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The EIC Machine

The EIC would be the only electron-nucleus collider operating in the world

Collider Components

The Electron-Ion Collider would consist of two intersecting accelerators, one producing an intense beam of electrons, the other a high-energy beam of protons or heavier atomic nuclei, which are steered into head-on collisions. Such a collider will be made up of specialized high-tech hardware including:

Ion Source

One method of generating ions is to trap atoms or ions in an electrically charged chamber inside a cylindrical magnet. The voltage holds the charged ions in the chamber while an electron beam generated at one end passes through, systematically stripping electrons off the trapped atoms. When the desired number of electrons is removed, the voltage is turned off and the ion beam is released from the trap.

Electron Source

Methods for generating electrons take advantage of the photoelectric effect—the tendency of materials to emit electrons when struck by light of an appropriate wavelength. In an electron gun, there’s a cathode and anode. When a voltage is applied to one of them, it sets up an electric field between them. Part of the cathode is coated with a photo-emissive material, so that when a laser is shined on it, electrons are liberated via the photoelectric effect.

Superconducting Magnets

A superconducting accelerator magnet is a complex electromagnetic device in which a powerful magnetic field is generated by running electricity through coils of superconducting wire. These wires are made of a material that can carry electrical current with no energy loss, but to operate they must be chilled to 4 degrees Kelvin, or -452 degrees Fahrenheit—just about as cold as anything can get.

Pre-accelerator(s)

A pre-accelerator provides the initial energy to particles, by having them “surf ride” on the downhill slope of radio frequency electromagnetic waves. The particles are propelled forward at higher and higher speeds, getting closer and closer to the speed of light. The pre-accelerator then feeds the beam into the collider ring for final acceleration before collisions occur.

Two proposed machine designs for an EIC build on existing U.S. accelerator facilities with some of the required elements in place.

EIC design: RHIC

Schematic of proposed EIC at Brookhaven National Laboratory. This design would make use of the existing ion sources, pre-accelerator chain, superconducting magnet ion storage ring, and other infrastructure of the Relativistic Heavy Ion Collider (RHIC). A new electron source and electron accelerator and storage rings would be added inside the RHIC tunnel so that interactions (collisions) can take place at points where the stored ion and electron beams cross (up to three detectors).

EIC design: CEBAF

Schematic of proposed JLab Electron-Ion Collider (JLEIC) at Thomas Jefferson National Accelerator Laboratory. This design would make use of the Continuous Electron Beam Accelerator Facility (CEBAF), which would steer accelerated electrons into two interaction points (IP) of a newly constructed figure-eight shaped ion accelerator, fed by a new ion source and associated pre-accelerator components.

Cutting-edge Expertise

Building the EIC will require the same core expertise that led to the versatility of the polarized proton and heavy ion beams at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory, and the unique polarized electron beam properties of the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson National Accelerator Facility.

These two Department of Energy laboratories have been collaborating on initial studies and developing designs that make use of key existing infrastructure and capitalize on investments in science and technology. Each design approach would require the development of innovative accelerator and detector technologies to answer the questions of greatest interest to the community of EIC physicists.

Inside an EIC Collision

As electrons collide with ions at an EIC, they will scatter off the quarks within the proton or nucleus. Particles ejected from the collision by these scattering interactions strike various components of a detector. Scientists study the patterns and characteristics of the particles produced to tease out the internal structure of the protons and ions, including the distribution of the quarks and gluons. 

electron-ion collision diagram

Key EIC Characteristics

To meet the science goals established for an Electron-Ion Collider, the machine will need:

luminosity icon

A high particle collision rate (called "luminosity") so scientists can collect as much data as possible.

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A large center-of-mass energy range so physicists can take high resolution snapshots of the internal structure of nuclei.

polarized beams icon

Polarized beams of electrons and ions so physicists can alter the alignment to get insight into proton spin and other physics questions.

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A large range of ion species so scientists can explore different structural features that vary with ion size.

detector icon

At least one large-acceptance detector that can capture most of the particles scattering from the collisions in all directions and at wide range of energies.

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Brookhaven National Laboratory advances fundamental research in nuclear and particle physics to gain a deeper understanding of matter, energy, space, and time; applies photon sciences and nanomaterials research to energy challenges of critical importance to the nation; and performs cross-disciplinary research on climate change, sustainable energy, and Earth’s ecosystems.