The global particle physics community agrees that the discoveries made using the world’s most powerful accelerator, the Large Hadron Collider LHC at the CERN research centre in Geneva, will need to be complemented by an electron-positron accelerator. Thanks to its uniquely precise measurements, such an accelerator would reveal the secrets of the terascale – the energy realm of trillions of electronvolts (teraelectronvolts) in which the physicists expect to make decisive new discoveries – in exquisite detail. The International Linear Collider ILC, in which DESY is strongly involved, is one such future-oriented project: an approximately 35-kilometre-long linear accelerator colliding electrons and positrons at energies of between 500 and 1000 billion electronvolts (gigaelectronvolts, GeV).
The ILC consists of two opposing linear accelerators in which electrons and their antiparticles rush toward one another at close to the speed of light. Superconducting resonators boost the particles to ever-higher energies, until they smash together with great force in the middle of the “racetrack”. The particle beams collide 14 000 times every second at record electron energies of 500 GeV. Each collision produces numerous new particles, which are recorded by two large detectors.
In contrast to proton accelerators such as the LHC in Geneva, in which composite particles collide with one another, the collisions in the ILC will be between point-like electrons and their antiparticles, positrons, which are also point-like. They annihilate each other to become pure energy, from which new particles are created. Although the energies that can be reached in this way are lower than those attained in collisions involving protons, the results are much easier to interpret than the results from the LHC. This is because the initial conditions of the particle production in the ILC are precisely known and no “fragments” of the colliding particles remain. The ILC is thus a genuine precision machine that ideally complements the LHC proton accelerator, whose real job is to produce new particles in the first place.
TESLA accelerator technology
The ILC is to be constructed and operated as a global project. Worldwide, there were several proposals for such a facility, which differed in their choice of accelerator technology. After a thorough assessment, the committee that represents particle physicists worldwide decided that the future linear accelerator will be realized using the superconducting TESLA technology developed by DESY and its international partners.
The same superconducting technology is also employed in the free-electron laser FLASH at DESY and the European XFEL X-ray laser, which is currently under construction in the Hamburg region – an outstanding example of the successful synergies provided by the multiple use of a completely new technology. DESY is thus excellently qualified to continue to play a leading role in the development of superconducting accelerator technology.
In addition, the DESY researchers are involved in the development of further important components for the ILC accelerator – mainly as part of international projects such as the TESLA Technology Collaboration or EU projects. The DESY scientists are also making a major contributions to the design and development of the high-precision detectors that will record the particle collisions in the ILC.
- Electron-positron linear accelerator
- Length: ca. 35 km
- Being planned, location still to be decided
- Two experiments at one collision zone
- Participation: 2000 scientists from more than 25 countries