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Detector gas handling system
Required controls and monitoring
The gas handling systems for both Focal Plane gas-filled detectors – the Ionization Chamber and the CRDCs – are remotely controlled via a single LabView application running on the computer S800FP-PC in the S3 vault. This computer can be accessed remotely via the u6pc5 computer in data-U6.
Note that since the same roughing pump drives the gas handling systems for both gas-filled detectors, extra precautions must be taken to protect one detector from the pressure of the other detector. The fact that the same pump drives both systems is not indicated on the graphics for the LabView control application
LabView Control Program
To start the gas handling system control application, click on the LabView icon FPGHS_TCPIP_Corrected_V01 on the S800FP-PC desktop.
Preparation of Gas bottles
In Data-U6
Ensure I265GV is closed (in PanelMate S800vac.MT2 page 07) to isolate focal plane vacuum chamber from the rest of the beamline
Confirm that the focal plane chamber is under vacuum
Confirm that the only open gas handling system valves are 4, 5, 6, 20, 21, and 22
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In the S3 vault
Ensure that the gas handling system roughing pump is running and has a good vacuum
The pump sits on the floor under the focal plane behind the south support post
The display unit for the pressure at the pump has a needle indicator and is mounted under the focal plane on the south support post
Ensure that the main valves on the gas bottles are open (see pictures below)
Ensure that the gas bottles are not empty
Filling Ion Chamber with Gas
Fill Ion chamber
Enter the desired fill pressure and start the automatic filling process
Click on the tab labeled Slot 8 (M-card) IC to access the page with the pressure set point control
Enter the desired pressure (typically 300 Torr) in the field under the knob labeled Set Point
Click button labeled Return to AUTO Mode on left to start filling/regulation
Click the Valves tab at the top of the LabView window to return to the overview display of the gas handling system to monitor filling. The flow readings for MFC #1 will increase and eventually disappear as the readout value overflows the display field (this is normal behavior)
If necessary, the filling process can be stopped at any time by pressing the valve button labeled Close MFC #1
Open valve 9
The filling process will take several minutes
Filling CRDC1 and CRDC2 with Gas
Fill CRDCs
Enter the desired fill pressure and start the automatic filling process
Click the Zero Sensor button
Click on the tab labeled Virtual Ch. 0 (CRDC) to access the page with the pressure set point control
Enter the desired pressure (typically 40 Torr) in the field under the knob labeled Set Point
Click button labeled Return to AUTO Mode on left to start filling/regulation
Click the Valves tab at the top of the LabView window to return to the overview display of the gas handling system to monitor filling. The flow readings for MFC #2 and MFC #3 will increase. The LabView application controls the gas mixing ratio based on the flow ratio (scaled with a calibration constant)
If necessary, the filling process can be stopped at any time by pressing the valve button labeled Close MFCs #2 & #3
Open valve 25
The filling process will take several minutes
Removing Gas from Focal Plane Detectors
Isolate the gas supply by closing valves 2, 12, 17, 10, and 15