Walter Scandale, Frank Zimmermann 18 January 2007 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 about 70 participants including 13 from US-LARP and 2 from KEK 53 presentations, 10 discussions, 4 posters topics: interaction-region upgrade beam parameters intensity limitations injector upgrade } Frank 1st 2.5 days } Walter 2nd 2.5 days

Walter Scandale: Status of LHC Upgrade

Roadmap for tracker/trigger upgrades Jordan Nash: CMS Perspective of Upgrade Roadmap for tracker/trigger upgrades 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

Inner detector-high luminosity upgrade issues 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

Gian Luca Sabbi: Nb3Sn Quad Development in US

Gian Luca Sabbi: Nb3Sn Quad Development in US

Tanaji Sen: IR Upgrade with Quadrupoles First

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

Solution with Modular ‘Triplet’ Layout Oliver Bruning & R. De Maria: Low-Gradient Triplets Solution with Modular ‘Triplet’ Layout b-max below 15 km: 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

Tanaji Sen: US Dipole 1st Optics

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

Open Midplane Designs With High Temperature Superconductors (HTS) 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

High-Z Liner (Inner Absorber) 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 TRIPLETS vanishing crossing angle & early separation space for D0 in ATLAS space for D0 in CMS Courtesy of M. Nessi, ‘Machine upgrade, ATLAS considerations’, June 2006

Emanuele Laface: Q0 with l*=3 m IP 13m Q0 A Q0 B Q1 IP 13m Magnet Min. Diameter Gradient Q0 A > 40 mm 165 T/m Q0 B

List of R&D topics Continue & expand Nb3Sn magnet R&D 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 m b*=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 ?

Rogelio Tomas: IR Upgrade Web Site

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

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

Rogelio Tomas: Crab Cavity IR with q=8 mrad

Rama Calaga: Crab Cavities

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

emittance growth and luminosity decrement 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

Functions: Vladimir Shiltsev: Electron Lenses for LHC #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”

Local cooling limitations Laurent Tavian: LHC Cryogenic System Upgrade Local cooling limitations Scenario BS cooling loop 1.9 K cooling loop [W/m/aperture] [W/m] Nominal 1.5 0.40 Ultimate 1.7 0.44 Short-bunch 16 0.81 Long-bunch 1.6 0.45 Local limitation 2.4 * 0.9 ** *: 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 NbTi magnets 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 with detector-integrated dipole Detector-integrated quadrupole Quad 1st flat beam Separate-channel quad 1st Nb3Sn or NbTi plus crab cavities Dipole first options with Nb3Sn 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 ++

Vladimir Shiltsev: IR Ranking Conclusions 1

Summary IR Upgrade Ranking Oliver Bruning: IR Ranking Conclusions 2 Summary IR Upgrade Ranking (personal observations for discussion) increased triplet aperture helps for almost everything:  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 decreased L* provides smaller -max: (field quality, DA and mechanical aperture) increased gradient provides more compact final focus:  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 symbol nominal ultimate 12.5 ns, short transverse emittance e [mm] 3.75 protons per bunch Nb [1011] 1.15 1.7 bunch spacing Dt [ns] 25 12.5 beam current I [A] 0.58 0.86 1.72 longitudinal profile Gauss rms bunch length sz [cm] 7.55 3.78 beta* at IP1&5 b* [m] 0.55 0.5 0.25 full crossing angle qc [mrad] 285 315 445 Piwinski parameter f=qcsz/(2*sx*) 0.64 0.75 peak luminosity L [1034 cm-2s-1] 1 2.3 9.2 peak events per crossing 19 44 88 initial lumi lifetime tL [h] 22 14 7.2 effective luminosity (Tturnaround=10 h) Leff [1034 cm-2s-1] 0.46 0.91 2.7 Trun,opt [h] 21.2 17.0 12.0 (Tturnaround=5 h) 0.56 3.6 15.0 8.5 e-c heat SEY=1.4(1.3) P [W/m] 1.07 (0.44) 1.04 (0.59) 13.34 (7.85) SR heat load 4.6-20 K PSR [W/m] 0.17 image current heat PIC [W/m] 0.15 0.33 1.87 gas-s. 100 h (10 h) tb Pgas [W/m] 0.04 (0.38) 0.06 (0.56) 0.113 (1.13) comment partial wire c. 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 parameter symbol 25 ns, small b* 50 ns, long transverse emittance e [mm] 3.75 protons per bunch Nb [1011] 1.7 4.9 bunch spacing Dt [ns] 25 50 beam current I [A] 0.86 1.22 longitudinal profile Gauss Flat rms bunch length sz [cm] 7.55 11.8 beta* at IP1&5 b* [m] 0.08 0.25 full crossing angle qc [mrad] 381 Piwinski parameter f=qcsz/(2*sx*) 2.0 hourglass reduction 0.99 peak luminosity L [1034 cm-2s-1] 15.5 10.7 peak events per crossing 294 403 initial lumi lifetime tL [h] 2.2 4.5 effective luminosity (Tturnaround=10 h) Leff [1034 cm-2s-1] 2.4 2.5 Trun,opt [h] 6.6 9.5 (Tturnaround=5 h) 3.6 3.5 4.6 6.7 e-c heat SEY=1.4(1.3) P [W/m] 1.04 (0.59) 0.36 (0.1) SR heat load 4.6-20 K PSR [W/m] 0.36 image current heat PIC [W/m] 0.33 0.78 gas-s. 100 h (10 h) tb Pgas [W/m] 0.06 (0.56) 0.09 (0.9) comment D0 + crab (+ Q0) wire comp. two new upgrade scenarios compromises between heat load and # pile up events

PAF/POFPA Meeting 20 November 2006 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

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

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

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

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)