Transcript Document
Chris Parkes The LHCb Upgrade Thanks to my LHCb Collaborators for advice/results/speculations… Vertex 2005, November 2005, Nikko • Why Upgrade ? •Trigger System •Radiation Hard Vertex Detector VElo Superior Performance Apparatus 1 Dedicated B System CP violation Experiment B , Bd,0 s, c , baryons •Full spectrum of B hadrons: • Bs system,All angles, sides of both CKM s •Lots of events ! σbb 500 μb, O (1012) bb pairs per year Dipole magnet Tracking system Muon system Calorimeters Vertex Locator p 10 mrad p RICH detectors 2 Velo Rôles • Primary / b decay Vertex reconstruction • Stand alone Tracking – A principle tracking device for the experiment • Second Level Trigger 1m – Fast tracking R / Phi measuring sensors •In vacuum •Retract each fill One set of half disks •Align each fill 3 Yet another B-Factory ? • LHCb - Dedicated B physics experiment at LHC designed for precision study of CP violation and rare decays – – – – BTeV Cancelled BaBar Closure forseen Super-Belle ? Likely to be only B-Factory in LHC era • LHCb now 47 institutes in 16 countries > 600 authors • But what is left to do after the B-factories? 4 What Did the 1st Generation B-Factories Do For Us ? • Spectacular progress from the B-factories: Baseline measurement ACP (J/y KS) 21.7 11..23 Agreement with Standard Model CKM • Impressive range of additional measurements •Significant constraints on 22 16 95% CL 5 Some Puzzles left by the B factories….. • New physics in b s ? – – – – • sin 2b s = sin 2b c? see in Bs f f ? increased BR for Bs mm ? Higher frequency ms ? Larger CP violation in Bs J/yf •Bs–Bs oscillation ms as Standard Model •CDF or D0 measure ? If beyond SM… •LHCb VELO / trigger required dms > 14.5 ps-1 xs > 21.1 (95% CL) 6 After 3 Years of LHCb….. • 3 Years of LHCb data taking – 1 day at LHCb = 100d at B Factory ! • In event rate but hadronic environment…. – Bs Oscillations measured LHCb: st = 43 fs • SM <25 ps-1, CDF • LHCb ms reach 68 ps-1 – measured • Theory error ~1% will be matched by LHCb ~ 5yrs – measured J/y K0 • theory error < 1%, 1 yr statistical error sin(2) 0.02 7 B Physics after 2010 (What will NOT be known after 3 years of LHCb running ?) 1. Precision Gamma (< 5 degrees) – Theoretically very clean, error only ~ 0.1% ! B D0 K Bs0 DS K • Improved vertex Resolution equiv. to more stats • Rare B-decays Bs0 m m •SM BR at most 3.5x10-9 ! • 5 events per 2 fb-1 (S/N Bd0 m m •SM BR at most 1.5x10-10 !! •Requires upgrade etc. •“Tree” only •New Physics in D mixing? • The other Triangle…. BsJ/yf Weak mixing phase 3:1) •Proper-time resolution important •8 independent parameters to determine 8 But NOT Limited by LHC Number of pp interactions/ beam crossing 1. Pile-up at high luminosity • B mesons identified by separation of primary interaction vertex and decay vertex (few mm) • Displaced Vertex trigger • 2nd level of triggering • Multiple Interactions • Limit Event reconstruction Defocus LHC beams •ATLAS/CMS 1034 cm-2s-1 but LHCb 2x1032 cm-2s-1 most events have single interactions Could LHCb cope with higher Luminosity ? 1033 cm-2s-1 2. Extreme Radiation Environment in VELO 9 Increase Luminosity – Trigger System • LHCb would have to cope with multiple interactions •Veto on multiple interactions ! •Trigger based on: •High pT Muons •& calorimeter clusters •4 of 10 benchmark LHCb channels have m+m- in final state 1st Level Trigger Rate (MHz) Existing 1st Level Trigger Trigger on BsJ/yfmmKK 5 X Yield Number of 4 X Yield Triggered Events 3 X Yield 2 X Yield Std. Yield Luminosity (x1032) Enhanced Rare B-decay Programme WITHOUT Trigger upgrade Radiation Damage, Occupancy 10 1st Level Trigger Rate (MHz) Trigger on BsJ/yfmmKK 1.8 X Yield Std. Yield Number of Triggered Events Hadron Channel Trigger •High ET Trigger not sufficient 1st Level Displaced Track Trigger Latency 4ms, 2ms for data processing Luminosity (x1032) • Massive use of FPGAs can allow us to make a Vertex trigger in ~2010 – BTeV assumed they could do this in 2009 – (though 132 ns not 25 ns) • Need pt information ? – Magnetic Field in VELO or include other silicon stations 11 Pile-Up Veto System •Two planes of R-measuring sensors •Identical to VELO sensors •Placed up-stream from interaction point •Strips ORed in groups of 4 •256 80 Mbit/s links per hybrid •Optical links to rad-free barracks •FPGA processing performed 12 Pile-Up Veto: Principle •Tracks from same ZPV have the ZPV - ZA same ratio k k RA RB = ZPV - ZB B k’ A Silicon Sensors (backward!) RA RB k ZB ZA ZPV ZPV’ • Histogram combinations • Find peaks – s(Zvtx) 2.8 mm – s(beam) 53 mm Primary Vertex 1 Primary Vertex 2 13 Displaced Vertex Trigger Current 2nd Level Trigger algorithm performed in CPU Farm 2D rz VELO tracking 2D Tracking –Tracks from beam line form straight lines in rz Primary Vertex search 2D track selection 3D rfz VELO tracking 3D confirm L0 m match 3D IP VELO-TT matching p, pT estimation L1 decision 3D Tracking –Add info. From Phi measuring Sensors –Only for displaced track candidates Add PT Information –Use silicon stations after magnet •Total: 1ms not 2ms ! 14 System Configuration Outline In Radiation Free zone R projection only Tasks 8 Clustering & Triplet finding & merging 4 sectors per half Track Identification & filtering Track merging Two halfs • 35 processing modules •2 crates • 2200 optical links •36 multi ribbon cables (8x8) – Vertex identification – Impact parameter calculation – Final vertex trigger decision 15 Extreme Radiation Environment • LHCb VELO will be HOT! Middle station Far station •Maximum Fluence •1.3x 1014 NIEL 1 MeV neq/cm2/year at 8mm •3.3x 1014 NIEL 1 MeV neq/cm2/year at 5mm •6.6x 1014 NIEL 1MeV neq/cm2/year at 8mm at 1033 •Strongly non-uniform • dependence on 1/r2 and station (z) VESPA needs 1015 neq/cm2 charged particle tolerance 16 Radiation Damage: When replace VELO? • Testbeam results, Simulations • System components specified to 500V • Confident to run to 300V •Maintain a reasonable S/N performance •6fb-1 (3-4 years) at 300V 17 Radiation Hard Technologies • Cz, n-on-p, 3D, or pixel technologies – – Active R&D, with RD50 Czochralski n-on-p 3D Extreme rad. hard For 4.5 x 1014 24 GeV p/cm2 Depletion voltage = 19V !!! 18 Strips or Pixels? • Both potentially rad. hard – 3D, Cz, n-on-p or hybrid pixel detectors BTeV • Pixels better pattern recognition properties – Not major problem (Velo trk eff 97.3%, ghosts 2.3%) – But could be trigger advanatge • Require approx. 50 mm2 pixels – Achieve same resolution as Velo • Strip geometry more `natural’ – Tesselate, strixels – But if you can read-out the pixels who cares ? • Material – Less pixel layers (not R/Phi) – Detector, Chip and services (cooling) • X0 per layer 1.2% (BTeV), 1.7% (CMS), 1.8% (ATLAS) • Thin electronics, typically 500mm, achieve 200mm 19 Move Closer 5mm limit from Accelerator • Current safe guard ring design 1mm • Edgeless technology exits – Dope edges – etch, laser cut Baseline first strip 8mm 7.1mm 10% improvement in IP Impact Parameter Sensor Design with 5mm active radius Simulation •RF foil removed •VELO Inner radius 5 mm •36% improvement ! 8mm VELO 5mm VELO 20 Material Budget: RF-foil Total: 19%Xo VELO RF-foil 250mm BTeV •BTev - 150mm thick wires/foil, 6mm from beam •In primary vacuum •Cryo panels for absorb outgassing •TOTEM •1mm from beam (v. diff optics) •150mm foil 21 Prototype in LHC ! • Four free station slots available – Equipped with cooling tubes • Can Prototype in the LHC ! – Add extra tracking points, and small amount of extra material 22 Conclusions • Rich Physics Programme for LHCb after 2010 • 1 st Upgrade at LHC, Increased lumi. – Necessitated by radiation environment • FPGA based Displaced Vertex Trigger – at 1 st Level of Triggering • VElo Superior Performance Apparatus – Radiation tolerant Si technologies – RF foil redesign • Reduce material, Move closer to beam Thus the Vespa came to be linked in my eyes with transgression, sin, and even temptation…. And it entered into my imagination not as an object of desire, but as a symbol of an unfulfilled desire." Umberto Eco 23 24 25