The shutter had not been working in the remote setting for the PSL DBB.  When Peter and Jason reseated the connectors on the shutter last week they fixed the problem.  They only tested the manual switch and left it open for the week. This morning I tested the remote control and the shutter open and closed as designed.

I have updated the gds software to v2.17.10 and the gstlal-calibration to v1.0.5 and restarted the dmt process manager. After a few tweaks, everything seems to be working.

11:44 NLN ~50MPc

12:55 damped PI mode 17 by by adding another -60 degrees to the phase.

12:58 Had to damp ITMX Roll mode. Changed phase to -60 and set the gain to 20.4 (incrementing as directed in the Wiki)

13:00 restarted/reset all FOMs

13:38 added another -20 degrees to the PI mode 17 phase. (-130 degrees total)

Follow up to alog 30294

I've re-measured the open loop transfer function of Mode2 a few times after decreasing gain and tweaking phase to try to move towards stability. Halving damping gain halves loop gain (31 --> 16) but neither changing damping phase (+/- 30 deg) or phase picked up from bandpass (30 deg --> 0 deg) changes overall loop phase; all still leave us with ~160 deg phase differential. 

• I had to use the CHECK_MICH_FRINGES state to get the Beam splitter re-aligned after the lock stretch that Patrick had pior to my shift. I also had to move PRM around to get flashes good enough to lock PRMI.

07:58 Back to NLN. Terra doing some excitations ~50MPc

• ITMX Roll Mode has to be damped. It got up to ~ e^-12
• There is a very annoying 'locking-up/freezing' on medm screens! I've logged in as Ops, myself and Controls. It happens under all of those accounts

10:02 Terra informs me she's about to do some pretty invasive injections

10:44 Injections caused PI to run away and break lock

10:56 put ISC-LOCK into INITIAL_ALIGNMENT to re-align green arms.

Lost more than 5 hour lock 10 minutes before end of shift. SUS OMC and HAM6 ISI tripped. Cause not immediately obvious. Handing over to Ed.

23:00 UTC Jenne is in LVEA by HAM6
23:23 UTC Gerardo back from overfilling CP3
23:27 UTC Disconnected and reconnected conlog-test-master to ~100,000 channels
23:41 UTC Starting initial alignment
23:46 UTC Changed from VERY_WINDY_NOBRSXY to WINDY. Improved X arm transmission and stability.
23:55 UTC Jenne back, whitening AS_A chassis swapped (Jenne, Mark, Filiberto)
00:21 UTC Initial alignment done. Jenne to LVEA.
00:42 UTC Jenne back. Starting relocking.
01:36 UTC NLN
01:55 UTC Jeff K. starting calibration sweeps
03:00 UTC Terra starting excitation of PI mode 2
03:18 UTC Jeff K. done
04:51 UTC Nutsinee to mezzanine to check TCS chiller
04:59 UTC Nutsinee back
05:36 UTC Jenne to LVEA to jiggle RF45 cable
06:01 UTC Jenne back
06:50 UTC Lost lock. SUS OMC and HAM6 ISI tripped.

Earlier this evening, I tried hand-tuning the a2l coefficients for PRM and SRM.  Just as I was finishing and trying to see if I actually did anything good, the RF45 went crazy, so we'll have to wait for a future lock to really start looking at coherences, etc.

• PRM Pit
  • Dither M3 at 20.125 Hz, 8 counts.
  • Change M3 P2L gain from 0 to +1.1 to minimize the peak in PRCL. 
  • No discernible change in the peak height in DARM.
  • Using P2L gain of +0.5 was better for minimizing the peak in DARM, but not for minimizing the peak in PRCL.
• PRM Yaw
  • Dither M3 at 20.125 Hz, 20 counts.
  • Change M3 Y2L gain from 0 to +0.87 to minimize peak in PRCL.
  • This makes the peak in DARM worse!  Why?
• SRM Pit
  • Dither M3 at 20.125 Hz, 10 counts.
  • Change M3 P2L gain from 0 to -1.0.
  • Minimizes peak height in SRCL.
  • Drastically reduces peak height in DARM.
• SRM Yaw
  • Dither M3 at 20.125 Hz, 10 counts.
  • Change M3 P2L gain from 0 to -1.2.
  • Minimizes peak height in SRCL.
  • Drastically reduces peak height in DARM.

After this, I ran A2L for the test masses.  Then RF45 went bad.  So, I'll come back to this tomorrow.

About an hour ago, I noticed that our sensitivity degraded significantly in the bucket.  This brought our range down to about 20-30 Mpc from the 50+ Mpc we had been at.

Glancing up, I noticed that the RF45 spectrum looks atrocious.  I'm not at all sure what is going on, but it is very bad, and changing with time.

In the attached screenshot, I have the DARM spectrum, the RF 45 and RF 9 spectra, as well as the RF coherences with DARM.  The colors are the same in each plot, with the start times of the data indicated in the DARM legend.  Dark blue is a good time, when our range was good.  Pink and green and red show different times when there was a weird peak in the RF45 spectra.  Brown and light blue are intermediate times when the RF45 is elevated, but not peaky. 

I don't know why this would have anything to do with the new barrel connector that Richard et al. put in earlier today (alog 30375), but maybe I'll go jiggle it.

EDIT:  Before any jiggling, Terra Patrick and I notice that it's steadily getting worse :(

J. Kissel, B. Weaver

Betsy launched charge measurements this morning, so I've processed them. The message: most quadrants of both test masses are at 0 [V] effective bias voltage, so we're again ready to start regularly flipping the bias voltage. We'll wait a bit for the IFO to have a higher duty cycle, or wait until the end of the week and just change it. Historically, if we change it when everything else is going wrong, the bias flip gets blamed and therefore it doesn't stick. We want to stick!

Remember that 
- we've now reverted back to compensating for the sign change in the SUS's DRIVEALIGN matrix (and not in the COILOUTF banks)
- we'll no longer change anything in the CAL-CS model, because the overall sign of the L3 stage doesn't change (LHO aLOG 29868)

Also, eventually, when the IFO's duty cycle picks up again and calibration team's analysis infrastructure re-solidifies, we can start making the comparisons against longitudinal actuation strength with calibration lines (e.g. LHO aLOG 24547), which should really be the metric for when to flip.

Looked at ISC Whitening Chassis in ISC-R5. Jenne reported one of the gain binary bits was not changing states. Went out to the floor and verified binary request was getting to the whitening chassis via the DB37 cable. We could see the states change from high to low with the cable disconnected.  When binary cable was connected to the whitening chassis, signal was pulled low. Replaced chassis S1101583 with S1101595. Will troubleshoot in EE lab.

F. Clara, J. Driggers, M. Pirello

WP 6229,

I have updated the TCS corner station model (h1tcscs.mdl). I confirmed that the model comiples without an error. The model is ready for installation tomorrow. The model change includes the followings.

• New simulated plant (T1600451-v2).
• Modification for routiing CO2 power values to the SIM block.

The first item is described in T1600451 in detail. The second point is something we newly implemented today in order to get rid of two paricular ezcaread blocks which had been referencing channels that are in the same front end model. To improve this self-referencing situation, we modified TCS_MASTER.mdl so that the TCS block returns the CO2 power as an output. See the attached screenshot for how we routing the CO2 powers to the SIM block.

Following discussions with Daniel and Jim, I've written some instructions in the CDS WIKI to manually ramp down any running excitation to zero prior to killing the excitation. This is only needed in cases where the normal ramp down does not result in a zero EXC input to the filter module (e.g. excitation filter with very long ramp down times).

https://lhocds.ligo-wa.caltech.edu/wiki/ManuallyRampDownExcitationPriorToStoppingExcitation

This procedure can be applied at any time during the measurement and does not need to be setup in advance.

The most troubling environmental coupling in O1 was the vibration coupling at HAM6. Not only were ambient vibration levels within a factor of as little as 2 of the DARM floor around 1000 Hz, but the coupling was the only highly non-linear environmental coupling (https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=23305, see especially summary attached to this log). Sound near 1000 Hz, and higher, could produce features in DARM at both higher and lower frequencies then the injection frequency. The fact that loud sound in the several thousands of Hz regions could down-convert into the detection band (one could imagine a chirp from the startup of a motor with squealing bearings) required special vetting (https://alog.ligo-la.caltech.edu/EVNT/index.php?callRep=11470).  The non-linear coupling is due to intermodulation with the 4100 Hz OMC length dither frequency. I think that the most likely explanation is that there are frequencies starting at about 1000 Hz where ISI suspension, OMC suspension, and OMC body resonances all overlap, allowing vibrations from outside to significantly modulate the OMC length and intermodulate with the length dither. The overlap is probably made possible because the many resonances are not quite as high Q, and not as clustered as the optic suspension violin resonances.

We attacked the path in from the outside world by damping ISI blade spring and flexures (analogous to suspension wire) resonances during the June HAM6 intervention. I have previously logged that this damping reduced the desired ISI suspension peaks (https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=27135), before we had the interferometer working. Figure 1, below, goes on to show that the damping resulted in a factor of about 3 reduction in vibration coupling to DARM, for a standard amplitude injection, for both linear and non-linear coupling (Figure 1 is for a shaker on the blue cross beams of HAM6; the measurement is for RMS in the band because the peaks moved around somewhat as well).

Figure 2 shows that we could further reduce the non-linear part of the coupling by reducing the dither amplitude. A factor of 8 (amplitude reduced from 6000 to 750, gain increased from 3 to 24 to compensate), gave a factor of roughly 8 reduction in non-linear coupling for a total reduction of more than 20.   Figure 2 also shows that there was no apparent increase in noise at lower frequencies in DARM, and that the linear vibration coupling stays the same.

The previous figures were for targeted injections at HAM6 (blue cross beam shaking). Figure 3 confirms that dither reduction reduces non-linear coupling for global shaking from an acoustic injection with a speaker at the X-manifold standard location.

I propose that we try running with CLK_GAIN of 750 and SERVO gain of 24. The ISI suspension resonances were also damped at LLO, and I think the dither was reduced in Feb. for other problems associated with non-linearity. The sidebands in DARM at the dither frequency are, at LLO already the size of the sidebands for the proposed LHO settings, so LLO may not need to make further changes. Of course we should check.

Robert, Kiwamu, Anamaria

ASC-POP_X shows a broken readback for its second whitening stage on one of its channels. If true, the second stage is engaged on one segment/RF phase. This problem developed on 10/7.

ASC-AS_A_RF45 shows a broken readback for a gain on one of its channels. If true, +12dB is added on one segment/RF phase. This problem developed on 10/9.

03:35 UTC Connecting to ~100,000 channels from conlog-test-master.