The RunII D0 Calorimeter Electronics Upgrade

1
The RunII D0 CalorimeterElectronics Upgrade
Its PerformanceNirmalya ParuaState University
of New York Stony BrookCalor 200210th
International Conference on Calorimetry in High
Energy Physics CalTech, Pasadena March 25-29,
2002
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Tevatron Run I (1992-96)

• Very successful Run I
• p-pbar collisions at vs 1.8 TeV
• ò L dt 120 pb-1 delivered to DØ and CDF
• Peak luminosity 1.6 x 1031 cm-2 s-1
• Many exciting studies, including
• Top discovery
• Mt 172.1 ? 5.2 (stat.) ? 4.9 (syst.) GeV/c2
• ?tt 5.9 ? 1.7 pb (DØ combined)
• W mass measurement
• MW 80.482 0.084 GeV (DØ combined)
• Limits on anomalous gauge couplings
• Limits on SUSY, LQ, compositeness, other exotica
• Tests of QCD Electroweak
• b-quark physics
• 116 published papers
• gt60 PhD theses

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Fermilab Accelerator Upgrade

• Two new machines at FNAL for Run II
• Main Injector
• 150 GeV conventional proton accelerator
• Supports luminosity upgrade for the collider
• Recycler
• 8 GeV permanent magnet (monoenergetic)
• storage ring
• permits antiproton recycling from the collider
• Tevatron Status and Schedule
• 1.8 Tev ? 1.96 TeV
• Goal ò L dt 2 fb-1 in Run 2a
• 15 fb-1 in Run 2b
• Run II started in March 2000.
• Very first p-pbar collisions seen (April 2000)

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Bunch Structure
Detector readout and trigger system upgrade must
take into account smaller bunch crossing time
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Overview of D0 Upgrade

• Upgrade Calorimeter Readout
• Add scintillator detector in muon system for
  faster trigger
• Silicon and Fiber tracker with 2 Tesla solenoid
  magnetic field for central tracking and momentum
  measurement.
• Add Pre-shower detectors.
• Pipelined 3 Level trigger

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Calorimeter Overview

• Liquid argon sampling
• Stable, uniform response, rad. hard, fine spatial
  seg.
• LAr purity important (Discussed in detail in A.
  Bessons talk)
• Uranium absorber (Cu or Steel for coarse
  hadronic)
• Compensating e/? ? 1, dense ? compact
• Uniform, hermetic with full coverage
• h lt 4.2 (? ? 2o), l int gt 7.2 (total)
• Energy Resolution
• e sE / E 15 /ÖE 0.3 p sE / E 45
  /ÖE 4

No Change in upgrade
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Intercryostat Detector (ICD)
FPS

• Objectives
• Improve coverage for the region
• 1.1 lt ? lt 1.4
• Improves jet ET and ET
• Maintain the performance in the presence of a
  magnetic field

• Design
• Scintillator based with phototube readout similar
  to Run I design. Re-use existing PMTs
  (Hamamatsu R647).
• 16 supertile modules per cryostat with a total of
  384 scintillator tiles
• WLS fiber readout of scintillator tiles
• Clear fiber light piping to region of low field
  40-50 signal loss over 5-6m fiber.
• Readout/calibration scheme for electronics same
  as for L. Ar. Calorimeter but with adapted
  electronics and pulser shapes
• LED pulsers used for PMT calibration
• Relative yields measured gt 20 p.e./m.i.p.

ICD
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Upgrade of Calorimeter Readout

• Objectives and Performance Criteria
• reduced minimum bunch spacing from 3.5 ?s to 396
  ns (132 ns at RunII B).
• Storage of analog signal for 4 ?s for L1 trigger
  formation
• Generate trigger signals for calorimeter L1
  trigger
• Maintain present level of noise performance and
  pile-up performance
• Methods
• Replace preamplifiers
• Replace shapers
• Add analog storage
• Replace calibration system
• Replace timing and control system
• Keep Run I ADCs, crates and most cabling to
  minimize cost and time

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Upgrade of Calorimeter Readout
Cable replaced for impedence matching
Trig. sum
Bank 0
Calibration
SCA (48 deep)
peak
SCA (48 deep)
x1
Filter/ Shaper
Preamp/ Driver
base
x8
Calorimeter
SCA (48 deep)
SCA (48 deep)
Bank 1
1
48
A n. D r
A D C
55k readout channels
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Preamplifier

55296 hybrids
1152 boards
FET

• New calorimeter preamp
• Hybrid on ceramic
• 48 preamps on a motherboard
• New low-noise switching power supplies in steel
  box

New output Driver for terminated signal
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Base Line Subtracter (BLS)
ADCs have 12 bit dynamic range. To achieve 15
bit dynamic range SCAs have low and high gain
path for each readout channel (X8/X1) SCAs are
not designed for simultaneous read/write
operations. Two banks of SCAs, upper and lower
(cant see in the picture), for alternate
read/write operation. Readout time 6 µs (length
of SCA buffers 132 X 46 gt6 µs). Trigger tower
formation 0.2 X 0.2 for Level 1.
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Timing Control cards

• Receives trigger, accelerator, clock information
• Samples BLS shapers at the signal peak and base.
• Keeps track of the memory location of crossings.
• Generates busy signal when system is not ready.
• Coordinates pulser calibration.

12 TC boards and 1 controller board is used
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Impedance Measurement
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Debugging and Noise
Presently we have very few bad readout channels
(lt0.1)
We are using 2.5? as the zero suppression limit
while taking data. Fine Tuning this limit is
underway.
Shows the level of Noise
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Finer Debugging
x8
down
L1 SCA
? ? ? ? ?
up
?
?
?
x1
L2 SCA
?
ADC

• Most problems are traced to SCA chips with slower
  settling time.
• More than 250 SCA chips (1) have been replaced

Mean value
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Coherent Noise Studies.

• Normalized Covariance
• (1/n) ? ( Xi Xave ) ( Yi Yave ) / ( ?x
  ?y )

Look at the coherence with other channels. Check
the noise introduced by the other detectors.
Preliminary study showed the coherent noise
is about 0.05 ADC counts.
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L1 Calorimeter Trigger
Miscabling
All towers at ? lt0.8 are instrumented,
complete coverage coming soon
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Summary of Installation Commissioning

• Only missing piece is Trigger readout for ?gt0.8

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Timing Studies

• Pedestal Values were different for
  Early, Nominal or Late sampling.
• Corrected after putting additional capacitors on
  BLS boards.

132 ns early
Sampling time vs amount sampled

• -50 ns 98.01
• -20 ns 99.69
• -10 ns 99.92
• 10 ns 99.93
• 20 ns 99.71
• 50 ns 98.23

Nominal sampling time varies from 10ns
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Online Data Quality Check

• Shifters are continuously monitoring
  quality of data.
• When hot cells are found corresponding readout
  channels are suppressed.

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Calibration Using Pulser
Pulser signal injected here (measured in DAC
counts)
saturation

• Non linearity lt0.5 for DACgt1000
• For Lower DAC values non linearity is significant
  but can be parametrized (same for all channels).

More in Ursula Basslers talk
DAC/1000
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W/Z candidate
335 events Signal200
Mean 83.7
W(?en)jets selection
118 events Signal75
Mean 89.4
With Non-linearity correction put in
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Multi jet events
A. Kupco

• 3-jets event
• ETjet1310GeV
• ETjet2240GeV
• ETjet3110GeV
• ET8GeV

• 2-jets event
• ETjet1230GeV
• ETjet2190GeV

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QCD Physics
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Jet Energy Scale
Photon-jet Events
Et27 GeV
Et24 GeV
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Outlook

• D0 has undergone major detector upgrade.
• Liquid Argon Calorimeter remained untouched.
• But major upgrade for readout has been done.
• We are making rapid progress in understanding new
  calibration, energy scale etc.
• Benchmark Physics processes are being scrutinized
  to better understand the detector.
• New results will become available soon.