I wrote a script to give the names of the channels with open test points, given the FE model name or DCUID #. The old way to do this was to:

• Run "diag -l" in a terminal
• > tp show DCUID#
• This would give a large amount of zeros and only a few numbers that would then have to be searched for in (target)/gds/param/tpchnnum_(model).par
• Then you have a channel name, yay!

This script lives here: (userapps)/cds/h1/scripts/get_open_tps.py

I also added it to the Operator's "Useful Scripts" wiki page.

Sample output:

I measured the open loop transfer function of MICH, PRCL and SRCL when DRMI is locked on POP (full resonance). It turned out that MICH and SRCL transfer functions showed some weird features at high frequency, due to cross-coupling to PRCL.

I retuned the POP9_I > SRCL sensing matrix element from -0.0467 to -0.02, and added a matrix element from POP9_I to MICH with a value of 0.009. In this way both MICH and SRCL open loop transfer functions have a smooth shape as expected.

For reference the table below shows the UGF and measured instability frequencies of all three loops (if measured)

[Jenne, Hang, Craig, Gabriele]

Summary

We can improve the recycling gain and simultaneously improve the beam centering on ITMs by moving PR3 in yaw.

We didn't get all the way to centered mirror, but we gained 3% more power.

Details

Motivated by the observation that the beam is mis-center by 2cm in yaw in the ITMs, we tried again to move it, continuing yesterday's attempt.

The strategy was different this time: we locked up to PREP_DC_READOUT_TRANSITION, with all ASC loop engaged and converged. We then moved PR3 in yaw by small steps. The idea here is that the PRM angular control will keep the beam spot in the same position on PR2, the soft loops will maintain the beams fixed on the ETMs, and the REFL WFS loops will ensure that the beam axis is well aligned into the IFO. The only free degree of freedom is then the beam spot position on the ITMs.

We dithered ITMX and ITMY in yaw at 21.3 and 21.9 Hz, and we were using H1:ASC-ADS_YAW2_DEMOD_I_OUT and H1:ASC-ADS_YAW3_DEMOD_I_OUT to monitor the beam centering.

By moving PR3 in yaw we could increase the recycling gain, increase the power in the arms and reduce the mis-centering. We lost lock a couple of times during the move, likely due to loop instabilities triggered by the larger circulating power.
We had to change the MICH gain from 2.8 to 2.0, SRCL from -25 to -15, and change the PRCL to SRCL sensing matrix from -0.045 to -0.02 to get rid of a weird shape in the SRLC open loop transfer function.

At this point we started losing sideband recycling gain (mostly RF18), so we tried to move the PRM set point in yaw (we could not improve RF18, but we lost most of the carrier power gain). We also tried to move MICH, but lost lock.

Unfortunately the new PR3 position is not compatible with the initial green lock, so we have to revert to the old positions every time we lose lock.

J. Kissel

It's always impressive when a ~8 Mag earthquake rolls through the earth. Today's was a 7.8 magnitude, who's epicenter was in Suva, Fiji. Attached are the BLRMS of the 0.03 to 0.1 and 0.1 to 0.3 Hz bands during the quake. Seismon warned us at 2600 seconds prior, but we tried to squeeze one more measurement in. As soon as we saw it on the BLRMS, however, we switched to VERY LARGE EQ mode on the seismic systems, and diverted our attention elsewhere for ~4 hours (though we probably could have started trying again sooner than we did). Only the Beam Splitter ISI tripped, nothing else. See LHO aLOG 43863 for a more precise timeline.

This morning LLO reported that their SEI nodes would crash when reloaded. Since we just had a big earthquake, we had time to test.  I tried random nodes for the most part:

The chamber managers seemed to be okay, but the ISIs and HPIs would most likely crash. The crashes were all because of a 20sec watchdog timeout. Doing a guardctrl restart would bring the nodes back without issue.

It's odd that we are just seeing this now, Jim has reloaded ISI_ETMX_ST2 a few times and not had an issue. There are a few other nodes listed above that crashed today, but have been reloaded since the new Guardian update as well. This could just be because they got lucky and finished whatever they needed to just before the timeout.

Attached a small bit of the log.

J. Kissel
https://tinyurl.com/LIGOSUSActuatorTuning Table

I've balanced the BS M2 coils using the demodulated optical lever method (LHO aLOGs 11392 and 9453).

I'll characterize in more detail later, but here're the results:
      Former          New       % Difference 100*(former-new)/former
UL   +1.01       +1.00112      +0.87921%
LL   -0.985      -0.988984    -0.40447%
UR   -1.015      -1.01108     +0.38621%
LR   +0.99       +0.998824    -0.89131%
Only a small change. They've been accepted into the SDF system.
   
I was only able to grab an L drive transfer function with the new balance before the Mpc Train started choo-chooing (instead of the full frequency dependent suite of L, P and Y drive with former, no, and new balance). Anyways, the one TF lives here:
    /ligo/svncommon/SusSVN/sus/trunk/BSFM/H1/BS/SAGM2/Data/
        2018-09-06_1900_H1SUSBS_M2_L_WhiteNoise.xml
For the record, the balance and thees transfer functions were measured with the BS optical lever damping OFF.
   

[Craig, Jenne]

We have been seeing several times this week that when we try to find IR, we are not able to hold at a steady value.  The COMM loop in particular, but also the DIFF loop, seem like they can't hold the beatnotes to a close enough frequency. 

Just now, Craig noticed that the PSL FSS common gain was at a low value of -10, when it should be +20.  Looking at the data, it has been at -10 since 4 Sept 2018 at about 05:30:00 UTC.

Looking at the PSL_FSS guardian, the FSS_OSCILLATING state checked if the FSS was oscillating.  If oscillating, turn the FSS common gain down to -10. When it's not oscillating, pause, then turn the gain back to +20 and return True.  What it didn't check was if the FSS was locked.  So, we were in the FSS_OSCILLATING state with the gain at -10.  The FSS unlocked and so reported that the loop wasn't oscillating.  But, since we had requested a different state of the PSL_FSS guardian at that same time (which the ISC_LOCK guardian does in the DOWN state), it jumped out of FSS_OSCILLATING and went to the new state, without the pause and increase gain.  So, we've probably never seen this before because it was a bit of a rare case that the FSS was oscillating then lost lock at almost exactly the same time that we requested a different state. 

I have added a check to the FSS_OSCILLATING state that the FSS be locked as well as not oscillating in order to continue.  Hopefully this will prevent this from happening again.  Also, yet another thing that if we were keeping up with SDF (really hard to do while things are so in flux during commissioning) we would likely have found.  Oh well. 

14:35 - 15:39 UTC Karen to LVEA to clean
14:36 - 14:52 UTC Chris to LVEA to shrink-wrap a pallet
15:11 UTC Vanessa to LVEA and then end X to clean
15:39 - 15:52 UTC Karen to end Y
15:54 UTC Verbal notification of 8.1 magnitude earthquake from Fiji
16:02 UTC Set seismic to very large earthquake
16:13 - 16:29 UTC TJ to TCSX table to check on leak
16:20 - 17:29 UTC Marc, Ed, Filiberto to end Y to pull cable for ESD power supply
16:29 UTC Jeff K. taking BS ISI to damped, coil balancing
16:50 - 18:43 UTC Gerardo to LVEA to decouple equipment from IP6
16:53 UTC ETMY guardian crashed, TJ investigating
17:02 - 17:07 UTC Tyler moving scissor lift from LVEA to staging building through high bay
17:09 - 17:18 UTC Nutsinee to ISCT6 rack
17:23 - 18:12 UTC Dave to end stations to look at computer racks
17:26 - 17:55 UTC Karen to H2 building
17:28 - 17:40 UTC Betsy to LVEA to take measurements
18:11 - 20:31 UTC Filiberto WP 7803
18:24 - 20:31 UTC Ed to LVEA WP 7803
18:30 - 18:44 UTC Betsy to LVEA
19:57 UTC Set seismic to recover from earthquake
20:56 - 22:03 UTC Gerardo to end X to retrieve leak detector
20:57 - 21:05 UTC Ed to CER

Today Gerardo valved in IP6 and also decoupled VE from the pump during a TOO from an earthquake. Attached is a pressure plot showing IP1 & IP6 being valved in and we now have all six IPs pumping on corner volume (IP2 has not been rebuilt yet). The pressure seems to be drifting up since we valved in IP1. We plan to leak check the corner station on Tuesday.

FAMIS 10473

Added 100 mL H2O to crystal chiller. The bottom left canister filter is discolored.

Kara Merfeld, Greg Mendell, Evan Goetz

We wrote a program that calculates the coherence between two channels using the short Fourier transforms used by DetChar and the CW group.  The program then generates plots of the coherence for every 100Hz interval of frequency.  

Ultimately this program will be used to calculate the coherence between any auxiliary channel and the calibrated strain channel, and the code will be used in the Fscan pipeline.  It will upload the plots to the DetChar summary pages every 24 hours, as well as make the raw data available.  
The fft length used in the calculation is determined by the sfts it is given, and no overlap is used.   

For the attached plot, the fft length used is 1800s, and there were 48sfts.  

FAMIS 7559

The following appear elevated:
BS_ST1_CPSINF_H1_I
BS_ST1_CPSINF_H3_I
BS_ST2_CPSINF_V1_I
ITMY_ST1_CPSINF_V2
ITMX_ST2_CPSINF_H3

TVo Aidan Danny Georgia

Following on from alog 43788. I had a look at the ITMY Hartmann wavefront sensor data after out final lockloss on Saturday, where we were locked at 8.3 W. I used Aidan's fitting script and method from LLO alog-14634, and fit the spherical power (thermal lens) as the test mass cooled down (second attachment). From this measurement I calculate the absorbed power, and from the circulating power estimate the absorption to be 394 +/- 107 ppb.

Details

The first attachment shows a ndscope screenshot of the ITMY HWS spherical power, prism values and the PSL power, after lockloss on Saturday. By fitting the spherical power decay time we can estimate the power absorbed in the optic. The initial kick in the spherical power is possibly due to the ITM misalignment after lockloss, this makes it tricky to tell when the fit of the ringdown should begin, I've just done it by eye. The fitted absorbed power is 17.1 +/- 4.6 mW, as shown in the second attachment with data in blue, fit in red, uncertainty in yellow. The uncertainty looks a bit excessive on this plot but depending on when I start the data to fit, the absorbed power can move around within these error bars.

The circulating power can be calculated:

P_circ = P_in * recycling gain * BS reflectivity * arm cavity gain

= 8.3 W * 37 * 0.5 * 282 = 43.3 kW

From this and the thermal lens the absorption is calculated. The script used to generate the plot and calculate absorption is here:

/ligo/home/georgia.mansell/TCS/20180904_ITMYAbsorption/LHO_ITMY_TL_20180901.m

A similar measurement on ITMX was not possible with this particular lockloss due to the bright ghost beam on the HWS, Danny has since closed the iris on this beam.

When we lost lock the ALS beam became unshuttered, as set in ISC_LOCK down state, saturating the end-station HWSs. I've since moved the unshuttering to LOCKING_ARMS_GREEN. Though if we want to take a meaningful measurement on the ETMs we will need ALS shuttered for ~5000 seconds after lockloss.

Jenne, Georgia, Craig, TVo, Hang

We parked the IFO at ENGAGE_SOFT_LOOPS and tried to center the spots on the ITMs.

Specifically, we put dither lines in yaw on the ITMs and turned off the Y2L FF gains. The lines were demodulated from DARM for us to monitoring the spots on the ITMs. We then opened the PRC1 loop (locking PRM pointing to ASC POP QPD) and used the pr3spotmove.py script at /ligo/home/controls/sballmer/20160927/ to minimize the dithering line. 

We could put the spots more centered on the ITMs in the yaw direction, however the recycling gain dropped significantly to only 28. The power on arm transmission was also low, 1020 for TR_X_NORM, and 1060 for TR_Y_NORM. We tried to open the soft loops and move the soft dofs around yet did not succeed in getting the PRG back (we might not tried hard enough though).

The slider and osem values for this config (spots roughly zeroed on the ITMs with low PRG). Also the ASC_POP_A_YAW_INMON value was -0.37 currently (originally +0.22).

Prompted by a discussion with Gabriele, I took some measurements of the first loop power stabilisation.

    isstf.png shows the transfer function using either PDA or PDB (ie, either of the two first loop
photodiodes).  No difference in the transfer function was observed.  The UGF was around 50 kHz.

    PDA.jpg and PDB.jpg show the measured power noise using photodiodes PDA and PDB respectively -
PDB was used as the in-the-loop sensor.  Both show a similar degree of suppression except at low
frequencies.  However it was noticed that whenever the second loop output was enabled, there was no
observed suppression with either PDA or PDB.  Engaging the second loop caused the reported diffracted
power to rail at ~3.3%.  I've since found out about the offset removal for the second loop (thanks Gabriele!).



  Gabriele / Peter