ATLAS made of
NiobiumNiobium
Niobium or columbium , is a chemical element with the symbol Nb and atomic number 41. It's a soft, grey, ductile transition metal, which is often found in the pyrochlore mineral, the main commercial source for niobium, and columbite...
is the primary metal used to construct the tubes http://www.phy.anl.gov/atlas/images/split_loop1.jpg in the individual in-line resonators. Niobium is used because it is relatively cheap, yet it is a superconductor at relatively high temperatures. The difficulties is in its malleability, which is quite poor making it difficult to construct the shapes needed for the resonators. The machinists working at ATLAS are some of the only people in the world able to work with niobium to the degree necessary for construction and repair of the ATLAS parts.
Target Areas
- Atom Trap at ATLAS
- Canadian Penning Trap Mass SpectrometerCanadian Penning Trap Mass SpectrometerThe Canadian Penning Trap Mass Spectrometer is one of the major pieces of experimental equipment that is installed on the ATLAS superconducting heavy-ion linac facility at the Physics Division of the Argonne National Laboratory...
- Enge Split Pole Spectrograph
- Fragment Mass Analyzer
- GammasphereGammasphereThe Gammasphere is a third generation gamma ray spectrometer used to study rare and exotic nuclear physics. It consists of 108 Compton-suppressed large volume, high-purity germanium detectors arranged in a spherical shell....
- Large Scattering Chamber
- Helical Orbit Spectrometer (HELIOS)Helical Orbit Spectrometer (HELIOS)The Helical Orbit Spectrometer is a measurement device for studying nuclear reactions in inverse kinematics. It is installed at the ATLAS facility at Argonne National Laboratory.-History:...