Download - Construction and first commissioning of the self-stretched gas electron multiplier (GEM) detector
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Construction and first commissioning of the self-stretched gas electron
multiplier (GEM) detector
J. Twigger, V. Bhopatkar, J. Wortman, M. Hohlmann
77th Annual MeetingMarch 2013
Barry University
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Outline
MotivationTime, cost, and construction environmentConstructionGEM foil stretching and framing by IR thermal methodMechanical self-stretching designCharacterizationFirst signal under X-rayGain measurements and rate plateausFuture WorkConstruction and testing of the Compact Muon Solenoid GEM detectors
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MotivationTime
•Previous methods of construction and foil stretching were measured in days.•With new assembly techniques complete detectors can be manufactured in hours.
Large Scale Production•In order for the design to be viable for mass production the required infrastructure was reduced to a minimum.•Assembly now only requires a clean room facility.
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Contrasting Foil Stretching Techniques
Low cost GEM stretching using IR heating
Mechanical Self-Stretching
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Redesigned Frame
Previous frame style was a single piece coatedin glued to seal the gas volume
New design integrates the drift and readoutinto the frame to provide a gas volume
with the assistance of an O-ring
Drift forms the foundation
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Difficulties in Construction
The screws that secure the foil stack deformed the readout
board and compromised the gas volume
Without the inclusion of cornerscrews reaching a uniform tighteningbecame more difficult as you move
away from the center of the foils
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Solutions
Applying voltage under air
In order to confirm that thefoils for our detector areparallel to each other weapply voltage between the foils under air.
If we are unable to reachthe normal operating voltagebetween foils then we have identified a problem.
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Possible Improvements
One of the major issues with mass productionwill be achieving uniform tightening of the
foils with precision
Electrical connection to the foils is made usingsprings. The problem is that properly securingthe springs to their points of contact and the
foils is extremely difficult. There is also no wayto check that connection is made once you place
the foil stack.
This spring broke from its solder point
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First Commissioning
Two arrangements for testing due to thethickness of our frame pieces
Vertical setup allows us to reach the drift region through minimal material
Must pass through our readout and GEM foilsto reach the drift gap
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The blue channel is displayinginformation directly from thepre-amplifier
While the red channel is ourlinear amplifier
5˚ collimator
Mini-X
Pre-amplifier
Linear Amplifier
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These signals were recorded while operating the detector at 4200 voltsand irradiating with the Amptek Mini-X portable X-ray source
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Rate Plateau
X1 X2 X3 X4 X5 X6
Y1
Y2 X
Y3
Y4
Y5
Y6
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Gain Curves
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Conclusion
What is the point?
Now that this design has been proveneffective and successful we can moveon to a larger scale.
We will now scale up our design to be usedin the CMS experiment at CERN.
Once we have shown that this we canproperly scale this design up to the size required we will experiment with zig-zagreadout structures.