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

2. CI SAC, 23-24 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

3. 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

4. CI SAC, 23-24 November 2006 4 Interaction region - Crossing angle choice 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 Very small 0 – 2 mrad Large 14 – 25 mrad Shared magnets => coupled design Separate magnets Incoming and outgoing beams

5. 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

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

7. CI SAC, 23-24 November 2006 7 Contributions to the test facilities : ATF2 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 Beam sizes before and after tuning 1mrad QD0 Rotation J. Jones Relative luminosity vs tuning knob

8. CI SAC, 23-24 November 2006 8 Contributions to the test facilities : ESA 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 vert beam size 83  m for collimator wakefield tests horz beam size 240  m for BPM studies F. Jackson

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

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

11. 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

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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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