Commissioning Results of the D Tracking System

1
Commissioning Results of the DØ Tracking System

• Design
• Installation and Commissioning
• Tracking/Vertexing Results

• Harald Fox
• Northwestern University
• May 24, 2002

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The Fermilab Tevatron Collider
3
The DØ Detector
antiprotons
4
Tracker Design
5
SMT Design
12 F Disks
4 H Disks
6 Barrels

• 4-layer barrel cross-section

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SMT Design

• Require good 3D track reconstruction performance
  for high-pT (top, Higgs, EW, NP) and low-pT (B)
  tracks out to ? lt 3
• Momentum resolution less than 10 at pT 1 GeV/c
• Impact parameter resolution within 30 ?m
• Forward H disks are employed to achieve these
  resolutions at high ?

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SMT Readout Electronics

• Interface Boards
• Refresh signals and adjust timing
• Power management and monitoring
• SEQencers
• Management of SVX
• Conversion to fiber optics
• VRB (VME Readout Buffer)
• Data buffer pending L2 trigger decision
• 50 Mb/s/channel
• 5-10 kHz L1 accept
• ?1 kHz L2 accept rate

• SVX IIe Chip
• 128 channel, 32 pipeline cells
• 8 bit ADC with sparsification
• 106 MHz digitization, 53 MHz readout
• Radiation hard
• Developed by LBL/Fermilab group

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CFT Design

• 8 layers of axial and 3 stereo fibers mounted on
  carbon fiber support cylinders.
• 20cm lt r lt 51cm.

• 76,800 individual fibers.
• Diameter 835µm. Length 1.8/2.6m.
• The interlocked fibers are precisely positioned.
• Hit resolution about 100µm.

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CFT Readout Electronics

• 8-11m long wave-guides to Visible Light Photon
  Counter (VLPC, solid state photo multiplier).
• VLPCs are operated at 9K. Quantum efficiency
  80.
• 1 mip 8 photo electrons ? Excellent S/N!

• High gain 17k 65k e per photon
• AFE boards provide
• Bias voltage
• Temperature control
• Fast digital trigger information
• Analog pulse information (SVX)
• SEQ VRB readout as SMT

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Installation

• Fiber tracker installation
• Cylinder installation was completed on 12/20/00
• A ½ cylinder of 3 barrels and 6 F disks was
  inserted into each end of the CFT bore
• H Disk installation was completed on 2/6/01
• The cabling (15,000 connections) and electronics
  installation was completed in May 2001
• Axial Fiber Tracker electronics installed in
  November 2001
• Stereo electronics completed April 2002

SMT cylinder
Interface Boards
Low Mass Cables
High Mass Cables
SMT
Calorimeter
Cryostat with AFE boards
Wave guides
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SMT Charge Collection

• Cluster charge (corrected for track angle) 1 mip
  25 ADC counts. Noise lt 2ADC counts.

• Charge correlation between p- and n-side of a
  detector

fL 4.5

• Lorentz angle The charge deflection due to the
  magnetic field

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CFT Commissioning
Z?ee candidate event. Mass 89.9GeV/c2
Light yield per sector vs pseudorapidity ?
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Tracking and Vertexing
CFT-SMT track matching
Impact parameter resolution
Vertex measurements
DCA
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Physics Results
E/p for W?e? candidates
KS ? pp- cand.
Z ? µµ- cand.
J/? ? µµ- candidates
First evidence for B decays
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Conclusions

• Design
• The DØ tracking detectors are designed to have a
  good impact parameter resolution over a wide
  range of ?.
• Commissioning
• The SMT was the first major DØ Upgrade detector
  system fully operational for Run 2A.
• About 95 of the channels are available for
  readout.
• Results
• Calibration, beam measurement, and alignment
  results are looking promising.
• Physics results coming in.
• Noise studies, tracking refinements, etc.
  continue.

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The work of many people...thanks to all of
them.
The DØ Collaboration
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Lorentz angle
P-side (axial)
Phi distribution for one strip clusters
h
e-

• Lorentz angle is different for p- and n-sides
• Lorentz shift is not visible for 90 deg stereo
  strips
• Lorentz shift is large for 2 deg stereo
• Lorentz angle can be measured in local phi
  distribution for one strip clusters
• Measurement is NOT affected by alignment or
  reconstruction

Data p-side
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SMT Design Stereo Angles

• Ladders
• 3-chip 72 single-sided, axial ladders in the two
  outer barrels
• 6-chip 144 double-sided, axial/90 ladders in
  the four inner barrels
• 9-chip 216 double-sided, axial/2 ladders in all
  barrels
• Wedges
• F Disks 144 double-sided, 15, 68 chip wedges
• H Disks 962 back-to-back single-sided, 7.5, 6
  chip wedges

9-chip ladder
H wedge
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Production Assembly Testing

• Probe Test
• Debug bad strips (broken capacitors), bonds,
  chips, etc.
• Determine the V-I characteristics of the sensors
• Measure V-max p-side breakdown voltage
  (micro-discharge effect)
• Burn-in
• Bias the ladder or wedge and test the readout for
  72 hours
• Measure pedestals, noise, gain and check sparse
  readout
• Laser
• Expose biased detectors to a narrow laser scan
• Measure the depletion voltage and leakage
  currents and identify dead channels
• Readout tested again after the detector has been
  mounted.

V-max
Fail
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SMT Readout Data Flow
HV / LV
I,V,T Monitoring
8 Low Mass Cable
19-30 High Mass Cable (3M/80
conductor)
25 High Mass Cable (3M/50 conductor)
3/6/8/9 Chip HDI
KSU Interface Board
CLKs
CLKs
Adapter Card
SEQ
SEQ
SEQ
Sensor
SEQ Controller
Optical Link 1Gb/s
Detector volume
Platform
Serial Command Link
VRB
VRB
VRB
VBD
68k/PwrPC
1 5 5 3
VRB Controller
Bit3
VME
PC
L3
MPM
Counting House
SDAQ
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Alignment Residuals

• SMT-only tracking with at least 4 hits
• Magnet off data
• Similarity of residuals from reconstruction with
  ideal and survey geometries indicates excellent
  internal alignment of the SMT

Ideal Geometry
Survey Geometry