FYI - I've updated the ISI/Common/ part of userapps with 3 new files:

models/Monitor_Library.mdl
medm/demo_peak.adl
src/PEAK_MON.c

-r 19184 and -r 19185

These are in prep. for a new monitor we'd like to add. These are not used anywhere (yet) so updating userapps should not impact anything in the detectors - at least not from these.

-Brian

This alog has been edited.

I think that we have understood one of reason that we have had trouble with the stability of our DARM loop over the last few months, which I've tried to explain in a dcc note: T1900148.  The summary is that we are using length to angle decoupling, and because our spot positions are far off center we also are using gains of about 5 in the angle to length decoupling on the ETX PUM (a DARM actuator) to avoid having the angular drive show up in length.  Since the output of the length to angle decoupling doesn't go through the angle to length decoupling filter, the output of that filter couples to DARM through the spot mis centering, which has been large enough to cause instabilities and calibration problems.  

• There is a systematic error in the calibration model of the PUM actuator, 47979, which is not seen when the measurement is made bypassing the drivealign matrix (driving at test)
• The DARM loop has been unstable at 8-9 Hz with the L2P and L2Y decoupling filters off, 47824  This seems likely to be a crossover instability similar to what we might have seen when the PUM gain was lowered to 15 over the weekend: PUM gain lower model

There have been several problems with the stability of the DARM loop over the last few months that might be explained by this, including the 4.2 Hz instability, which was initially solved by adding a boost to the PUM lock filter (47164) but has come back in the last few weeks, There have also been several attempts to change the DARM loop in ways that should have been stable according to the model but weren't, this effect is probably contributing to that difficulty.

This morning Niko and Jenne have been struggling with 4.2 Hz locklosses again, so we took a guess that turning off the L2P and L2Y might help fix the problems at 4.2 Hz, and that turning off the boost in the PUM stage would give us more phase margin for the crossover around 8 Hz and might help us avoid the locklosses we've had with the L2A off.  So far it seems that this is working.  If we can run like this it would make the calibration more accurate and make understanding our DARM loop easier. 

The two most obvious ways to get rid of this parallel DARM actuation path are to set the A2L gains to zero, and turning off the L2A decoupling.  We don't want to set the A2L gains to zero because we do not want the spot to be centered on the optic (power recycling gain, point absorbers). We would expect that turning off the L2A decoupling will increase the size of the ASC control signals.  We have never had accurate measurements for the length to angle decoupling above 2.5 Hz, these filters are rolled off at around 10 Hz. 

Some other conclusions from thinking about these cross couplings more: (updated)

• Making the L2A filters more accurate to higher frequencies doesn't get rid of the cross coupling to length. Rolling the filters off faster (even if that makes them less accurate) would help.  
• If the output of the length to angle filters are summed into the angle drives at the input to the drivealign matrix, this would reduce the unintended length actuation at frequencies where the angle to length decoupling is accurate.  This becomes more important the further our spots are from the center of the opitc. 
• We could copy the L2L filter into the L2A banks, so that it can just be updated if the L2L filter is changed with out revisiting the decoupling.  (Not doing this might be the reason we have had difficulty any time that we have tried to make changes in the L2L filters).
• If we want to do frequency dependent angle to length decoupling, and continue to be able to move the spots around, we could use two parallel filters in the place where P2L and Y2L are currently.  (some modeling might be helpful to decide how important this is).

1616 UTC out of Observing to start the measurements.

TITLE: 03/29 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 109Mpc
OUTGOING OPERATOR: Travis
CURRENT ENVIRONMENT:
    Wind: 3mph Gusts, 1mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.23 μm/s
QUICK SUMMARY: Looks like a ~22hr lock, there was some times that we went out of the Nominal Low Noise state which reset the lock clock.

TITLE: 03/29 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 110Mpc
INCOMING OPERATOR: TJ
SHIFT SUMMARY:  H1 locked for the entire shift, 13+ hours total.  One brief drop out of Observing for as yet unknown reason.
LOG:  Managed to stay awake for my first Owl shift of ER14/O3 era?

Unknown cause.  I had stepped out of the control room and noticed it was in Commissioning upon return.  No SDF diffs.  There was a notification on Verbal Alarms of an EX saturation at 12:10 UTC.  I had earlier noticed the scheduled injection running at 12:00 UTC in the DARM spectrum.  Lock is now 10 hours young.

TITLE: 03/29 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 108Mpc
OUTGOING OPERATOR: Patrick
CURRENT ENVIRONMENT:
    Wind: 12mph Gusts, 9mph 5min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.22 μm/s
QUICK SUMMARY:  H1 locked for 5:15 (according to the lock clock) and in Observe for the past 15 minutes (due to drop out due to violin modes, Guardian transients, etc.)

TITLE: 03/28 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 104Mpc
INCOMING OPERATOR: Travis
SHIFT SUMMARY:

- Switching the violin mode guardian to simple takes us out of observing
- It would be useful if there was a log of the channels that change in SDF when they kick us out of observing (if there is not one already). Sometimes the change is temporary and too quick to catch by eye.
- Jim found issues with the guardian switching SEI blends.
- Sometimes the violin mode guardian thinks a mode is growing, and it turns off the gain in response, but it was only a short term increase, and turning off the gain then makes it grow steadily. I believe this happened with ETMX mode 13 and 6.
- Rahul would like us to make certain that the ETMX mode 9 gain is set to -3 (the violin mode guardian may turn it off, and we want to test keeping it on).


LOG:

23:17 - 23:30 UTC Changed from earthquake to windy. Jim had to intervene to fix blends. Calibration measurements restarting.
00:05 UTC Observing.
00:25 UTC ETMX mode 13 was growing because the guardian had turned the gain off. When I took the violin mode guardian to simple, it took us out of observing. Turning the gain back on brought it back down. Left out of observing for Jeff K. Now ETMX mode 6 is having the same problem.
00:45 UTC Damping on simple. Set ETMX mode 6 gain to 5. Put back to IDLE and then Damping_On_DC.
01:03 UTC Changing the state of the violin mode guardian might have turned off the ETMX mode 9 gain. I set ETMX mode 9 gain back to -3 without changing the violin mode guardian. Seemed to work.
01:15 UTC Set observatory mode to calibration (late)
01:53 UTC Back to NLN
01:55 UTC Observing
02:42 UTC Violin mode damping guardian knocked us out of observing when it changed one of the gains?
02:43 UTC Observing
03:48 UTC Realized I forgot to set observatory mode to observing. Did so.
05:00 UTC Twice dropped out of observing by violin mode damping guardian. Unmonitored ITMX mode 17 gain in SDF and set back to observing.
06:05 UTC Dropped out of observing. Not certain why. Set back to observing.
06:51 UTC Dropped out of observing by TCS_ITMY_CO2 guardian. Waited for it to settle, set back to observing.

J. Driggers, S. Dwyer, J. Kissel, Y. Lecoeuche, J. Warner

H1 was able to ride through a 6.1 Mag EQ on the pacific coast of Russia this afternoon by switching to the recently developed "robust" IFO-basis common-mode sensor correction system that the SEI team has been creating for the past few months. The only other configuration change was that Jenne increased the SNR of the ~20 Hz Alignment Dither System lines to "ridiculous" (a factor of 1000 higher than they normally are), and compensated for the amplitude increase by decreasing the loop gains by a corresponding amount. This was to avoid the lines being washed out by the scattering arch glitches that were appearing in the performance of the interferometer. 

The peak BLRMS during the EQ's arrival on site was ~1 um/s in the 0.03-0.1 Hz band, and it spilled into the 0.1-0.3 Hz band at the 0.5 um/s level.

Note that the scattering arches were likely not caused by the earthquake, but the degradation in microseismic band performance currently necessary for the common-mode EQ configuration. Jim thinks this can be improved.

The EQ occurred at 2019-03-28 22:06 UTC, and arrived on site about 15 minutes after. 
We received a ~10 minute warning from SEISMON, which successfully warned us to go into the above mentioned robust mode.
We returned successfully out of this robust mode into nominal configurations ~1 hour after the first waves hit the site, once the BLRMS in the 0.03 to 0.1 Hz band went below ~0.5 um/s.

A great testament to all the hard work the ISC and SEI teams have done between O2 and O3 to improve IFO robustness.

A final note that during this EQ, the calibration crew was "measuring" the CAL-CS calibration paths, so the calibrated performance of the detector, DELTAL EXTERNAL and any down-stream products are non-sense. If you need to look at the performance of the IFO, look at less calibrated but perfectly useable DARM loop channels, like H1:LSC-DARM_IN1_DQ, or H1:CAL-DARM_ERR_DBL_DQ. All other IFO channels, including those for other IFO DOF lengths and all IFO angles were perfectly functional and can be used for further investigation.

Jenne and Jim may have some plots and further comments to attach later.

05:00 UTC I believe the violin mode guardian may have changed the gain for ITMX mode 17, which happened to be monitored in SDF, and this took us out of observing. I have unmonitored this channel in SDF (see attached screenshot) and put us back into observing.

These injections are scheduled to begin at 23:00:00 PDT 28 March 2018, the first injection should occur at 23:00:10 PDT 28 March 2018, and the entire excitation should last only 91 sec.

The expected GPS times of all these injections can be found in GraceDb via: https://gracedb.ligo.org/search/?query=H1+Test+HardwareInjection+gpstime%3A+1237874418+..+1237874510+HWINJREQ&query_type=E&results_format=S

I have started another, somewhat slower IMC VCO sweep, in the frequency region around 78.8 MHz.  Andy's plot in alog 47970 indicates that this is our best candidate for a whistle-free region. 

I started moving the offset slider at about 19:16:50 UTC to get my starting place where I wanted it, a little low of 78.8 MHz.  Then at about 19:23:35 UTC I started the script. 

Picking upper and lower limits of the clean region of Andy's plot by eye, I'm sweeping the VCO between 78.8 MHz (-3.37 V) and 78.95 MHz (-1.48 V). 

As with last night, this is a very slow change, and today we should be out of the whistle region for almost all of the sweep time, so we're leaving the IFO in Observing (with Keita's permission).

Craig Dan Danny Georgia + Jeff B and Ed

Over the past week we've taken a couple of steps with the ring heaters, trying to find a more optimal TCS configuration for 35 W input power. Craig and Dan previously set up the AWG_LINES guardian to inject frequency noise, intensity noise, and 9MHz RIN lines. I wrote a quick matlab script to demodulate these lines, and have made some plots of how these couplings change over time with the ring heater steps. This is building on an ipython notebook Dan had already written, but it cuts the data into chunks so it doesn't require the cluster to run. This work is ongoing but I'm posting what we've got so far.

It's a bit loose for now, but for interested TCS'ers, script lives here:

     /ligo/home/georgia.mansell/TCS/AwgLineDemod/plotTCSDemodLines.m

20190325 - Common decrease in ITM RH power

On Monday Jenne decreased the ITM ring heaters in common by ~250 mW. She saw:

• improvements in POP_RF18, POP_RF90, circulating power, and power recycling gain
• a decrease in the cavity pole and Kappa_C
• ~5 Mpc decrease in the BNS range

The first attachment shows an ndscope of the diagnostics, as well as the ring heater powers. The second attachment shows the demodulated lines, normalised to t ~ 700 s (sorry it's a bit dodgey for now). The time axis starts just after the first step down, at roughly the same time as the cursor in the first attachment (the lines were not on before this time), the lower plot shows the ring heater set_upper_power, which is controled by Danny's ring heater guardian. 

The interferometer was well thermalised before this change, having been locked for 19 hours. Things to note: the coupling of the 9 MHz line, and high-frequency frequency noise appears to grow with this ring heater step. The high-frequency intensity noise coupling drops, though seems to turn back up towards the end - maybe we overshot some minimum coupling? The ring heater time constant is very slow. The frequency and intensity lines in the bucket seem unaffected.

20190325 - Differential decrease in ITM RH power

Later the same night, we tried a slightly differential step down in the ring heaters, lowering ITMX by ~0.1W and ITMY by ~0.26W. We see similar behaviour in our diagnostics (third attachment), increase in RF18 and circulating power, decrease in the f_c and range. Note that this step was taken sooner after locking, and that the interferometer was still thermalising. The fourth attachment shows the demodulated lines. Changes before the step at t~7500 are due to the thermalisation of the interferometer. After the ring heater step, the high frequency intensity noise again takes a dip (with a pretty fast time constant), while high-frequency frequency noise and RF9 increase. Craig noted that the high frequency line and the 9MHz RIN line (at 72.3 Hz) are moving together. With this step intensity noise in the bucket seems to rise, and frequency noise in the bucket seems improved.

20190323 - Common increase in ITM RH power, followed by decrease

On Friday night Danny and Ed took a 0.1 W common increase in the ring heater power. Note earlier that night we had seen that a 0.5 W increase on ITMY only caused POP_RF18 to plummet potentially causing a lockloss. During this step the interferometer was still thermalising, see for example RF90 (purple trace in fifth attachment) dropping before the ring heater step. I originally got excited to see the range increase but probably that was due to some squeezer shenanigans happening at the same time? With the increase in power RF18 looks like it drops a little, but other diagnostics don't show much. I think the demodulated lines (sixth attachment) are dominated by the thermalising IFO.

Tonight (@ 10:57:43 UTC) we have tried increasing the power on ITMX ring heater only, we requested 0.8 W from the filter input, where nominally it is 0.5 W. If future operators or commissioners would like to return this value to nominal after lockloss (eg if ASC is problematic), this can be done in the command line:

     caput H1:TCS-ITMX_RH_INVERSE_FILTER_IN 0.5

Given that H1 is still in commissioning mode, I hesitate to report on lines that may be due to ongoing work, but I'm seeing a very strong 1-Hz comb in DARM as of last Wednesday, which I suspect is unintended. Below are spectra of 20-120 Hz and its 20-Hz sub-bands from yesterday's data (typical of daily spectra since Wednesday). 

Note that the lines are on exact 1-Hz multiples (to ~0.5 mHz resolution), but they have flat shoulders of O(0.01 Hz) full width. An arbitrary but typical example at 34 Hz is shown.

Also, the amplitudes of the lines do not fall entirely monotonically with frequency. There are clusters of lines with a spacing of roughly 7-8 Hz.

Any ideas on what changed, perhaps during the last Tuesday maintenance?