1. Collimation in the ILC BDS Carl Beard ASTeC Daresbury Laboratory People Requirement Recent Successes Future Aims

2. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 People Task Leader – Nigel Watson (Bham) Damage Studies L. Fernandez (ASTeC), A.Bungau (Manc) R. Barlow (Manc) G. Elwood (RAL), J. Greenhaulgh (RAL). Wakefield Simulation and TDR C. Beard (ASTeC), J. Smith (Lanc), R. Jones (Manc), R.Carter (Lanc), S Jamison (ASTeC), P Corlett (ASTeC)… I. Zagorodnov (DESY), M.Kärkkäinen, W.Müller, T.Weiland (TEMF) Beam Tests (T-480 Experiment) Frank Jackson…plus most of the above SLAC ESA Team – Steven Malloy, Mike Woods…

3. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Need for Collimation Reduce the background levels in the detector, by removing halo particles built up over the long linac. Machine Protection, in the event of a beam miss-steer. Collimators are introduced, as a result of this the change in impedance has detrimental effects to the beam quality. The collimators have to be robust to withstand the full impact of several ILC Bunches. Design / optimisation of spoiler jaws (geometry and materials) for wakefield and beam damage performance

4. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Development of Advanced EM modelling methods Benchmarking of wakefield calculations against experiments SLAC ESA beam test / data analysis RF bench tests (training/code comparisons) Tracking simulations with best models of wakefields Simulations of beam damage to spoilers Material studies using beam test Submitted 7 papers at EPAC, several EUROTeV reports/memos Objectives

5. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Collimator Parameter and Beam Parameters Beam Energy, GeV250, 500 MaterialCu, Ti, C Penetration (mm)2 to 10 e- Particles/bunch2 x 10 10 Copper Fracture temperature ~200 °C (473 K) Melting temperature 1085 °C (1357.77 K)

6. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Collimator Proposals 0.3 Xo of Ti alloy each side, central graphite part (blue). 0.6 Xo of Ti alloy leading taper (gold), graphite (blue), 1 mm thick layer of Ti alloy Ti/C 2 mm, 10mm 250, 500 GeV e-

7. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Cu+Graphite spoiler T [K]; 250 GeV e - T [K]; 500 GeV e - 2 mm from top 465 K860 K 10 mm from top 440 K870 K Difference-5%1% Fracture temp. Melting temp. Carbon zonesCu zones 500 GeV: σx = 79.5 µm, σy= 6.36 µm 250 GeV: σx = 111 µm, σy= 9 µm

8. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Ti / Graphite Spoiler Tmax = 575 K per a bunch of 2E10 e- at 500 GeV σ x = 79.5 µm, σ y = 6.36 µm 270 K 405 K 540 K 2 mm deep from top Ti alloy and graphite spoiler 400 K Temperature data in the left only valid the Ti-alloy material. Top increase of temp. in the graphite ~400 K. Dash box: graphite region. [L.Fernandez, ASTeC]

9. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Fluka Benchmark Measurements courtesy of SLAC, Marc Ross et al. Fluka Prediction of beam Damage (Evaporated material not considered Measurements of Beam damage crater in cooper on the FFTB.

10. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Damage Studies Beam tests are being planned to benchmark the Fluka/Geant Simulations No electron beam is available with sufficient intensity Or probability to hit the same point due to beam jitter. Dynamic Simulations in ANSYS are being studied in support of the FLUKA/GEANT Simulations

11. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Wakefield Analysis Analytical Formula SimulationBench Tests (TDR) Tests with Beam Instant solution for only simple geometry Real life measurements, slow turnaround time for measurements Good indicator – poor resolution Fast Results – Limited by Resolution/ confidence

12. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Simulation and Wire tests Current TDR and TDT measurements are limited to 10 ps Pulse lengths. TDR and TDT are being used to measure the Impedance of a vessel and its loss factor

13. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Achieving a 1 ps Pulse (In development)

14. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 MAFIA Simulations

15. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Limitations / Advances Limiting the simulations to short structures or only sufficient resolution for >>300 um bunch length. A new technique is being applied to allow full structures to be simulated with substantially higher resolution MAFIA/HFSS GDFIDL / ECHO 2 &3D

16. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Beam Tests in ESA Simple Shapes to allow benchmarking with Calculations/Code Geometric Wakefields Resistive Wall Wakefields Surface Roughness

17. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 T-480 Experiment Vertical mover BPM 2 doublets ~40m BPM Two triplets ~16m Wakefields measured in running machines: move beam towards fixed collimators Problem Beam movement oscillations Hard to separate wakefield effect Solution Beam fixed, move collimators around beam Measure deflection from wakefields vs. beam-collimator separation Many ideas for collimator design to test…

18. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 T-480 Experiment Vertical mover BPM 2 doublets ~40m BPM Two triplets ~16m Wakefields measured in running machines: move beam towards fixed collimators Problem Beam movement oscillations Hard to separate wakefield effect Solution Beam fixed, move collimators around beam Measure deflection from wakefields vs. beam-collimator separation Many ideas for collimator design to test…

19. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Wakefield Box ESA z ~ 300 m – ILC nominal y ~ 100 m (Frank/Deepa design) Magnet mover, y range = mm, precision = 1 m 1500mm E beam =28.5GeV

20. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Initial Comparison of Results Analytical: 0.562 V/pC/mm MAFIA: 0.408 V/pC/mm Beam Test 0.556 V/pC/mm

21. Carl Beard – Cockcroft SAC Meeting 23 rd – 24 th November 2006 Future Work Continue study into beam damage/materials In the process of designing a 4th beam test Collimators designed and built in EU, to be installed at SLAC ESA. 3 rd Physics run Mar/April 2007 Application of the Moving Mesh Technique TDR Measurements with Optically generated 1 ps Pulse. Combine information on geometry, material, construction, to find acceptable baseline design regarding all of Wakefield optimisation Collimation efficiency Damage mitigation