Bunch Compressor and Linac Design Linac Design Whatever

Bunch Compressor and Linac Design (Linac Design? Whatever!) SLAC R & D Status Meeting 10 -April-2006 P. Tenenbaum, SLAC 1

RTML Personalities since 2005 Mike Church, Eun-San Kim, Sergei Nagaitsev, Kellen Petersen, Tor Raubenheimer, Peter Schmid, Sergei Seletskiy, Jeff Smith, PT, Andy Wolski, Mark Woodley, Jiajun Xu Special thanks to: Karl Bane, Paul Emma, Igor Zagorodnov 10 -April-2006 P. Tenenbaum, SLAC 2

RTML Requirements • • • Collimate DR halo in 6 DOF Correct DR extraction jitter via feed-forward Rotate polarization to arbitrary direction Compress bunch length to value required at IP Provide beam extraction points for tuneup or response to MPS fault • Provide MPS and PPS Segmentation prior to linac • Provide adequate diagnostic and correction capacity do perform all of these tasks to required specifications while limiting transverse emittance growth to tolerable levels 10 -April-2006 P. Tenenbaum, SLAC 3

RTML Optics Not final optics – new and improved BC 2 wiggler needs to be integrated (today or tomorrow) 10 -April-2006 P. Tenenbaum, SLAC 4

RTML Footprint 10 -April-2006 P. Tenenbaum, SLAC 5

Technical Information • Building a small nest of web pages on the ILC wiki: http: //www. linearcollider. org/wiki/doku. php? id=rdr: rdr_as: rtml_home • What’s there now: – Lattice files • not final versions • RTML matched into beta/alpha functions of BCD linac – 1 quad / 4 CM – CFS page • Spreadsheet with component locations • With final design in hand, other TS/GS pages will be populated ASAP • ILC DCB review of RTML on 25 April 10 -April-2006 P. Tenenbaum, SLAC 6

RTML Emittance Preservation • First explorations going on now • No results to report just yet 10 -April-2006 P. Tenenbaum, SLAC 7

Main Linac Design and Emittance Preservation: Participants Linda Hendrickson, Frank Jackson, J. K. Jones, Roger Jones, Kiyoshi Kubo, Kirti Ranjan, Daniel Schulte, Jeff Smith, Nikolay Solyak, Nick Walker, PT, Glen White, Andy Wolski, plus several Euro. Te. V post-docs Disclaimer: I am only peripherally involved in this effort at this time, and don’t necessarily have the most up-to-date information on everything going on around the world. 10 -April-2006 P. Tenenbaum, SLAC 8

Main Linac Design • Baseline main linac design: – 8 cavities per CM – 1 quad / 4 CM • Quad at center of its CM • 75°/60° phase advance per cell – Vertical curvature follows gravity • 6370 km radius of “cueball Earth”, per Halliday and Resnick – Breaks in the lattice periodicity • Extra 2 m drift every 12 CMs • Additional extra drift every 48 CMs 10 -April-2006 P. Tenenbaum, SLAC 9

Main Linac Curvature • From the beam dynamics POV, this is the major new feature of the ILC • Strong desire to get an early start studying this using a common lattice • At the Feb 06 LET meeting we assembled an approximately correct curved lattice http: //www-project. slac. stanford. edu/ilc/acceldev/LET/ilc_linac. xsif – Doesn’t have the breaks in the CM spacing symmetry – Uses XSIF “GKICK” to represent changes in the survey axis • Not supported in MAD-8 10 -April-2006 P. Tenenbaum, SLAC 10

Main Linac Curvature (2) • Several studies of emittance preservation in curved main linac ongoing – Mainly involve DFS – Many variations • Vary only the linac energy gain, or energy gain and injection energy? • Vary the energy gain for the entire linac, or only part of it? • Studies of sensitivity to BPM offsets, resolutions, scale factors, quad errors, cavity/CM misalignments… 10 -April-2006 P. Tenenbaum, SLAC 11

Projected and Normal Mode Emittance – Perfect Linac Courtesy K. Ranjan, FNAL 10 -April-2006 P. Tenenbaum, SLAC Courtesy K. Kubo, KEK 12

DFS / DMS Studies Courtesy K. Kubo, KEK Courtesy K. Ranjan, FNAL 10 -April-2006 P. Tenenbaum, SLAC 13

Why are the Results so Good? • Nominal parameters: projected emittance always dominated by normal-mode vertical emittance – Dispersion from Earth’s curvature small – Energy spread from 2 -stage compressor relatively small • For other configurations, things will be much harder – 150 um bunch length: • Can anticipate 4 x as much emittance growth – 9 mm DR bunch length: • Can anticipate 2 x as much emittance growth – Additional techniques and bumps will be necessary 10 -April-2006 P. Tenenbaum, SLAC 14