Summary:

1) Beam-Beam Imperfections vs. Instability and Luminosity Loss vs. Optimization -- Juhao Wu

Juhao presented an analytic analysis of luminosity loss as a function of

• bunch-bunch offset
• bunch-bunch angle
• sine-like bunch structure (modulation) within the bunches (i.e. wake induced banana effects)

due to the beam-beam interaction. The solutions were expressed as series approximations to the integral solutions of the equations of motion in both a perturbative limit and a asymptotic limit.

He compared the solutions with Guinea Pig simulations as a function of the independent variable, one at a time and mixed together, for various strengths of the beam-beam interaction, as specified by the disruption parameter D_y.  In general agreement with simulation was good.

2) ILC BSY Tune Up Dump Issues -- Mark Woodley

Mark review the 2003 NLC Tune Up dump / Beam Switchyard solutions that he developed for NLC and that Brett Parker developed for the US Cold design. and tried to construct a hybrid solution for the NLC.  Realistic magnets based on the SLC Single Beam Dumpers and on Brett's designs still lead to incompatibilities that will not be resolved in time for next week's PAC'05 conference.  The high +/- 20% bandwidth specification as well and how best to incorporate fast beam energy diagnostics were notable items of discussion by the group.

Tom Markiewicz, for Andrei Seryi, 05/03/05