Participants: M. Aiba, C. Collette, R. Corsini, B. Dalena, K. Elsener, M. Jonker, R. Mutzner, G. Rumolo, J. Pfingstner, D. Schulte, J. Snuverink, G. Sterbini, F. Stulle, R. Tomas, A. Vivoli
via WebEx: P. Burrows, J. Jones, A. Latina, E. Marin, S. Molloy, J. Resta Lopez, A. Toader
J.R.L. reported on studies of an intra-train feedback at the IP and orbit correction in the BDS. He compared simulations for different sample sites with different ground motion spectra. Both systems are required to achieve high luminosities. The performances of the orbit correction in the simulations is not yet satisfactory. The SVD algorithms needs further improvements, e.g. eigenvalues are not yet filtered. D.S. and R.T discussed the importance of DFS to reduce dispersion induced beam position jitter. J.P. asked about the importance of non-linear signals. D.S. answered the impact should be minor.
B.D. showed results of tracking simulations utilizing DFS for orbit correction in the BDS. They are very promising and a lot better than obtained by 1-to-1 steering. She asked to fix the matching section between main linac and BDS. D.S. agreed.
R.T. discussed tuning issues in the final focus system. The major problem is that the luminosity will not be sufficiently well measured. Hence, a prior the influence of the tuning would have to be known. K.E. said bremsstrahlung photons or incoherent pairs might be useful. D.S. pointed out that there would either be too much background at good luminosity or too low signal a low luminosity.
D.S. commented on IP feedback and feedforward issues. A concept has been proposed and studied. Further work is need before a full simulation can be performed. K.E. asked if this scheme foresees more equipment inside the detectors. D.S. answered that like in previous plans only ground motion sensors will be included there.
R.M. showed results of BDS simulations including resistive wall wake fields. He compared copper and stainless steel chambers for different apertures. Some improvements are still required, e.g. better wake field formulas in the collimators, before conclusions can be drawn.
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