Visual inspection

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  Fig. 1 Broken glass

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  Fig. 2 Wrapping issue: teared Aluminized mylar, can be fixed without disassembling module

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  Fig. 3 Wrapping issue: Al layer peeled off

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  Fig. 4 Wrapping issue: Al layer peeled off, teared wrapping foil

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  Fig. 5 Damaged PMT

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  Fig. 6 Colored lead glass module, possible radiation damage issue. Can be seen without removing steel flange.

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  Fig. 7 Colored lead glass module

Possible issues with lead glass module

1. Broken lead glass, see Fig. 1 (module taken from the FCAL prototype)
   • some problems can be seen by some problems can be seen by looking on the lead glass block from the side opposite to the PMT
   • lead glass module has to be disassembled; the glass block has to be replaced.
2. Issues with wrapping:
   • small damages (holes) in the Aluminized mylar, see Fig. 2. This can be fixed by using Al sticky tape, thickness < 20 um
   • Aluminum layer in the wrapping foil peels off or adheres to the glass block (penetrates into the block):
     • Fig. 3 and Fig. 4: Aluminum layer peeled off resulting in some transparent holes in wrapping.
     • Recommend to disassemble and re-wrap the lead glass block
3. Issues with Silicon cookies and PMT
   • look inside the crystal from the side opposite to the PMT