26 Feb 2007 R & D Meeting Global Design Effort 1 RTML (2.6.1) and Main Linac Beamline Design (2.7.1) PT SLAC

26 Feb 2007 R & D Meeting Global Design Effort 2 Participants Y. Nosochkov, J.M. Paterson, S. Seletskiy, PT, M. Woodley, F. Zhou SLAC: Non-SLAC: K. Kubo, I. Reichel, D. Schulte, J. Smith, A. Wolski

26 Feb 2007 R & D Meeting Global Design Effort 3 RTML – What we promised for FY07 The FY07 plan presented to ART leadership in April 2006 had the following milestones: –December 2006 Complete static, standalone tuning studies of full RTML Complete RTML chapter of RDR Begin static, integrated RTML + ML tuning studies –March 2007 Complete next iteration RTML lattice based on engineering input Begin dynamic, standalone tuning studies of full RTML Begin detailed studies of RTML component specifications –September 2007 Complete dynamic, standalone tuning studies of full RTML

26 Feb 2007 R & D Meeting Global Design Effort 4 RTML – What we’re promising now The FY07 plan presented to ART leadership in October 2006 assumed the following FY07 progress: –Complete RTML portion of RDR –Begin work on engineered RTML lattice –Perform static, standalone tuning studies Note that this massive descoping was despite receiving basically full funding of from ART. WHAT HAPPENED?

26 Feb 2007 R & D Meeting Global Design Effort 5 What Happened? The RTML efforts for FY07 were redirected into 2 areas which were not anticipated in April of 2006: –Design for support of central injector Wasn’t on the radar in April 2006, no way to anticipate it –Initial cost estimation and cost reduction efforts My mistake – I should have foreseen that this was going to be a MAJOR focus of RTML activity in FY07 and planned accordingly Also, some RTML labor siphoned off into “off the books” editorial work on RDR

26 Feb 2007 R & D Meeting Global Design Effort 6 New RTML Design Why change the design? –Support for central injector –Reduce cost of pre-CI design Fewer magnets Fewer RF stations Fewer access points to surface (“shafts”) Full-power pulsed dump after BC2  1/3 power dump Proved to be a major job –Very little of pre-CI optics is left in the design!

26 Feb 2007 R & D Meeting Global Design Effort 7 New Optics and Layout Note: Vertical curvature of return line suppressed in these images, but it is properly represented in the lattice e+ beamline floor coords (e- lattice is 1.2 km longer)

26 Feb 2007 R & D Meeting Global Design Effort 8 New Optics (2) Bunch length out of DR increased –Was 6 mm RMS before Valencia –Now 9 mm RMS –Saves RF cavities in DR Significant R 56 in DRX arc and turnaround Need new BC configs Generated two –Final length 0.3 mm –Final length 0.2 mm These look pretty good –Voltages –SR emit growth –Energy spread at end BC1 and end BC2 0.2 mm approaching limits of the achievable

26 Feb 2007 R & D Meeting Global Design Effort 9 New Optics (3) Remaining Issues: –Connection to DRX not yet designed Needs to be fully compatible with geometry of e- and e+ injection lines so we can all share one tunnel –Matches around BC2 linac are bad M. Woodley is taking a look –Match into linac probably wrong Just needs to be taken care of –Should redo designs of pulsed extraction lines They were already poor in pre-CI optics –Space charge in return line FNAL group agreed to take a look Hope to also get LBL group involved With all this done, we’d like to do a fresh bottoms-up cost estimate with all new parts counts, magnet families, etc.

26 Feb 2007 R & D Meeting Global Design Effort 10 Plans for EDR RTML costs dominated by CFS and RF systems –Those two items make up ~80% of RTML –Outside of RTML WBS IE, not our problem! Focusing EDR efforts on DRX arc, return line, and BC1 wiggler, especially magnets –Main cost, schedule, and technical risks inside RTML WBS

26 Feb 2007 R & D Meeting Global Design Effort 11 Emittance studies Mainly done with pre-CI optics –Need to migrate everyone to new optics Expect no trouble upstream of BC1 –KM steering + dispersion knobs can correct down to wire scanner resolution Corroborated study –Decoupler right in front of emit wires can correct coupling down to wire scanner resolution Uncorroborated study Expect these results to still hold for post-CI optics –Some simple and uncorroborated studies done to determine this

26 Feb 2007 R & D Meeting Global Design Effort 12 Emittance Studies (2) Recent study found some issues in BC –Emit growth from quad misalignments  2.1 nm even with knobs (90% CL = 4.7 nm) –With cavity pitches added, mean emit growth balloons out to 9.2 nm (90% CL = 17.6 nm) Attempt to repeat this study got much better results –Emit growth from quad misalignments  1.5 nm with knobs (90% CL = 3.3 nm) –With cavity pitches added, mean emit growth goes to 3.9 nm (90% CL = 7.5 nm) Discrepancy not yet understood May be able to further improve even the good results –Not clear what the best tuning signal is, nor is it clear what the best tuning figure of merit is

26 Feb 2007 R & D Meeting Global Design Effort 13 Main Linac Design MDW has Full set of lattices, including –Earth’s curvature and dispersion match –Undulator insertion in electron linac With room for 200 m of undulator –Needed for polarization –Undulator energy makeup But only enough for 100 m of undulator (3 GeV) –Cryo system segmentation All of Peterson’s bells and whistles (as of 31-May-2006) and all the associated aperiodicity of the linac optics and dispersions BUT: –It’s still got the 8-8Q-8 cryomodule configuration

26 Feb 2007 R & D Meeting Global Design Effort 14 Main Linac Design (2) Straightforward to get to 9-8Q-9 –All the matching etc is automated –Just need the time to get back to it for a couple of days –While we’re at it, can do some misc. cleanup of the lattice, improve the dispersion match, etc.

26 Feb 2007 R & D Meeting Global Design Effort 15 Main Linac Design (3) ART funding request specified a lot of emittance studies as part of the package Currently none of these are happening at SLAC –The good news is that is consequently well under budget right now Lots of activity in this area outside of SLAC –Fermilab (K. Ranjan, mat-LIAR and Lucretia; N. Solyak and A. Valishev) –KEK (K. Kubo, SLEPT) –CERN (D. Schulte, PLACET) –LEPP (J. Smith, BMAD / TAO) But he’s writing his thesis right now Should we re-think SLAC’s commitment to this work package? –Economic theory of comparative advantage…

26 Feb 2007 R & D Meeting Global Design Effort 16 Simulation Codes DIMAD –New version with some bugfixes in test –Possibly last ILC-supported version? Lucretia –New release on 13 February Some bugfixes SR integral calculator Improvements in floor coordinates calculation and matched Twiss computation Documentation website now includes links to original Lucretia My Reflection video on YouTube, plus a live version by some garage band

26 Feb 2007 R & D Meeting Global Design Effort 17 Questions / Comments? “What’s the matter with your life? Is the poverty bringing u down? Is the mailman jerking u round? Did he put your million dollar check in someone else’s box?” -Prince, “Pop Life”