Editing International Linear Collider (section)

== Design ==
The electron source for the ILC will use 2-nanosecond [[laser]] light pulses to eject electrons from a [[photocathode]], a technique allowing for up to 80% of the electrons to be polarized; the electrons then will be accelerated to 5&nbsp;GeV in a 370-meter linac stage.  Synchrotron radiation from high energy electrons will produce electron-positron pairs on a titanium-alloy target, with as much as 60% polarization; the positrons from these collisions will be collected and accelerated to 5&nbsp;GeV in a separate linac.

To compact the 5&nbsp;GeV electron and positron bunches to a sufficiently small size to be usefully collided, they will circulate for 0.1–0.2 seconds in a pair of damping rings, 3.24&nbsp;km in circumference, in which they will be reduced in size to 6&nbsp;mm in length and a vertical and horizontal [[Beam emittance|emittance]] of 2&nbsp;pm and 0.6&nbsp;nm, respectively.

From the damping rings the particle bunches will be sent to the [[Superconducting Radio Frequency|superconducting radio frequency]] main linacs, each 11&nbsp;km long, where they will be accelerated to 250&nbsp;GeV.  At this energy each beam will have an average power of about 5.3 [[Watt|megawatts]].  Five bunch trains will be produced and accelerated per second.

To maintain a sufficient [[Luminosity (scattering theory)|luminosity]] to produce results in a reasonable time frame after acceleration the bunches will be focused to a few [[nanometre|nanometers]] in height and a few hundred nanometers in width.  The focused bunches then will be collided inside one of two large [[particle detector]]s.

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File:A 1.3 GHz nine-cell superconducting radio frequency.JPG|A [[niobium]]-based 1.3&nbsp;GHz nine-cell superconducting radio frequency cavity to be used at the main linac<ref>{{cite book|title=The International Linear Collider Technical Design Report 2013|date=2013|publisher=International Linear Collider|url=http://edmsdirect.desy.de/edmsdirect/file.jsp?edmsid=D00000001021265&fileClass=native|access-date=14 August 2015}}</ref>
File:A 1.3 GHz nine-cell superconducting radio frequency - cross section.JPG|An interior view of the niobium superconducting radio frequency cavity
File:International Linear Collider main linac cryomodule - exterior.jpg|A [[cryomodule]] being tested at [[Fermilab]]
File:International Linear Collider main linac cryomodule - cross section.jpg|Cross section of the cryomodule. A large tube at the center is helium gas return pipe. The closed tube below it is the beam axis.
File:International Linear Collider main linac cryomodule - flange.jpg|A flange of the cryomodule is used to connect instrumentation wires and cables.
</gallery>