Frank Zimmermann, LHCb Upgrade Meeting 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 )

Frank Zimmermann, LHCb Upgrade Meeting 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?”).

Frank Zimmermann, LHCb Upgrade Meeting machine upgrade plan

Frank Zimmermann, LHCb Upgrade Meeting Two Strong Reasons for LHC Upgrade J. Strait ) 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! hypothetical luminosity evolution

Frank Zimmermann, LHCb Upgrade Meeting staged approach to LHC upgrade “phase-1” 2013: new triplets, D1, TAS,  *=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 Nb 3 Sn triplet &  *~0.15 m complementary measures : 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,… phase-2 might be just phase-1 plus complementary measures + injector upgrade

“Piwinski angle” luminosity reduction factor nominal LHC constraint crossing angle  c /2 effective beam size  →  /R  other constraints: beam-beam e- cloud collimation

Name Event Date Name Event Date7 LHC upgrade paths for IP1 & 5 ultimate beam (1.7x10 11 protons/bunch, 25 spacing),  * ~10 cm ultimate beam (1.7x10 11 protons/bunch, 25 spacing),  * ~10 cm early-separation dipoles in side detectors, crab cavities early-separation dipoles in side detectors, crab cavities → hardware inside ATLAS & CMS detectors, first hadron crab cavities; off-  stronger triplet magnets D0 dipole small-angle crab cavity J.-P. Koutchouk early separation (ES) stronger triplet magnets small-angle crab cavity ultimate LHC beam (1.7x10 11 protons/bunch, 25 spacing) ultimate LHC beam (1.7x10 11 protons/bunch, 25 spacing)  * ~10 cm  * ~10 cm crab cavities with 60% higher voltage crab cavities with 60% higher voltage → first hadron crab cavities, off-  -beat L. Evans, W. Scandale, F. Zimmermann full crab crossing (FCC) wire compensator larger-aperture triplet magnets 50 ns spacing, longer & more intense bunches 50 ns spacing, longer & more intense bunches (5x10 11 protons/bunch)  *~25 cm, no elements inside detectors  *~25 cm, no elements inside detectors long-range beam-beam wire compensation long-range beam-beam wire compensation → novel operating regime for hadron colliders, beam generation F. Ruggiero, W. Scandale. F. Zimmermann large Piwinski angle (LPA)

parametersymbolnominalultimateEarly Sep.Full Crab XingL. Piw Angle transverse emittance  [  m] 3.75 protons per bunchN b [10 11 ] bunch spacing  t [ns] beam currentI [A] longitudinal profile Gauss Flat rms bunch length  z [cm] beta* at IP1&5  [m] full crossing angle  c [  rad] Piwinski parameter  c  z /(2*  x *) hourglass reduction peak luminosityL [10 34 cm -2 s -1 ] peak events per #ing initial lumi lifetime  L [h] effective luminosity (T turnaround =10 h) L eff [10 34 cm -2 s -1 ] T run,opt [h] effective luminosity (T turnaround =5 h) L eff [10 34 cm -2 s -1 ] T run,opt [h] e-c heat SEY=1.4(1.3)P [W/m] 1.07 (0.44) 1.04 (0.59) 0.36 (0.1) SR heat load KP SR [W/m] image current heatP IC [W/m] gas-s. 100 h (10 h)  b P gas [W/m] 0.04 (0.38) 0.06 (0.56) 0.09 (0.9) extent luminous region  l [cm] comment nominalultimateD0 + crab crabwire comp. large Piwinski angle (LPA) full crab crossing (FCC) early separation (ES)

Name Event Date Name Event Date9 luminosity leveling ES or FCC LPA average luminosity initial luminosity peak may not be useful for physics (set up & tuning?) experiments prefer ~constant luminosity, less pile up at start of run, higher luminosity at end ES or FCC: dynamic  squeeze, or dynamic  change (either IP angle bumps or varying crab voltage) LPA: dynamic  squeeze, or dynamic change of bunch length how can we achieve this?

Name Event Date Name Event Date10 25 ns spacing 50 ns spacing IP1& 5 event pile up for 25 & 50-ns spacing w/o leveling ES or FCC LPA

Name Event Date Name Event Date11 reasons for injector upgrade Need for reliability: Need for reliability: Accelerators are old [Linac2: 1978, PSB: 1975, PS: 1959, SPS: 1976] Accelerators are old [Linac2: 1978, PSB: 1975, PS: 1959, SPS: 1976] They operate far from their design parameters and close to hardware limits 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 The infrastructure has suffered from the concentration of resources on LHC during the past 10 years Need for better beam characteristics Need for better beam characteristics Roland Garoby, LHCC 1July ‘08

Name Event Date Name Event Date12 PSB SPS SPS+ Linac4 (LP)SPL PS LHC / SLHC DLHC Output energy 160 MeV 1.4 GeV 4 GeV 26 GeV 50 GeV 450 GeV 1 TeV 7 TeV ~ 14 TeV Linac2 50 MeV (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 cm -2 s -1 ) DLHC: “Double energy” LHC (1 to ~14 TeV) Proton flux / Beam power present and future injectors PS2 Roland Garoby, LHCC 1July ‘08

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

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

collimation phase 2 linac4 + IR upgrade phase 1 new injectors + IR upgrade phase 2 early operation Roland Garoby, LHCC 1July ‘08 extended shutdowns: 2012/13 & 2017

Frank Zimmermann, LHCb Upgrade Meeting machine shutdown plans

Frank Zimmermann, LHCb Upgrade Meeting 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 minimum duration of 12 weeks of interruption of LHC beam every year, without any major intervention/modification information from R. Garoby

Frank Zimmermann, LHCb Upgrade Meeting time slots with >6 months access in present upgrade schedule: (1)4 th quarter 2012 – 2 nd quarter 2013 ~7.5 months for PSB cooldown, PSB modifications, PSB commissioning with LINAC4 → LHC peak luminosity in IP1&5 ~ 2x10 34 cm -2 s -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 ~ 1x10 35 cm -2 s -1

Frank Zimmermann, LHCb Upgrade Meeting luminosity scenarios in point 8 after phase-2 upgrade what about LHCb?

Frank Zimmermann, LHCb Upgrade Meeting PAF/POFPA Meeting 20 November upgrade feasibility study

Frank Zimmermann, LHCb Upgrade Meeting from 2001 upgrade feasibility study … (note: 2006 nominal and ultimate parameters are slightly different)

Frank Zimmermann, LHCb Upgrade Meeting from 2001 upgrade feasibility study nominal tune footprint up to 6  with 4 IPs tune footprint up to 6  with 2 IPs tune footprint up to 6  with 2 IPs at ultimate intensity L=10 34 cm -2 s -1 L=2.3x10 34 cm -2 s -1 SPS, Tevatron, RHIC experience: beam-beam limit ↔ total tune shift  Q~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 ~0.01

Frank Zimmermann, LHCb Upgrade Meeting aim to minimize contribution to beam-beam tune shift (note:  Q is independent of  *) aim to provide optimum LHCb luminosity of 2x10 33 cm -2 s -1 /2808 per bunch crossing, or 1/50 th of luminosity in IP1 & 5 can we make (upgraded) LHCb compatible with upgraded LHC?!

Frank Zimmermann, LHCb Upgrade Meeting 50-ns upgrade with 25-ns collisions in LHCb bunch structures 25 ns 50 ns nominal 25 ns ultimate & 25-ns upgrade (ES & FCC) 50-ns upgrade (LPA), no collisions in LHCb! 50 ns 25 ns

Frank Zimmermann, LHCb Upgrade Meeting 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 3x10 10 p/bunch to add <5% to beam-beam tune shift and to avoid e-cloud problems; 3x10 10 ~ 1/16 th of main-bunch charge  function of ~3 m would result in desired luminosity equivalent to 2x10 33 cm -2 s -1 ; easily possible with present IR magnets & layout [simpler alternative with lower rate: collide displaced 50-ns bunch trains in  *~ 25 m (R. Garoby)]

Frank Zimmermann, LHCb Upgrade Meeting here head-on collisions add to beam-beam tune shift of bunches colliding in ATLAS & CMS potential ways out: –collisions with transverse 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  Q x ~0 LHCb schemes for 25-ns scenario

Frank Zimmermann, LHCb Upgrade Meeting L = L 0 exp (-d 2 /(4  2 )) LHCb collisions with transverse offset d luminosity:  Q LHCb = 2  Q IP1or5 / (d/  2 tune shift: suppose tune shift from LHCb should be less than 10% of that from CMS or ATLAS → d>4.5  then luminosity L ~ L 0 if we wish L LHCb ~0.01 L IP1or5 (~1-2x10 33 cm -2 s -1 ) we need  * ~0.08 m → IR triplet upgrade! offset collisions w/o IR upgrade L LHCb ~ 4x10 31 cm -2 s -1

Frank Zimmermann, LHCb Upgrade Meeting other concerns for 4-5  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

LHC Upgrade Beam Parameters, Frank ZimmermannFrank Zimmermann, LHCb Upgrade WorkshopPAF/POFPA Meeting 20 November 2006 LHCb luminosity for 25 ns with offset & 50 ns 25 ns spacing, 4.5  offset,  *~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

LHC Upgrade Beam Parameters, Frank ZimmermannFrank Zimmermann, LHCb Upgrade WorkshopPAF/POFPA Meeting 20 November ns spacing 50 ns spacing tune shift during store for 25-ns & 50-ns spacing change  Q ~ LHCb 25-ns collisions from middle of each store?!  *~3 m (5 h turnaround time is assumed)

LHC Upgrade Beam Parameters, Frank ZimmermannFrank Zimmermann, LHCb Upgrade WorkshopPAF/POFPA Meeting 20 November 2006 LHCb luminosity for 25-ns late collisions & 50 ns 25 ns spacing,  * ~ 3 m, no transverse offset 50 ns spacing,  *~3 m, satellites (5 h turnaround time is assumed)

LHC Upgrade Beam Parameters, Frank ZimmermannFrank Zimmermann, LHCb Upgrade WorkshopPAF/POFPA Meeting 20 November 2006 LHCb collision parameters parametersymbol25 ns, offset25 ns, late collision50 ns, satellites collision spacingT coll 25 ns protons per bunchN b [10 11 ] & 0.3 longitudinal profileGaussian flat rms bunch length  z [cm] beta* at LHCb  [m] rms beam size  x,y * [  m] 640 rms divergence  x’,y’ * [  rad] 8013 full crossing angle  c [urad] Piwinski parameter  c  z /(2*  x *) peak luminosityL [10 33 cm -2 s -1 ] initial lumi lifetime  L [h] length of lum. region  l [cm] rms length of luminous region: (in cases w/o transverse offset)

LHC Upgrade Beam Parameters, Frank ZimmermannFrank Zimmermann, LHCb Upgrade WorkshopPAF/POFPA Meeting 20 November 2006 summary time slots for LHCb upgrade: annual shutdown: > 3 months; phase /13: > 7 months; ATLAS/CMS upgrade: 2015/16/17? ~18 months; phase /17: > 7 months three paths to 10 x 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  *~3 m; e- lenses & crab-waist option to be studied