Online Calibration of the D0 Vertex Detector

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Online Calibration of the D0 Vertex Detector

• Initialization Procedure and
• Database Usage

Harald Fox D0 Experiment Northwestern University
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Online Calibration of theD0 Vertex Detector

• What is Online Calibration?
• Determination of
• Threshold for zero-suppression of the read out.
• Pedestals and gains for the Level 3 Trigger and
  the Prompt Reconstruction.

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When and Where?

• When?
• Special calibration run between 2 machine
  fillings.
• The time window for calibration is negotiable
  between D0, CDF, and the accelerator.
• The Secondary Data Acquisition (SDAQ) is foreseen
  for this task.

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When and Where?

• Where?
• The calibration process runs on the front end
  processor of each readout crate.
• Data is transferred to the CPU instead of the
  Level 3 Trigger.
• Pedestals and gains are calculated locally and
  stored in the database.
• New threshold values are calculated from
  pedestals.

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What?

• The D0 Silicon Tracker consists of 6 barrels, 12
  F-disks, and 8 H-disks ? 800,000 channels.
• Commissioning and testing requires read out of a
  complete barrel (432 SVX, 55300 channels).
• Each SVX read out chip has its own parameters.
• ?

Database GUI Manipulation Monitoring
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Calibration Steps

• Start a calibration run (Taker/COOR).
• Initialization of the electronics (download).
• The initialization is part of COMICS.
• An ORACLE database is used to store
• Download Parameters
• History of time dependent information

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Calibration Steps (cont.)

• Determine pedestals and gains (Huaming Wang).
• 5 Calibration voltages.
• Pedestals and gains ? Calibration Manager.
• The Validator checks errors and consistency.

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Calibration Steps (cont.)

• Calibration data ? Calibration Database.
• New thresholds are calculated.
• Used for next initialization.

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Design of theElectronics Database

• The hardware is mirrored
• Crates, modules, module channels, and silicon
  detectors.
• Multiple to multiple connections between modules
  are allowed.
• Download parameters are stored.
• The path from a VME Readout Board (VRB) to a
  silicon detector (HDI) is traceable.
• A history of all modifications is kept.

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The Initialization Process

• The initialization is integrated in the online
  environment (COMICS).
• A Python (OO-scripting language) program is used
  for downloading.
• The program is partitioned into 3 layers
• Hardware layer
• Knows about module and register addresses.
• Communication via EPICS.

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The Initialization Process (Program Layers)

• The database layer
• The hardware configuration is determined in a
  database lookup.
• Download parameters are extracted.
• GUI for expert interaction
• Allows modification of the database.
• Manipulation of each hardware module.
• Status display.

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Database Layer

• Each hardware module and database table is
  represented by an object.
• The database is accessed via an interface design
  pattern.
• This allows an optimization of the database
  access.
• The electronics configuration is determined on a
  crate to crate basis.
• Each module is initialized in the proper sequence.

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GUI Layer

• The GUI is an interaction tool for the experts.
  It replaces a PC based support tool.
• It gives an overview for each crate allowing
  basic operations.

• Used for the barrel read out right now.

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GUI Layer (cont.)
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GUI Layer (cont.)

• A detailed view allows interaction with all
  hardware modules. This allows the initialization
  of single modules or module chains.
• Allows modification of the database
• Enable/disable of modules for the subsequent
  download.
• Change of hardware configuration (re-cabling).
• Change of initialization parameters.
• Calculation of new thresholds.

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Use Cases

• Three test stands are available

Northwestern 1 (SiDet) 10 (SiDet) Complete Barrel
2 HDI 2 HDI 7 (72) HDI
2 VRB 1 VRB 5 (9) VRB
768 Channel 2304 Channel 4992 (55296) Channel
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Milestone Goal Achieved!

• We successfully demonstrated the Online
  Calibration at the 10 test stand!
• The Silicon Tracker is the first detector using
  the complete Online Calibration System!
• Pedestals and gains were calculated and stored in
  the Online Database.
• Data was send to the Level 3 Trigger and saved to
  disk. SMT examine was used to monitor the data
  taking process.

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Conclusion

• The D0 Silicon Tracker requires online
  calibration.
• Demanding task with 800,000 channels!
• We developed database and GUI tools necessary to
  meet the challenge.
• We developed the program running on the Front End
  Processor determining pedestals and gains.
• These tools were successfully tested in the D0
  Online Calibration Framework.

We are leading the development.
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Hardware Configuration

• VRB VME Read Out Board
• SEQ SVX Sequencer

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Hardware Configuration

• VRB VME Read Out Board
• SEQ SVX Sequencer

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UML Diagram of the Database Layer