KAGRA Logbook

PEM (Center)

takaaki.yokozawa - 13:35 Sunday 30 April 2023 (25035)

Tapping test 230429

YokozaWashiMiyoki (center area)
Tomaru, Uchiyama, Nishizawa (Remote)

We performed the tapping test 2023/04/29,especially for center area
The detail report would be performed by Washimi-san, I briefly report about it.

1. Beam duct between BS and IXC/IYC/PR3
Peaks around 30 Hz appeared between BS and IXC.
Peaks around 33, 66 and 100 Hz appeared between BS and IYC

2. Beam duct and/or chamber between BS and SRM
Several peaks appeared below 100 Hz, when we tapped them, the RMS of BS and SR3 oplev became larger (no significant change in SR2 oplev from my eye)
When tapped the chamber near the SR3 oplev (Injection port), such peaks not appeared.

3. Chambers/gate valve/beam duct at OMC area
Large excess detected when we tapped the OMC area.
Bellows leg is not so large, the chamber tapping is more serious in current situation.
Some unexpected connection between OMC and chamber or stray light or something(?)
The DARM spectrum during the tapping test can be found here (OMC chamber +X,+Y side)

4. No serious excess PR3 and PRM area

Comments to this report:

tomotada.akutsu - 12:39 Sunday 30 April 2023 (25037)

> 3. Chambers/gate valve/beam duct at OMC area

Maybe this would be related to the known ghost beams in the OMC chamber... but anyway it might be nice to start with checking OSEM signals for OMMT1, 2, and OSTM.

> 2. Beam duct and/or chamber between BS and SRM

It might be nice to check also some IP signals... hopefully not due to scattered light. I do not remember whether the oplev QPDs for these suspensions would have already had the IR/Gr stop optical filters..

tatsuki.washimi - 0:45 Monday 01 May 2023 (25054)

I summarized the results

https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=14941

tomotada.akutsu - 0:52 Monday 01 May 2023 (25055)

OMC-OMMT responses might be due to already-known scattered light around OMC.
SR3 response might be due to undamped ghost beam from SRM, as we do not do any "alignment" for SRM so far.