Final Focus and Beam-Beam Effects

Strong and Stable Focusing System

After the full acceleration in the main linacs, the final focus system focuses the electron and positron beams down to a nano-meter size and makes them collide stably. This requires strong lenses (focusing magnets) and an active feed-back system to remove their vibrations.

Nano-meter Technology

In order to make nano-meter size beams head-on-collide stably, JLC makes use of nano-meter technology being developed for VLSI fabrication or ultra-high-precision machining.

High Density Beam-Beam Interactions

When ultra-high density electron and positron beams collide, they pinch each other and oscillate due to the strong electromagnetic field produced by the opposing beams. This phenomenon is called beam-beam effects. The high luminosity of JLC requires a careful choice of beam shape parameters, which in turn necessitates detailed computer simulations of the beam-beam effects.

Collision of electron and positron beams (a computer simulation) 1 femto-second =10^-15 seconds.

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