Presentation on theme: "December 6 2006 Ground Motion Group Global Design Effort 1 LET Status report, December 06 Paul Lebrun Fermilab CD/AMR."— Presentation transcript:
December 6 2006 Ground Motion Group Global Design Effort 1 LET Status report, December 06 Paul Lebrun Fermilab CD/AMR
December 6 2006 Ground Motion Group 2 Status, I Benchmark CHEF/Merlin, Misaligned and Steered Tesla design. –Tracking: Completed, results send to Jeff Smith, month(s) ago. Writing internal FNAL memo.. -DFS Steering: -Coding completed, analysis mostly done. -Documenting. DFS Steering Studies in CHEF On the above Linac, finishing up studies, documenting.
December 6 2006 Ground Motion Group 3 Benchmark, Fixed dipole setting Non trivial emit emittance growth! Ups and down because D taken out.. and coming back.. Agreement not perfect, sensitivity to small local difference in tracking.. Improves if Dispersion if corrected.
December 6 2006 Ground Motion Group 4 Status, I, II : DFS, in depth. DFS Steering Tricky if… Many variants of the basic DFS have been proposed, with not always good agreement between what works and does not work. A lot of dedicated software is needed, to duplicate these algorithms. Tedious to document ( rarely done!) Semi-Qualitative agreement between codes on the performance (Emittance vs S), substantial disagreement on what the “best” solution (dipole corrector settings) really is..
December 6 2006 Ground Motion Group 5 Benchmark, Fixed dipole setting Sorting this out took considerable amount of time…
December 6 2006 Ground Motion Group 6 Status, I, II : DFS, in depth. DFS Steering Tricky, one “root” cause Many perturbations of the orbit occurs with too few “knobs”, or dipole corrector. Cavity tilts: 24 of them per dipole correctors. Individual cavity tilts : ~200 micro-radiants Quadrupole displacements: ~ 350 microns At ~5 GeV, integrated kicks over 2 cryo-modules (24 cav.) delta y’ about the same size as the kick given by the quadrupole..
December 6 2006 Ground Motion Group 7 Kicks, Cavity vs Quadrupole. Plot has been produced, hopefully correctly. No time to included in this talk..
December 6 2006 Ground Motion Group 8 Accurate tracking through Cavities If cavity rotation matter, Shouldn’t be worried about tracking accuracy.. With rotated fields With realistic field map (kick depends on XY) A solution (Lynn Garren): G4 Runge Kutta integration G4/CHEF integration: allows to simulate halo, and interaction of halo with cavities…
December 6 2006 Ground Motion Group 9 Other Actuators In Bunch Compressor and early LINAC, exploring the possibility of tilting either cryo- modules or individual cavities. –Not Baseline ( = Not to be investigated. (?)) –Beam Based Alignments Algorithm for back- tilting do exist, just the right variant of DFS. –Coded in CHEF, running, need to document performance.
December 6 2006 Ground Motion Group 10 Dynamical DFS In CHEF, DFS was re-implemented keeping in mind the need to establish steering while the machine, burping, ( not belching?), creaking and moaning. –Iteration and convergence criteria. –Rudimentary controls ( beam permit dropping when x mm excursion at BPM Pause while we change DFS section. –Crude visualization, analysis code.. ATL Ground Motion integrated. Ready to Crank at bit more jobs.
December 6 2006 Ground Motion Group 11 ILC Main Linac Lattice. In CHEF, –Using corrected sBend/rBend code, got a matched bunch through the LINAC, with fraction of emittance growth. But the Dispersion at injection is close to 0. ? Am I really bending? Need checking. If checks, start DFS steering into it. –Few days of work to check if CHEF/DFS implementation good enough..
December 6 2006 Ground Motion Group 12 Plans, Short term Finishing documenting DFS steering, cavity tilt relevance. Prepare talk for Daresbury meeting. Keep running dynamical steering Dynamical Steering with ILC-ML Lattice, after tuning static tuning.