The scintillators are recleaned using windex.

The panels are wrapped in a layer of aluminum foil. This serves as a first light barrier, and may serve to direct photons to the phototube and increase the efficiency of the detector. Care should be taken to avoid tearing the foil, especially at the corners. No tape should be placed in contact with the plastic scintillator panel.

Then, the wrapped panel is placed back inside the original CASA light box, which has meanwhile been cleaned. Then all edges, corners, and the rubber gasket around the PMT are sealed with black electrical tape. It is CRUCIAL at this step to NOT STRETCH the tape. This tape, if applied while stretched, is more likely to pull off and create light leaks later. Corners are especially hard to seal, and a couple of layers of tape are recommended there. The next step is connecting the detector to an oscilloscope and checking for light leaks, and if there is a light leak, you'll come back to this step and apply more tape.

With some of the PMTs we used in the WALTA workshop in the summer of 2001, we found very significant light leaks at the PMT itself. These were due to the original lightproof paint coming off the PMT due to age or mistreaTMENT. The fix on this involved cutting, wrapping, and taping a "shroud" of thick black plastic sheeting over the entire PMT, just allowing the cabling to stick out the top.