1. Report of 2 nd ILC Workshop (Snowmass) Working Group 1 20050830 Kiyoshi KUBO references: Slides of the plenary talks in the workshop by P.Tenembaum and D.Shulte. Slide of presentations in WG1 sessions.

2. ILC WG1 Job of WG1 (not really given, defined by ourselves) Emittance preservation from DR exit to IP –Studying entire region’s design, tunability and stabilization –Ensuring that instrumentation and controls necessary to achieve design luminosity are included in design Working Group Co-Convenors Peter Tenenbaum (SLAC) Daniel Schulte (CERN) Kiyoshi Kubo (KEK)

3. from here to the beam dump Damping ring - Diagnostics -Turnaround - Spin rotator - Diagnostics - Collimation - Bunch compressor - Diagnostics - Main Linac (Diagnostics in the middle?) - Diagnostics - Collimation - Final Focus - IP to beam dump (diagnostics) - Extraction for Machine protection Low Emittance Transport Dump IP

4. Plan for the 2 Weeks Week 1: Mostly presentations –Up-to-date picture of studies performed so far –Figure out what’s not known and needed for recommendations Week 2: More interactive –Performing and discussing studies –Preparing recommendations –Making the plan for the next 16 months

5. Week 1 Tue.Wed.Th. 08:30 – 09:00 Bunch Compressors Plenary Linac Dynamics 09:00 – 09:30 Chair: KuboWith WG2 10:00 – 10:30 Bunch Comp (ctd)CM Vibration w/WG2 Linac Dynamics 10:30 – 11:00 (Conf Ctr/Hoagland)With WG2 (ctd) 11:00 – 11:30 RF Stability w/WG2IntegratedChair: Schulte 11:30 – 12:00 Simulations(Conf Ctr/Hoagland) 13:30 – 14:00 Overall LayoutIntegratedLinac Module w/ WG2 14:00 – 14:30 Chair: SchulteSimulations (ctd)(Conf Ctr/Hoagland) 14:30 – 15:00 Survey/AlignmentChair: KuboGM + BDS w/WG4 (Conf Ctr/Erickson) 15:00 – 15:30 Chair: PT(Layout in coffee break) Chair: PT

6. Week 2 Mon.Tue.Wed.Th. Making “input” from WG1 for “Decision items” PlenarySimulation codes Plenary Plans of designing LET beam line. Future plans of LET simulations Communication (web, e-mail, meeting) Week-1 Participants: 20~25, from Asia ~2, from Japan ~1 Week-2 Participants: 10~15, from Asia ~ 2, from Japan ~1.3 Presentations (week-1): ~20, from Asia 4, from Japan 3.

7. Recommendation of a Bunch Compressor configuration –Recommend 2-stage design. Recommendation of a main linac configuration (with WG2, WG5, and GG4) –quad spacing: about 24 cavities/quad or less. –quads in RF cryomodules or separate ones: Independent movement is recommended. –straight, bent, or curved tunnel: Curved beam line will be fine, but straight has least risk. –Cavity Shape: Need to evaluate long-range wake. What had been planned, and results. (1)

8. Agreement on beam parameters for LET and IP (with GG1) –Agree to work on the suggested parameter range. Development of some “nuts and bolts” standards –deck formats, benchmarking of codes and repository.: Done. –Format of MAD and SAD (at least) should be prepared. –Benchmarking of many codes. –Web page: http://www-project.slac.stanford.edu/ilc/acceldev/LET/ for the moment. Review assumptions in several areas –Wakefield models: Exist for TESLA cavity. Need to evaluate for others. –Ground motion models: Use “model A, B, C and K”. –RF stability: Agree with WG2, amplitude ~ 0.1%, phase ~0.05deg (?). –Fast MPS [“Hazard Avoidance Logic (HAL)”]: Need more study. –Instrumentation performance: ?No time? What had been planned, and results. (2)

9. Review progress on full-system static + dynamic simulations. –Main Linac: most progressed, but still need more study. –Bunch Compressor and BDS: just started (?) Plan for delivering specifications to costing/engineering groups Agreement on a plan and schedule until end 2006 –Done, but concrete plans are mostly for 2005 (for BCD) as follow. Make baseline optics design of Bunch Compressor (BC), Main Linac (ML) (and Beam Delivery System (BDS) by WG4). Make baseline LET layout. Construct static tuning in BC, ML and BSD. Estimate hardware spec in BC, ML and BDS. etc.. What had been planned, and results. (3)

10. Input of WG1 for the decision items (1) (Not planned before Wed. Week-1) Parameter –Do not know if we can meet luminosity target in a realistic environnement. Studies are ongoing. Energy Upgrade Path –Bunch compressor must be immediately before main linac –Prefer linac in first part of tunnel Vertical curvature or laser straight –Can follow curvature of the earth –But prefer not to if comparable price (Laser straight has least risk.) Positron source –Undulator affects primary beam. Would like to understand its impact. Cavity shape –Long-range wakefield effects need to be studied

11. Input of WG1 for decisions (2) Ground motion –Should be added as critical choice since it can have significant impact on performance or cost Bunch compressor layout –Need 2-stage for 0.15 mm. Prefer 2-stage even if 6  0.3 mm. Turn-around after DR –Strongly recommended, for feed-forward Bypass for low energy operation –Seems not necessary from beam dynamics (continue to study). Position quadrupole in module –Separation of RF and quadrupoles seems useful –Possible reduction in quad vibration –Simplifies use of HOM BPMs and movers on cryomodules if we do.

12. SUMMARY We agreed on the plans of WG1 (Low emittance transport – Beam dynamics) for BCD, in 2005. We agreed on the rough plans of 2006 We made “input” from WG1 for the suggested “decision items”. For details, see: http://alcpg2005.colorado.edu:8080/alcpg2005/program/accelerator/WG1 http://www-project.slac.stanford.edu/ilc/acceldev/LET/