J. Kissel The IFO is down (and has been for ~4 hours, most likely because of the 6.4 [mag] EQ in Indonesia) and I'm beginning updates to the LSC, OMC, SUSMC2, and CALCS models to fix up the IMC/CARM calibration paths, so I've turned OFF the observation intent bit around 14:50 UTC (6:50a PT). I've also switched the ISC LOCK and IMC LOCK guardians to the DOWN state. I found that MC2 had not had its alignments saved, so I've saved them.
Gabriele, Sheila, Alexa, Evan
We have engaged the DHARD WFS Y (and P) at 3 Hz on resonance with a reduced oplev damping gain in the ETMs. Again, to start off we closed the DHARD Y WFS with 3 Hz BW at 50pm CARM offset. Since this loop is also stable at low BW, we will leave it in the low BW configuration at this point, so that we are at a 3 Hz BW on resonance.
We had tried engaging the new DHARD Y loops as described in LHO#17006. However, we quickly found that this configuration was unstable. So, we removed the partial plant inversion FM6 and took a plant TF. We found that the plant that Gabriele had measured with the oplevs was slighlty different than the @50pm plant (see Gabriele's comment). We adjusted FM6 accordingly to compenstate for the peaks seen between 1 and 5Hz. FM6 is now zpk([-0.3303+i*15.1459;-0.3303-i*15.1459;-1.9027+i*16.6711;-1.9027-i*16.6711; -0.2672+i*19.227;-0.2672-i*19.227],[-0.6659+i*18.7;-0.6659-i*18.7;-0.509+i*11.519; -0.509-i*11.519;-1.0404+i*15.4844; -1.0404-i*15.4844], 1)gain(0.469248).
To close the loop at low BW at 50pm CARM offset, we engage FM2, FM3, FM4, FM6, FM9 with a gain of 30. FM6 is described above, and the remaining filters are the same as in LHO#17006. With a gain of 360, this gives a UGF of 3 Hz and a phase margin of 36 deg.
On resoncance with a gain of 30, we measured that the UGF is 3.5 Hz with a phase margin of 36 deg.
This is in the guardian now.
In the first attached plot the blue circles show the measured DHARD plant transfer function, at 50 pm CARM offset. The red trace is a fit, which matches quite well the measurement. To be able to run the loop with a 3 Hz bandwidth and a simple controller like the one we used for pitch, we had to compensate for the two higher pole/zero pairs.
The second plot compares the DHARD plant measured today at 50pm using the ASC signals, with the one I measured on Saturday using only ETMY and its optical lever. They are clearly quite different. It's unclear to me why this happens. It can be that ETMX and ETMY are significantly different, and when driving DHARD we are using the sum of the two.
Sheila, Gabriele, Evan
We are on dc readout with the following loops locked (pitch and yaw):
dETM is high bandwidth (~3 Hz), as is BS. cETM is lower bandwidth (probably by a factor of 10 or so) because we found it was injecting noise into the DARM spectrum up to ~50 Hz. PRM is very low bandwidth (more than 30 s time constant; this is probably too long). IM4 and PR2 are something like 100 mHz or less.
The CHARD P,Y WFS have the same filters engaged as for the DHARD P, Y WFS respectively. The gains for CHARD (P,Y), are (-20, -40). If we want a 3 Hz BW, the open loop we took last night indicated we were about 10dB too low.
Here is an estimate of DAC noise propagated forward to the ETM ESDs. I've used Peter's recent DAC noise model, an ETM ESD force coefficient of 2×10−10 N/V2, a bias of 380 V on each ETM, and some hints from Jeff about the DAC → ESD signal chain.
Evidently this is somehow an overestimate, but the shape and magnitude are roughly in agreement with the spectrum between 50 and 100 Hz.
As a quick test of whether DAC noise is really a limiting source here, we could try ramping down the ETMY bias during full lock (since we're not using the ETMY ESD).
Also, Nic and Jamie have inquired about the uptick in the ASD above a few kilohertz. The noise there seems to be largely uncorrelated between the two DCPDs (see attachment), which seems to suggest that it's still shot noise. (Based on measurements that Dan and I took of the DCPD dark noise, I believe this feature is too big to be explained by excess noise in the DCPDs or their signal chain.)
Evan, Alexa, Gabriele, Sheila
We have closed 8 DRMI ASC loops with the arms off resonance. Ordered fast to slow they are:
These loops are now all turned on by the guardian, mich comes on first, there is a pause and the rest come on. We can leave these on for the first steps of the CARM offset reduction. We have manually been turning off all of them except for MICH at this point. We tried leaving the PRM loop on once, this caused bad drift without the 2 refl loops closed.
WARNING: the guardian turns on 6 loops durring the DRMI ASC step that need to be turned off manually before the CARM offset is reduced too much
Washing is complete from corner station to double door X-1-4. Lights and equipment are relocated to single door between X-1-4 and X-1-5 doors. Cleaning will begin tomorrow moving south.
730 Karen, Cris - LVEA
849 Corey - EY
902 Kyle - LVEA Looking for parts for tomorrow
906 Bubba - LVEA Check on the cleanroom test stand
916 Bubba - Out
918 Kyle - Out
918 Corey - Out
1537 Dave B. - CER
Have posted two sets of plots; one is with no zoom and the other with zoom in on ITMX and BS. The four peaks on ITMX has some time correlation with the peaks on ITMY and ETMY. The time of the second peak on the BS correlates with the third peak on ITMX. There is no clear pattern with the peaks on all 7 OpLevs being plotted. Will discuss with the OpLev folks. These plots are run with minute trends not second trends, due to an error with plotting the second trend data. I an looking into the cause of this error.
Laser Status: SysStat is good Output power is 32.3 W (should be around 30 W) FRONTEND WATCH is Green HPO WATCH is Red PMC: It has been locked 0 day, 15 hr 14 minutes (should be days/weeks) Reflected power is 2.0 Watts and PowerSum = 24.9 Watts. (Reflected Power should be <= 10% of PowerSum) FSS: It has been locked for 0 h and 17 min (should be days/weeks) Threshold on transmitted photo-detector PD = 1.18V (should be 0.9V) ISS: The diffracted power is around 9.3% (should be 5-15%) Last saturation event was 15 h and 17 minutes ago (should be days/weeks)
Coherences for last nigh lock are available here:
https://ldas-jobs.ligo.caltech.edu/~gabriele.vajente/bruco_1109322016/
Here is my summary of the summary:
The coherence of DARM with the BS ISI pitch sensor was no more present in last night lock, likely because Evan engaged the ISI second stage.
In the first attached plot, the red traces are with ISI stage2 on, blue traces off.
However, be aware that the alignment status of the IFO is likely different in the two locks, so we might have less coherence because of a better alignment.
The first attached figure shows a spectrogram of the DARM signal during last night lock. I had a look at one hour of data from 9.00 UTC.
The noise is highly non stationary almost everywhere. Looking at the longer spectrogram in the summary pages, it seems that the ~3 kHz bump got better later in the lock. However, I'm focusing at lower frequencies.
The second and third plots show a clear signature of scattered light arches, that contribute to the sensitivity quite often, and up to 120 Hz some times. I don't know what is causing them yet, but they're quite loud in the low frequency region, which is still relatively noisy.
The region between 50 and 500 Hz is very non stationary, see the 4th plot for a zoom in the spectrogram. To understand this I computed the BLRMS of DARM in the band between 130 and 160 Hz. There are a lot of quite fast excursions, probably glitch like.
I tried to correlate the BLRMS with angular signals. I could use both the ASC error signals or the local sensors of the optics (optical levers or shadow sensors). The 5th plot shows the result of the fit of local sensors (and their square) to the BLRMS. Altough I'm not able to properly reconstruct the largest BLRMS excursions, the trend seems quite explained by the angular motion. It's likely that when we have a larger than normal angular excursion, some highly non linear phenomenon create an increase of noise that I can't easily catch with my analysis.
I used a channel ranking algorithm to find out which angular motion is mostly rsponsible for the BLRMS variation. The algorithm is the same already used at LLO, with small improvements. The code is attached. basically, the algorithm starts with the BLRMS and fit every channel one by one to it. It selects the channel that gives the largest reduction in the residual error. It then moves on again, fitting the residual of the first fit again with every single channel, and select again the best one as before.
The result ranking, shown in the last attached picture, is that the most relevant motions seem to be: ETMY_YAW, SRM_PIT, SRM_YAW and BS_YAW. As a reminder, DHARD PIT has 3 hz bandwidth, while YAW is still low.
Reminder: Morning meetings are now on Monday, Tuesday, and Thursday at 8:30.
SEI:
SUS
CDS
3IFO
Vac
FMCS
OpLev
Alexa, Evan, Gabriele, Sheila
We have closed 6 low bandwidth loops with DRMI locked with arms off resonance today, based on what we learned from talking to LLO yesterday:
INP1: REFLA9I-REFLB9I -> IM4 PIT and YAW
PRC2: REFLA45I-REFLA9I -> PR2 PIT only (YAW signal seems to have an offset)
SRC1: ASB36I-> SRM pit only, although error signal loks OK for Yaw as well
MICH: ASB 36Q -> BS, PIT and YAW
In the past we had phased AS36 to maximize the BS signal in Q, but we noticed today that the Q signal is contaminated by SRM. We rephased AS B 36 to minimize the SRM signal in Q, this reduced the SRM pitch motion seen by AS36 B Q by 40 dB.
We have not attempted to close the AS_C-> SR2 loop, since we are far off center on AS_C. It seems that we will have to check search for the alignment that minimizes clipping on the Faraday and use picomotors to re-center AS_C,; we already know that we are clipping on AS_C when we are well aligned for the OMC PDs. (alog 16831 ). Despite this, it looked like ASB 36 I was a decent signal for SRM in both pitch and Yaw.
Nice progress all around on alignment controls! For AS36, what is the phase difference between maximizing for the BS and minimizing the SRM?
We moved the phase by 15 degrees (we only tuned this to within 5 degrees)
The wind gusts are at around 30mph, we could see from the ALS control signals that the arms are moving more than usual, so I changed the end stations to the high blends and we are using BRS sensor correction at end X. (configuration described in alog 16583)
we are back to 45mHz blends, since the wind has died down, but the BRS sensor correction is still on.
S. Dwyer, J. Kissel Speaking with Sheila this morning, the improvement in the ALS performance was "not as clear" as the last time, when the winds were 40 [mph] at EY (i.e. LHO aLOG 16526). This could be that the wind only got to roughly ~30 [mph] during the above configuration switch. Recall that in LHO aLOG 16526, the X-end was *not* changed, and the wind amplitude was large only at the Y-end.
I was checking ISI configurations this morning and found that X&Y sensor correction at EX was actually OFF on the ISI, but it was turned off at a different point in the path than I usually try to steer commissioners and operators toward using.This would have made it look like sensor correction was on, when no STS signal was actually going to the ISI. I hope this explains some of why "the improvement was not as good as before". I've been meaning to make some edits to Hugo's new SensCor MEDM to make this clearer, but haven't gotten around to it. I also found a few other configuration errors, but I didn't bother writing them down. Time to get more serious about SDF's, I guess.
Gabriele, Alexa
Gabriele had accidently unlocked the MC this morning, and had trouble relocking it. I know people had trouble with the MC yesterday morning, but there was no alog about this ... :(
The input power this morning was set to 5 W. When MC would try to acquire lock, the MC2 M3 LOCK L would reach the limit. I adjusted the input power to 2.8W and we locked immediatly. The IMC "DOWN" guardian adjusts the MC common mode board input gain depending on the input power (Power <4, 4
On the bottom left of the LSC overview you can set the power scaling for the LSC (channel H1:PSL-POWER_SCALE_OFFSET). I think in order for the MC to lock, this power scaling needs to match tyhe PSL power. So an alternative to aleways locking the MC at 2.8W is to change this power scaling in the LSC screen.
I had confirmed that the power normalization in the LSC was the same as the input power, so it seems we had different problems.
Jim, Krishna, Ryan, Jeff, Sheila, Alexa, Evan, everyone
We have been having trouble keeping the Y arm locked with green, due to cavity motion of about 10 um in about 10 seconds. The winds at end Y are approaching 40 mph, and have been climbing for an hour and a half. We have copied the 90mHz blends for X and Y from the ETMX ISI into ETMY and blending high has allowed us to lock ALS for now.
The attached screen shot shows the Y arm control signal (from the end station PDH with no slow feedback on) in beige, and the X arm in yellow. The blends were switchd at about -21 minutes.
Here are a few more PEM screenshots of the wind and what it has been doing.
J. Kissel, S. Dwyer For the record, Sheila only remembers changing the blend configuration for ISI ETMY, which is why only the brown trace (ALS-Y_REFL_CTRL) gets visibly better in the StripTool.