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Update on the LHC collimation system design : status, deadlines and next steps

Update on the LHC collimation system design : status, deadlines and next steps. R. Assmann AB/ABP. Status. OCT02. Start of project. Phase 2 R&D design, production. Definition of phased approach Collimator specifications for phase 1. JUL03. System layout (optics, energy deposition, …).

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Update on the LHC collimation system design : status, deadlines and next steps

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  1. Update on the LHC collimation system design : status, deadlines and next steps R. Assmann AB/ABP

  2. Status OCT02 Start of project Phase 2 R&D design, production Definition of phased approach Collimator specifications for phase 1 JUL03 System layout(optics, energy deposition, …) Radiation, collimator shielding Collimator mechanical design Motors, control electronics Budget Prototyping, verification with SPS test MAY-OCT04 2005-2006 Series production 2006-2007 Installation, commissioning

  3. Project steering E. Chiaveri Collimation project Leader: R. Assmann Project engineer: O. Aberle Organization, schedule, budget, milestones, progress monitoring, design decisions AB division (S. Myers, LTC) LHC project (L. Evans) report to Resources/planning R. Assmann, E. Chiaveri, M. Mayer, J.P. Riunaud Supply & ordering O. Aberle, A. Bertarelli Beam aspects R. Assmann, LCWG System design, optics, efficiency, impedance (calculation, measure-ment), beam impact, tolerances, diffusion, beam loss, beam tests, beam commissioning, functional specification (8/03), operational scenarios, support of operation Energy deposition, radiation A. Ferrari (collimator design, ions) J.B Jeanneret (BLM’s, tuning)M. Brugger (radiation impact) FLUKA, Mars studies for energy deposition around the rings. Activation and handling requirements. Collimator engineering & HW support O. Aberle Sen. advice: P. Sievers Conceptual collimator de-sign, ANSYS studies, hardware commissioning, support for beam tests, series production, installation, maintenance/repair, electronics&local control, phase 2 collimator R&D Mechanical eng-ineering (EST) Coord.: M. Mayer Engin.: A. Bertarelli Sen. designer: R. Perret Technical specification, space budget and mecha-nical integration, thermo-mechanical calculations and tests, collimator mechanical design, prototype testing, prototype production, drawings for series production. Machine Protection R. Schmidt Vacuum M. Jimenez Beam instrum. B. Dehning Dump/kickers B. Goddard Integration into operation M. Lamont Local feedback J. Wenninger Controls AB/CO Electronics/radiation T. Wijnands rearranged Aug03

  4. System layout • Space requirements 1.2 m per primary collimator (was 0.4m) 4.0 m per secondary collimator (was 0.7m) • Optics that provides required space optimizes inefficiency minimizes impedance provides basis for LHC layout IR3/7 • Energy deposition for new optics detailed geometry including collimators different shielding options • Final layout with required absorbers with required shielding (cooled?) with required handling OCT03 JAN04 FEB04 Schedule as presented 12/02 and 6/03. Discussed and agreed with C. Hauviller et al again in 10/03 (some installation of services had started in IR3/7).

  5. Remark on space coverage Available space between doglegs in V6.4: 340.9 m Required for secondary collimators: 128.0 m(16 times 4 m times 2 beams)(beam1 and beam2 collimators at different locations) Space taken by collimators: ~ 40 % (~15% for phase 1 collimation) (keep this in mind when talking about “local collimator shielding”)

  6. Basic optics choices IR7 • Standard solution with special phase advances(DJ optimized, J.B. Jeanneret and D. Kaltchev) • Solution with 90 degree FODO • Relax phase advance conditions • Match regular (close to 90 degree) lattice • Move collimators towards equal beta to minimize impedance • June03: Approach works for generic lattice (RA/VK), good efficiency (twice better), low impedance (2-3 times better) • Something in between Optics work done in ABP optics team, matching work done by D. Kaltchev, TRIUMF. Coordinated in collimation WG.

  7. Cleaning efficiency: Full system RA/VK 7/7/03 At 10 s: 3.49·10-4 (full C, V6.2) → 1.66·10-4 (full C, 90)

  8. Real LHC solutions IR7 MADX #TCS Lmin(TCS) Beam1/2 Inefficiency Impedance Option 0 standard6.4 16 0.7 m yes/yes 3.5e-4 10.2 Option 1 6.4new 16 4.0 m yes/yes 5.2e-4 9.3 Option 2 64imp12 12 4.0 m yes/no 12.3e-4 4.3 Option 3 regular 16 4.0 m yes/yes 9.7e-42.8 Option 4 IR7warmQ6 16 4.0 m yes/no 11.9e-4 ? VERY PRELIMINARY RESULTS – STUDIES ONGOING… Impressions: We cannot get close to 1.7e-4 inefficiency, even with 16 secondary collimators! Clear trade-off inefficiency – impedance! Optics “6.4new” has smallest changes to V6.4 optics.

  9. How to decide? Phased approach: Phase 1: Maximum robustness at impedance limit with good efficiency. Phase 2: Same optics as phase 1 but fix impedance problem with hybrid collimators. IMPORTANT: Optics choice fixes best achievable inefficiency (forever?). Criteria for decision: • Solution should provide best inefficiency! • Fix impedance with hybrid secondary collimators. • Phase 2 collimation remains indispensable (after 1 year)! Supported by results from ABP collective effects team: Possible gain in impedance not sufficient to rely only on phase 1 collimation!

  10. Margin in inefficiency Cleaning inefficiency is the most important performance measure of the cleaning system: Required: 10e-4 Best IR7 optics: 5e-4 Uncertainty in inefficiency: up to factor 3 higher Effects of imperfections: loose factor 1.5-3.0 THERE IS NO MARGIN! (Gain with tertiary collimators factor 2-10?) More detailed studies in ABP with new fellow and new PhD student: More realistic tracking with all errors an imperfections. Beam-based tuning of collimator settings.

  11. Phase 1: Used for early physics as a 3-stage system Phase 1 (early physics): Operating at impedance limit with high robustness (7/10.5/13.5s). Relaxed tolerances: mechanical and for orbit/beta beat, good efficiency. Triplet protection and local cleaning at triplets.

  12. Present conclusion for IR7 • Not enough space in IR7 to make 90 degree lattice work (with cold Q6). • Warm Q6 does not help either (a little bit puzzling)!? • Achievable best efficiency (with V6.4 modified) is already at limit with 16 secondary collimators. • Reduced number of collimators (as foreseen) will cost a little more in efficiency. • Impedance is not reduced by this optics! • Phase 2 collimation is indispensable (after 1 year?)!

  13. Other collimator regions IR3: New optics should be re-matched without problem (no re-design, just make space). TCSH: Included into IR3/IR7 design. TCSP: Short objects, not yet included in IR3, IR7 design (should be no problem). TCT: Start engineering change requests soon (agreed with LHC installation). TCLI: Space as reserved in layouts has not been respected. Can we live without them? TCLP: In layout. No change expected. Integration problem with TOTEM (phasing).

  14. Status OCT02 Start of project Phase 2 R&D design, production Definition of phased approach Collimator specifications for phase 1 JUL03 System layout(optics, energy deposition, …) Radiation, collimator shielding Collimator mechanical design Motors, control electronics Budget Prototyping, verification with SPS test MAY-OCT04 2005-2006 Series production 2006-2007 Installation, commissioning

  15. Material choice First action after approval of phased approach with first phase graphite collimators: Ordering of jaw material (graphite C, fiber-reinforced graphite CC). Companies: STEINEMANN Carbon AG (DE), SNECMA Propulsion Solide (FR), POCO Graphite (US), Tatsuno Company Limited (JP), SGL Carbon AG (CH), ERODEX LTD (UK/US) Delivery delays: 3-7 months promised Sufficient material now at CERN for material studies, clamping test, early prototyping, … Best electrical resistivity: 7 mW/m with CC (O. Aberle)(twice better than assumed  gain ~ 25% in impedance) Material of choice: Low resistivity fiber-reinforced graphite Ordering 9 jaws now for SPS test (min. 3 required) from 3 different companies…

  16. Mechanical collimator design Effort led by strong EST team: A. Bertarelli, M. Mayer, R.Perret, … assisted by AB/AT: O. Aberle, R. Assmann, P. Sievers, …  Collimator design meeting (organized by M. Mayer) Some dates: Dec03 Test of clamping for graphite on metallic cooling support May04 Prototypes of secondary collimator ready Aug04 Installation into SPS Dec04 Drawings for series production

  17. Status of mechanical design A flexible design for all secondary (and primary) collimators has been developed with… • IR3/IR7 space constraints (small inter beam distance) • required cooling for graphite jaw • required impedance measures (tapering, RF contacts) • required mechanical precision movements • no local shielding • LEP type motors close to the jaws Design is being verified with ANSYS calculations and experimental tests (clamping & cooling Dec03). First full prototype in May 2004.

  18. Risks • Clamping technique cannot be used  adopt state-of-the-art technique as used for example for ITER (2-3MCHF + 2years). • Heating of metallic collimator parts (cooling everywhere?) • The need for shielding may require different collimator design (see SNS). • Major design changes if motors must be put outside of shielding or far away from jaws (LEP motors require yearly human maintenance). • … • Simple and fast collimator design is being pursued and will ensure to provide prototypes for SPS test. However, we realize that boundary conditions are very difficult. Accept risks in order to ensure that LHC collimators are ready in time for phase 1.

  19. Advanced solutions Consumable NLC design (courtesy J. Frisch) High robustness Liquid metal recoatable NLC colli-mator (courtesy J. Frisch) Low radiation SNS design (courtesy G. Murdoch) Bent crystral collimator(courtesy V.M. Biryukov et al)

  20. Design of other collimators TCS Being worked out. TCP Short version of TCS. TCSP Short version of TCS? TCT Special design, specific to IR’s. TCLI Special design. TCLP Use TCS basic design with Cu jaw? TCSH Advanced design done with SLAC? Lot’s of work still ahead…

  21. Status OCT02 Start of project Phase 2 R&D design, production Definition of phased approach Collimator specifications for phase 1 JUL03 System layout(optics, energy deposition, …) Radiation, collimator shielding Collimator mechanical design Motors, control electronics Budget Prototyping, verification with SPS test MAY-OCT04 2005-2006 Series production 2006-2007 Installation, commissioning

  22. Motors, electronics, control Responsibility of AB/ATB with support from AB/CO. We must realize: <10 micron step size ~15 micron reproducibility of settings 35 mm maximum travel Initially: ~300-400 motors Maximum: ~600 motors BIG SYSTEM: RELIABILITY IS CRUCIAL! Difficult access to motors: High radiation close to jaw… Inside shielding? LEP motors might not be adequate: Yearly human maintenance!? AB/ATB effort will be starting to review possible solutions. AB/CO will provide interface to control system (SPS test).

  23. Status OCT02 Start of project Phase 2 R&D design, production Definition of phased approach Collimator specifications for phase 1 JUL03 System layout(optics, energy deposition, …) Radiation, collimator shielding Collimator mechanical design Motors, control electronics Budget Prototyping, verification with SPS test MAY-OCT04 2005-2006 Series production 2006-2007 Installation, commissioning

  24. Radiation & collimator shielding Radiation a concern from the start onwards: Work in CWG with M. Brugger / S. Roesler Phased approach relies on the possibility to install collimators after one year of running. This was verified without shielding: Intense tracking campaign with graphite collimators (M. Brugger). Recent news: Shielding at collimators is required!

  25. Dose rate for a carbon collimator - One day of cooling All results are shown in mSv/h. Collimator Pipe Shield Tunnel without shield Tunnel with shield M. Brugger, S. Roesler 1h40m intervention to change a carbon collimator (1 day cooling): Primary collimator 0.7 mSv (unshielded) 10 mSv (shielded) Secondary coll. 0.07 mSv (unshielded) 1 mSv (shielded) We do not want shielding at the collimators, if at all possible!

  26. The shielding problem in IR7 Goal: Reduce environmental impact from collimators by factor 12. 20cm full shielding: gives factor 3-4 Complete shielding: gives factor 12 Complete shielding is one attractive option!? Problems: - Very restricted space. - Increase dose rate per human intervention by factor 15. - Collimators cover up to 40% of longitudinal space (local shielding is important). Studies are ongoing. Still various lines of attack!?

  27. The loss in IR7 (critical) Memo S. Roesler to R. Assmann (23.10.2003): Environmental studies: 5e16 p/year Induced radioactivity, etc: 2e16 p/year Assumed scenarios (I take nominal, they use ultimate): Scenario Filled in 180days Fraction lost in IR7* one 20h fill/day 6e16 p/year 83% two 8h fills/day 12e16 p/year 42% *Assume all losses in betatron cleaning. Gain a factor 2-4 on these assumptions? Factor 12 seems hard for nominal running (would require IR7 losses < 3-7% at 7 TeV)? However, losses at 7TeV are most important, … Switching momentum (10 times lower losses) and betatron cleaning  NO. Phased approach for shielding in cleaning insertions? Further detailed analysis is required for losses in IR3/IR7!

  28. Status OCT02 Start of project Phase 2 R&D design, production Definition of phased approach Collimator specifications for phase 1 JUL03 System layout(optics, energy deposition, …) Radiation, collimator shielding Collimator mechanical design Motors, control electronics Budget Prototyping, verification with SPS test MAY-OCT04 2005-2006 Series production 2006-2007 Installation, commissioning

  29. SPS test • The SPS is an ideal test-bed to verify the performance of an LHC prototype collimator in various important aspects (and gives us some additional rigid deadlines): • The robustness of the proposed Carbon-based jaw can be tested with the specified LHC maximum shock impact of protons on the collimator face (impact of a full 450 GeV SPS batch – 4 PS batches). • Predictions on shower development and heating downstream of shock beam impact can be verified. • The functionality of a prototype collimator can be tested with minimum gaps down to 3.0 mm, close to LHC minimum closure (SPS stored beam at 270 GeV and collimators at 3 s). • The impedance of the carbon jaws can be measured with the SPS beam in various ways: detuning of a dense single bunch, threshold for beam instability with closing jaws (real time measurement with 100k turn BPM set-up), dipole kick, tune shift. • Unforeseen HOM’s would be observed. • The beam loss maps downstream of the installed LHC collimator can be recorded with Beam Loss Monitors and then compared with simulations. • The LHC type orbit feedback can be tested close to a collimator with special emphasis on studying systematic effects induced by beam loss and associated showers. • Vacuum behavior close to the Carbon-based jaws can be monitored during the robustness test and “regular” operation.

  30. LHC collimator test in the SPS Goal: Show that the LHC collimator has the required functionality and properties (mechanical movements, tolerances, impedance, vacuum, loss maps, …). Equipment: Full LHC V collimator prototype (secondary collimator, length with flanges = 2.0 m). Includes two fully movable carbon-based jaws (1.2 m), all motors, cables,cooling water, all local monitoring, tapering, RF contacts, local electronics and controls, interface to SPS/LHC control system, simple controls application, outbaking equipment, … Jaws without coating… Maximum full gap is 60 mm. Installation: 11 Aug 2004 Location: QF522 Beam: 270 GeV stored beam, single bunch plus LHC type beam Time: 9 shifts (3 setup, 6 measurements) Approved last week…

  31. TT40 robustness test Goal: Show that an LHC collimator jaw survives its expected maximum beam load without damage (no damage to jaw material nor metallic cooling support nor water leak). Equipment: Single carbon collimator jaw (secondary collimator, length = 1.2 m) Installed on regular metallic support with cooling Remote moving mechanism, coating must be decided Jaw is under vacuum Installation: 11 Aug 2004 Location: Upstream of TED dump Beam: Nominal LHC extracted batch (450 GeV, 3e13p, nom emittance, 2.3 MJ) Time: 3 shifts (1 setup, 1 measurements, 1 experiment by RS/VK) Approved last week…

  32. Summary of milestones 1) System layout: Oct 2003 Choose optics (1 month late), start MARS/FLUKA Nov 2003 ECR for tertiary collimators in IR1/IR2/IR5/IR8 Start first loop in IR3/IR7 with installation group Decide on TCLI collimators Jan 2004 Review energy deposition calculations Feb 2004 Freeze cleaning insertions 2) Mechanical design: Oct 2003 Order jaw material for prototypes Nov 2003 Start preparatory work for SPS test (support, …) Dec 2003 Clamping and cooling test May 2004 Delivery of prototypes for SPS test Jun 2004 Start design of other collimator types Aug 2004 Installation of prototypes into SPS and TT40 Dec 2004 Drawings for series production

  33. 3) Motors/electronics/controls: Nov 2003 Order/organize cables for SPS test Review radiation impact on motors Start work with AB/CO Dec 2003 Discuss market survey and MTBF Order a few candidates Feb 2004 Radiation hardness tests? … Jun 2004 Install motors on prototype Jul 2004 Test local and remote control Aug 2004 Everything ready for SPS test Jan 2005 Order motors, electronics, cables, … 4) Radiation and shielding: Nov 2003 Start calculations for different shielding options Review loss assumptions Decision on collimator shielding (TCC)?

  34. Critical challenges • Show that fast and simple clamping technique works. (Dec03) • Show that layout with carbon collimators has acceptable energy deposition. (Feb04) • Show that motors can survive close to the jaws. (Mar04?) • Show that the developed collimators and required shielding can co-exist, including remote handling equipment. (Mar04?) Each of these challenges can cause deep trouble (money, time, …)! • Show that efficiency is good enough and that system can be optimized as required with beam. (2004/5) Here we do the best possible (IR3/7, tertiary collimators). No way out!? 6) Low impedance design for secondary hybrid collimators!

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