Removing the LGD cover plate

To remove the LGD cover plate do the following:

• Schedule a time for riggers to come with a crane and carry the cover plate out of the way. This is done by contacting the Liason Engineer. The current L.E. is Joe Scaduto (x4826)
• Make sure the LGD high voltage system is OFF. This means that the voltages as measured in the hut are ALL zero. Consult an expert if you need help with this.
• Also make sure the photo-diodes (powered from on top of the LGD) and the monitoring system normalization PMT (powered from the LeCroy 4032A supply in the hut) are off.
• Move the transporter into a convenient position. Typically this is defined as horizontally far away from TDX4 and vertically low enough that reaching the mounting bolts is easy.
• Find at least two long (~3") bolts that are the same size as the bolts in the cover plate. These long bolts will serve as pins to hold up the cover plate after the other bolts are removed.
• Use the 3" bolts to replace a few (at least two) of the bolts holding the cover plate on. You will probably want to use an impact wrench for removing bolts from the cover plate. Contact the L.E. to borrow one.
• After the 3" bolts are securely in place, remove all the other bolts.
• Using a screwdriver, pry the cover plate away from the black steel picture frame.
• The riggers should now be able to attach slings and shackles through the bolt holes in the top of the cover plate. After they have assumed the load of the plate, remove the 3" bolts.
• At this point someone should be on top of the transporter to guide the plate as it is raised by the crane.

To re-install the cover plate:

• Use ethanol and lint-free wipes to clean the outer surface of the plexiglas.
• From the top of the transporter guide the plate carefully as it is lowered into position.
• Install the 3" bolts and remove the riggers shackles and slings.
• Slide the cover plate in until it is flush to the black picture frame on all sides.
• Loosely insert the remaining bolts.
• Tighten the bolts with the impact wrench. Suggestion: tighten one bolt on top, one on bottom, one on the left side, one on the right side etc.
• Obtain a tube of BLACK caulking. This is not a stock item. In the past it has been obtained from Gray's Hardware on Rte 25 in Middle Island. This caulking should be spread around the seem between the picture frame and the cover plate to form a light-tight seal.
• You may want to check to see that there are no light leaks in the front of the detector by using a phototube.