Commissioning, operation and first physics results

1

• Commissioning, operation and first physics
  results
• of the CDF Run2a Silicon
• and
• status of its future upgrade for Run2b
• Gino Bolla
• Purdue University
• For
• CDF RUN2 Silicon Group

2
CDF RunII (The need for a strong tracker)

• Physics with 2-9 fb-1
• Precise Measurements of Mtop and MW
• CP violation, Bs mixing
• More
• B,C quarks tagging is crucial
• Long lifetime (mm to cm)
• Vertex finding
• High impact parameter resolution
• Efficient trigger
• SVT (secondary Vertex Trigger)
• Fast (_at_L2) displaced tracks trigger.

SVXII ISL L00 7-8 silicon layers 722000
ch rf, rz views z0max45 cm, ?max2 1.3ltRlt30cm
COT 30240 ch, 96 layer drift chamber s(1/pT)
0.1/GeV s(hit) 150mm
3
A top candidate

• Typical travel distances
• Bottom 5 mm
• Charm 1 mm
• Impact parameter resolution
• 35 mm in F
• Will improve by using L00

4
CDF Silicon (What does it look like)
SVXII
Use L00/SVXII for vertexing trigger high
density precise alignment crucial! Use ISL for
tracking simpler design precise alignment not
so important
L00
ISL

• 1 layer (L00) very close to the beam improve IP
  res. b-tagging

• HIGHLIGHTS
• High speed
• Dead-timeless operation
• Displaced track trigger

• 5 layers (SVXII) very compact in r,f,z 3D
  vertexing tracking

• 1 central / 2 forward layers (ISL) at large
  radius tracking

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SVXII the center piece
10.6 cm
2.5 cm

• 5 double sided layers
• 3 x 90o and 2 x 1.2o
• Very compact
• Tight alignment tolerances
• For the trigger
• Very symmetric
• Many (maybe too many) different components

x
y
Note wedge symmetry
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ISL on the outside and L00 on the inside

• Precision position measurement before scattering
• One SS layer on the Beam pipe
• 25 mm pitch (50 mm readout)
• Low material budget
• High Radiation
• Actively cooled LHC-like sensors
• Electronic at larger radii

ISL
L00

• One central layer
• Link tracks from COT to SVXII
• Two forward layers (2 m long)
• Extend tracking up to h2 (COT stops at 1)
• Simpler design
• Not used on the trigger (relaxed alignment)
• Hybrids mounted OFF silicon
• A single flavor
• Lot of space (compared to SVXII)

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The heart of it all (the SVX3d chip)

• Analog Front End (FE) and Digital Back End (BE)
• Compatible with 396/132 nsec bunch spacing
• FE has relatively low noise integrator with 128
  channels and 46 cell analog pipeline with 4
  buffer cells
• BE has comparator, 8-bit Wilkinson ADC, and
  sparse readout with neighbors logic
• Dead-timeless
• Capable of analog operations during digitization
  and readout
• Dynamic pedestal subtraction
• Enables on-chip common mode noise suppression

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Integration and Commissioning

• A long list of troubles to deal with
• Most of them specific to the CDF system
• Others are of common interest
• A good monitoring strategy
• First look at the whole thing as a piece of
  hardware
• Second look at it as a particle detector
• Now 90 is producing good data for physics

Wire-bonds with current in the 100 mA range if
pulsed at the right frequency can oscillate due
to small (10-50 mg) Lorentz forces because
resonance behaviors can be excited. Fatigue
induces cracks on the heel and the electrical
continuity is lost

• Large effort on the offline as well
• Clustering
• Alignment
• Tracking algorithms

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Performance (1)
Single hit Efficiencies99
dE/dx particle identification
S/N gt10
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Performance (2)

• Measurements using triggered J/Psi candidate
  events since January 2003 shutdown.
• No background subtraction is performed.
• A further 3 increase on efficiency is expected
• Performing a background subtraction (about 1).
• Improvements of ISL alignment and retuning of the
  the tracking road sizes (about 2 )

Average tracking Efficiency is 87.8 0.1 (stat)
Average fake rate is 1.7 0.4 (stat)
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Performance (3)

• At a higher level things get more complicated
• B-tagging efficiencies in the 40-50
• Visible degradation of performances in the
  regions between barrels
• Will improve in the future
• Adding L00 will help in between barrels
• h coverage will increase by using ISL
• Lots of CDF physics talks at this conference

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SVT (Secondary Vertex Trigger)

• Input (L1A 10-40 KHz)
• Outer drift chamber trajectories
• Silicon pulse height for each channel
• Output ( 20 ms later)
• Trajectories that use silicon hits
• 150 VME boards
• Find and fit silicon tracks with offline
  accuracy In 15 microseconds
• look for 2 tracks with
• impact parameters gt 120 mm

L1 5.5ms, synchronous, fast programmable logic
(CAL, m, COT tracks)
L2 30ms, asynchronous, programmable logic CPU
(jets, silicon tracking)
L3 200 PCs spend 1s/event on full reco
(full-precision tracking, form masses, etc.) 140
separate trigger paths (e, m, t, n, g, jet,
displaced track, b-jet, )
a few mm
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SVT performance
500
d (mm) vs f (raw)
0
-500
0 p 2p
500
d (mm) vs f (subtracted)
0
-500
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A paper with only 12 pb-1

• Results M(Ds) M(D)
• 99.41 0.38 0.21 MeV/c2
• PDG 99.20.5 MeV/c2

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What is there ahead of us
Until the LHC turn-on, the Fermilab Tevatron has
the highest energy collisions and is the only
place to search for the Higgs and other new
particles. The Run II Physics Program extends to
5-15 fb-1. Expected life of the Run IIa Silicon
detector 4-5 fb-1 . Run IIb Silicon Detector
replaces the inner 6 layers with an improved and
radiation tolerant detector. Need to be built in
a very tight schedule
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The CDF Run2b Silicon

• Improvements in RunIIb Design
• Rad hard RO chips (0.25mm technology)
• Extension of the contained b-jets region
  (active length 1.2 m vs 0.9m in RunIIa)
• larger and more uniform radial distribution (R
  2.1 16.4 cm compared to 1.3-10.6cm in RunIIa)
• Good impact parameter resolution with low mass L0
  design
• Strengthened inner tracking - redundant axial
  layers at L1
• Larger radius outer staves - better connection to
  ISL
• Fewer component parts 4-chip hybrids used on 93
  of staves

Layer 0 12 fold Axial Layer 1 6 fold
Axial-Axial Layer 2 12 fold Axial-Stereo
(1.2o) Layer 3 18 fold Axial-Stereo (1.2o) Layer
4 24 fold Axial-Stereo (1.2o) Layer 5 30 fold
AxialAxial
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Run2b Silicon
Well advanced project
prototype stave

• the SVX4 chip works!
• the stave concept works!
• prototyping of most components finished
• most parts well in time

prototype barrel
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Summary

• The CDF silicon detector is doing its job and
  produces good data necessary for the physics
  program of the experiment
• A lot of struggling during the commissioning
• A well organized maintenance plan in place
• The innovative Fast displaced tracks trigger is
  enhancing the experiment capabilities
• Still work to be done to fully exploit the Si
  capabilities (L00 and ISL on the offline
  analysis)
• The TeV program extends over the lifetime of the
  existing hardware
• To fully explore the potential for new physics at
  CDF the RUN2b silicon is approaching its
  production phase.