Betsy, Sheila, Camilla, Fil, Oli
The biggest conclusion from today is the concern that we might not be able to really move ETMX without creating the rubbing that seems to be the cause of our L1 LL issues.
Partway through troubleshooting today we changed the EUL2OSEM for ETMX L1 to be the tripod (coil driver switching) version. I only changed this one and not the L1 OSEM2EUL, and have purposely not SDF'd it since we don't know if this is correctly working or if we'll even be able to utilize it. We only did a quick check on whether it was working and it seemed to be super cross coupled, but we didn't look too far into it. I got this matrix from /opt/rtcds/userapps/release/isc/h1/scripts/sus/etmx_l1_out_ll.snap, which is meant to be used when needing to actuate at L1 while swapping the coil driver state for LL.
M0 L2L Transfer function
I took an ETMX M0 L2L transfer function and found that it is seeing rubbing. June 5, 2026 was the last time an M0 L2L TF was taken, and it looks perfect with no rubbing(black trace). This narrows our scope of when we believe something happened to L1 LL osem from between March 5 and August 20, 2026 to sometime between June 5 and August 20, 2026. When I first started the transfer function, LL didn't seem to really be reacting to the excitation even though the other osems on L1 were moving by at least a few hundred counts(L1 OSEMINF). Then 1.5 minutes into the measurement, the LL OSEMINF IN suddenly saw a DC change of 300 counts. At this same time, LR also dropped by ~300 counts, the upper osems saw maybe a bit of motion, and some of the osems on the M0 stage saw movement of up to a few microns as well (OSEMINF_IN, OSEMINF_OUT).
Data: /ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGM0/Data/2026-08-25_2030_H1SUSETMX_M0_WhiteNoise_L_0p01to50Hz.xml
R0 L2L Transfer function
We took a transfer function for R0 L2L and found that it also looks like it sees the rubbing. This should rule out rubbing coming from an earthquake stop on M0.
Data: /ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGR0/Data/2026-08-25_2125_H1SUSETMX_R0_WhiteNoise_L_0p01to50Hz_noVoffset.xml
M0 and R0 height adjustments
The LF and RT (Vertical) OSEMs for both M0 and R0 are reading lower than we expect, and although they seem to have been in that configuration for a long time, we're still suspicious of them and wondered if we might be seeing touching due to them being higher than they should be (smaller OSEMINF IN value = more OSEM light occulted by flag). We tried putting Vertical offsets of +/- 200,000 counts in the M0 and/or R0 TEST banks and taking transfer functions, but all the configurations we tried still looked like there was the same amount of rubbing every time.
Some of the measurements we were seeing some 'glitching' happening on LL as well, but for the most part we still weren't seeing much other movement.
