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Super LHC - SLHC

Super LHC - SLHC. LHC Detector Upgrade Dan Green Fermilab. Outline. Physics Basics Z’ vs Rapidity Range Minbias Pileup and Jets Occupancy and Radiation Dose Tracker Upgrade Calorimetry Muons Trigger and DAQ.

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Super LHC - SLHC

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  1. Super LHC - SLHC LHC Detector Upgrade Dan Green Fermilab

  2. Outline • Physics Basics • Z’ vs • Rapidity Range • Minbias • Pileup and Jets • Occupancy and Radiation Dose • Tracker Upgrade • Calorimetry • Muons • Trigger and DAQ CERN-TH/2002-078 “Physics Potential and Experimental Challenges of the LHC Luminosity Upgrade” [10x will be challenging]

  3. Mass Reach vs L VLHC LHC Tevatron The SLHC defines a decades long LHC Physics program. In general mass reach is increased by ~ 1.5 TeV for Z’, heavy SUSY squarks or gluinos or ~ 20% of extra dimension mass scales. A ~ 20% measurement of the HHH coupling is possible for Higgs masses < 200 GeV. However, to realize these improvements we need to maintain the capabilities of the LHC detectors.

  4. Kinematics 5 TeV 1 TeV barrel y barrel Heavy States decay at wide angles. For example Z’ of 1 and 5 TeV decaying into light pairs. Therefore, for these states we will concentrate on wide angle detectors.

  5. LHC SLHC s 14 TeV 14 TeV L 1034 1035 100 1000 Bunch spacing dt 25 ns 12.5 ns N( interactions/x-ing) ~ 12 ~ 62 dNch/d per x-ing ~ 75 ~ 375 Tracker occupancy 1 5 Pile-up noise 1 ~2.2 Dose central region 1 10 Detector Environment Bunch spacing reduced 2x. Interactions/crossing increased 5 x. Pileup noise increased by 2.2x if crossings are time resolvable.

  6. Pileup and Luminosity • For ~ 50 mb, and = 6 charged pions/unit of y with a luminosity and a crossing time of 12.5 nsec : • In a cone of radius = 0.5 there are ~ 70 pions, or ~ 42 GeV of transverse momentum per crossing. This makes low Et jet triggering and reconstruction difficult.

  7. WW Fusion and “Tag Jets” Pileup, R=0.5, |y|=3 These jets have ~ pileup R = 0.5 and <y> ~ 3. Lose 5x in fake rejection. We must use the energy flow inside a jet cone to further reduce the fake jets due to pileup (~ uniform in R). WW fusion

  8. Tracking Detectors • Clearly, the tracker is crucial for much of the LHC physics [e.g. e, , jets (pileup, E flow), b tags]. • The existing trackers will not be capable of utilizing the increased luminosity as they will be near the end of their useful life. • It is necessary to completely rebuild the LHC tracking detectors.

  9. Tracker - Occupancy • The occupancy, O, for a detector of area dA and sensitive time time dt at (r,z) is • e.g. Si strip 10 cm x 100 m in a 12.5 nsec crossing at r = 20 cm is 1.5 % • For higher luminosity, decrease dA, or decrease dt (limit is x-ing time) or increase r – smaller, faster or further away.

  10. Tracker Occupancy • Preserve the performance using : • Push Si strips out to ~ 60 cm. – development • Push pixels out to 20 cm. – development • For r < 20 cm. Need new technologies – basic research • Shrink dA 5x at fixed r to preserve b tagging? If 12.5 nsec bunch x-ing, need 5x pixel size reduction. • Possibilities • 3-d detectors – electrodes in bulk columns • Diamond (RD42) - radhard • Cryogenic (RD39) – fast, radhard • Monolithic – reduced source capacity.

  11. Tracker ID vs. Radius 1 2 3 naive Define 3 regions. With 10x increase in L, need a ~ 3x change in radius to preserve an existing technology. The ID scales as ~

  12. 10mm P. Sharp Industry 1mm Research 0.1mm 1985 2000 Electronics – Moore’s Law • Micro-electronics: line-widths decrease by a factor 2 every 5 years. DSM (0.25 m) is radiation hard.Today 0.13 m is commercially available. In the lab 0.04 m, e.g. extreme UV lithography, is in existence. Expect trend will continue for a decade. • R&D • Characterize emerging technologies •  more radiation tolerance required – dose and Single Event Effects •  advanced high bandwidth data link technologies • system issues addressed from the start

  13. HCAL and ECAL Dose ecal hcal naive The dose ratio is ~ . Barrel doses are not a problem. For the endcaps a technology change may be needed for 2 < |y| < 3 for the CMS HCAL. Switch to quartz as in HF? SD ~ ID/sin.

  14. HCAL - Coverage Reduced forward coverage to compensate for 10x L is not too damaging to “tag jet” efficiency, SD ~ 1/3 ~ e3

  15. Scintillator - Dose/Damage |y|=2, 1 yr. This technology will not survive gracefully at |y| ~ 3. Use the technology that works at LHC up to |y|~ 5, quartz fibers/plates ?

  16. Muons and Shielding There is factor ~ 5 in headroom at design L. With added shielding, dose rates can be kept constant if angular coverage goes from |y|<2.4 to |y|<2. r r z

  17. Trigger and DAQ • Assuming LHC initial program is successful, raise the trigger thresholds? • Rebuild trigger system to run at 80 MHz? Utilize those detectors which are fast enough to give a BCID within 12.5 nsec (e.g. Calorimetry, Tracking, Muon?). • Examine algorithms to alleviate degraded e isolation, for example. • Design for the increased event size (pileup) with reduced L1 rate and/or data compression. • For DAQ track the evolution of communication technologies, e.g. 10 Gb/sec Ethernet.

  18. Level-1 Trigger Table (2x1033) Steeply falling spectra. Use muons and calor only? Jets and muons ~ clean  HLT is resolution on spectral “edge”

  19. Level-1 Trigger Table (1034) L1 Trigger on leptons, jets, missing ET and calib/minbias. Does this suite cover all the Physics we want?

  20. L1 at 1035 ? • Muons are ~ clean. Issue of low momentum muons from b jets. Jets are ~ clean. ECAL jets are mostly “garbage”  need tracker to make big L1 improvements. • Rutherford scattering ~ 1/PT3.

  21. Higgs Self Coupling Baur, Plehn, Rainwater HH  W+ W- W+ W-   jj jj Find the Higgs? If the H mass is known, then the SM H potential is completely known  HH prediction. If H is found, measure self-couplings, but ultimately SLHC is needed. CMS will not, in all scenarios, be moving to higher masses. Sometimes rarer processes must be measured at the same mass scale.

  22. HLT Summary: 2x1033 cm-2s-1

  23. HLT Performance — Efficiency Gains in HLT? Tracker (pixel) biggest gain for e. Single muon and electron still the highest rates.

  24. Level-1 Trigger • Trigger Menus • Triggers for very high pT discovery physics: no rate problems – higher pT thresholds • Triggers to complete LHC physic program: final states are known – use exclusive menus • Control/calibration triggers with low thresholds (e.g. W, Z and top events): prescale • Impact of Reduced Bunch Crossing Period • Advantageous to rebuild L1 trigger to work with data sampled at 80 MHz ? Work out the consequences • Require modifications to L1 trigger and detector electronics • Could keep some L1 trigger electronics clocked at 25 ns? • R&D Issues • Data movement is probably the biggest issue for processing at 80 MHz sampling • Processing at higher frequencies and with higher input/output data rates to the processing elements. Technological advances (e. g. FPGA ) will help • Synchronization (TTC) becomes an issue for short x-ing period

  25. HCAL Timing

  26. Summary • The LHC Physics reach will be substantially increased by the higher luminosity of the SLHC program. • To realize that improvement, the LHC detectors must preserve performance. • The trackers must be rebuilt – with new technology at r < 20 cm. • The calorimeters, muon systems, triggers and DAQ will need development. • The upgrades are likely to take ~ (6-10) years. Accelerator is ready ~ (2012, 2014). The time to start is now. • The work on the SLHC for CMS are beginning.

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