Evaluation of ground motion generator from SLAC and update of optimised pulse-to-pulse trajectory feedback performance at the ATF2 IP － Yves Renier (LAL)
This is an update of the presentation made in Annecy for the French-Japanese collaboration meeting on ATF2. The ground motion generator developed at LAL has good frequency behavior but underestimates the spatial coherence in comparison with measurements of the ATF floor. Since the stability of the beam at the IP relies to a large extent on coherence, this means that results obtained, both with and without applying pulse-to-pulse feedback, can be expected to be pessimistic. Andrei Seryi and Glen White at SLAC have now made available their ground motion generator. Although overall behavior seems better, more work is needed for a full assessment. With this generator, residual IP movements are small. The feedback uses two BPMs and a vertical corrector near the IP. The controller algorithm used is a standard PID (proportional integrator derivative) with coefficients optimized through Takahashi’s method. In the future, the full lattice from extraction to IP will also be simulated.
Review and discussion of ILC EDR BDS and Beam Dynamics Expressions of Interests --- Philip Bambade (Laboratoire de l''Accelerateur Lineaire (LAL) (IN2P3) (LAL))
LAL activities on ATF2 & ILC - BDS / MDI were discussed to prepare contributions to EDR, including Beam-beam modeling, Beam-induced backgrounds, Evaluation of head-on scheme, Beam phase-space injected into ATF(2) EXT, Pulse-to-pulse feedback at IP in ATF2, Final focusing at ATF2 IP, 2 mrad scheme, e-e- option, IP Compton lumi / polari-meter, BeamCal. The focus of the group for the EDR phase will be on the three ATF2-related tasks and on the beam-beam modeling, for which resources are guaranteed. These will be included in the LAL Expression of Interest (EOI). In addition, the important beam-induced background task may be included too, if additional resources become available (extension of Olivier Dadoun’s contract and participation of a second IN2P3-funded scientist, staff or post-doc). The LAL group also plans to send an EOI to finalize the 2 mrad alternative IR design. Our participation is however conditional on there being other groups with suitable technical competence available to help check the parameters of some of the required magnets (warm Panofsky and SC magnets), and do basic pre-design investigations to assess feasibility and costs.
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