Particle accelerator

A particle accelerator is a device that uses electric and/or magnetic fields to propel electrically charged particles to high speeds.

Higher energies

At present the highest energy accelerators are all circular colliders, but it is likely that limits have been reached in respect of compensating for synchrotron radiation losses, and the next generation will probably be linear accelerators 10 times the current length. An example of such a next generation accelerator is the 40 km long International Linear Collider, due to be constructed between 2015-2020.

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As of 2005, it is believed that plasma wakefield acceleration in the form of electron-beam 'afterburners' and standalone laser pulsers will provide dramatic increases in efficiency within two to three decades. In plasma wakefield accelerators, the beam cavity is filled with a plasma (rather than vacuum). A short pulse of electrons or laser light either constitutes or immediately trails the particles that are being accelerated. The pulse disrupts the plasma, causing the charged particles in the plasma to integrate into and move toward the rear of the bunch of particles that are being accelerated. This process transfers energy to the particle bunch, accelerating it further, and continues as long as the pulse is coherent.{{ref|Wright2005}}

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Energy gradients as steep as 200 GeV/m have been achieved over millimeter-scale distances using laser pulsers{{ref|Briezman}} and gradients approaching 1 GeV/m are being produced on the multi-centimeter-scale with electron-beam systems, in contrast to a limit of about 0.1 GeV/m for radio-frequency acceleration alone. Existing electron accelerators such as SLAC could use electron-beam afterburners to increase the intensity of their particle beams. Electron systems in general can provide tightly collimated, reliable beams; laser systems may offer more power and compactness. Thus, plasma wakefield accelerators could be used — if technical issues can be resolved — to both increase the maximum energy of the largest accelerators and to bring high energies into university laboratories and medical centers.

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Astrophysics

In next few decades, the possibility of black hole production at the highest energy accelerators may arise, if certain predictions of superstring theory are accurate (Scientific American, May 2005). If they are produced, it is thought that black holes would evaporate extremely quickly via Hawking radiation. However, the existence of Hawking radiation is controversial.{{ref|Helfer2003}} It is also thought that an analogy between colliders and cosmic rays demonstrates collider safety. If colliders can produce black holes, cosmic rays should have been producing them for aeons, and they have yet to harm us. However, this is also controversial. Models in which colliders cause trouble and cosmic rays do not have been proposed.

Related Topics:
Black hole - Superstring theory - Hawking radiation

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Black hole production would necessitate the development of new methods for investigating in a terrestrial accelerator the kinds of extremely massive particles that are thought to exist in dark matter and to have existed during the Big Bang.

Related Topics:
Black hole - Dark matter - Big Bang

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