Damping Rings

The International Linear Collider will have two 6-kilometer circular damping rings to make each bunch of electrons and positrons six millimeters long and thinner than a human hair. In order to achieve the maximum number of collisions inside the machine, the electron and positron beams must be extremely thin and extremely precise, presenting a number of challenges that physicists around the world are collaborating to overcome. Each bunch spends roughly two tenths of a second in the damping ring, circling it 10,000 times before being kicked out. Going around in circles, the positrons emit light. Hitting the interior of the beam pipe, the light sets free electrons—an "electron cloud"—that disturb the positron beam and hinder the physics that the ILC will produce.

Fermilab physicists are contributing to this area of research by developing the necessary computing infrastructure for large-scale, multi-physics simulations of the damping rings. By using advanced computing technology, Fermilab physicists are able to run 3D simulations for both the electron and positron damping rings. Fermilab’s damping rings group is studying potential emittance growth and halo creation for different operational parameters of the baseline design. In addition, they are participating in the effort to develop electron cloud models, including cloud generation and cloud effects on beam dynamics.