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ATLAS TileCal Production at UIUC

Maggie Geppert, UIUC

Dr. Steven Errede, project head

July 9th, 2001

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Overview

• Project Background

• Submodule Production

• Photomultiplier Tube (PMT) Testing

• What’s Next

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Overview of ATLAS

• Located at Cern in Switzerland, ATLAS will be largest Particle Accelerator in the World

• Five Stories Tall

• Accelerates Protons to 7 trillion eV

• Scheduled to be Completed in 2005

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Submodule Production

• Submodules are the framework of the detector.

• Hold the detector plates that glow in the presence of radiation from subatomic particles.

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Submodule Production

• Seven easy steps to a submodule– Washing spacers and masters

– Sanding and drying

– Gluing

– Welding

– Measuring

– Painting

– Banding

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Production Pictures

• Submodule assembly with glue machine

• Banding and wrapping

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Photomultiplier Tubes (PMT’s)

• Signals from the detector array are amplified using PMT’s

• Currently testing 3,000 of the 10,000 to be used in ATLAS

• Run the tubes through a series of computer programs

• Right now finishing STEP 1– DC light used during testing process

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What do We Test?

• Drift– The % change in current over ~30 hrs

– Not to be greater than +/- 2%

• Dark Current– Current through tubes when light isn’t on

– must be < 2 nAmps at 800 Volts

– must be < 4 nAmps at 900 Volts

• These are the 2 most important factors

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Testing

• Problem– Systematic increase in the Drift of all tubes, including

the reference tubes

• Solution– Look for external causes for the problem

– Check testing setup for flaws in circuits or fiber-optic cable

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First Look

• Looked at temperature, humidity, and other external factors– Little correlation

Change in Drift vs. Change in Humidity

-3

-2

-1

0

1

2

3

-10 0 10 20 30

Change in Drift

Ch

an

ge

in

Hu

mid

ity

delta #1

delta #2

delta #3

delta #4

Change in Drift vs. Change in Temperature

-3

-2

-1

0

1

2

3

-1.5 -1 -0.5 0 0.5 1 1.5

Change in Temperature (C)

Ch

an

ge

in

Dri

ft

delta #1

delta #2

delta #3

delta #4

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Next Steps

• Check hardware for internal problems– Currently running diagnostic tests

– Then change the circuit setup in the light source

• After problem is fixed, run STEP 2 tests– Use pulsed light to test PMT’s

• Continue Submodule Production

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Questions?

• Contact me– mgeppert@uiuc.edu

• Contact Dr. Errede– 435 Loomis Lab

– serrede@uiuc.edu

• UIUC ATLAS Website– http://www.hep.uiuc.edu/atlas/