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ILC Beam Delivery System Layout and Lattice Design

ILC Beam Delivery System Layout and Lattice Design. Deepa Angal-Kalinin ASTeC, Cockcroft Institute. Cockcroft Institute SAC 23-24 th November 2006. Lattice Design and Simulation Team@CI. ASTeC Frank Jackson

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ILC Beam Delivery System Layout and Lattice Design

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  1. ILC Beam Delivery System Layout and Lattice Design Deepa Angal-Kalinin ASTeC, Cockcroft Institute Cockcroft Institute SAC 23-24th November 2006

  2. Lattice Design and Simulation Team@CI ASTeC • Frank Jackson • James Jones • Stephan Tzenov • Deepa Angal-Kalinin Manchester • Rob Appleby • Dragan Toprek • Adina Toader Ph.D. Student • Anthony Scarfe CI SAC, 23-24 November 2006

  3. Background • Before the technology decision for the linear collider (August 2004) – studies were mainly focussed on TESLA design • Problems related to head-on extraction • Poor collimation performance • Local chromaticity final focus system was designed but was not integrated with rest of the BDS • Alternative solutions to head-on : small vertical or small horizontal crossing angle – collaborations with LAL(Orsay), CEA(Saclay) • The team developed understanding of BDS design and requirements, implemented the required simulation codes in order to contribute to the evolving designs, established good collaborations After the technology decision • Small crossing angle solution and extraction line design required urgently • NLC collimation and final focus design was adapted to ILC, performance poor than NLC CI SAC, 23-24 November 2006

  4. Interaction region - Crossing angle choice Very small 0 – 2 mrad Large 14 – 25 mrad Challenges in both the schemes • Large aperture shared magnets or compact magnets • No/ marginal/complete reliance on crab crossing • Axial/Non-axial field in the solenoid • Preserve pre-IP beam or emphasis post-IP beam • Reflected backgrounds or pre-IP constraints Physics prefers head-on with minimum background Incoming and outgoing beams Shared magnets => coupled design Separate magnets CI SAC, 23-24 November 2006

  5. 2mrad crossing angle extraction line design • CI team took a lead role in developing the 2 mrad extraction line design (part of SLAC-BNL-UK-France Task Force) • Due to higher cost of this line and challenges in magnet design, this crossing angle solution is now an alternative to the baseline with 14 mrad • CI team is working with LAL to optimise the extraction line to minimise the beam losses and magnet apertures • The optimised doublet (Appleby, Bambade, Toprek) at 500 GeV CM show significantly less losses in the IR region • Re-designing the rest of the line –minimum line to start with (Appleby) • Comparison of number of hits in VXD for the 2 mrad and 20 mrad (with DID) showed that the pair background increases for 20 mrad with DID => 14 mrad + anti-DID solution, now adapted for the RDR CI SAC, 23-24 November 2006

  6. Contributions to the ILC : collimation optics • Tools to estimate the collimation depths for different crossing angle geometries • Better collimation efficiency Halo Tracking to FD entrance Original Performance Collimation depth Optimisations still continuing F. Jackson New Performance CI SAC, 23-24 November 2006

  7. Contributions to the test facilities : ATF2 Beam sizes before and after tuning 1mrad QD0 Rotation • Tuning procedures and tolerances for the ATF2 • Several generic options for tuning of final-focus beam at IP – Traditional, Rotation Matrix, ‘dumb’ • Would like to test these algorithms at ATF2, which will present an ideal opportunity to provide some limited analysis of the viability of these methods. • Aim to increase our contributions with the help of Ph.D. student Anthony Scarfe • Expertise in tuning area, used to define the correction method in the long undulator section • The techniques developed are applicable to any accelerator Relative luminosity vs tuning knob J. Jones CI SAC, 23-24 November 2006

  8. Contributions to the test facilities : ESA vert beam size 83m for collimator wakefield tests • Optics design for several experiments at ESA, SLAC (January’06 and April’06 beam tests) • Require small beam sizes in x and y planes for collimator wakefield and BPM experiments • Optics modelling challenges: high dispersion and SR in A-line • Careful emittance and Twiss measurements followed by beam tuning • Achieved goals of y100m and x~200m in separate lattice configurations horz beam size 240m for BPM studies F. Jackson CI SAC, 23-24 November 2006

  9. 15 - 20 mrad gg 25 mrad 2 - 7 mrad gg 25 mrad ILC BDS Layout Changes First ILC Workshop, KEK, November 2004 Working hypothesis CI SAC, 23-24 November 2006

  10. ILC BDS Layout Changes to Vancouver, July 2006 Snowmass, August 2005 CI SAC, 23-24 November 2006

  11. ILC BDS Layout Changes At Vancouver (July 2006), first cost estimates indicated significantly higher costs for 2 mrad line => base line configuration changed to 14/14 from 20/2. ILC GDE 14mrad 14mrad CI SAC, 23-24 November 2006

  12. ILC BDS Layout Changes Valencia, November 2006 1 IR; two complementary push-pull detectors discussed with detector concepts and WWS ILC GDE 14 mrad CCR will be submitted this week by the BDS area leaders CI SAC, 23-24 November 2006

  13. Present activities and Objectives • Contributing to several critical decisions on the ILC Interaction Region(s) • The BDS lattice design for the new baseline configuration • Risks vs performance • Push-pull task force • Optimisations and tuning studies • Layout details : CFS (shafts/caverns, IR halls) • Surface assembly for the detectors • Muon walls • Contributing to the RDR costing and writing • Optimisations for 2 mrad and modified head-on extraction line designs : cost effective, with input from magnet designers • studying the minimum layout design for these options without downstream diagnostics CI SAC, 23-24 November 2006

  14. Future Plan : Beam Line Integration • Continue lattice optimisations for better performance, include realistic beam and machine errors • ATF2 skew/emittance LW, final focus, tuning, tail folding tests • Large crossing angle issues • Beam Line Integration :Major involvement of CCLRC’s engineering expertise • Lattice design and simulations • Collimation design • Vacuum design • Other CI major activities viz; crab system and beam dumps integrate naturally with this proposal Depends on the outcome of LC-ABD2 funding request Background & wake fields : main concern CI SAC, 23-24 November 2006

  15. Future Plan : Collimation Design • BDS and extraction lines include ~20 different types of collimators • Most critical ones are with the adjustable gaps <mm and long tapers • CI is a leading contributor (with CCLRC, Birmingham and SLAC) on critical collimator issues: wakefields, survivability • ESA and simulations (C. Beard’s talk) • Future programme builds on this and will prototype ILC collimators for: • optimal mitigation of wakefields and component damage (and its detection); • overall engineering design: tolerances, alignment, movable jaws, cooling, machine protection. Depends on the outcome of LC-ABD2 funding request CI SAC, 23-24 November 2006

  16. Future Plan : Vacuum Design • BDS has complex vacuum design : • Spoilers with fraction of millimetres openings to beam pipe radius of 200mm in the extraction lines • Synchrotron radiation at 250-500 GeV is significant • No experimental photon/electron desorption data exists at such energies • The interaction region geometry is most complex • Backgrounds in the detector are critical • Push-pull detectors will need special engineering solutions • Real vacuum chamber design (material and detailed designs) to estimate the wakes • Manufacturing and alignment tolerances - stringent • MPS issues Depends on the outcome of LC-ABD2 funding request CI SAC, 23-24 November 2006

  17. ILC BDS : Collimation, crab system, beam dumps Layout & lattice design has a close link with the other tasks lead by the CI Collimation : Carl Beard Crab system : Peter McIntosh Beam dumps: Rob Appleby Next two talks ILC GDE CI SAC, 23-24 November 2006

  18. The ILC beam dumps • ILC beam dumps and collimators are challenging - high power (18MW @1TeV CM) and short energy deposition showers • No experience with such beam dumps. Designs have been scaled from low power beam dumps • More simulation and prototypes required • Using CCLRC’s expertise in high power targets (ISIS, T2K), a programme lead by CI (Appleby) and CCLRC (Densham) has been initiated. • Definition of UK beam dumps programme, consisting of physics (CI) and engineering (CCLRC) • UK contribution to dumps and collimator costing • Physics simulation studies CI SAC, 23-24 November 2006

  19. Future plans : Beam Dumps • The CI (Appleby) will lead physics simulation of dumps and collimators throughout the ILC • Energy depositions • Shielding and activation of water dump baseline and collimators • Costing and engineering expertise (CCLRC+CI) • Study of only viable alternative to main dump: the Noble gas dumps (Will seek new funding). Crucial if unknown show-stopper for water dump and alternative needed. • Site dependent Depends on the outcome of LC-ABD2 funding request CI SAC, 23-24 November 2006

  20. Summary The CI team • has developed a skill base for optics and simulations • has made significant contributions to the ILC baseline and is contributing to the Reference Design Report • is very well integrated with the global design effort • intends to take a bigger role during the technical design phase with CCLRC’s engineering expertise Most of the proposed work depends upon the outcome of LC-ABD2 funding proposal submitted to PPARC CI SAC, 23-24 November 2006

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