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CMS Upgrade Issues

CMS Upgrade Issues. SPC 15 September 2008. Topics. Potential Physics motivations Implications for the detectors Tracking detectors Requirements for phase I Requirements for phase II Tracking Trigger Muons and Calorimeters

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CMS Upgrade Issues

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  1. CMS Upgrade Issues SPC 15 September 2008 J. Nash - CMS SLHC Issues

  2. Topics • Potential Physics motivations • Implications for the detectors • Tracking detectors • Requirements for phase I • Requirements for phase II • Tracking Trigger • Muons and Calorimeters • Implications for the detector of Upgrades which place machine elements inside 19m J. Nash - CMS SLHC Issues

  3. SLHC is about the maximizing the output of LHC physics • We should be led by getting the best physics out of any upgraded machine/detector • Not by the highest peak luminosity • Even maximum integrated luminosity may not be the most important metric • Issues • Integrated luminosity • Backgrounds • Acceptance • Pile-up J. Nash - CMS SLHC Issues

  4. Peak luminosity… New injectors + IR upgrade phase 2 Linac4 + IR upgrade phase 1 Early operation Collimation phase 2 J. Nash - CMS SLHC Issues

  5. Integrated luminosity… New injectors + IR upgrade phase 2 Linac4 + IR upgrade phase 1 Early operation Collimation phase 2 J. Nash - CMS SLHC Issues

  6. What are the key timescales/issues? • Phase 1 • How well do detector components handle the increasing luminosity? • Both instantaneous and integrated effects • What detector elements will need replacement/modification to cope? • Detectors will record >500 fb-1, can they withstand this? • Phase 2 • What detector elements will need replacement? • What do machine plans imply for interaction regions • Is there a requirement for a long shutdown? • How long – 18 Months? (1 Full calendar year without beam +) • When – sometime after the middle of the next decade • Developing and building new tracking detectors will take many years • We have to plan this now in order to have any chance of running detectors with high luminosity • ATLAS and CMS now agree on the dates • No sense in having two long shutdowns • Reach 700 fb-1(potential limit) • Likely 2017 J. Nash - CMS SLHC Issues

  7. Issues discussed at the CMS May Upgrade workshop • What are the “strawmen” for upgrades of each of the systems? • Define the scope of the upgrade projects • What is done in Phase I/Phase II • What requires a long shutdown? • What can/should we attempt to do before the long shutdown • How should we use the lengthy shutdown in 2013? • When do we need to prepare a LOI • For CMS Upgrades • For subsystems • When do we need to prepare TDRs http://indico.cern.ch/conferenceDisplay.py?confId=28746 J. Nash - CMS SLHC Issues

  8. Some Physics themes • Different physics channels require different conditions • Three main directions for Phase II • Damn the torpedos - FULL Luminosity • Maximum of quality luminosity • Luminosity leveling? • Forward acceptance • We won’t know which is the most important until we have first data from the LHC • Important not to eliminate a physics opportunity until we are sure it makes sense to do so • We have to be ready to build detectors for any of these scenarios J. Nash - CMS SLHC Issues

  9. SLHC Physics: Extra gauge bosons • SLHC extends reach for Z’ • Cross sections fall with E • SLHC gives access to higher E • Good electron resolution required (including understanding saturation) Just give us the Integrated Luminosity! J. Nash - CMS SLHC Issues

  10. SUSY searches - measurements Here we need a lot of Integrated Luminosity, but needs to be high quality. Lower pile-up may be important. • SLHC statistics will be vital in reaching understanding of complicated SUSY channels • Sparticles seen, but statistics for reconstruction limited at LHC • Performance of the detector here is vital • B-tagging • Lepton id J. Nash - CMS SLHC Issues

  11. Pixels • The pixel 3D hits are ideal seeds for tracking and  reconstruction • Pattern recognition, all 5 track parameters well constrained • Excellent position resolution makes pixels essential : • for primary and secondary vertex reconstruction • for b and  identification Dark matter candidate J. Nash - CMS SLHC Issues

  12. What if no Higgs is found? Fake fwd jet tag (|| > 2) probability from pile-up (preliminary ...) ATLAS full simulation Forward tagging is essential • Will need to look at WW scattering • Some mechanism required to avoid unitarity violation • Forward Jet Tagging Essential 3000 fb-1 (SLHC) J. Nash - CMS SLHC Issues

  13. Higgs Boson Couplings qqHWWqqHtt HWWHZZ Some modes are systematically limited at LHC luminosities - no improvement at SLHC ttH/ttHbb HggHZZ WHggHgg WHWWWHWW • Ratios of Higgs couplings to fermions and gauge bosons • Independent of uncertainties on • stotHiggs, GH and integrated luminosity • Mostly statistics limited at the LHC J. Nash - CMS SLHC Issues

  14. Precision Electroweak meaurements 14 TeV 100 fb-128 TeV 100 fb-1 14 TeV 1000 fb-128 TeV 1000 fb-1  DkZ Z Z • 5 parameters describe these TGCs: • g1Z (1 in SM), • Dkz, Dkg, g, z(all 0 in SM) • Look in Wg Ing , WZ  lnll • Wg final state probes Dkg, g • WZ probes g1Z, Dkz, z • Experimental precision can reach 10-3 level at SLHC • Compares to SM prediction level J. Nash - CMS SLHC Issues

  15. Extending MSSM searches, Rare Decays • rare modes not observable at the LHC HSM Zg (BR ~ 10-3), HSM m+m- (BR ~ 10-4) Can extend region where more than one Higgs is seen (in MSSM) LHC 300 fb-1 SLHC 3000 fb-1 HSM Zg  l+l-g 120 < MH < 150 GeV, LHC with 600 fb-1 signal significance: 3.5s SLHC (two exps, 3000 fb-1each)signal of 11s HSM m+m- 120 < MH < 140 GeV, LHC (600 fb-1)significance: < 3.5s, SLHC (two exps, 3000 fb-1each) ~ 7s J. Nash - CMS SLHC Issues

  16. Detector ChallengesCMS from LHC to SLHC 1032 cm-2 s-1 1033 1035 1034 The tracker is the key detector which will require upgrading for SLHC Phase 2 I. Osborne J. Nash - CMS SLHC Issues

  17. Radiation environment for trackers Except for the very innermost layers many current technologies should survive SLHC R. Horisberger J. Nash - CMS SLHC Issues

  18. CMS Pixel system can be removed in a very short time period J. Nash - CMS SLHC Issues

  19. Trial insertion of Pixel system Insertion of the Pixel was done in a few hours J. Nash - CMS SLHC Issues

  20. Phase I issues for tracking • Rough estimate of pixel layer lifetimes 4cm layer should survive a minimum of 200fb-1 • Will have to replace the pixel detector during phase I • How often? • How much to replace? • New features • Looking at reducing the material in the replacement pixel detector, and potentially adding a fourth layer • Outer tracker looks robust to survive Phase I J. Nash - CMS SLHC Issues

  21. Limitations in Phase 1 • Radiation damage due to integrated luminosity. • Sensors designed to survive 61014neq/cm2 ( 300 fb-1 ). • n-on-n sensors degrade gradually at large fluences 300 fb-1 • Dead time will rise to 12% due to increase in peak luminosity 500 fb-1 J. Nash - CMS SLHC Issues

  22. BPIX Optionsfor 2013 replacement/upgrade – R. Horisberger Option 0 1 2 3 4 5 Layer/Radii 4, 7, 11cm 4, 7, 11cm 4, 7, 11cm 4, 7, 11cm 4, 7, 11cm 4, 7, 11, 16cm Modules 768 768 768 768 768 1428 Cooling C6F14 C6F14 CO2 CO2 CO2 CO2 Pixel ROC PS46 as now 2x buffers 2x buffers 2x buffers 2xbuffer, ADC 160MHz serial 2xbuffer, ADC 160MHz serial Readout analog 40MHz analog 40MHz analog 40MHz analog 40MHz m-tw-pairs digital 320MHz m-tw-pairs digital 640 MHz m-tw-pairs Power as now as now as now as now as now DC-DC new PS as 2008 J. Nash - CMS SLHC Issues

  23. CMS - What stays, what goes phase 2 Much of CMS is well shielded and Built to last through SLHC J. Nash - CMS SLHC Issues

  24. Reminder what CMS will need to upgrade This will stay! HCAL Barrel crystal calorimter J. Nash - CMS SLHC Issues

  25. Tracker Readied for Transport to Pt5 This will be replaced J. Nash - CMS SLHC Issues

  26. Key issues for tracker upgrades(Not just more channels!) • Power • How to get current needed to the electronics • More complicated front ends, more channels may want more power • DC-DC converters, Serial powering • Material Budget • Can we build a better/lighter tracker? From Physics TDR Vol 1 (LHCC 2006-001) J. Nash - CMS SLHC Issues

  27. The effect on physics of large pile-up • We need to evaluate how well we can extract any physics at all in the presence of up to 400 pile-up events per crossing • This is not a trivial study • Technically difficult • Also depends on geometry of a new tracking device • Timescale for full answers is more like years than months • CMS Tracker simulation group has been creating tools for modeling new tracker designs • Expect detailed simulation results from “strawman” designs in the coming year J. Nash - CMS SLHC Issues

  28. Tracking with 500 min Bias events • Efficiency • Fake Rate nhit > 12 • Study of current CMS tracker for Heavy Ion events • Track density very similar to 50ns running • dnch/dh/crossing ≈ 3000 • Tracker occupancy very high • Need more pixel layers/shorter strips • Tracking possible • When tracks are found they are well measured • Efficiency and fake rate suffer • CPU Intensive Inner layers of strips reach 30% occupancy on every xing! Pixel layers Transverse Impact Parameter Resolution Momentum Resolution C. Roland J. Nash - CMS SLHC Issues

  29. Level 1 Trigger Level 1 Trigger has no discrimination for PT > ~ 20 GeV/c • The trigger/daq system of CMS will require an upgrade to cope with the higher occupancies and data rates at SLHC • One of the key issues for CMS is the requirement to include some element of tracking in the Level 1 Trigger • One example: There may not be enough rejection power using the muon and calorimeter triggers to handle the higher luminosity conditions at SLHC • Adding tracking information at Level 1 gives the ability to adjust PT thresholds • Single electron trigger rate also suffers • Isolation criteria are insufficient to reduce rate at L= 1035 cm-2.s-1 J. Nash - CMS SLHC Issues

  30. Cone 10o-30o ~dET/dcosq Amount of energy carried by tracks around tau/jet direction (PU=100) Tracking needed for L1 trigger@ 1035 Muon L1 trigger rate L= 1034 Single electron trigger rate Isolation criteria are insufficient to reduce rate at L= 1035 cm-2.s-1 L= 2x1033 5kHz @ 1035 Standalone Muon trigger resolution insufficient τ We need to get another x200 (x20) reduction for single (double) tau rate! MHz

  31. Concepts:Tracking Trigger γ Search Window High momentum tracks are straighter so pixels line up Pairs of stacked layers can give a PT measurement • Why not use the inner tracking devices in the trigger? • Number of hits in tracking devices on each trigger is enormous • Impossible to get all the data out in order to form a trigger • How to correlate information internally in order to form segments? • Topic requiring substantial R&D • “Stacked” layers which can measure pT of track segments locally • Two layers about 1mm apart that could communicate • Cluster width may also be a handle Geometrical pT-cut - J. Jones, A. Rose,C. Foudas LECC 2005 J. Nash - CMS SLHC Issues

  32. Example PT module Correlator Data out 64 x 2 128 x100µm x 2x2.5mm 12.8mm data 2 x 2.5mm Such a design has potential for inexpensive assembly, using wire bonding, with low risk and easy prototyping Vertex 2008

  33. Pt - Trigger for TOB layers R Horisberger W Erdmann Two-In-One Design 50mm strips 2mm 2 x DC coupled Strip detectors SS, 100m pitch ~8CHF/cm2 Strip Read Out Chip 2 x 100m pitch with on-chip correlator wire bonds Hybrid spacer 2mm 1mm track angular resolution ~20mrad  good Pt resolution W.E. / R.H.

  34. More Realistic Strawman A • A working idea from Carlo and Alessia • Take current Strawman A and remove 1 “TIB” and 2 “TOB” layers Strawman A r-phi view (RecHit ‘radiography’) 4 TOB short strips Remove 2 2 TOB strixels Adjust chn count 2 TIB short strips Remove 1 2 TIB strixels Adjust chn count 4 inner pixels Vertex 2008

  35. More Realistic Strawman B • Adjust granularity (channel count) of Strawman B layers • Keep the TEC for now until someone can work on the endcaps Strawman B r-phi view (RecHit ‘radiography’) r-z view Vertex 2008

  36. Endcap CSC Muon Phase 1 Upgrade (ME4/2) “Empty” YE3 ready for ME4/2 J. Nash - CMS SLHC Issues R-Z cross-section

  37. Phase 1 : Muons ME4/2 upgrade motivation Compare 3/4 vs. 2/3 stations: (Triggering on n out of n stations is inefficient and uncertain) Recent simulation with & without the ME4/2 upgrade: The high-luminosity Level 1 trigger threshold is reduced from 48  18 GeV/c Target Rate 5 kHz Rick Wilkinson, Ingo Bloch J. Nash - CMS SLHC Issues

  38. RE RE RE RE RE RE RE RE RE RE RE RE 1/1 1/2 1/3 2/1 2/2 2/3 3/1 3/2 3/3 4/1 4/2 4/3 No. of chambers 36*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2 18*2 36*2 36*2 The start up RPC endcap system RE i/3 Three stations up to h = 1.6 REi/1 REi/2 J. Nash - CMS SLHC Issues SLHC workshop, CERN, May 2008 G. Iaselli on behalf of CMS RPC group

  39. RPC trigger efficiency Trigger CMS TDR, four stations Importance of high h restoration CMSSW 1.7.5, three stations Importance of four stations restoration J. Nash - CMS SLHC Issues SLHC workshop, CERN, May 2008 G. Iaselli on behalf of CMS RPC group

  40. CMS HCALs Had Barrel: HB Had Endcaps:HE Had Forward: HF HO HB HE HF J. Nash - CMS SLHC Issues

  41. HF Damage • Tower 1 loses 60% of light during LHC, down to 4% of original after SLHC. • Tower 2 down to 23% after SLHC. • SLHC “kills” a few high eta towers. Andre Gribushin J. Nash - CMS SLHC Issues

  42. Calorimeters/Muons Phase 2 • ECAL • Crystal calorimeter electronics designed to operate in SLHC conditions • VPT in Endcap and Endcap crystals themselves may darken at SLHC • Very difficult to replace – Highly activated • HCAL • HF may be blocked by potential changes to the interaction region • HF/HE vital in looking for WW scattering • Both Calorimeters suffer degraded resolution at SLHC • affects electron ID, Jet resolutions – • simulations needed • Increased segmentation for HCAL may help – SiPM • MUON • system front end electronics look fairly robust at SLHC • Cathode Strip Chambers/RPC Forward : Drift Tubes /RPC Barrel • Trigger electronics for the muon systems would most likely need to be replaced/updated • Some Electronics is “less” radiation hard (FPGA) • Coping with higher rate/different bunch crossing frequency • May have to limit coverage in ( > 2) due to radiation splash • This effect will be known better after first data taking, potential additional cost of chamber replacement J. Nash - CMS SLHC Issues

  43. Upgrade Scope J. Nash - CMS SLHC Issues

  44. Documents Phase I Upgrades Phase 2 Upgrades J. Nash - CMS SLHC Issues

  45. Next Steps • Produce an Integrated project plan for Phase I • Large number of systems expect to produce upgrades many of which involved interleaved installation issues • Some of these are already rather advanced and need to be integrated into the planning • Define timescales/scopes for reviews of each upgrade • PDR > ESR/EDR > PRR? • Request milestones/deliverables down to level … for each project • TDR > Production > Installation > • Start to track these milestones • Will require resources J. Nash - CMS SLHC Issues

  46. Planning for Phase 2 • Too early for detailed planning of phase 2 upgrades • Must understand the overall scope of the upgrade • This is driven by the geometry/functionality of the new tracker • Simulations will be vital in understanding • Tracker TP should focus the direction of upgrades in other systems which may depend on tracker functionality • For example the inclusion of tracking information in the trigger • Build a detailed plan by the time of the phase 2 TDRs • Will also have a much clearer idea of the machine timescales • However a key issue which may come up earlier than this is the date of the long shutdown J. Nash - CMS SLHC Issues

  47. Implications of Early Separation • Could we do this without replacing HF? • No way without obscuring part of the detector • But perhaps lower eta region still usable • Will the HF still be useful at SLHC J. Nash - CMS SLHC Issues

  48. What about maintenance? Triplet moves closer to IP These wheels move for maintenance Either D0 has to clear the EE, or it has to move for maintenance J. Nash - CMS SLHC Issues

  49. Forward beampipe LHC thin pipe 13-16 m believed good for 1034 pp CASTOR & TOTEM easily installed/removed for special runs (eg heavy ion), interspersed with high lumi pp SLHC wide pipe (400mm) after HF and in its shadow J. Nash - CMS SLHC Issues

  50. Infrastructure modifications: Yoke Reinforced Shielding inside forward muons: up to h~2 --> automatically implies replacement of inner CSC, RPC (alternatives with protection from new high h HE/EE not considered) Supplement YE4 wall with borated polythene Improve shielding of HF PMT’s possibility of increased YE1-YE2 separation to insert another detector layer? J. Nash - CMS SLHC Issues

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