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I may be asked to remove the collars from the fibers in the dark box so we can test them for crosstalk. To do this, I should use two collars to hold the fibers in place. One will be temporary and put on in the most convenient way as soon as I tighten the Kapton strips. The temporary collar will be in an inconvenient position for removing once the fibers are in the dark box, so I need to turn the fibers over and put on a permanent collar. After the permanent collar is on, I can remove the temporary collar before putting the fibers in the dark box.
I may be asked to remove the collars from the fibers in the dark box so we can test them for crosstalk. To do this, I should use two collars to hold the fibers in place. One will be temporary and put on in the most convenient way as soon as I tighten the Kapton strips. The temporary collar will be in an inconvenient position for removing once the fibers are in the dark box, so I need to turn the fibers over and put on a permanent collar. After the permanent collar is on, I can remove the temporary collar before putting the fibers in the dark box.
One method of aligning the fibers that I used is to get them through the Kapton strips and pull them fairly tight but still let the fibers move. There should be a collar near the popsicle stick and one near the middle of the bundle. Then you can take fibers one by one between the collars and push them into alignment. If it appears that the bottom 15 fibers (the ones that come to the front) are aligned adequately but the top 15 (the ones set back) are not yet aligned, you can put a strip of paper between the top 15 and the bottom 15 so that you will be able to take just the top 15 and push them forward. When checking the alignment, the collar should be tight so the fibers will not slip. If they need to be adjusted, the collar must be loosened. Once they are aligned correctly, the collar should remain tight.
One method of aligning the fibers that I used is to get them through the Kapton straps and pull them fairly tight but still let the fibers move. There should be a collar near the popsicle stick and one near the middle of the bundle. Then you can take fibers one by one between the collars and push them into alignment. If it appears that the bottom 15 fibers (the ones that come to the front) are aligned adequately but the top 15 (the ones set back) are not yet aligned, you can put a strip of paper between the top 15 and the bottom 15 so that you will be able to take just the top 15 and push them forward. When checking the alignment, the collar should be tight so the fibers will not slip. If they need to be adjusted, the collar must be loosened. Once they are aligned correctly, the collar should remain tight.
I think it is good practice to put a piece of paper on the bottom of the dark box to protect the polished ends of the fibers from being scratched.
I think it is good practice to put a piece of paper on the bottom of the dark box to protect the polished ends of the fibers from being scratched.
Use a razor blade to make a hole in the strap coinciding with the hole in the washer. Be careful not to damage the strap elsewhere with the blade.
Use a razor blade to make a hole in the strap coinciding with the hole in the washer. Be careful not to damage the strap elsewhere with the blade.
==Preamp-Backplane Connection Problems==
Sometimes a preamp does not connect completely to the backplane. Symptoms of this problem include unusually low data values from particular SiPMs that do not follow a bell curve. The loose connection has sometimes affected SiPM 23. This problem appeared in runs 1898-1906.
The cause of the loose connection is that the backplane is flexible. It may bend too much when the preamps are inserted.
To solve this problem, it is necessary to make sure the ethernet cable is unplugged from the control board first. Unplugging the cable prevents short circuits when you press on the backplane to complete the connection.
The preamps should be inserted and the screws tightened on the parts that hold them. Then go to the back of the dark box and press gently on the the double row of pins on the backplane with your thumbs. Giving a little push can help the pins connect to the preamp.
==Popsicle stick Storage==
==Popsicle stick Storage==