Difference between revisions of "Visual inspection"
From GlueXWiki
(→Possible issues with lead glass module) |
|||
| Line 11: | Line 11: | ||
<gallery> | <gallery> | ||
Image:glass_pmt_prob.jpg | Fig. 5 Damaged PMT. | Image:glass_pmt_prob.jpg | Fig. 5 Damaged PMT. | ||
| − | Image:glass_color_prob.jpg | Fig. 6 Colored lead glass module, possible radiation damage issue | + | Image:glass_color_prob.jpg | Fig. 6 Colored lead glass module, possible radiation damage issue. |
Image:glass_color_prob1.jpg | Fig. 7 Colored lead glass module. | Image:glass_color_prob1.jpg | Fig. 7 Colored lead glass module. | ||
</gallery> | </gallery> | ||
| Line 31: | Line 31: | ||
# Possible damages of PMTs during deinstallation (see Fig. 5) | # Possible damages of PMTs during deinstallation (see Fig. 5) | ||
# Glass blocks with discoloration signs (due to radiation) | # Glass blocks with discoloration signs (due to radiation) | ||
| − | #* some glass blocks may have a brown tint (see Fig. 6 and Fig. 7) | + | #* some glass blocks may have a brown tint (see Fig. 6 and Fig. 7). Can be checked without removing steel flange. |
#* recommend to replace this module | #* recommend to replace this module | ||
Latest revision as of 11:26, 18 October 2022
Fig. 1 Broken glass.
Fig. 2 Wrapping issue: teared Aluminized mylar, can be fixed without disassembling module.
Fig. 3 Wrapping issue: Al layer peeled off.
Fig. 4 Wrapping issue: Al layer peeled off, wrapping foil is teared. A newly wrapped module is shown on the top.
Fig. 5 Damaged PMT.
Fig. 6 Colored lead glass module, possible radiation damage issue.
Fig. 7 Colored lead glass module.
Possible issues with lead glass module
- Broken lead glass, see Fig. 1 (module taken from the FCAL prototype)
- 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.
- 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
- Issues with Silicon cookies
- Inspect optical coupling of the glass block and the PMT by looking inside the crystal from the side opposite to the PMT
- Possible damages of PMTs during deinstallation (see Fig. 5)
- Glass blocks with discoloration signs (due to radiation)
- some glass blocks may have a brown tint (see Fig. 6 and Fig. 7). Can be checked without removing steel flange.
- recommend to replace this module
