Creation Of Control Systems In PVSS For Devices In The ALICE Detector

ABSTRACT Robert Thomen, Physics Department, Creighton University, Omaha NE 68178

ALICE (A Large Ion Collider Experiment) is one of the main detectors in the LHC (Large Hadron Collider) at CERN.

PVSS (Prozessvisualisierungs- und Steuerungssystem) is a control system used to operate, monitor, and collect data from hardware devices and record the data which they produce.

This project is concerned with the development and testing of several PVSS subsystems. Prototype systems have been created for voltage/current temperature monitors, front end electronics control, high and low voltage controls, and video monitoring. User interfaces will be presented and measurements of control response times will be compared to design requirements.

ALICE

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A Large Ion Collider Experiment A dedicated heavy-ion detector at LHC (Large Hadron Collider) Studies proton-proton and nucleus-nucleus collision Experiment consists of 15 detectors including the inner tracker system and electromagnetic calorimeter

Figure 1. Graphical image of the ALICE detector

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PVSS

Prozessvisualisierungs und Steuerungssystem Process visualization and control system.

Monitors and operates hardware and software devices Projects implemented in PVSS:

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Temperature monitoring for EMC High voltage control for EMC Alignment monitor for Inner Tracker System

ELMB

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Embedded Local Monitor Board Used for temperature monitoring Board contains Analog to Digital Converter EMC signal gain is temperature dependant

Inner Tracker Camera

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Required for precise positioning of the inner tracker Picture of laser is compared with a control image for exact alignment.

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Latest captured image and comparison image are displayed (pixels with differences appear red, unchanged pixels appear white) Design requirements demand an image processing time of less than 10 seconds.

Figure 4. A sample panel created in PVSS for the Inner Tracker Camera. Includes control buttons, camera image, and comparison image.

Timing Measurements

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The time required for an individual image capture and processing was measured to be 5.1 ± 1.2 seconds. (Distribution shown in Figure 5.)

EMC

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Electromagnetic Calorimeter Measures energies of particles created in the collision

ITS

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Inner Tracking System Consists of Silicon Pixel Detector, Silicon Drift Detector, and Silicon Strip detector.

Tracking must be matched between the ITS and the other tracking chambers Alignment is critical for accurate measurements

We gratefully acknowledge the Office of Science of the US Department of Energy for its continued support of this project.

Figure 2. The ELMB and corresponding monitor panel.

High and Low Voltage

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Used by avalanche photodiodes to produce large signal gain in EMC Low Voltage supplies are used for EMC readout and digitization electronics

Figure 3. ISEG EHC 238 high voltage crate and corresponding panels Figure 5. Chart of time delay data

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Evaluation and Future Plans

Response time is within design specifications.

The ITS camera and software will be implemented on at CERN in December 2006.

Voltage supplies and temperature monitors are ready use with the prototype EMC detector at a test beam setup in July 2007 Future plans involve fitting a Gaussian curve to the intensity distribution of laser image. More accurately locating the beam’s location will allow a more precise alignment of the ITS.