KAGRA Logbook

CRY (Cryostat IX)

takafumi.ushiba - 20:58 Tuesday 05 March 2024 (28749)

Investigation of viewports on the radiation shields at IXC

This log is related to klog28716.

[Tamaki, Ushiba]

We investigated the viewports on the radiation shields at IXC.
There seems three kinds of contamination.
1. fogs like contamination (fig1): almost entire area of window
2. oil like contamination (fig2): almost entire area of window
3. crystal like contamination (fig3): localized

I tried to wipe them out by using vectra alpha 10 and followins are the result.
1. getting worse if just wiping because the area of fog will increase.
2. can be removed (I'm not so sure they are removed perfectly).
3. no change

So, in my personal opinion, 1 and 2 could be removed by First Contact but 3 might be not.
Since contamination 3 cannot be removed by wiping, one possibility of 3 is just a broken AR coating due to thermal shurink.
We need to discuss how to treat them.

Images attached to this report

Comments to this report:

masahide.tamaki - 19:08 Thursday 07 March 2024 (28778)

[Ushiba, Tamaki]

We removed them for cleaning.
They are left in IXC now.

takafumi.ushiba - 21:13 Thursday 07 March 2024 (28781)

Since we don't have enough time to remove everything, we removed only three: -X -Y side of MN inner viewport, +X -Y side of MN inner viewport, and -X -Y side of MN inner viewport, which have contamination of No1, 2, 3, respectively.
We will try to clean them and see what happens tomorrow.

masahide.tamaki - 13:19 Friday 08 March 2024 (28789)

1: -X -Y side of MN Outer viewport
2: +X -Y side of MN inner viewport
3: -X -Y side of MN inner viewport