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Installation of focal-plane scintillator
Vent focal-plane chamber
Open focal-plane chamber
After venting the FP chamber, the pressure inside the chamber is slightly above atmospheric due to the dry N2 pumped. Before opening the chamber, it is recommended to vent the extra N2 by “forcing” the chamber flange with e.g. a screwdriver
Unlock the padlock protecting the power brakers of the switch controls to open the chamber, and press the
START button
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Turn on the switch to activate the motor opening the chamber. It takes about 10 minutes to get the chamber totally opened
Installing FP scintillator
The figure below shows the FP chamber open, with the “old” FP scintillator to be replaced by the new one
Unplug the bases of the up and down phototubes. The platic tie holding the cable of the up phototube to the chamber needs to be cut
Using an allen wrench, unscrew the two bolts attaching the scintillator frame to the base of the chamber
Climb to the chamber and pull the scintillator frame up. Once unplugged, handle it to a second person
With the help of a second person, hold the new scintillator by its frame and place it in the right spot. A second person should be ready to screw the frame to the base of the chamber
Connect the bases of the up and down phototubes. The later is quite difficult because one cannot see the pins
Using a plastic tie, attach the cable of the up phototube to the scintillator frame
Closing focal-plane chamber
Turn the switch to move the chamber to position “UP”, and keep it that way for about 10 minutes (the time it takes the chamber to be closed)
When the chamber is almost close, turn the know to close the clamps
Before pumping the chamber down, make sure that the scintillator is properly connected. This can be done by biasing the detector and checking the signals, either from the scalers or with a scope. One should clearly see cosmic rays; if that is not the case, the phototubes are likely miss connected
In order to pumpdown the chamber, make sure that the manual vent valve is closed. Start manual pump to get a pressure below 50 mtorr
Close the manual pump; open PanelMate S800vac and go to page 07. Select window PUMPDOWN STATUS and click on button START PUMPDOWN. The PUMPDOWN STATUS and VENT STATUS windows should display “PUMPDOWN IN PROGRESS”
Wait for some hours until vacuum is good