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Overview of LHC Machine Upgrade Plans from an LHCb Perspective -

Overview of LHC Machine Upgrade Plans from an LHCb Perspective - . Frank Zimmermann LHCb Upgrade Meeting CERN, 5 August 2008. We acknowledge the support of the European Community-Research Infrastructure Activity under the FP6

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Overview of LHC Machine Upgrade Plans from an LHCb Perspective -

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  1. Overview of LHC Machine Upgrade Plans from an LHCb Perspective- Frank Zimmermann LHCb Upgrade Meeting CERN, 5 August 2008 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)

  2. outline • (1) general LHC upgrade plan • (2) shutdown plans for the machine, i.e. time- windows with longer than normal shutdown detector access • (3) luminosity scenarios in point 8 after phase 2 (“and maybe phase 1 - if there is a change?”).

  3. machine upgrade plan

  4. Two Strong Reasons for LHC Upgrade J. Strait 2003 hypothetical luminosity evolution 1) after few years, statistical error hardly decreases 2) radiation damage limit of IR quadrupoles(~700 fb-1) reached by ~2016  time for an upgrade! 3) extending physics potential!

  5. staged approach to LHC upgrade “phase-1” 2013: new triplets, D1, TAS, b*=0.25 m in IP1 & 5, reliable LHC operation at ~2-3x luminosity; beam from new Linac4 “phase-2” 2017: target luminosity 10x nominal, possibly Nb3Sn triplet & b*~0.15 m complementary measures 2010-2017: e.g. long-range beam-beam compensation, crab cavities, new/upgraded injectors, advanced collimators, coherent e- cooling??, e- lenses?? longer term (2020?): energy upgrade, LHeC,… + injector upgrade phase-2 might be just phase-1 plus complementary measures

  6. constraint crossing angle “Piwinski angle” qc/2 luminosity reduction factor nominalLHC effective beam size s→s/Rf other constraints: beam-beam e- cloud collimation

  7. LHC upgrade paths for IP1 & 5 early separation (ES) full crab crossing (FCC) L. Evans, W. Scandale, F. Zimmermann J.-P. Koutchouk stronger triplet magnets stronger triplet magnets D0 dipole small-angle crab cavity small-angle crab cavity • ultimate beam (1.7x1011 protons/bunch, 25 spacing), b* ~10 cm • early-separation dipoles in side detectors , crab cavities • → hardware inside ATLAS & CMS detectors, • first hadron crab cavities; off-d b • ultimate LHC beam (1.7x1011 protons/bunch, 25 spacing) • b* ~10 cm • crab cavities with 60% higher voltage • → first hadron crab cavities, off-d b-beat larger-aperture triplet magnets large Piwinski angle (LPA) • 50 ns spacing, longer & more intense bunches • (5x1011 protons/bunch) • b*~25 cm, no elements inside detectors • long-range beam-beam wire compensation • → novel operating regime for hadron colliders, beam generation wire compensator F. Ruggiero, W. Scandale. F. Zimmermann

  8. large Piwinski angle (LPA) full crab crossing (FCC) early separation (ES)

  9. luminosity leveling initial luminosity peak may not be useful for physics (set up & tuning?) ES or FCC LPA experiments prefer ~constant luminosity, less pile up at start of run, higher luminosity at end average luminosity how can we achieve this? ES or FCC: dynamic b squeeze, or dynamic q change (either IP angle bumps or varying crab voltage) LPA: dynamic b squeeze, or dynamic change of bunch length

  10. IP1& 5 event pile up for 25 & 50-ns spacing w/o leveling ES or FCC 50 ns spacing 25 ns spacing LPA

  11. reasons for injector upgrade • Need for reliability: • Accelerators are old [Linac2: 1978, PSB: 1975, PS: 1959, SPS: 1976] • They operate far from their design parameters and close to hardware limits • The infrastructure has suffered from the concentration of resources on LHC during the past 10 years • Need for better beam characteristics Roland Garoby, LHCC 1July ‘08

  12. present and future injectors Proton flux / Beam power Linac4 Linac2 50 MeV 160 MeV (LP)SPL PSB 1.4 GeV 4 GeV (LP)SPL: (Low Power) Superconducting Proton Linac (4-5 GeV) PS2: High Energy PS (~ 5 to 50 GeV – 0.3 Hz) SPS+: Superconducting SPS (50 to1000 GeV) SLHC: “Superluminosity” LHC (up to 1035 cm-2s-1) DLHC: “Double energy” LHC (1 to ~14 TeV) PS 26 GeV PS2 50 GeV Output energy SPS SPS+ 450 GeV 1 TeV LHC / SLHC DLHC 7 TeV ~ 14 TeV Roland Garoby, LHCC 1July ‘08

  13. layout of the new injectors SPS PS2 SPL PS Linac4 R. Garoby, CARE-HHH BEAM07, October’07; L. Evans, LHCC, 20 Feb ‘08

  14. injector upgrade schedulesynchronized with LHC IR upgrades R. Garoby, LHCC 1 July 2008 LHC IR phase 1 LHC IR phase 2

  15. staged upgrade: peak luminosity in IPs 1 & 5 vs year new injectors + IR upgrade phase 2 linac4 + IR upgrade phase 1 Roland Garoby, LHCC 1July ‘08 early operation extended shutdowns: 2012/13 & 2017 collimationphase 2

  16. machine shutdown plans

  17. regular annual shutdown minimum duration of the annual accelerator shutdown (analysis for 2007 by Simon Baird,ATC mtg. 4 May‘07) basic  needs: • 6 weeks for mandatory maintenance (legal obligation), • 3 weeks for hardware tests/cold check-out, • 3 weeks for setting-up of the accelerators, • adding up to incompressible minimumduration of 12 weeks • of interruptionof LHC beam every year, without any major • intervention/modification information from R. Garoby

  18. time slots with >6 months access in present upgrade schedule: 4th quarter 2012 – 2nd quarter 2013 ~7.5 months for PSB cooldown, PSB modifications, PSB commissioning with LINAC4 → LHC peak luminosity in IP1&5 ~ 2x1034 cm-2s-1 (1-2) ATLAS [& CMS] may need 18 months downtime as early as 2015 (N. Hessey, LHCC 1 July 2008) (2) mid-November 2016 – end June 2017: ~7.5 months for SPS cooldown, SPS modifications, SPS commissioning with SPL+PS2 → LHC peak luminosity in IP1&5 ~ 1x1035 cm-2s-1

  19. luminosity scenarios in point 8 after phase-2 upgrade what about LHCb?

  20. PAF/POFPA Meeting 20 November 2006 2001 upgrade feasibility study

  21. from 2001 upgrade feasibility study … (note: 2006 nominal and ultimate parameters are slightly different)

  22. from 2001 upgrade feasibility study ~0.01 ~0.01 ~0.01 ~0.01 tune footprint up to 6s with 2 IPs tune footprint up to 6s with 2 IPs at ultimate intensity nominal tune footprint up to 6s with 4 IPs L=1034 cm-2s-1 L=2.3x1034 cm-2s-1 SPS, Tevatron, RHIC experience: beam-beam limit ↔ total tune shift DQ~0.01 going from 4 to 2 IPs we can increase ATLAS&CMS luminosity by factor 2.3 this and all following upgrade studies were based on assumption of only 2 IPs

  23. can we make (upgraded) LHCb compatible with upgraded LHC?! • aim to minimize contribution to beam-beam tune shift (note: DQ is independent of b*) • aim to provide optimum LHCb luminosity of 2x1033 cm-2s-1/2808 per bunch crossing, or 1/50th of luminosity in IP1 & 5

  24. bunch structures nominal 25 ns ultimate & 25-ns upgrade (ES & FCC) 25 ns 50-ns upgrade (LPA), no collisions in LHCb! 50 ns 50-ns upgrade with 25-ns collisions in LHCb 50 ns 25 ns

  25. LHCb recipe for 50-ns scenario • add satellites at 25 ns spacing • these can be produced by highly asymmetric bunch • splitting in the PS (possibly large fluctuation) • in LHCb satellites collide with main bunches • satellite intensity should be lower than 3x1010 p/bunch • to add <5% to beam-beam tune shift and to avoid • e-cloud problems; • 3x1010 ~ 1/16th of main-bunch charge • b function of ~3 m would result in desired • luminosity equivalent to 2x1033 cm-2s-1; • easily possible with present IR magnets & layout • [simpler alternative with lower rate: collide displaced • 50-ns bunch trains in LHCb @ b*~ 25 m (R. Garoby)]

  26. LHCb schemes for 25-ns scenario • here head-on collisions add to beam-beam tune shift of bunches colliding in ATLAS & CMS • potential ways out: • collisions withtransverse offset • collide at LHCb only in later part of each store, when the beam-beam tune shift from IP1 & 5 has decreased (H. Dijkstra) more “exotic” / advanced (need studies): • “electron lenses” for tune-shift compensation • flat-beam “crab-waist” collisions for DQx~0

  27. LHCb collisions with transverse offset d luminosity: L = L0exp (-d2/(4s2)) tune shift: DQ LHCb = 2 DQIP1or5 / (d/s)2 suppose tune shift from LHCb should be less than 10% of that from CMS or ATLAS →d>4.5 s ; then luminosity L ~ 0.006 L0 if we wish LLHCb~0.01 LIP1or5 (~1-2x1033 cm-2s-1) we need b* ~0.08 m → IR triplet upgrade! offset collisions w/o IR upgrade LLHCb ~ 4x1031 cm-2s-1

  28. other concerns for 4-5s offset collisions: • offset stability • interference with LHC collimation • effect on beam lifetime • effect on detector background • experience at RHIC, SPS, HERA and Tevatron was • discouraging (see slides with examples presented • at LHCB Upgrade Workshop of January 2007); • but interpretation of past results and their application • to LHC is a bit controversial

  29. LHCb luminosity for 25 ns with offset & 50 ns 25 ns spacing, 4.5s offset, b*~0.08 m 50 ns spacing, satellites LHCb 50-ns luminosity decays 2x more slowly than 25-ns luminosity or that at ATLAS and CMS PAF/POFPA Meeting 20 November 2006

  30. tune shift during store for 25-ns & 50-ns spacing 50 ns spacing change DQ ~ -0.0033 25 ns spacing LHCb 25-ns collisions from middle of each store?! b*~3 m (5 h turnaround time is assumed) PAF/POFPA Meeting 20 November 2006

  31. LHCb luminosity for 25-ns late collisions & 50 ns 25 ns spacing, b* ~ 3 m, no transverse offset 50 ns spacing, b*~3 m, satellites (5 h turnaround time is assumed) PAF/POFPA Meeting 20 November 2006

  32. LHCb collision parameters rms length of luminous region: (in cases w/o transverse offset) PAF/POFPA Meeting 20 November 2006

  33. summary • time slots for LHCb upgrade: annual shutdown: > 3 months; phase-1 2012/13: > 7 months; ATLAS/CMS upgrade: 2015/16/17? ~18 months; phase-2 2016/17: > 7 months • three paths to 10x higher luminosity in IP1&5: 25-ns or 50-ns bunch spacing; early LHC experience may decide • original upgrade plans did not consider LHCb, however LHCb can be made compatible • 50-ns upgrade: satellite bunches at 25 ns could yield desired LHCb luminosity nearly transparently • 25-ns upgrade:LHCb collisions with transverse offset + LHCb IR upgrade not too promising; better: late collisions with b*~3 m; e- lenses & crab-waist option to be studied PAF/POFPA Meeting 20 November 2006

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