Introduction D. Schulte for K. Kubo and P. Tenenbaum

Programme Wednesday –Lattice Design –Main Linac Thursday –Beam delivery system –Ring to main linac –RDR preparation Friday –Polarisation –Instrumentation Saturday –Summary

Areas for LET Work Performance predictions (our core work) Lattice design (help area systems) Instrumentation requirements (help technical system) Availability (help global systems) Machine protection issues (help global system) Subjects are linked For now worry about RDR and post RDR –RDR: Studies that affect cost –Post RDR: Worry about performance –Cannot cleanly separate the two –Need to decide on the fly

Lattice Design At Snowmass we agreed on conceptual design Need to define –Which lattices have priority –Who is working on them –Where are additional needs –What do we want to modify with respect to Snowmass

Main Linac Design needs to be agreed on Work for alignment studies is ongoing Results seem to differ somewhat –Need to understand differences Beam-based alignment is crucial –Need to understand details to ensure correctness Curved linac needs verification Tuning bumps seem to be very effective –Needs detailed study and benchmarking Specific questions –Emittance measurement stations in main linac –Instrumentation requirements, e.g. BPMs, wake measurement in cavities –Long list from Main Linac Area Group

Ring to Main Linac Transport Lattice design –Many parts Need to specify diagnostics needs –Detailed understanding of Alignment procedures Tuning procedures Feedback systems –Also will allow performance prediction Integrated studies are important –E.g. interaction of bunch compressor and main linac/BDS

Interaction Region Need to evaluate reference lattices BDS alignment and tuning is crucial –Alignment seems to be less covered than main linac –Will also be relevant for ATF2 –E.g. definition of tuning knobs Need to verify that instrumentation is sufficient Need to study beam-beam tuning/ beam properties reconstruction procedures Need to understand post collision line Feedback is important –Dispersion can create a problem due to energy jitter –Stability requirements, e.g. ground motion needs to be determined

RDR Preparation Many of the things we do will have impact on the cost –Lattice design –Tolerance studies –Instrumentation requirements –Performance studies We need to react to input from area leaders Need to decide on priorities –Understand what people are doing –Try to find volunteers –Make sure that they deliver Start with lattices Need to see how to organise other work

Polarisation Issues Polarisation is important for the electrons and for the positrons as an upgrade Need to ensure that all sub-systems are compatible with polarisation preservation Need to understand generation of polarised positrons (and electrons) Need to improve simulation tools, e.g. only CAIN contains polarisation for beam-beam interaction Need to understand relevance of polarisation measurements (averaged vs correlated effects)

Instrumentation Will be important for all sub-system Need to agree on ways to specify the needs –E.g. BPM resolution, long term stability etc. –Will need studies to determine what is relevant Need studies to determine specification values Direct cost impact Iterative process with instrumentation experts –They will tell us if they can provide us with what we want –And how much it costs –Trade-off cost vs performance

Performance Studies Will last longer than RDR –But parts are need for the RDR Need to develop simulation codes –Benchmarking –Additional effects Need to develop optimisation strategy –Alignment –Tuning –Feedback –Flight simulator –Benchmarking of algorithms Need to understand imperfections/models –Pre-alignment –Ground motion –Instrumentation performance

Conclusion Your accelerator physics working group needs you