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Reports until 16:46, Tuesday 26 October 2021
H1 SUS (SQZ, SUS)
sheila.dwyer@LIGO.ORG - posted 16:46, Tuesday 26 October 2021 - last comment - 12:59, Wednesday 27 October 2021(60408)
ZM4 apparent alignment shift

Camilla and I returned to HAM7 this afternoon to do a final alignment check.  We saw that there has been a large (~2.5mrad) shift in alignmet since the irses were placed yesterday. 

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keita.kawabe@LIGO.ORG - 16:55, Tuesday 26 October 2021 (60409)

I used the alignment slider in PIT and YAW, all OSEM responded but UR's response is much weaker than the others (1st attachment left) and suspected rubbing.

However, when I and Lee ran the P->P TF template, it looked the same as Rahul's previous measurements damped and undamped (1st attachment right).

I also gave offsets to individual coils (2nd attachment). Strange that UR responds to LR offset more than UR offset.

Images attached to this comment
rahul.kumar@LIGO.ORG - 22:13, Tuesday 26 October 2021 (60412)

I took some quick OSEM  spectra on DTT and the results attached below doesn't say much (except that it looks noisy), although there is significant difference (more than an order of magnitude) between DAMP_P_IN, DAMP_Y_IN vs Damp_L _IN DoF. Spectra for COILOUTF (along with comparison with a healthy ZM6 BOSEM) also shows everything is normal.

Tomorrow I will plot ASD to compare the noise of the BOSEMs.

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keita.kawabe@LIGO.ORG - 08:58, Wednesday 27 October 2021 (60417)

Some more details about the suspicous time I mentioned above.   In the times when we were actuating the piezo for beam profile measurements, M1 osems saw 0.62urad pitch per V on the PZT.  At the earlier time (around 18UTC on the 25th, 11am local time) there was a drop in the voltage applied to the PZT about 3 minutes before the requested voltage dropped.  The alignment shift seen by the osems does seem consistent with the shifts seen during the mode matching measurements, so this might just have been an issue with the onputer restarts.  This seems unlikely to be related to the source of our gross misalignment. 

It is interesting to note that because of the way this is designed, when the digital request was lost (the computer goes down) the PZT voltage jumps to 100V.

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camilla.compton@LIGO.ORG - 12:59, Wednesday 27 October 2021 (60420)SQZ

Rahul, Sheila, Betsy, Camilla 

Started by checking alignment on ZM4, looked fine-ish (photo), ZM5 alignment was off as in previous photo.

Rahul adjusted ZM4 physical pitch adjustment on to center beam on ZM5. We then re-centered OESEMS. Then we changed ZM4 yaw slider from 0 to +6010. This centered the beam on ZM5 (Photo), but now it was way off the first iris (photo). 

Shelia pointed out ideally we would adjust ZM4 to center on 1st iris and ZM5 for 2nd iris. So we reversed our changes as best we could (have NOT readjusted OSEMS) and used sliders ([P: 1024, Y: -1805] to center beam on 1st iris. This has put it way off on ZM5 again (photo) and off on 2nd iris (photo), similar to yesterday. 

We wonder how precise we were with initial centering on ZM4 and ZM5.

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