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Baseline Scenario for the LHC Luminosity Upgrade Summary of CARE-HHH LHC-LUMI-06. Walter Scandale, Frank Zimmermann 18 January 2007. CARE-HHH APD workshop ‘LUMI 06’ Towards a Roadmap for the Upgrade of the LHC and GSI Accelerator Complex IFIC, Valencia (Spain), 16-20 October 2006. topics:
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Baseline Scenario for the LHC Luminosity Upgrade Summary of CARE-HHH LHC-LUMI-06 Walter Scandale, Frank Zimmermann 18 January 2007
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
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
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”
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
Tom Taylor & Ranko Ostojic: Nb3Sn & NbTi Hybrid IR NbTi present triplet Nb3Sn NbTi+ NbTi+ NbTi+ hybrid upgrade
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
Riccardo De Maria: Dipole 1st Optics w Chromaticity and Dynamic Aperture
Angeles Faus-Golfe, R. De Maria, R. Tomas: Chromaticity Limits Linear Chromaticity Correction Limits on Chromaticity Correction
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
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
Francesco Broggi: Energy Deposition in Triplet peak power deposition almost constant for all cases
Jean-Pierre Koutchouk: Insertion Solutions from Parametric Study
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
Emanuele Laface: Q0 with l*=3 m IP Q1 Q0 A Q0 B 13m
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
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 ?
Ulrich Dorda: Wire Compensation of LR Beam-Beam current scan color: amplitude distance scan color: tune diffusion
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
Joachim Tuckmantel: Technological Aspects of Crab Cavities Proposal F. Caspers, similar J. Frisch, SLAC (ILC) ???? Does this really help or not ????
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
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”
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”
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 ++
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
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)
two new upgrade scenarios compromises between heat load and # pile up events
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
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)
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
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
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
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
IP1& 5 event pile up for 25-ns and 50-ns spacing 50 ns spacing 25 ns spacing PAF/POFPA Meeting 20 November 2006
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
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
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)