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The LHCb experiment

USA. Brazil. Ukraine. Finland. France. UK. Switzerland. Germany. PRC. Romania. Russia. Italy. Netherlands. Spain. The LHCb experiment. Poland. Outline. Physics motivation LHCb at LHC The LHCb detector Front-End electronics Timing and Fast Control (TFC) DAQ Conclusions.

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The LHCb experiment

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  1. USA Brazil Ukraine Finland France UK Switzerland Germany PRC Romania Russia Italy Netherlands Spain The LHCb experiment Poland Richard Jacobsson, CERN

  2. Outline • Physics motivation • LHCb at LHC • The LHCb detector • Front-End electronics • Timing and Fast Control (TFC) • DAQ • Conclusions Richard Jacobsson, CERN

  3. Physics motivation 1 • Ultimate questions: • Matter - Anti-matter imbalance in the Universe • CP violation a la Standard Model not sufficient Least tested aspect of the Standard Model • Flavor physics : More accurate Standard Model measurements in this sector (some parameters known with an accuracy level of only O(30%) • Flavor Changing Neutral Currents? (Not in SM) • New physics beyond the Standard Model • More CP violation Richard Jacobsson, CERN

  4. u c t d s b d sb d’ s’b’ d sb = V Lcc = 2-1/2g (u, c, t)LgmVW+m+ h.c. VudVus Vub VcdVcs VcbVtdVts Vtb VCKM = Physics motivation 2 Yukawa couplings involve quarks from different generations ==> eigenstates of the weak interaction not the same as the mass eigenstates W- That is b c Kobayashi and Masukawa 1973 VCKM not diagonal. The structure of the charged current coupling is t b c s u Richard Jacobsson, CERN

  5. 1-l2/2l Al3(r-ih) -l 1-l2/2 Al2Al3(1-r-ih) -Al2 1 VCKM ~ Im a Vtd/(l|Vcb|) (1-l2/2)V*ub/(l|Vcb|) g b Re r(1-l2/2) Physics motivation 3 In addition, introducing complex phase into the three-generation mass matrix generates CP and T violation in weak interaction---> (too) small in SM ==> So far, only observed in K mesons (1964) Supersymmetry, left-right symmetric model, leptoquark, …all extensions have strong influence. AIM: Measure flavor parameters as accurately as possible Ex: Unitarity conditions (V+CKMVCKM = 1) Wolfenstein parametrization: VudVub + VcdVcb + VtdVtb = 0 Richard Jacobsson, CERN

  6. Physics motivation 4 • |Vcb|, |Vub|, |Vtd| ==> r and h ==> calculate a, b, g • Also measuredirectlya, b, g from CP asymmetries: • b + g from B0dp+p- (background B0d K+p-) • b from B0d J/y Ks • g from B0dD0K*0, D0K *0 ,D01K*0 • B0d - B0d and B0s - B0s oscillations • Rare b-decays Richard Jacobsson, CERN

  7. LHCb • LHC is the most intensive source of Bu, Bd, Bs and Bc and b-baryons • 1012 b-pairs per year (75 kHz) • Branching ratios of interesting channel 10-5 - 10-4 • 5 Hz interesting events • LHCb emphasis: • B decay reconstruction • Particle identification (K/p: ~1GeV/c < p < 150GeV/c) • Trigger efficient for both leptonic and hadronic final states.(ATLAS and CMS: no real particle ID and only with lepton triggers Richard Jacobsson, CERN

  8. LHCb detector 1 Richard Jacobsson, CERN

  9. LHCb detector 2 • Spectrometer: • A single-arm spectrometer covering qmin = ~15 mrad (beam pipe and radiation) to qmin = ~300 mrad (cost optimisation) i.e. h = ~1.88 to ~4.89 • has an equal bb acceptance • as a large central detector. • Locally tunable luminosity Richard Jacobsson, CERN

  10. LHCb Detector 3 Calorimeters Tracker Coil Yoke Shieldingplate RICH-1 ~20m Muons Vertex RICH-2 Richard Jacobsson, CERN

  11. High PT leptons photons hadrons High PT muons Pile-up veto Level-0 decision unit LHCb Trigger (L0) 40 MHz crossing rate 1 MHz accept rate Richard Jacobsson, CERN

  12. SN CN CN CN CN CN CN SN CN CN CN CN CN CN CN SN CN Computing Node SN CN CN CN CN CN y SN CN CN CN CN CN CN Source Node SN CN CN CN CN CN CN SN CN CN CN CN CN CN LHCb trigger (L1) • Purpose • Select events with detached secondary vertices • Algorithm • Based on special geometry of vertex detector (r-stations, -stations) • Several steps • track reconstruction in 2 dimensions (r-z) • determination of primary vertex • search for tracks with large impact parameter relative to primary vertex • full 3 dimensional reconstruction of those tracks • Technical Problems: • 1 MHz input rate, ~4 GB/s data rate, small event fragments, latency restrictions Richard Jacobsson, CERN

  13. LHCb Read-out LHC-B Detector Data rates VDET TRACK ECAL HCAL MUON RICH 40 MHz Level 0 Trigger 40 TB/s Level-0 Front-End Electronics Level-1 1 MHz Timing & Fast Control L0 Fixed latency 4.0 ms 1 TB/s 40 kHz L1 Level 1 Trigger LAN 1 MHz Front-End Multiplexers (FEM) Front End Links 6 GB/s Variable latency <1 ms RU RU RU Read-out units (RU) Throttle Read-out Network (RN) 6 GB/s SFC SFC Sub-Farm Controllers (SFC) Variable latency L2 ~10 ms L3 ~200 ms Control & Monitoring Storage 50 MB/s Trigger Level 2 & 3 Event Filter CPU CPU CPU CPU Richard Jacobsson, CERN

  14. Front-End electronics Richard Jacobsson, CERN

  15. CERN TTC system 1 • Developed in the CERN RD12 project: Timing, Trigger and Control distribution system • Used by all LHC experiments • Transmitting two channels multiplexed • Low latency 40 MHz • Encoded long and short broadcasts Richard Jacobsson, CERN

  16. CERN TTC system 2 • LHC: Distribute LHC clock (40.08 MHz) and LHC orbit signal (11.246 kHz) to experiments over fiber with minimal jitter (~8ps RMS) • Experiments: Distribute clock, trigger and control commands to the detectors over fiber with minimal jitter Prevessin Control Room Experimental hall Richard Jacobsson, CERN

  17. Timing and Fast Control 1 Richard Jacobsson, CERN

  18. Timing and Fast Control 2 • Experiment orchestra director • Readout Supervisor • Clock, trigger and command distribution and support partitioning • TFC switch • Throttle feed-back • Throttle Ors and Throttle switches (L0 & L1) Richard Jacobsson, CERN

  19. ECS Throttles LHC clock L0 L1 ECS interface - Module - Clock distribution(TTC) Trigger generator - L0 distribution (TTC) - L1 distribution (TTC) Trigger controller - Auto-trigger generator Reset/command generator - Trigger controller - Reset/cmd generator RS Front-End L0/L1 - “RS Front-End” TTC encoder - ECS interface Ch A/B DAQ Timing and Fast Control 3 Readout Supervisor: Richard Jacobsson, CERN

  20. Timing and Fast Control 4 Richard Jacobsson, CERN

  21. Note: There is no central event manager Timing & Fast Control LAN Front-End Multiplexers (FEM) Front End Links 6 GB/s RU RU RU Read-out units (RU) Throttle 6 GB/s Read-out Network (RN) SFC SFC Sub-Farm Controllers (SFC) Variable latency Control 50 MB/s L2 ~10 ms & CPU CPU Storage L3 ~200 ms Monitoring Trigger Level 2 & 3 CPU CPU Event Filter LHCb DAQ 1 • Readout Units (RUs)/Front-End Multiplexers (FEM) • Multiplex input links (Slink) onto Readout Network links (RU) or Slink (FEM) • Merge input fragments to one output fragment • Destination assignment for Readout Network • Readout Network • provide connectivity between RUs and SFCs for event-building • provide necessary bandwidth (6 GB/sec sustained) • Subfarm Controllers (SFCs) • assemble event fragments arriving from RUs to complete events and send them to one of the CPUs connected • dynamic load balancing among the CPUs connected • CPU farm • execute the high level trigger algorithms • execute reconstruction algorithm • Processing needs: ~100 kSI95, i.e. ~1000 processors Richard Jacobsson, CERN

  22. LHCb DAQ 2 - RU • Two alternative approaches to Readout Unit/FE Multiplexer • 1. Customized hardware Richard Jacobsson, CERN

  23. LHCb DAQ 3 - RU • 2. Software driven Readout Unit on IBM network processor • The IBM NP4GS3 is a network processor designed for wire-speed switching/routing and frame manipulation • It can handle over 4.5 Million packets per second on 4 1-Gigabit full duplex links • It is fully software programmable Richard Jacobsson, CERN

  24. FEM FEM FEM FEM FEM FEM FEM FEM FEM FEM FEM DAQ RU DAQ RU GbE GbE GbE GbE GbE GbE GbE GbE GbE GbE GbE Phy Phy Phy Phy Phy Phy Phy Phy Phy Phy Phy GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII Mem Mem PCI PCI IBM NP4GS3 IBM NP4GS3 Ethernet Ethernet Switch Bus DASL ECS ECS CC CC - - PC PC Switch Bus DASL Switch Bus Switch Bus Mem Mem IBM NP4GS3 IBM NP4GS3 GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII GMII Phy Phy Phy Phy Phy Phy Phy Phy Phy Phy Phy Phy GbE GbE RN RN LHCb DAQ 4 - RU • Readout Unit implementation Richard Jacobsson, CERN

  25. LHCb DAQ 5 - FEM • Front-End Multiplexer implementation Richard Jacobsson, CERN

  26. LHCb DAQ 6 - SubFarm Sub Farm Architecture Richard Jacobsson, CERN

  27. Conclusions • Exciting years ahead with design and flavor physics • Two TDRs submitted (September 2000) • Calorimeters • RICHes • Building the LHCb readout system is progressing well • DAQ TDR end of the year, a lot of work ahead • Timing and Fast Control Richard Jacobsson, CERN

  28. Richard Jacobsson, CERN

  29. LHCb RICHes RICH1: 5cm aerogel n = 1.03, 2-11 GeV 4 m3 C4F10 n = 1.0014, 10-70 GeV RICH2: 100 m3 CF4 n = 1.0005, 17-150 GeV HPD Richard Jacobsson, CERN

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