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Maximizing LHC Performance: Strategies for the Upgrade Roadmap

This summary outlines the key findings and strategies discussed in the LHC Luminosity Upgrade workshop, including tracker/trigger upgrades, inner detector issues, and perspectives from various stakeholders. The roadmap emphasizes maximizing annual integrated luminosity at minimum peak luminosity. Topics such as Nb3Sn magnet development, IR upgrades, and collision debris handling are covered in detail to enhance LHC performance. Key areas of focus include the development of new detector systems, upgrading accelerator components, and advancing R&D for higher luminosity and peak performance levels.

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Maximizing LHC Performance: Strategies for the Upgrade Roadmap

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  1. Baseline Scenario for the LHC Luminosity Upgrade Summary of CARE-HHH LHC-LUMI-06 Walter Scandale, Frank Zimmermann 18 January 2007

  2. CARE-HHH APD workshop ‘LUMI 06’ Towards a Roadmap for the Upgrade of the LHC and GSI Accelerator ComplexIFIC, Valencia (Spain), 16-20 October 2006 topics: interaction-region upgrade beam parameters intensity limitations injector upgrade about 70 participants including 13 from US-LARP and 2 from KEK 53 presentations, 10 discussions, 4 posters } Frank 1st 2.5 days } Walter 2nd 2.5 days

  3. Walter Scandale: Status of LHC Upgrade

  4. Roadmap for tracker/trigger upgrades Jordan Nash: CMS Perspective of Upgrade • Within 5 years of LHC start • New layers within volume of current Pixel tracker which incorporate some tracking information for Level 1 Trigger • “Pathfinder” for full tracking trigger • Elements of new Level 1 trigger • Upgrade to full new tracker system by SLHC (8-10 years from LHC Startup) • Includes full upgrade to trigger system Target: Summer 2007

  5. Per Grafstrom: ATLAS Perspective of Upgrade Inner detector-high luminosity upgrade issues • x 10 in luminosity  most sensors of inner detector will die in a couple of months • x 10 in luminosity  10 000 charged particles in  < 3.2 The TRT will have occupancy close to 100% For the Inner Detector we are not talking about an “upgrade” but a complete replacement i.e a NEW Inner Detector • replacement of SS beam pipe by Al or Be • beam pipe (reduced background) • potential slots for “slim” magnets inside ATLAS “We want maximum annual integrated luminosity at minimum peak luminosity”

  6. Jim Strait: LHC Upgrade from US Perspective • LHC program, including LHC upgrade, is high-priority component of US HEP program. • US participates in R&D towards upgrades of experiments (ATLAS and CMS) and of LHC accelerator. • US contributions to accelerator upgrade focus on IR, in particular on Nb3Sn magnet development; recent successes: fields 10-12 T reached in different prototype magnets

  7. Gian Luca Sabbi: Nb3Sn Quad Development in US

  8. Gian Luca Sabbi: Nb3Sn Quad Development in US

  9. Tanaji Sen: IR Upgrade with Quadrupoles First

  10. Tom Taylor & Ranko Ostojic: Nb3Sn & NbTi Hybrid IR NbTi present triplet Nb3Sn NbTi+ NbTi+ NbTi+ hybrid upgrade

  11. Oliver Bruning & R. De Maria: Low-Gradient Triplets b-max below 15 km: Solution with Modular ‘Triplet’ Layout QX1  100T/m QX2  80 T/m QX3  100T/m QX4  80 T/m • peak coil field: 9 T, aperture: 180 mm diameter, 10% operation margin LHC LUMI 2006; 16.10.2005; Valencia Oliver Brüning 11

  12. Riccardo De Maria: Dipole 1st Optics w Chromaticity and Dynamic Aperture

  13. Tanaji Sen: US Dipole 1st Optics

  14. Angeles Faus-Golfe, R. De Maria, R. Tomas: Chromaticity Limits Linear Chromaticity Correction Limits on Chromaticity Correction

  15. Ramesh Gupta: Open Midplane Dipoles and Crab-Cavity Quadrupoles Open Midplane Designs With High Temperature Superconductors (HTS) • HTS in a hybrid design with Nb3Sn coils • Such magnets could operate at very high field (>16 T) • HTS could tolerate large energy deposition

  16. Nikolai Mokhov: Handling Collision Debris High-Z Liner (Inner Absorber) Liner Coils Energy deposition design goal for Nb3Sn quads is reached with W25Re liner 7.2-mm thick (+1.5mm) in Q1 and 1-mm thick (+1.5mm) in the rest of triplet Handling Collision Debris - N. Mokhov

  17. Francesco Broggi: Energy Deposition in Triplet peak power deposition almost constant for all cases

  18. Jean-Pierre Koutchouk: Insertion Solutions from Parametric Study

  19. Guido Sterbini: D0 and its Integrability D0 D1 TRIPLETS D0 TRIPLETS D1 Courtesy of M. Nessi, ‘Machine upgrade, ATLAS considerations’, June 2006 vanishing crossing angle & early separation space for D0 in ATLAS space for D0 in CMS

  20. Emanuele Laface: Q0 with l*=3 m IP Q1 Q0 A Q0 B 13m

  21. Peter Limon: LHC Luminosity Upgrade Using Quads • List of R&D topics • Continue & expand Nb3Sn magnet R&D • Model quads, Long quadrupoles • More Nb3Sn magnet R&D • Even more aggressive Nb3Sn magnet R&D • What else? • Much more work on energy deposition & cooling • Support structure, alignment techniques, etc. • Lots of detector R&D

  22. Ezio Todesco: Scaling Laws for b* in LHC IR Triplet aperture and length vs b*, technology, l* Ex.:l*=23 mb*=0.28 cm • Nb-Ti: aperture 94 mm, triplet length 30 m, gradient 160 T/m • Nb3Sn: aperture 81 mm, triplet length 20 m, gradient 275 T/m • Solutions can be found for both materials • Large apertures: is this possible? • Stresses, aberrations ?

  23. Rogelio Tomas: IR Upgrade Web Site

  24. Ulrich Dorda: Wire Compensation of LR Beam-Beam current scan color: amplitude distance scan color: tune diffusion

  25. Wolfram Fischer: LRBB Compensation Test @ RHIC wires (2.5m long) with strong-back (-profile)7 support points attempts to improve lifetime, small changes in (Qx,Qy) Single LR effect at injection (24 GeV p) NEG coated chambersduring assembly

  26. Rogelio Tomas: Crab Cavity IR with q=8 mrad

  27. Rama Calaga: Crab Cavities

  28. Joachim Tuckmantel: Technological Aspects of Crab Cavities Proposal F. Caspers, similar J. Frisch, SLAC (ILC) ???? Does this really help or not ????

  29. Kazuhito Ohmi: Beam-Beam Effect with Ext. Noise emittance growth and luminosity decrement • strong-strong tolerance more severe than weak-strong • turn-to-turn offset jitter tolerance about 0.1%s • build-up of dipole oscillations • bunch by bunch feedback may relax tolerance

  30. Vladimir Shiltsev: Electron Lenses for LHC Functions: #1: LEL as Head-On Compensator at design intensities and with x(2…4?)Np/bunch #2: LEL as Beam Stabilizer (Tune Spreader) to help octupoles @ design Np=1.15e11 #3: LEL as soft hollow collimator #4: LEL as soft “beam conditioner”

  31. Laurent Tavian: LHC Cryogenic System Upgrade Local cooling limitations *: limited by the hydraulic impedance of the cooling channels and calculated for a supply pressure (header C) of 3 bar. **: limited by the sub-cooling heat exchanger capacity “The Short-bunch scenario requires an increase of the sector cooling capacity by a factor 4 and shows local limitations in the beam screen cooling circuits. These two showstoppers render this scenario cryogenically unfeasible”

  32. Frank Z., W. Scandale: HHH IR Ranking Proposal Low-gradient large-aperture NbTimagnets with large l* Risk -, Return + Quad 1st“pushed” NbTi: tailored aperture & length, 2x better cooling, ~20% higher field NbTi-Nb3Sn hybrid scheme Quad 1st Nb3Sn Quad 1st withdetector-integrated dipole Detector-integrated quadrupole Quad 1stflat beam Separate-channel quad 1st Nb3Sn or NbTipluscrab cavities Dipole firstoptions withNb3Sn Pulsed or dc beam-beam compensator Risk -, Return ++ Electron lens Risk -, Return + Risk +, Return ++ Risk ++, Return +++ Risk ++, Return +++ Risk +, Return +++ Risk -, Return ++ Risk +++, Return + retain options with perceived lowest risk or highest return (in red) Risk +++, Return + Risk +++, Return ++

  33. Vladimir Shiltsev: IR Ranking Conclusions 1

  34. Oliver Bruning: IR Ranking Conclusions 2 increased triplet aperture helps for almost everything: increased gradient provides more compact final focus: decreased L* provides smaller -max: Summary IR Upgrade Ranking (personal observations for discussion) •  allows lower * (luminosity) •  allows larger crossing angle (beam-beam) •  allows larger collimator gap opening • (impedance and beam intensity) •  more room for absorber material and liners (field quality, DA and mechanical aperture)  allows lower -max (field quality and DA and aperture) LHC LUMI 2006; 18.10.2005; Valencia Oliver Brüning 34

  35. baseline upgrade parameters 2001-2005 abandoned at LUMI’06 total heat load far exceeds maximum local cooling capacity of 2.4 W/m (SR and image current heat load well known)

  36. two new upgrade scenarios compromises between heat load and # pile up events

  37. for operation at beam-beam limit with alternating planes of crossing at two IPs, luminosity equation can be written as ↑↑ 50 ns ↓ 50 ns ↓↓ 25 ns ↓ 50 ns where DQbb = total beam-beam tune shift PAF/POFPA Meeting 20 November 2006

  38. 25-ns upgrade scenario • stay with ultimate LHC beam (1.7x1011 protons/bunch, 25 spacing) • squeeze b* to ~10 cm in ATLAS & CMS • add early-separation dipoles in detectors starting at ~ 3 m from IP • possibly also add quadrupole-doublet inside detector at ~13 m from IP • and add crab cavities (fPiwinski~ 0) → new hardware inside ATLAS & CMS detectors, first hadron-beam crab cavities (J.-P. Koutchouk et al)

  39. CMS & ATLAS IR layout for 25-ns option stronger triplet magnets D0 dipole Q0 quad’s small-angle crab cavity ultimate bunches & near head-on collision merits: negligible long-range collisions, no geometric luminosity loss challenges: D0 dipole deep inside detector (~3 m from IP), Q0 doublet inside detector (~13 m from IP), crab cavity for hadron beams (emittance growth) PAF/POFPA Meeting 20 November 2006

  40. 50-ns upgrade scenario • double bunch spacing • longer & more intense bunches with fPiwinski~ 2 • keep b*~25 cm (achieved by stronger low-b quads alone) • do not add any elements inside detectors • long-range beam-beam wire compensation → novel operating regime for hadron colliders

  41. CMS & ATLAS IR layout for 50-ns option stronger triplet magnets wire compensator long bunches & nonzero crossing angle & wire compensation merits: no elements in detector, no crab cavities, lower chromaticity challenges: operation with large Piwinski parameter unproven for hadron beams, high bunch charge, larger beam current PAF/POFPA Meeting 20 November 2006

  42. IP1& 5 luminosity evolution for 25-ns and 50-ns spacing 25 ns spacing 50 ns spacing average luminosity PAF/POFPA Meeting 20 November 2006

  43. IP1& 5 event pile up for 25-ns and 50-ns spacing 50 ns spacing 25 ns spacing PAF/POFPA Meeting 20 November 2006

  44. old upgrade bunch structure nominal 25 ns ultimate 25 ns 12.5-ns upgrade 12.5 ns abandoned at LUMI’06 PAF/POFPA Meeting 20 November 2006

  45. new upgrade bunch structures nominal 25 ns new alternative! ultimate & 25-ns upgrade 25 ns 50-ns upgrade, no collisions @S-LHCb! 50 ns new baseline! 50-ns upgrade with 25-ns collisions in LHCb 50 ns 25 ns PAF/POFPA Meeting 20 November 2006

  46. Outcome of LUMI’06 Part 1 IR upgrade and beam parameters • quadrupole 1st preferred over dipole 1st • pushed NbTi or Nb3Sn still pursued, or hybrid solution - new • slim magnets inside detector (“D0 and Q0”) – new • wire compensation ~established; electron lens – new • crab cavities: large angle rejected; small-angle – new • 12.5-ns scenario strongly deprecated • e-cloud/pile-up compromise: 25-ns w b*~8 cm, or 50-ns spacing long bunches – new We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6 "Structuring the European Research Area" programme (CARE, contract number RII3-CT-2003-506395)

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