Jonathan, Dave:

The LVEA 3IFO Dewpoint sensors went offline last week 08:48 Wed 16sep2026. We restarted the IOC this morning at 08:28, but the code cannot connect to the sensors. The comtrol eth-serial converter h0seriall0 is pingable, so the problem could be on the serial side.

TITLE: 09/24 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 4mph Gusts, 2mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.22 μm/s 
QUICK SUMMARY:

• Temps, and dust look good
• CDS shows 2 DAQ warnings
• Microseism has been above the 50th percentile for the past 24 hours

We began looking into whether the recent noise made by GV-20 is new or has been increasing with time by making spectrograms of the period of the audio recording in alog 91930. We optimized the 30s spectrograms to make the 4 events in the audio recording as visible as possible and then we made 600 second spectrograms of openings and closings over the past few years. These 600s spectrograms are about twice as long as the gate valve opening or closing so that we could compare the time while it was moving to the time before and after. In cases where the sound and vibration level at EX was not much louder than during the Sept. 8 events, we found similar densities of glitches during openings and/or closings back to 2020, and much lower densities of glitches (from other sources) when the valves were not actuating (see figure).

Miranda, Alex, Robert

TITLE: 09/23 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY: DRMI and SQZ were commissioned today, we can lock on DRMI_3f now.
LOG:

• 15:16 - 15:50 UTC EQ mode from a 5.7 from Tonga
• 20:56 UTC ETMX ST1,ST2 ISI watchdogs tripped (T240 trip) from scaffolding work around GV20.

There is infrastructure in the CRS HOQI parts to calculate the power and contrast ration of the HOQI interferometers, outlined in T2400088, but we hadn't engaged the filter banks in the path for those calculations. I've turned the filter banks on, set gains and offsets where appropriate.  There's no MEDM that shows this path, or exposes any channels for checking this, so someone should probably look at that. The calculation is almost missing a factor of 8 for the contrast, that needs to be added in the model. I've added that to the CRS library part, so CRSPROC should be ready for a restart on Tuesday. 

Ryan S, Sheila, Camilla

NLG looks good, green and IR flashes a factor of 3 below O4 levels. Can improve Green flashes only by ZM2 PSAMS.

Increased Seed power from 0.3mW to 75mW (as used in vent). With sliders (FC1, ZM1-6) in settings they were we had 0.4mW on SQZT7 IR PD, when I moved sliders back to as during the vent attached, this increased to 1mW as expected how we left sliders at end of the vent.

Adjusted sqzparams.py  opo_grTrans_setpoint_uW to 10.5  as this is typical value with no ISS, then checked NLG 76542. Still OPO ISS would not work. We expect it's as AOM alignment needs work.

*OPO Trans power is lower than O4 as is this is just leakage from OPO mirrors which now have different transmitted powers as the OPO has been swapped. 

Adjusted wave-plates in Green pump path to minimize rejected power. 

Looking at FC

Ryan touched up FC1 and FC2 alignment, we were only getting green flashes on H1:SQZ-FC_TRANS_C_LF_OUT_DQ of 6 and IR flashes on H1:SQZ-FC_TRANS_D_LF_OUT_DQ around 0.04. We then did a walk of ZM2 PSAMS and ZM2 Pitch, with touch ups of FC1 and FC2 and ZM2 yaw. Once we got gren flashes >12 we were able to stay in SQZ_FC at GR_SUS_LOCKING. We started at ZM2 PSAMS  strain gauge 6.55V and sliders as in vent (attached).  We got to ZM2 PSAMS at 8.3V with sliders and scopes as attached, this gave us green flashes of 30 and IR flashes of 0.2, plot. In O4 we had green flashes ~60 and IR flashes ~0.7, plot. We are still a factor of 2 or 3 below O4 with what we expect is an incorrect ZM2 PSAMS setting. 

We do not think that the ZM2 strain gauge should be different as no offloading was done to ZM2. When we put ZM2 back to nominal 6.55V and touch up alignment attached, our max FC green flashes were 20, IR flashes 0.2. But at this location the IR light on SQZT7 is decreased, plot comparing best green flashes to original vent sliders. We later with these vent sliders + FC2 changes got IR flashes to 0.4, but the IR camera showed not a real beam, just a stripe fo light as we saw in February (maybe the beam is at the edge of the FC2 coating).

Elenna, Sheila

Summary:  We reverted a large move of SR3 to be more like O4 in the SRC alignment, which we hope will help with the mode hopping problems.  We made phased reflair 135 phasing, and can now lock DRMI on 3F.  

• Elenna did a careful manual alignment in PRMI.
• We moved SR3 pitch back to the alignment slider values that it was at in O3.  This was changed during BBS alignment, without the arms, to match where we thought we needed ITMY to be (see 91567).  While the Yarm was open we moved ITMY but hadn't un done the move of SR3.  We have been seeing mode hopping problems, which in the past had been a sign of some change in alignment in the SRC.  
  • Elenna locked SRY and walked SR3 back to the O4 sliders, SR2, and SRM to keep SRY locked.  
  • At the end of this process we checked the power on AS_C, with 8.8W on PRM according to IM4 trans, which was in agreement with expectations (22mW into HAM6 according to AS_C, we expect 20mW but this power has always reported slightly high.)
• With DRMI locked, Elenna walked SR2 in steps until build ups got worse, then corrected the build ups with SRM.  After each step we looked at AS_C centering to judge if this was a step in the right or wrong direction.  By the time AS_C was centered there was a clear improvement in the power in OPO18 and more stablity of POP18, although the powers have been higher other days.  Screenshot
• With DRMI locked, Elenna transitioned PRCL to 27I (matrix element doubled compared to what it used to be).  We then put a line on SRM M3 test at 88 Hz, 30000 counts, and turned on notches in all DRMI loops.  We saw that SRM was mostly showing up in 135 Q, not I, so we adjusted the phase from 145 to 55 degrees to get SRCL into I.  
  • Elennal did a broadband SRCL excitation and sees that the 135I error signal matches 45I error signal well with a matrix element of 1.3 for 135I to SRCL.  We also did a prcl excitation and see that to cancel the PRCL signal in 135 I we will want to add a matrix element of 1.5 for 27I to SRCL.  (We used userapps/lsc/h1/template/phase_REFLAIR_3F.xml)
  • SRCL moved to 3F with 27I at 1.5, 135I at 2.5, this worked. (SRCL, used to be 2.1 27I, 1.7 135I)
• In 2018, we added a 27I to MICH matrix element: 43183 and 43190.  We rechecked this with the same PRCL exctitation used to tune the SRCL element, it should be -1.88, used to -0.67 .  Elenna measured a braodbadn MICH excitation, determined the matrix element should be 2.82 (used to be 1.115) 
• DRMI is transitioned to 3F, and Elenna put these matrix values in guardian.  
• OLGs of all three DRMI LSC loops are attached, on 3F.

Summary: Ran test of SPI TIA chassis noise - TIA chassis noise seems fine, QPD B electronics in chamber have elevated noise.

Following on from yesterday's alog today I went to the floor and unplugged the input cables from TIA variant 1 in the SUS-R2 rack (SPI_HAM2_009) and TIA variant 2 in the SUS-R3 rack (SPI_HAM3_015).

Then I remeasured the dark noise in CDS after resetting the offsets in QPDA and B to 15050 counts and 16750 counts, respectively, as they were yesterday.

In the attached ASDs you can see that I compare my dark noise measurement from yesterday when the laser was shuttered ( and the JAC/IMC was unlocked to avoid scatter in HAM2/3) and one done today with the QPDs unplugged from the TIA chassis.

 I have done two comparison plots for each quadrant with QPD A on the top plot and QPD B on the bottom, segments 1, segments 2, segments 3, segment 4.

For QPDA the overall noise magnitude is unchanged between each measurement. For QPD B all four segments are different when the QPD is unplugged.

Segment 4 is by far the worst. This implies to me that the TIA is ok but there is something wrong with the QPD B electronics in chamber.

Closes FAMIS85524

No new issues, LVEA5 is still not connected. The optics lab continues to have dust excursions likely caused by the wind conditions, the PSL anteroom and laser room also see these but at a lesser magnitude.

Closes FAMIS 85574, last checked in alog91931
Laser Status:
    NPRO output power is 1.853W
    AMP1 output power is 70.55W
    AMP2 output power is 139.2W
    NPRO watchdog is GREEN
    AMP1 watchdog is GREEN
    AMP2 watchdog is GREEN
    PDWD watchdog is GREEN

PMC:
    It has been locked 1 days, 0 hr 4 minutes
    Reflected power = 28.55W
    Transmitted power = 105.5W
    PowerSum = 134.1W

FSS:
    It has been locked for 0 days 2 hr and 22 min
    TPD[V] = 0.3879V

ISS:
    The diffracted power is around 3.4%
    Last saturation event was 0 days 20 hours and 15 minutes ago

Possible Issues:
    PMC reflected power is high
    FSS TPD is low, its at its lowest in over 2 months

S. Koehlenbeck, B. Lantz [posted by J. Kissel]

We're looking at the results posted by Jeff in LHO:91990, and are suspicious of the new ISI-DIFF channels. Here, Sina compares various available versions of the HAM2 table motion, 

    (1) H1:ISI-HAM2_BLND_CPSX_IN1_DQ      capacitive position sensor, pre-blend
    
    (2) H1:ISI-HAM2_CAL_CART_X_OUT_DQ     GS13s, pre-blend, but calibrated already into displacement units 
  
    (3) H1:ISI-DIFF_H2_BLND_SS_X_DQ       blended CPS + GS13s, re-constructed in seiproc for the input to the DIFF channel

    (4) H1:ISI-HAM2_ISO_X_IN1_DQ          blended CPS + GS13s, in loop in the HAM2 feedback. Contains loop suppression

    (5) H1:ISI-HAM2_ISO_X_OUT             feedback control signal

    (6) H1:ISI-DIFF_H23_SS_X_OUT_DQ       differential HAM3 - HAM2, using the HAM2 blended CPS+GS13 reconstructed in seiproc (3).

The message -- where we use the pre-blended sum of (1) and (2), it should look identical to (4) the reconstructed HAM2 super sensor, but it does not.
Or, the GREEN trace is a factor of ~2x larger that RED below 0.2 Hz, and BLUE above 0.2 Hz.

The discussion and investigation continues...

The HV at EndX was switched back on yesterday afternoon, I ran the OPLEV charge measurement for ETMX first thing this morning. The GRD state of ETMX was changed from ALIGNED to MISALIGNED in the last ~2 minutes of my measurement for some reason, I had unmanaged it from ALIGN_IFO. It was during the last LR measurement, LR Yaw has the largest error bars so that might have played into that. There was also a ground motion increase from a 5.7 earthquake near Tonga from the 2nd measurement till the 4th but my coherences were all >0.9 and the errors looked ok.

15:16 - 15:50 UTC EQ mode

The charge has decreased towards zero on 3/4 quadrants in both P and Y, UL being the odd one out mostly in Yaw. All quadrants/dofs are now under +/- 50 V.

TITLE: 09/23 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 2mph Gusts, 0mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.17 μm/s 
QUICK SUMMARY:

• JAC and IMC were left in down overnight
• LVEA6 dust alarm
• GVs are still shut
• CDS shows 10 chans disconnected, DTS channels

[Elenna, Louis, Keita]

Today we continued working on the transition of DRMI to the 3f signals. We have not gotten there yet. What follows is a rough list of events. 

* After maintenance I measured the OLG of MICH, PRCL, and SRCL in DRMI (ISC_DRMI:PREP_DRMI_ASC). 

    - PRCL UGF was at 50Hz. 

    - MICH UGF is at about 7.2Hz. We don't understand the OLG TF feature at 30Hz+. We suspect that this is due to cross-coupling with other dofs. The MICH gain during the measurement is 3. There was discussion in the control room regarding the drop in MICH gain by a factor of 3 in 92004 (which helped the mode hopping at the time). It's not clear how/why this gain adjustment worked since it looks like the gain would have dropped the UGF through 0deg phase and should have gone unstable(?). i.e. Elenna & I would have expected the drop in gain to not have worked if this OLG TF is representative of MICH during Keita's adjustments on Monday night.

    - SRCL UGF is at 35Hz. 

* DRMI LSC is cross-coupled: At Keita's suggestion, I ran the OLG templates with the MICH, PRCL, and SRCL inputs to gauge the cross-coupling from each excitation to the other two LSC dofs. These are attached as the <_inj>. png files (MICH exc, SRCL exc, PRCL exc). Judging from the coherence alone (top right subplot), there is a substantial degree of cross-coupling at the moment in DRMI 1f.  For instance, it PRCL has more coherence than MICH during the MICH excitation above 10Hz.

* The 3f transition is only partially working right now. PRCL transition works well consistently. MICH is not yet working (it fails immediately). We decided to work on SRCL before coming back to MICH. 

* For the SRCL 3f transition, we measured the 3f input matrix gains today and got -3.7 for REFLAIR_B_RF135I and +2.7 for REFLAIR_B_RF27I. We put these gains into the 3f input matrix for YARM and measured YARM (3f) /SRCL_IN (1f) at 80Hz and showed that we pretty much get unity, suggesting good agreement between the 1f and 3f signals. So we're pretty sure that the input matrix gains are correct (assuming no dominant frequency-dependent contribution that we aren't seeing at 80Hz, chosen because notches already exist for this frequency in the relevant feedback loops). However, when we load the (ramping) input matrix values to transition to 3f it fails every time. 

* We decided to inject PRM, SRM, and BS lines to populate a full 3x3 sensing matrix and invert it to construct proper diagonalized input signals. As Elenna was injecting a PRM line Keita noticed that it was poorly phased in REFLAIR RF45. We paused to get that phased back up. Not sure why it wasn't phased properly. There was discussion about just having done that recently. We changed REFLAIR_A_RF45 by 20 degrees (from -171 to -151). Following that we changed the PRCL gain by 3dB, SRCL by 6dB, and had to change the SRCL RF9 input matrix element from -1.7 to -1.2 to account for how much PRCL was making it into RF9 due to the phase change.

* After this we started seeing bizarre features in the OLG tfs in both 1f and 3f (MICH OLG, PRCL OLG, SRCL OLG). During the SRCL excitation we pulled up the REFLAIR_B_RF135I (45 3f) signal (gold) and see a 15 Hz instability that we really don't understand. It's our conclusion for the evening that we can't transition to 3f while we don't understand the broadband nature of this signal. 

* We didn't finish collecting the full 3x3 sensing matrix measurements. We should probably restart and complete those measurements so that we can try diagonalizing the input matrix in both 1f and 3f.

I also want to mention that we lost lock several times today due to JAC suddenly unlocking throughout the day. 

* 22:55:56 UTC while Elenna was tuning up the alignment

* 23:45 UTC while we were debuggin the 3f transition

* again at 00:09 UTC 

* and again at 00:59 UTC

While would usually be able to acquire DRMI relatively quickly after JAC came back, the JAC-induced lock losses did make the process a bit more painful than it otherwise would have been.

Jennie W, Jeff K, Keita K,

Summary: Scattering nosie from IFO couples into QPD A, QPDB segment four has larger dark noise b y factor of ~40 compared to other segments.

After we broke the ground loops on the TIA chassis inputs last week I redid the QPD dark noise measurements.

First I measured the average value of each quadrant input on both QPDs using diaggui to take a triggered time measurement withe the shutter open.

Then I closed the shutter and set the QPD_{A,B}_SEG{1,2,3,4}_OFFSET values to the average value for all four QPD A segments (15050 counts) and all four QPD B segments (16750 counts).

Then I measured the dark noise using the template in /ligo/home/jennifer.wright/git/2026/SPI/20260922_SPI_dark_noise_ASD.xml

The first measurement looked like it had some glitches on QPD A so Jeff got me to check the time series. At his suggestion we checked for coherence with ASC_AS_C (anti-symmetric port of H1) and it seems to be correlated. The AS port was flashing through fringes hence the fringing seen on the time series.

Zooming in this becomes more obvious.

I unlocked and mis-aligned the IMC and unlocked the JAC to stop scattered light through HAM 2 and 3 while I retook the measurement.

The QPDA dark noise now looks better but QPD B segment four is still significantly noisier than the other quadrants.

Looking at the time series this noise is obvious also.

Keita and I then checked the raw signal inputs before the anti-whitening filter on the QPD segments and these still show this noisier segment four. NB: this measurement was done with the IFO back to locking so scatter is again visible in the QPD A spectrum. The noise is flat, which suggests that the whitening stages in the TIA are not engaged so its not a whitening gain problem.

We then did a test with the SPI unshuttered and the dark offsets back to nominal. QPD B segment 4 now looks not that different to the others, which suggests that the four segments do not have wildly different electronic gains.

Try swapping chassis for TIA or disconnectiong input and measuring output ASD for TIA.

Next steps: 

- Measure TIA output spectra from each quadrant on QPD B with input unplugged.

Summary: guardian change messed up servo controller, will trial changes this weekend, have now backed out problematic part.

I changed the lines in the JAC temperature servo add in the PZT fb signal to the JAC temperature servo error point during maintenance.

I thought that I had it setup so the heater control error point gets changed as the JAC length changes, unfortunately I had a mistake in the code so this offset was only being added to the temperature servo once when the servo was switched on.

After updating it, this caused overshoot in the JAC temperature which kept unlocking it.

I have taken out these lines (line 46 in JAC_HEATER.py) so now the servo just tracks the set temperature of the heater.

I will leave this to settle overnight.

As part of our efforts to keep the JAC servo locked we had put the power output on the JAC heater to 0, I have turned this back to its nominal at 3W, and the set temperature back to its nominal at 25.4 degrees C.

I will also do another test at the weekend where I put the set temp up further to 30 degrees. The PMC has a set temperature of 32 degrees. While this is in air and so benefots from air cooling, a larger headroom in set temperature would make our control loop faster at cooling.

J. Kissel

Sina has posted some of the first SPI L results in LHO:91794 and subsequent comments in LHO:91861. They conclude, via passive ASD measurement and minimal unit conversion, that "the visual agreement is remarkably good."

Here I post some retrospective results from the driven transfer function set I took on 2026-09-03 (LHO:91798) to get a more quantitative comparison.
Using all channel conversions described in LHO:91809, which are, in summary "just" calibrating the front-end channels into the SI order of magnitude units (i.e. diplacement channels from [nm] to [m], and inertial sensor channels "inertial sensor response asymptoting to 1 [nm/s] at high-frequency" to [m]), I compare the ASDs and transfer functions during the reference time and HAM2 injection times, 
    Reference Time  2026-09-03 17:09:49 UTC 
    HAM2 excitation 2026-09-03 18:34:14 UTC - 18:58:09 UTC

Note -- while I had thought the CRS as blended into the HAM3 sensor array during this time, Jim confirms that it was NOT in play in the HAM3 RY loop (LHO:91866).
Also -- there were questions why "I didn't just use the same excitation that Jim did for the optical lever signals;" the real answer is that I hadn't had the chance to talk to him, couldn't find it easily on my own, and assumed it was some matlab infrastructure that I wouldn't know how to use. I now have talked to him, and he's pointed me to LHO:91754, which points to LHO:91607, which points to the actual path to the file in LHO:91179. But, even if I did find that text file to drive awggui with, it has a low-frequency-focused tilt de-coupling color too it, which is different from what I ended up concocting in DTT. C'est la vie, I think both sets of TFs will be interesting. Certainly this one was.

Attachment 1
Building up an understanding of the front-end-computed HAM3-HAM2 super sensor signal, H1:ISI-DIFF_H23_SS_X_OUT_DQ.

This ASD collection compares the CPS and GS13s of HAM2 and HAM3 against the differential super sensor during the HAM2 excitation (only). Since HAM3 was NOT being driven, we can treat this like the "reference" performance for the HAM2 ISI -- because the HAM2 and HAM3 ISI typically perform similarly in the longitudinal, or ISI and IFO X direction (when the CRS is not engaged into the HAM3 blend). 

- Compare BLUE, DARK GREEN, and HOT PINK traces. We see that the drive on causes displacement on HAM2 is factors of 2x to 50x above the reference level
- Compare THIN DARK PURPLE against CYAN and BRIGHT GREEN traces. We see that the blended input to the super sensor for HAM3 has -- for some reason -- a lot more motion than the "raw" blended CPS and GS13s input. 
- COMPARE BLUE, DARK GREEN, HOT PINK, and BLACK traces. Where the CPS and GS13s are not noise limited (i.e. where're signals are used in the blend to form the super sensor sum), All of the HAM2 and the differential HAM3-HAM2 signal agree, showing the excitation on HAM2.

Conclusion: the front-end computed measure of the differential motion between HAM3 - HAM2 using the onboard CPS and GS13s is functional, comes with a calibration that makes sense, and is measuring the right thing.

Attachment 2
Building up more trust in the HAM3-HAM2 super sensor signal, H1:ISI-DIFF_H23_SS_X_OUT_DQ as a faithful signal for comparison with the SPI L signal H1:SPI-H23_DIFFDISP_MAIN_OUT_DQ.

This ASD collection compares the CPS- and GS13-computed differential X motion (BLACK) and SPI L measured differential X motion (RED) during both the reference quiescient time (DASHED traces) and during the HAM2 excitation (SOLID traces). The excitation is also shown (H1:ISI-HAM2-ISO_X_EXC, calibrated into displacement units [m]).

- During the reference time (DASHED), the SPI L and the on-board sensors only agree above 5 [Hz]. *very interesting* We know the low-frequency-end -- below ~2 [Hz] -- is dominated by the SPI seed laser's frequency noise -- which is dominated by the IMC's displacement. Remember, at the time of measurement, only the IMC is locked (but now with the JAC locked between the PSL and IMC). It looks like -- at least during this measurement -- that's larger or different or incoherent with the HAM3-HAM2 motion. So... maybe this is all suspension noise (or ISI tilt)? Needs more study / noise budgeting.

- During the excitation time (SOLID), the SPI L and the on-board sensors agree across a much broader frequency-band, only disagreeing between 1.5 and 10 [Hz]. *very interesting*. *great* that the excitation i.e. this amount of differential motion *makes* the SPI L and on-board sensors agree for the most part. I have even less of a guess at an explanation for the frequency region where they're not, tho.

Conclusion: Under large differential displacement, the SPI L agrees with the on-board sensors over a very broad range of frequencies, from 0.005 - 2 [Hz] and 10 - 60 [Hz] Lots still to investigate, tho.

Attachment 3
Linear transfer function between the HAM3-HAM2 super sensor signal, H1:ISI-DIFF_H23_SS_X_OUT_DQ and the SPI L signal H1:SPI-H23_DIFFDISP_MAIN_OUT_DQ, as well as the length/frequency control channel for the input mode cleaner (H1:IMC-F_OUT_DQ. 

I show the driven transfer function magnitude for these signals on a log-log plot. Coherence shown separately below.

- Where the SPI noise didn't match the ISI-DIFF noise between ~2 - 10 [Hz], the TF is incoherent (coherence shown separately below), so ignore that.
- At other frequencies, where the ASD "visually agree" the transfer function is NOT exactly 1.0 -- see more discussion of the values of the TF magnitude in the semilogx version of the plot below. *very interesting* 
- I don't understand the magnitude of the IMC-F transfer function at all below 1 [Hz]. The next plot shows it's coherent... *very interesting* or *I'm missing something obvious*

The IMC-F channel has the following calibration into [m]:
    Gain: 1.1683e-06
    Poles: 0
    Zeros: (none)
I don't remember how I calculated this, or where I got it from. To be (re)investigated... but I would have guessed -- since IMC-F_OUT_DQ is already calibrated into [kHz], that it *should* be something like a factor of (2 * L_IMC * lambda / c) = 1.1724e-13 [m/Hz] or 1.1724e-13 [m/kHz] with no poles at 0 [Hz], from df / f0 = dL / L_rt math, but that doesn't seem to be it at all. I probably just need to go back to the code used to produce plots in the SPI final design doc ... just haven't had time.

Also -- side note -- looked into the IMC_X calibration infrastructure that uses the length drive to MC2 to calibrate the control signal into displacement units and that doesn't work.

Attachment 4

Coherence between SPI L and the ISI-DIFF channel and the IMC-F channel for the two TFs shown above.
I also show the coherence between the SPI L channel and the individual ISI CPS and GS13s to understand from where the coherence comes (expecting more from HAM2 since this is during the HAM2 drive.)
I also show the coherence between the ISI-DIFF channel and the IMC just to see how that's different.

Conclusion: Lots to see here, but I haven't really digested it or tried to make sense of it.

Attachment 5
Same transfer function as in Attachment 3, just shown in semi-log x so we can read off what the magnitude of the TF is at coherent frequencies.

- The TF is indeed almost a flat 1.0 [m/m] above 10 Hz; but not quite. *very interesting*
- Between 0.1 and 1 [Hz], where the SPI and ISI-DIFF are *definitely* coherent, the TF magnitude is *not* 1.0, not is it flat. It's got bumps and wiggles between 1.0 and 0.7. Best first guess it that this has something to do with gain peaking in the blend filters. *very interesting*

Conclusion: this TF is going to be very interesting, and we won't be able to "just" blend the SPI "right in" with a simple filter. And, I need to try to get more coherence below 0.1 [Hz].

Very interesting! 

(Travis S., Jordan V., Richard M., Gerardo M.)
After the installation of CHeTA viewports, we connected an ISP-1000 scroll pump and a SS-500 cart to each of the main turbo pumps at the X beam manifold and Y beam manifold.  After getting power sorted out to the ISP-1000s, thanks Richard, we started the pumpdown for both of the manifolds.
Something that we did noted was the new gauge for PT-180 shows almost 1000 Torr for pressure at atmosphere, this is not correct, then the other gauge for PT-170 shows 750 Torr for pressure at atmosphere, also not right.
Pumpdown has been stopped at the end of the day, and will be restarted tomorrow morning by Jordan.

Attached is a plot of both manifolds initial pumpdown.

Over the last few days, Oli and I removed four unused chiller lines at the Yarm termination slab. Two were old TCS lines that were already cut off and mostly empty, the other two were valved out around the spool area but unused after. We cut, vacuumed, and removed all the copper pipes and their support hardware up to that spool area. Still to do is solder an end cap to the two cut lines.

M. Todd, J. Wright, S. Dwyer

Here is my attempt to summarize as many of the OMC scan measurements of the input beam overlap with the OMC mode, as well as PRC and SRC gouy phases -- all at different thermal states.