Commissioning Team
We will write a more meaningful entry later, but here is a list of things we did/tried this afternoon, so we don't forget:
We collected a ~ 2h lock with range around 36 Mpc (not clean data).
SudarshanK. RickS
After doing some alignment work and calibrating the ENDX photon calibrator yesterady, we are running the pcal lines now at 33.1 Hz (38 cts excitation amplitude) and 534.7 Hz (28570 cts excitation amplitude) both producing an SNR of about 20. These frequencies are in line with the agreed upon frequencies as reported in LLO alog #15870. The calibration coefficient for these pcal lines can be found in LHO alog #17525.
Because of Dan's effort in damping the violin modes (alog17502 and alog17365) I was able to come up with a modes pair-up scenario. A total of 33 lines were found but not all of them are identified (we don't know which test mass some of them belong to) so I had to make a decision and cast one of the unidentified lines aside (501.486) as it may not have come from the violin modes and not seen in the most recent lock stretch. According to Agnus the line saperations anywhere from 0 to 0.15 is reasonable. The tables below contains the frequencies of the lines we found, the averages of the pairs, the width of saperations, and the test masses they belong to. Dan was able to identify most lines unless note otherwise (as "unidentified"). The original Excel file also attached. The next step would be identifying which fibers these lines belong to!
ITM pair | Average | |width| | test mass |
500.0535 | 500.13275 | 0.08 | ITMX |
500.212 | ITMX | ||
501.092 | 501.15 | 0.06 | ITMX |
501.208 | unidentified | ||
501.254 | 501.352 | 0.1 | ITMX |
501.45 | ITMX | ||
502.621 | 502.6825 | 0.06 | ITMX |
502.744 | ITMX | ||
503.007 | 503.063 | 0.06 | ITMY |
503.119 | ITMY | ||
504.803 | 504.83725 | 0.03 | unidentified |
504.8715 | ITMY | ||
501.606 | 501.6775 | 0.07 | unidentified |
501.749 | ITMY | ||
501.682 | 501.7465 | 0.06 | ITMY |
501.811 | unidentified |
ETM pair | Average | |width| | test mass |
507.992 | 508.069 | 0.08 | unidentified |
508.146 | ETMY | ||
508.0095 | 508.10775 | 0.1 | ETMY |
508.206 | ETMY | ||
508.22 | 508.25425 | 0.03 | ETMY |
508.2885 | ETMY | ||
508.585 | 508.623 | 0.04 | ETMY |
508.661 | unidentified | ||
505.587 | 505.647 | 0.06 | ETMX |
505.707 | ETMX | ||
505.71 | 505.7575 | 0.05 | unidentified, sometimes distinguishable from 505.707 |
505.805 | ETMX | ||
506.922 | 507.0405 | 0.12 | ETMX |
507.159 | ETMX | ||
507.194 | 507.2925 | 0.1 | unidentified |
507.391 | ETMX |
Using the latest BRUCO results, I've annotated a hi-res spectrum from last night's lock. Peaks, bumps, and so on are labeled with the largest coherent channels.
There are a few peaks, at 46, 166, 420, and 689Hz, that are coherent with PRCL/SRCL, and they have changed since the blue reference (Mar 19th at 18:00). This might be due to the POP --> POPAIR switch.
The source of the 300Hz lines has been identified, it's the BS violin modes. The frequency is given in Mark Barton's table of predicted violin resonances (thanks Jeff!).
We turned off all the ring heater power supplies yesterday; this got rid of a line at ~74Hz but didn't change the 55Hz line and its harmonics. These lines are certainly due to some electronics in the EX racks.
Features coherent with the IMC WFS and the PSL persicope are probably the same thing (input beam jitter), hopefully from the same source (PSL PZT mount).
As I think is known, there is a filter solution for the ring heater driver to eliminate the fan noise. It is the same basic design as was used in the Seismic Coil Driver fans. We just need to make these available for installation soon. Added this to my to-do list.
The 160 and 420 Hz peaks are moving in frequency with a timescale of some minutes. The moves in a coherent way, in the sense that the frequencies seem pretty much to maintain a ratio of 2.5
See my previous log entry for an analysis of the line wandering.
It turns out the 55Hz line is actually a 57Hz line, and it's the Hartmann camera. This was explored in detail at LLO a long time ago, I should have remembered.
I have turned off the HWS box in the EX electronics rack. This eliminated the 57Hz line and harmonics from the rack magnetometer, but for some reason the overall noise floor has increased, see attached. Probably turning off the camera is a better solution, as Aidan recommends in the LLO log. We'll see if this affects the noise.
== Activities ==
7:40 Cris to LVEA
8:00 Cris out of LVEA
9:00 Lock Loss
Kiwamu to EY to reset ETMY ESD
9:22 Kiwamu back
11:14 Jodi to Mid X and Mid Y
14:50 Kyle back from mid stations (No notes of when he went out... Kyle and Jodi together?)
Best lock range at LHO ever. Happy Friday.
Kyle, Gerardo Pressurized lines -> no leaks. Attempting to clear a path for under tube pallet jack traffic and ease 3IFO storage and also to eliminate need for overhead crane. Instrument air and copper grounding cable still need to be re-routed off of the floor
Scott L. Ed P. Chris S. The crew was able to complete tube cleaning to the X-1-7 double doors. Results are posted here. The afternoon will be spent doing P Ms on the equipment and relocating to the next section to be cleaned.
I have added two buttons to the CDS OVERVIEW MEDM screen:
Press All Diag Reset Buttons
The name says it all. It opens an xterm window, and then sequences through all running models pressing the DIAG_RESET button on the GDS_TP screen
EDCU disconnected channels
This is a small yellow button, labeled with an exclamation mark, next the the EDCU status LED. When the LED is purple, pressing the button will open an xterm and list the EDCU channels which are disconnected. The xterm is held open so you can read it at your leisure, please close it when you are done with it.
Here are some notes on the recent DARM calibration for future reference.
(A) We intentionally do not switch the simulated ETM actuators in the CAL-CS model when we switch to ETMY for low noise in the DARM control.
Even though we switch the actuator from ETMX to ETMY for the LSC DARM control to achieve low noise, the calibration filters for the actuators in CAL-CS remain using the *ETMX simulated actuator path*. Since we adjusted the ETMY ESD digital gain such that the response of ETMX and ETMY ESDs are the same with a precision of 10 % in frequency band from 20 to 60 Hz, the calibrated spectrum after the ETMY transition should be still valid with a precision of 10 %. In other words, we forced the actual ETMY ESD to be identical to that of ETMX so that we don't have to manipulate the filters in CAL-CS. In fact, when we transition from ETMX to ETMY, we do not see visible reduction or increment in the DARM spectrum at low frequencies below 100 Hz, which convinced us that the calibration remained consistent. Then, once we decrease the ETMX ESD bias all the way to zero, we see noise reduction in 20-100 Hz band due to lower ESD noise.
The adjustment of the ETMY ESD digital gain was done on the last Tuesday, Mar-24th (alog 17411). The following is some detail of what I did for the adjustment. First, I measured the transfer function from ETMX_L3_LOCK_L_IN1 to LSC-DARM_IN1 in 20-60 Hz band by swept sine while the interferometer stayed fully locked on DC readout. Then I measured the same transfer function but with the ETMY ESD driven. So the transfer function I took was from ETMY_L3_LOCK_L_IN1 to LSC-DARM_IN1. At this point, I noticed that the ETMY ESD response was weaker than that of ETMX by an overall scale factor of 1.25. Note that both ESDs use the linarization. So I increased the ETMY ESD gain by the same factor in ETMY_L3_LOCK_L_GAIN. So this gain is now 1.25 and this is already coded in the ISC_LOCK guardian. Then in order to check how good the matching is between ETMX and ETMY, I ran another swept sine on ETMY with the new gain. However this still gave me a bit too-weaker ETMY ESD by 10% (I attach the dtt xml file). Since we knew that the overall scaling factor of our calibration is already uncertain by the same level (on the order of 10%, see for example alog 17082), I did not try to get better matching between them. We will revisit the ETMY calibration at some point.
(B) The DARM spectrum below 2 Hz is not trustable.
There are two reasons.
By how much is the calibration off at low frequencies because we do not include the low-frequency control filters, i.e. Kiwamu's point (B)2? See attached. This is the (driven) transfer function from the DARM_CTRL input of the CAL CS model (actually H1:CAL-CS_DARM_FE_ETMX_L3_ISCINF_L_EXC) to the output of the actuation function chain (actually H1:CAL-CS_DARM_DELTAL_CTRL_WHITEN_IN1). At these low frequencies, the formulation of DELTA L EXTERNAL is entirely dominated by the actuation function times the control signal, A * DARM_CTRL. So, any discrepancies between what we believe is the most accurate reconstruction of A and the real A is by how much that calibration is off. To give a few frequency points in words, at 0.1 [Hz] the discrepancy is roughly an order of magnitude too low, and at 0.02 [Hz] is almost two orders of magnitude off. In other words, any plots of DELTA L EXTERNAL is *under* estimating the displacement by ~10 at 0.1 [Hz] and by 100 at 0.02 [Hz]. This transfer function comparison also reveals (maybe?) what problems that Kiwamu mentions in (B)2. One can see *without* the low frequency compensation, the TFs clean. *With* the low frequency filters engages, the transfer function becomes ratty both at low and high frequencies. Maybe this is a problem with numerical precision in the filter computation?
SudarshanK, RickS
Yesterday, we adjusted the transmitter module optical layout to address the s-pol light downstream of the AOM (see notes appended below).
We then calibrated the system using Working Standard WS1. The details are in LIGO-T1500129.
The calibration of the TxPD output (H1:CAL-PCALX_TX_PD) is 8.517e-13 *1/f^2 (m/V).
The calibration of the RxPD output (H1:CAL-PCALX_RX_PD) is 6.799e-13 *1/f^2 (m/V).
Notes:
LHO Xend calibration
Every time commissioners improve the sensitivity, I have to run again my brute force coherence. Luckily, it's fast enough now. Here is the sumamry page:
https://ldas-jobs.ligo.caltech.edu/~gabriele.vajente/bruco_1111482016/
MICH is dominant between 20 and 150 Hz (first plot). PSL periscope peaks are prominent (third plot). Intensity noise is a factor of few below DARM at frequencies above 100 Hz (fourth plot). There are many lines coherent with suspension or environmental signals, too many to list all of them here.
SRCL and PRCL show a broad band coherence basically everywhere (second plot), giving a noise projection a level of few below the DARM signal. This is the usual thing we already saw, and I believe is due to the IMC locking offset, somehow converting frequency noise into intensity noise. Still to be proven though.
J. Kissel, J. Warner, J. Romie, H. Radkins, N. Kijbunchoo, K. Izumi, G. Moreno SUMMARY: We just finished ~7 HOUR lock stretch at our best sensitivity ever, between 32 and 34 [Mpc]! We've all been pleasantly surprised this morning to see that the lock stretch that Sheila Evan, Dan and Lisa started last night lasted the entire night. Unfortunately, as of ~10 minutes ago (~8:40a PDT, ~15:40 UTC), there are GIANT glitches and non-stationarity that keep popping up, spoiling the sensitivity. There's no one in the LVEA, so we're not at all sure what's caused the sudden change in behaviour. Wind seems fine at ~5 [mph], ground motion is still pretty low, the 1-3 [Hz] hasn't even come up yet. Anxious to explore things, Jim installed some low-pass filters in the HAM5 and HAM6 ISIs at around 8:45 to try to reduce scattering / acoustic coupling to the ISI, and Kiwamu began exploring MICH coupling to DARM. But, as I write this log, we lost lock. However, for DetChar purposes, one can assume the detector was undisturbed from March 27 9:00 UTC to March 27 ~15:00 UTC.
K. Izumi, J. Kissel For the record: Kiwamu drove down to the EY end station to check: *this* lock loss did *not* cause the EY ESD Driver to trip. Huh.
Looking at spectrograms of DARM during the first hour of lock (first plot) and the last hour (second plot), it seems to me that the noise is more or less stationary, but there are huge glitches. They are so big that you can even see them easily in time domain (third plot). A zoom in is visible in the fourth plot. They look like bursts of oscillations at about 5.5 kHz.
We now believe that the glitches we had in the lock stretch from this morning was due to the ISS which repeatedly unlocked. This is a typical behavior of the ISS when the diffraction power is too low. Indeed the diffracted power had been 4% on average during the time when the interferometer was locked. There was clear correlation between arm cavities' power and the ISS diffracted power. See the attached trend of some relevant channels. Elli adjusted the diffracted power in this after noon so that the diffracted power is now at 8% with only the inner loop closed.
Looking at glitch-to-glitch coupling between auxiliary channels and DARM shows a large number of glitches in the > 1kHz range that are coincident with glitches in CARM, REFL 9 PIT/YAW, and REFL 45 PIT. Interestingly, CARM is highly correlated with high frequency glitches until about 12:00:00 UTC, at which point REFL 45 PIT becomes the stronger veto.
It looks like REFL 45 Q PIT was offset by about 2500 counts during the lock, is it possible that intensity fluctuations on an uncentered WFS are showing up as alignment glitches? I've attached a time series covering 2 hours of the lock from 11 UTC to 13 UTC.
We're currently running code to see if the lower frequency (50-200 Hz) glitches are caused by zero-crossings in the 18-bit DACs.
I've attached an Omicron glitchgram for the whole day, it seems as if the higher frequency glitches and the glitches populating the 50-200 Hz region are the two dominant populations right now. There are also a few high SNR glitches scattered around in the 100-400 Hz region that we'll follow up individually.
-2^16 Crossings in ETMY L3 ESD causing many of the glitches in this lock:
In addition to the arches reported in 17452 and 17506 we found DAC glitches in this lock when ETMY L3 ESD DAC outputs were crossing -2^16 counts. Attached is a PDF with a few examples that were lined up by hand. We will follow up more closely to see if other suspensions and penultimate stages also add glitches. Note: At Livingston, SUS MC2 M3 DACs were also a problem.
If you'd like to see the primary culprits from this long lock, here is a tar file of omega scans (thanks to Joe Areeda) of the loudest 100 glitches between 30 and 200Hz. The vertical lines that repeat are DAC glitches, the crazy wandering features are the arches described in the pages linked above, those two mechanisms account for most of the glitches we see.
We made it to 34 Mpc by managing to do at the same time all of the things we have tried before (low noise ESD on ETMY, low noise coil drivers for all the optics, POPAIR for vertex length DOF, more aggressive SRCL cut-off), plus some more ASC cut-offs. Implementing all of these things at the same time happened to be more challenging that expected because of a few problems that slowed us down today:
Some more details
Final IFO & Guardian state
Spectrum attached.
Great work! I will update our slides for the quarterly briefing.
Excellent progress!
Nice work. Great headline, too.
Note that ISI Stage2 was a State3 trip meaning that the Damping Loops were still functional. It would be nice to know when/why the stage tripped. But I'd guess that the Guardian was set to fully isolated before the ~0700utc short lock and was untripped during the short lock, likely triggering during acquisition and then triggering again at the trip. That is what I first thought.
See attached--It looks like the stage2 when isolated survived the IFO lock loss but not the MICH reacquisition. This means, we can use the Guardian to transition the ISI between Isolated Damped and Fully Isolated with tripping nor requiring operator intervention.
This is a 50 minute stretch so the IFO lock Loss is only a couple minutes before the St2 WD trigger but there may be enough time to deisolate stage2. Looking at a zoomed in full data, looks like a full 70+ seconds after lock loss based on this CAL_DELTAL channel. The second lock loss had even more time so I don't think it is tied to the lock loss but more to the reacquisition.
Noise budget attached, with new the anticipated ETMY ESD noise. We have many other traces to add here: intensity coupling, frequency coupling, auxiliary dofs, etc.
I believe the 10 W quantum noise and the DAC→ESD noise alone limit us to no more than 60 Mpc, although based on the previous performance of the ETMX ESD, the ESD trace here may be an overestimate.
Earlier in the evening we tripped the RMS watchdog on ETMX, and had to drive out the end station to power cycle the coil driver.
This wasn't obvious from the control room. Three things that would help are to
1) add this to the OPS overview screen
2) add it to the SYS_DIAG gaurdian
3) add it to the SUS guardians
They are now in SYS_DIAG.
Here is a plot of coherences with some PEM accelerometers. We have been thinking that the noise around 200-250 Hz was due to the PSL periscope PZT, based on coherences like the one in the lower left plot. However, there is suscpicously similar coherence between the ISCT6 accelerometer and DARM. Indeed, the coherence between these two accelerometers is high in this frequency range, suggesting that some cross talk could be the dominant signal in these accelerometers.
The right two panels show that the accelerometers which have coherence with DARM around 13 Hz and 16 Hz are also coherent with each other, but not nearly as much.
There is some cabling work that needed to be completed on this particular channel (ISCT6_ACC). Hope to bring it online on Monday.
Replaced Shutter Controller S1203610 with S1203612. Daniel reported CH1 on S1203610 is not functioning, thus we were controlling the shutter with CH2. I reconnected the shutter to CH1 of the new unit and changed the jumper settings to VS35 on both channels.
Same story. Channel 1 opens and closes immediately. Next thing to check are cabling and slow controls.
We now have a problem we haven't encoutnered before. The ISC_LOCK guardian has SPM DIFFs errors, because of dead channels. There are ten channels related to the ALS_COMM guardian listed as the SPM diffs, I don't know if these are all of them or just the first ten. Attached screen shot shows the list, and also that we can caget these channels. Kiwamu and I restarted the guardians, which made no difference, then we tried destroying them as well, with the same result.
This morning Elli and I retuned the dark offsets for the transmon QPDs, after doing this we were able to do the entire CARM offset reduction without using the in air transmission PDs. After this succeeded we closed the beam diverters, redid the initial alignment, and attempted to lock. We failed at the TR_CARM step three times in a row, so we opened the beam diverters and re did the initial alignment. After that we were able to lock without using the In air PDs, which is what we have been doing all day.
The current situation is that the End X beam diverter is closed, and End Y is open. Kiwamu re did the initial alignment in this situation, and when we have ALS locked we can see that the spots are well centered on X end transmission QPDs. We were hopping to try locking like this, but ran into difficulties with the mich lock acquisiton attempts breaking the lock of ALS DIFF. We saw that the beat note power has slowly drifted down over the last few weeks, (from 0.5 dBm to -0.5 dBm), so we though it could be that a small alignment kick to the BS is enough to loose the beat note completely. Its hard to verify this theory since we don't trust the timing between the Beckhoff and the RCG.(alog 17455) I went to the table and touched up the beat note alingment, now it is about 0 dBm.
I tracked down the guardian communication problem to the following code in the /opt/rtcds/userapps/release/isc/h1/guardian/bs_m2_switch.py module:
This is NOT OK to put in any module being imported by guardian code. This creates a second, separate instance of the EPICS interaction object, that interferes with the one created and supplied by guardian itself. It effectively breaks all EPICS interaction in the guardian node, which is what happened here.
If you think you need to do something like this please contact me and we'll figure out a better way.
Presumably this module was newly added to the ISC_LOCK node before the problem arose, and the reported breakage happened after it was reloaded. After removing those lines from bs_m2_switch.py everything now appears to be working normally.
As an aside, please always provide FULL DISCLOSURE when reporting problems like this. Usually things don't break spontaneously on their own. Whatever was being done right before you saw the problem is probably what caused it. (Kiwamu: if you didn't know about this change when we spoke on the phone then you're off the hook).
Evan, Dan
The Guardian issue was fixed when we returned from dinner, but then the winds came. We switched the end station ISI's to the 90mHz blends and increased the tidal gains; the common UGFs are now 0.1Hz (were 0.05Hz) and the X-arm tidal UGF is 0.1Hz (was 0.06Hz).
Initially we observed the same problem that Sheila reported, the ALS would lose lock as soon as the DRMI started to drive the mirrors. But after mucking with the DRMI alignment for a little while (not at all sure that this helped), I have been able to acquire lock with DRMI a couple of times. A test of applying a large DC offset into the BS longitudinal drive does not break the ALS_DIFF lock, so maybe that problem is no longer a problem.
There is now a new problem, the DRMI Guardian isn't happy with the state DRMI_LOCKED_1F_ASC (which is the requested state from the ISC_LOCK Guardian). Upon finishing this state is recalculates the path and jumps back to LOCK_DRMI_1F, see the attached log, and the attached graph. This has happened three times now.
Also attached is a plot of our progress since Monday night. I am leaving the IFO set to CHECK_IR to acquire ALS data during the windy conditions.
For MICH FF, the filters used are FM6 and FM7 (which are stopbands for the violin modes and harmonics), and FM9 (which inverts the BS M2→M3 plant). The gain is 0.040 ct/ct.
For SRCL FF, the filters used are FM6 and FM7 (as above). The gain is −2.5 ct/ct.
Both feed back only to ITMY L2.
Also attached is a text file and noise budget of a good spectrum from today. I would like to remark that
Thank you so much Jamie.
I think bs_m2_switch.py is a code that TJ, Sheila and I have been preparing today. I was aware of the active coding effort that TJ has been putting today, but I simply did not know that bs_m2_switch had been already loaded in the ISC_LOCK guardian. My apologies that I did not collect and did not provide all information about the coding activities on ISC_LOCK at around the time.
Dan: the ISC_DRMI assert_drmi_locked GuardStateDecorator (defined in ISC_library.py) is wrapping the methods in DRMI_LOCKED_1F_ASC, and it returns 'LOCK_DRMI_1F' if DRMI_locked() returns False. The obvious explanation for the behavior you saw is just that DRMI_locked() was False. Here's what's currently defined in that function (at least from what's currently committed to the USERAPPS):
The epics problem was my bad. I imported bs_m2_switch but didn't think of it when I called Jamie since we weren't calling it I assumed it couldn't be doing much. Apologies.