# Presentation: 265846

## Online Calibration of the D0 Vertex Detector

- Initialization Procedure and
- Database Usage

- Harald Fox
- D0 Experiment
-  Northwestern University

## Online Calibration of theD0 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.

## 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.

## 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.

## 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 |
| --- | --- | --- |

## 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

## Calibration Steps (cont.)

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

## Calibration Steps (cont.)

- Calibration data  Calibration Database.
- New thresholds are calculated.
- Used for next initialization.

## Slide 9

## Design of theElectronics 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.

## 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.

## 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.

## 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.

## 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.

## GUI Layer (cont.)

## 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.

## 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 |

## 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.

## 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.

## Hardware Configuration

- VRB: VME Read Out Board
- SEQ: SVX Sequencer

## Hardware Configuration

- VRB: VME Read Out Board
- SEQ: SVX Sequencer

## UML Diagram of the Database Layer