Upgraded D Detector and B Physics D Detector

Upgraded D Detector and B Physics • D Detector Upgrade at Run II Overview • Focus on Inner Tracker and the Trigger • B physics in D , mainly sin(2 b) • Preliminary performance report using real data Collider – Accelerator Department, June 6, 2002 Kin Yip (Physics Dept. )

The Tevatron Run II Tevatron upgrade: • Increased energy 1. 8 Te. V 1. 96 Te. V • Increased luminosity 0. 1 fb-1 2 fb-1 15 fb-1 (Run 1) Detector upgrades: • Higher event rates and backgrounds (electronics, DAQ, trigger) • Considerable expansion of the physics capabilities (Run 2 a) (Run 2 b) CDF D 0 Physics opportunities: • Top • Higgs • New Phenomena • Electroweak • Beauty • QCD Run 1 b Run 2 a Run 2 b #bunches 6 x 6 36 x 36 140 x 103 s (Te. V) 1. 8 1. 96 1. 6 x 1030 8. 6 x 1031 5. 2 x 1032 Ldt (pb-1/week) 3. 2 17. 3 105 bunch xing (ns) 3500 396 132 interactions/xing 2. 5 2. 3 4. 8 typ L (cm-2 s-1)

Run II Physics Prospects: High-p. T Ø Some highlights * Top physics * Electroweak Ø Improvements in Run II * increased statistics * better jet energy measurement * better b-tagging · · * Ø Ø RUN II (2 fb-1 per experiment) silicon tracker w/ preshower info better muon finding Precision Measurements * MW from ~80 -90 Me. V to ~40 Me. V per experiment * Mtop from ~6 Ge. V to experiment ~2 -3 Ge. V per There is a chance that Higgs may be discovered at Fermilab … Constraints to Higgs * precision measurements of W, Z bosons, combined with Fermilab’s top mass, set an upper limit of MH ~ 212 Ge. V * direct searches for Higgs production exclude MH < 114. 1 Ge. V

The DØ Detector The DØ upgrade builds upon the strengths of the existing detector (excellent calorimetry, muon coverage) and augments it with a high resolution Silicon/Scintillating Fiber tracker. • calorimeter: replacement of preamps/shapers • muon system: –replacement of muon chamber readout electronics –Iarocci drift tubes replace forward muon chambers –central and forward scintillator pixel layers enhance trigger capability. • DAQ & trigger: add track and vertex triggering, add buffering, add processing power • central tracker: – 2 T supraconducting coil inside r=70 cm calorimeter bore –lead/scintillator preshower detector with fiber/VLPC readout – 16 layer Sci. Fi/VLPC tracker (80 k channels) – 4 barrel / 16 disk Silicon tracker (1 M channels) • forward tracker/preshower: scintillator cells with fiber/VLPC readout

DØ Tracking l Solenoid l l 2 Tesla superconducting calorimeter cryostat 1. 1 Central Fiber Tracker (CFT) – – 16 doublet layers of Sci-Fi ribbon • 8 axial (parallel to the z-axis) TRIGGER • 8 stereo(2 o pitch), NOT used in TRIGGER 76, 800 830 m fibers (multiclad) coverage: 20<r<52 cm, polar angle to ~22 In the radial plane, CFT is divided into 80 sectors (4. 5 ) • Silicon Tracker • Preshowers 1. 7 50 cm • Central • Forward 1. 3 m z-axis

Designed DØ Upgraded Detector Performance – Good Momentum resolution: • – (Silicon + Scintillating Fiber Trackers) High tracking efficiency: • – dp. T/p. T 2 ~ 0. 002 at least 95 % | | < 3. 5 (disks) Vertex Reconstruction: primary vertex: svertex ~ 15 -30 m (r- ), 50 m (r-z) • secondary vertex: svertex ~ 40 m (r- ) , 100 m (r-z) • – – Excellent lepton coverage, trigger and ID efficiency: • muons: p. T > 1. 5 Ge. V, | | < 2 • electrons: p. T > 1. 5 Ge. V, | | < 2. 5 Impact parameter trigger

CFT: Performance (cosmic ray test) Ø Cosmic Ray Test Results: * Scintillating Fiber Tracker (axial and stereo fiber doublets) with full electronic readout chain Ø Ø Doublet position resolution: ~100 m Doublet Efficiency: > 99. 5% * probability that signal from a doublet is greater than threshold Stereo (u, v) Axial (z) CFT ribbons: r– view of an alternative stereo and axial (interlocking) doublet configuration

Particle signatures with preshowers: (e. g. , FPS) * Particle electron pion o pion muon Ø “MIP” Layer + “Lead” radiator + “Shower” Layer MIP deposition Shower cluster (FPS Layers 1, 2) “Upstream” (FPS Layers 3, 4) “Downstream” Yes No Yes (MIP hit) narrow wide little energy (MIP) (MIP hit) Particles traversing the FPS detector: electron L 1 L 2 -Pb-L 3 L 4 pion o; ( ) L 1 L 2 -Pb-L 3 L 4 Particle signature in FPS four layers: MIP and Shower (50 Ge. V MC generated events, passed through DØ Detector Simulater)

Trigger Schematic 7 MHz, 132 ns crossing times* Detector L 1 Trigger 7 MHz L 1 Frame work 4. 2 s 5 -10 k. Hz 128 bits L 2 100 s 1000 Hz 128 bits L 3 1 k. Hz 10 k. Hz CAL L 1 CAL FPS CPS L 1 PS L 2 PS CFT L 1 CFT L 2 CFT Muon FPD L 2 Cal L 1 Muon L 2 Muon L 1 FPD Maintain Run I e, jet, acceptance L 1 FW: towers, tracks Deadtime: <5% (due to pipeline) Global L 2 STT SMT 100 ms 50 nodes Accommodate : L=2 x 1032 cm-2 s-1 & 20 -50 Hz Bunch Crossings 132 ns * L 2 Trigger L 2 FW: Combined objects (e, , j)

L 1 Trigger Overview · Fiber hit pattern recognition in the CFT and PS to look for tracks consistent with momentum PT > 1. 5 Ge. V/c · Match with the Calorimeter showers and Muon hits L CA CPS CFT e- PS & CAL are matched for each quadrant

Visible Light Photon Counters Scintillating Fiber Optical Connector Mirror Waveguide Fiber Photodetector Cassette VLPC Cryostat Electrical Signal Out

ANALOG/DIGITAL BOARDS LVDS links (> 20 Gbits/s) M I X I N G B O X 8 or 12 MCM board 2 Trigger Sectors per board • Each MCM (Multi Chip Module) has 1 SVX(ADC) and 4 SIFT (discriminator); • CFT axial fiber signals are all managed by “ 8 MCM” boards; • CPS/CFT(stereo)/FPS fiber signals are all mixed in the “ 12 MCM” boards;

CFT and PS Front-End Qin VLPC X% of Qin 18 18 SIFT 18 Discriminator Out 1 -X% of Qin Each CFT/CPS Analog board has 8/12 MCM’s 18 VLPC SVX 72 inputs X% of Qin 18 SIFT 18 Discriminator Out 8 Data, 1 DVALID to Level 3 Discriminator Out 18 1 -X% of Qin 18 18 SIFT Threshold A Discriminator Out Threshold B MCM * Charge splitting only for Pre. Shower

Track Trigger Algorithm • There are 80 sectors in CFT, each subtending 4. 5 ; Sector boundary Track • Seamless tracking requires fiber sharing between nearest sectors; • Tracks with PT 1. 5 Ge. V are contained within 2 neighbor sectors; • Fiber hits are transmitted from a sector to either side for track matching. CFT Sector 1 CFT Sector 2 No crack in tracking

Track Trigger Algorithm (cont. ) • Basic algorithm : matching hit patterns in all 8 layers (A, B, …, H) with a preprogrammed set of “equations” ; • Compute allowed trajectories ( equations ) analytically for all possible tracks for momentum PT 1. 5 Ge. V; • based on the fact PT magnetic field strength (2 T) radius of curvature; • equation - a set of 8 fiber indices; • There about >16000 equations for each sector ; • Algorithm uses 8 out of 8 doublet layers; • with an option to require only 7 out of 8 layers at highest PT later in the run; • Use the outermost layer (8 th layer, H layer) as the anchor layer (reference layer) where there are 44 fibers in each sector.

Track Trigger Algorithm (cont. ) • The equations can be downloaded to the Programmable Logic Devices (PLD) on the FE boards as many times as you like; • Use the largest PLD’s available (each with several 105 logic gates) to handle the trigger logic; • Use HDL (Hardware Description Language)* to implement the tracking logic like: T 1013172227323945 = A[10] AND B[13] AND C[17] AND D[22] AND E[27] AND F[32] AND G[39] AND H[45] ( There are >16000 of them in each sector ! ) * There are quite a few ways (schematic/various languages) to program the PLD’s.

Track Equations in HDL T 1520243035404652 <= AL(15) AND BL(20) AND CL(24) AND DL(30) AND EL(35) AND FL(40) AND GL(46) AND HL(52) ; T 1520253035404652 <= AL(15) AND BL(20) AND CL(25) AND DL(30) AND EL(35) AND FL(40) AND GL(46) AND HL(52) ; T 1520253035414652 <= AL(15) AND BL(20) AND CL(25) AND DL(30) AND EL(35) AND FL(41) AND GL(46) AND HL(52) ; T 1620253035404652 <= AL(16) AND BL(20) AND CL(25) AND DL(30) AND EL(35) AND FL(40) AND GL(46) AND HL(52) ; T 1620253035414752 <= AL(16) AND BL(20) AND CL(25) AND DL(30) AND EL(35) AND FL(41) AND GL(47) AND HL(52) ; T 1620253036414752 <= AL(16) AND BL(20) AND CL(25) AND DL(30) AND EL(36) AND FL(41) AND GL(47) AND HL(52) ; p(8) <= T 1520243035404652 OR T 1520253035414652 OR T 1620253035404652 OR T 1620253035414752 OR T 1620253036414752 ; Equations with the H-bin and PT bins are OR-ed together.

Track Trigger Algorithm (cont. ) • Input fiber patterns are matched with the equations tracks at certain (PT, ) bin; • A matrix of PT (H fiber position) : PT • Scan the matrix “horizontally” in groups and put in priority encoder which outputs the indices of PT bins with the highest priority; 1 -D list of indices and concatenated in a binary tree structure down to a list of 6 (tracks with the highest PT) in each PT threshold; · A mixture of parallel/serial modes to reduce latency while keeping resources low.

PLD Simulation Testing Result: • Algorithm and timing have been tested in the vendor software simulation and implemented in a trigger test board with PLD’s; • The measured timing in the real PLD’s agrees very well with the simulation and the result of the trigger logic is what is expected. simulation result Tracking logic < 85 ns completed

Monte Carlo Simulation • FORTRAN C++ code in Run II software framework • Full monte carlo simulation studies using the D upgrade configuration in GEANT (d gstar) have been done in various physics samples. • Single electron/muon samples are used to tune the efficiency of the trigger algorithm. For PT >3 Ge. V, efficiencies: • >97% for muons and • ~95% for electrons, limited by multiple scattering and various radiation effects. • Plot shows how the CFT trigger efficiencies when different sets of equations (belonging to certain PT thresholds) are used.

CFT track efficiency CFT Track efficiencies only for tracks from beam spot

Trigger Efficiency vs Impact parameter

# of Equations vs PT/offset NPT ~ 1/PT

Typical B physics spectrum B Physics requires triggers at Low Pt

Track Binning • PT binning yields sharper turn-on than offset binning offset = [(projection of H layer fiber hit on A layer) - A layer fiber hit] in units of fibers Eqn # }15% } 20% } 50%

Trigger Tracking Algorithm • From Monte Carlo simulation studies, we can limit ourselves by allowing only 2 tracks in each PT bin and 6 tracks in each of the 4 PT thresholds in each sector virtually without losing any tracking efficiency. • Need 2 tracks because of extra hits at high luminosity which create a fake track (7 points on original track and 1 fake). • Fake track can be higher or lower in PT than the real one. • ~90% — only 1 track passes through a fiber ; • ~10% — 2 tracks pass through a fiber. • Only 48 tracks per broadcaster. Inefficiencies

Misalignment increase in number of CFT track equations Case considered : misalignment Cylinder surface C One end CFT l y C FT Shift The other end is x A r inde CFT

Misalignment Effect • If I give a d /dz such that at the end of C layer, fibers are gradually (and linearly) shifted by 4 mils ( like a stereo layers ) almost no inefficiency. • The outer layers are more susceptible to misalignment effect. H CFT layers C A Interaction point z-axis

B Physics challenge at Tevatron Large production cross section Even larger inelastic cross section (S/B 10 -3) specialized triggers: Single lepton triggers Dilepton triggers such as J/ + Track triggers moved to L 1 (Run. II) In Run II, L 2 trigger on displaced tracks using SVX will allow CDF/D to trigger purely hadronic B decays and study such as B 0 + , Bs Ds +. . . Precise 2 nd vertex reconstruction At 2 Te. V At Z 0 At (4 S)

CP Violation in B J/ + KS CP violation can be manifested as: CP violation in the decay CP violation in the mixing if the neutral mass eigenstates are not CP eigenstates CP violation in the interference between decays with and without mixing to a CP eigenstate V* t b W B 0 d td d W t B 0 b Direct and mixed decays interfere with different amplitudes - leading to different decay rates into the same CP eigenstate: CP VIOLATION J/ K 0 s B 0 B 0 J/ K 0 s B 0 Time dependent asymmetry

The Cabibbo-Kobayashi-Maskawa Matrix In SM, CP violation arises from a single (complex) phase in the CKM matrix (in Wolfenstein parameters): ( which transforms (u, c, t) to (d, s, b) and vice versa. ) – A and l have been measured to a few percent (l is the sin of the Cabibbo angle) – CP violation is put into the formalism with the complex phase h – unitarity condition: gives the unitarity triangle ( , ) a g (0, 0) b (1, 0)

Sin(2 ) and CKM matrix elements According to previous unitary triangle : For Bd J/ + Ks , it involves sin(2 ) B 0 -B 0 Mixing Ratio of K 0 -K 0 mixing

Golden channel for sin( 2 b ) Asymmetry (in the Standard Model) is directly related to sin 2 : = sin(2 ) sin( mdt) b is one of the 3 angles in the unitary CKM triangle This is a “golden” channel due to: • readily accessible final states with small background • relatively large branching ratio • negligible theoretical uncertainty • penguin amplitude is expected to be small since cc pair must be popped from vacuum • penguin diagram contribution to the asymmetry has the same phase as tree level

Sin(2 ) via B J/ + KS – full reconstruction of final state – same side flavor tag B b – opposite side flavor tags |Qjet| > 0. 2 + KS – measure decay length – tag flavor at production + + J/ • two V’s • soft pions • lepton charge • jet charge - - • pion charge b Efficiency (e) and dilution factor (D) D = 2 P – 1 = (NR –NW) / (NR +NW) P is the correct tag probability e. D 2 is the tag’s effectiveness

B J/ KS Reconstruction • It looks like we can reconstruct KS + -. DØ Run II GEANT (cm) DØ GEANT/Trig. Sim.

B J/ KS Reconstruction • Combined m +m - + invariant mass • (before fit) RECO MCFAST (with vertex constraint fit) ( Ge. V )

Flavor Tagging Note : Observerd Asym. CP = D • Asym. CP

Current Measurement of sin(2 ) CDF Run I: +0. 41 sin 2 =0. 79 -0. 44 (stat. + sys. ) BABAR: sin 2 =0. 75 0. 09 (stat. ) 0. 04 (sys. ) BELLE: sin 2 =0. 99 0. 14 (stat. ) 0. 06 (sys. )

Sin 2 b Expectations for 2 fb-1 For a time dependent analysis: – (S/B ~ 0. 75) – e D 2 ~ 9. 8 % – st ~ 128 fs assuming luminosity ~ 2 fb-1 { as in the report “B Physics at the Tevatron : Run II and Beyond”, hep-ph/0201071 [FERMILAB-Pub-01/197]. }

The Past Year • • About 40 pb-1 delivered so far Used for commissioning of – Detectors – Offline processing – Worldwide data access – Analysis • e, , jets, EM and jet energy scales, etc. Instrument Fiber Tracker Detector commissioning, timing, improve electronics, DAQ and offline First Collisions Run 2 start reconstruction processing ~ 12 pb-1 now on tape DØ detector roll-in (SAM)

Silicon Microstrip Tracker Status K 0 signal, silicon standalone tracking 100% commissioned Barrels: 95. 2% operational F-disks: 95. 8% operational H-disks: 86. 5% operational Barrels + disks Barrels only Work in progress: Integrating disks into tracking KS 0 p+p- p-side pulse-height 1 MIP 4 f. C 25 ADC counts S/N > 10 Efficiency > 96%

Central Fiber Tracker (CFT) - 20 cm < r < 51 cm - 8 layers of axial and stereo 830 mm scintillating fibers - ~12 m long clear wave-guide to Visible Light Photon Counter (VLPC) • 9 K operating temperature • 85% QE, excellent S/N (SMT+CFT) Global tracks - ~77 k readout channels p. T>3 Ge. V - Fast pick-off for trigger DCA resolution ~ 60 m (unaligned!) Completed CFT Mechanical beam spot ~ 30 -40 m Fiber Tracker Electronics Axial: complete Stereo: recently completed y track x CFT tracks DCA: Distance of Closest Approach

Muon System Muon system 100% commissioned shielding Muons + CFT J/ signal, central + fwd triggers work in progress Mean = 3. 08 ± 0. 04 Ge. V Sigma = 0. 78 ± 0. 08 Ge. V J/ + Muon System standalone

Present status of the DØ tracker performance (2) Data: sx = 46 m; sy = 43 m; Beam spot size = 30 m MC: sr = 30 -33 m for PV with ntracks > 14 After beam spot subtraction, very good agreement between MC and real data

Present status of the DØ tracker performance Impact Parameter resolution in data is close to Monte Carlo simulation { IP’s calculated usingle tracks }

Trigger simulation running on real data

Physics analysis is starting • Physics and object ID groups are very active • Interesting events being collected, point to our future physics direction – +MET candidate extra dimensions (ee+ ) W candidate – W+4 jets = top candidates Electron MET j 1 j 2 j 3 trilepton candidates (SUSY) e j 4 e e e

Future …. . . • Finish detector commissioning • Debugging, calibration, alignment • Continue refining reconstruction algorithms • Full tracking secondary vertexing, electron id (J/ ee) … • Complete triggers and improve DAQ • Level 2 trigger coming online • Level 1 central track trigger Summer 2002 • Level 2 silicon track trigger End summer 2002 • Hope for the best luminosity

CFT: System Performance ~14. 5 pe Pulse Height Read-out Platform: Waveguides and VLPCs Ø Detector installed and hooked-up to VLPCs Ø Measure MIP response: light-yield * 11. 2 m clear light-guide * doublet: 14. 5 photoelectrons (light-yield ~ 3 -4 higher than minimum required for efficient tracking)

CFT: Performance (cont. ) Ø Ø p. T resolution * p. T/p. T ~ 8% for at = 0 p. T = 45 Ge. V Importance for DØ * E/p matching for e-id * Calorimetry calibration * Muon momentum resolution * Charge sign determination

Analog/Digital Front End • 80 identical Analog Front End (AFE) boards mounted on 40 VLPC cassettes; • 40 identical Digital Front End mother boards in two 6 U VME crates ; • each DFE mother board processes two sectors of the detector independently, one on each of two daughter boards ; • In each daughter board, there a few Programmable Logic Devices (PLD) involved to make trigger logic decisions – PLD is used because it is fast and can be reprogrammed; • Collector/Broadcaster system (using the same DFE mother boards) to organize trigger information to be sent to L 1 trigger framework and L 2 preprocessor.

Truncation effect

Silicon Microstrip Tracker — Geometry — 4 -layer barrel cross-section Ø Interspersed Barrel/Disk Design * * * 6 -silicon barrel sections (4 -layers per barrel): (r- info) Layers 2, 4: double-sided, 2 o-stereo Layers 1, 3 of 4 inner-barrels (about z = 0): double-sided, 90 o-stereo Layers 1, 3 of 2 outer-barrels: singlesided F-Disks: (r- and r-z info) double-sided, 15 o-stereo H-Disks: (r- and r-z info) · 2 single-sided detectors, 7 o-stereo Ø Operate at ~10 o. C Ø Total of 792, 576 channels Ø Read out by SVX-II chips Ladder (layer 4) Beryillium 72 ladders 12 cm-long bulkhead Cooling channel Carbon-fiber half-cylinder support SMT Summary

Misalignment increase in number of CFT track equations

Silicon Microstrip Tracker (SMT) Ø Precision measurement of charged particle tracks upto | | < 3. 0, region Ø Interspersed disk/barrel design Ø Radiation hard to 1 Mrad Ø Performance/Expectations: * * near interaction Hit resolution: 10 m Secondary Vertex resolution · r- : 40 m · r-z: 80 m * Tagging Efficiency at p. T = 50 Ge. V · ~50% for b-quark jets, ~10% for c-quark jets · ~ 0. 5% fake tag rate for u, d, s quarks jets z=0 12 F-Disks Beam Line 4 H-Disks (forward, high- ) 6 Barrel sections/modules

How many Bd may we get ? assuming luminosity ~ 2 fb-1

Muon Triggers PT(B)> 4 Ge. V and | | < 3 max level 2 rate for all DØ triggers is 1000 Hz DØ GEANT/Trig. Sim.