CERN Accelerating science

Particle accelerators and their applications.

The Large Hadron Collider, LHC, located in the Geneva valley.

A Cockcroft-Walton Generator used at CERN as pre-accelerator for the proton beams. The device is meanwhile replaced by the more compact and efficient Radio Frequency Quadrupole (RFQ) technique.

A typical example of a Tandem-van-de-Graff Accelerator. These are very reliable machines for precision measurements in atom and nuclear physics. (Photo: Max Planck Institute for Nuclear Physics, Heidelberg)

Schematic view of the Wiederoe principle as fundamental concept for AC (or "RF") acceleration.

The frequency, and so the period of the RF system, and the particle speed determine the length of the~drift tubes in the structure.

Unilac at GSI, Darmstadt; the structure of the drift tubes and their increasing length as a function of the~particle energy is clearly visible.

Dipole field of a storage ring and the schematic path of the particles.

Superconducting dipole magnets of the LHC.

Super conducting quadrupole of the LHC storage ring.

Schematic layout of a synchrotron.

TSR storage ring, Heidelberg, as a typical example of a separate function strong focusing storage ring.

Coordinate system used in particle beam dynamics. The longitudinal coordinate {\it s} is moving around the~ring with the particle considered.

Field configuration in a quadrupole magnet and the direction of the focusing and defocusing forces in both planes.

Schematic principle of the effect of a focusing quadruole magnet.

Schematic principle of the effect of a de-focusing quadrupole magnet.

Calculated particle trajectory in a simple storage ring.

Horizontal (top) and vertical (bottom) closed orbit oscillations, measured in LHC during the commissioning of the machine.

Tune signal of a proton storage ring (HERA-p).

Many single particle trajectories form in the end a pattern that corresponds to the beam size in the~ring.

Ellipse in x-x' phase space.

Schematic picture of the trajectories in a beam. Small emittance means high quality of the particle ensemble, which in turn means small amplitudes and angles of the trajectories.

The LHC vacuum chamber with the beam screen to shield the super conducting magnet bore from synchrotron radiation.

Schematic view of the wake fields induced due to a sudden change of the vacuum chamber geometry.

Schematics of a moving particle $A$ colliding with a target particle $B$ at rest.

Schematics of the collision of two colliding particle beams with equal energies.

"Typical" event observed in a collider ring: A Higgs particle in the ATLAS detector.

ATLAS detector at LHC: 46 m in length, overall weight 7000 t.

The beam envelope in the neighborhood of a symmetric waist: the smaller the beta function at the~IP, the~faster the beam size is growing.

Cross section of the Higgs for different production processes (court. CMS collaboration).

Schematic view of the beam-beam interaction during the crossing of bunch trains.

Beam-beam force as a function of the transverse distance of the particle to the centre of the opposing bunch.

Calculated tune shift due to the beam-beam interaction in LHC.

Measured horizontal orbit of the LEP electron beam. Due to synchrotron radiation losses the~particle orbit is shifted towards the inner side of the ring in each arc.

Schematic view of a 100 $\! $ km long ring design in the Geneva region for the FCC study.

Proposed location of the CLIC linear collider along the Jura mountain in Geneva region.

Accelerating structure of the CLIC test facility CTF3; on the right side a electron microscope photo shows damage effects on the surface, created due to discharges in the module.

electron beam accelerated in the wake potential of a plasma cell. Up to 4 GeV are obtained within a few cm length only \cite{pwa}.