No. 34 (2004): Beam-beam interactions

Issue Editor: D. Rice, Editor-in-Chief: W. Chou

The recent decision and widespread endorsement of the Linear Collider ITRP is a vitally important milestone in accelerator development, not only in paving the way for the next stages of R&D work, but also as an indicator of the level of interlaboratory and international cooperation. Included in this newsletter are comments from ICFA BDP Chair Weiren Chou (above), ILCSC Chair Maury Tigner, the Executive summary of the ITRP, and links to more detailed information.

This issue of the ICFA Beam Dynamics Newsletter also has a special section on beam-beam interactions. Throughout the history of colliding beam machines the beam- beam interaction has been one of the most critical phenomena in determining machine performance, yet at the same time one of the least understood.

Advances in computing power and program algorithms have played a large role in our increased understanding of the results of the beam-beam interaction. The simulations are supported by improvements in analytical treatment, both by providing a physical explanation for tracking and measurement results, and by making the tracking algorithms faster and more realistic.

Several machines now operate with significant parasitic crossings - from two to 89. These parasitic crossings can easily limit performance, as has been found in CESR and the Tevetron (see paper by T. Sen). Some machines operate with strong sextupoles and wigglers, adding more lattice nonlinearities to be considered. Including these effects in tracking codes pushes again the need for faster and/or parallel machines (see paper by J. Qiang).

I would like to thank the authors for their excellent work in research and preparation of the papers included in this newsletter.

Following the beam-beam papers are reports from the Workshop on the Physics of Seeded FEL’s, the Workshop on XFEL Short Bunch Measurements and Timing, and a status report from the Working Group on Remote Experiments in Accelerator Physics.