Lost lock at 01:09 UTC. Back to DC_READOUT. Damped first fundamental violin modes. Working on second harmonics.
Sheila, Daniel, Marc, TVo
To eliminate some possible candidates for the 10-80Hz noise, Sheila and Daniel wanted to install a shield grounding box at EX and test various configurations to see if there is any affect on DARM, which there wasn't.
This afternoon we made an attempt to transition to ETMX ESD in low noise to see what impact it would have on our noise. We spent most of our commisioning window damping violin modes, so didn't make a lot of progress on this.
Attached is some text which can be copied and pasted into a guardian terminal to do the transition (read comments). We were able to transition half way to ETMX by setting the gains equal. The red trace in the attached screenshot is the OLTF measured with equal gains on the two ETMs, the gold is a reference from before any changes. Based on this, I think that we should use a gain of 1.5 in L3_LOCK_L to transition to ETMX (ETMY is 1.25) and preserve the UGF.
The IFO unlocked at the end of this measurement, I am not sure why.
M 5.1 - 74km WNW of Ferndale, California Showed up in BLRMS around 00:08 UTC. H1 remained locked.
TITLE: 07/28 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Lock Acquisition
OUTGOING OPERATOR: Jim
CURRENT ENVIRONMENT:
Wind: 10mph Gusts, 8mph 5min avg
Primary useism: 0.16 μm/s
Secondary useism: 0.14 μm/s
QUICK SUMMARY:
Jim and Sheila were damping violin modes at DC_READOUT. I damped ETMY mode 9 (1009.2 Hz) using FM4, FM5, FM7 +100 gain in YAW. Sheila requested that we attempt NLN. We made it to NLN in time for ~5 mag earthquake from California. Have remained locked through it. Sheila went to end X. PI mode 28 started ringing up and my changes in phase did not seem to affect it. It seems to be slowly coming back down on its own. We are not ready to go to observing, but there are SDF differences that I do not know what to do about (see attached).
Per Jim's text: Set H1:ISI-HAM4_SENSCOR_GND_STS_Y_WNR_GAIN to 0. Reverted the SDF difference (attached).
<b>TITLE:</b> 07/28 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
<b>STATE of H1:</b> Observing at 6Mpc
<b>INCOMING OPERATOR:</b> Patrick
<b>SHIFT SUMMARY:</b>
<b>LOG:</b>
Locked until the commissioning window, then the transition to ETMX ESD broke the lock. We're now damping more violins because DARM looks crazy.
21:30 Kyle to VEAs, then ends to take pictures of turbos.
FAMIS4738
ETMY is trending near -10urad, but everything else looks good.
On 2017-07-27, during the lock loss around 2 UTC, I noticed a sudden increase in kappa_tst from about 1.05 to 1.07. See the summary page for that day: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170727/cal/time_varying_factors/ It is likely correlated with the end reaction mass being moved at that time: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=37800 LLO observed a similar issue, reported here: https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=31108
Attaching plot for easier reference. Links to aLOGs: Documentation of the reaction mass move: LHO aLOG 37800 Documentation that LLO has seen this as well: LHO aLOG 31108
Plots showing changes in both kappa_tst and ETMY Pitch (at the same time).
J. Kissel, B. Weaver, S. Dwyer, D. Sellers, G. Traylor, T. Hardwick I'm writing down some of the ideas we've had on what might have mechanically changed with the QUADs to cause the symptoms that we see. (1) PUM Flags have gotten bumped. - This could explain some of the discrepancy between optical levers and the PUM stage OSEMs. (LHO aLOG 37799) - This might also explain why some of the violin mode damping coupling has changed. (LHO aLOG 37507) - This could not explain why we need more torque at the top mass to make the test mass realigned. (LHO aLOG 37799) - As long as they’re not rubbing, this wouldn't show up in top-to-top transfer functions. (LHO aLOG 37689) (2) The pitch adjusters on the UIM / TOP mass have moved, creating a new static “DC” pitch alignment. - A small move in these pitch adjusters can cause misalignments at this level (~100 urad) of pitch change. - This could explain a relative misalignment that is described by what we see in the OSEM vs. Optical Lever story. - This could explain why we need more torque at the top mass to move the test mass back to the optical lever positions. - This could not explain why some of the violin mode coupling has changed. - They have not caused any new rubbing, this would not show up in the top-to-top transfer functions. - This may show up in top-to-top mass transfer functions as a shift in frequency of some modes due to the moment of inertia change. (3) The UIM to PUM suspension wires have slipped slightly in there prisms - This would explain a relative misalignment that is described by what we see in the OSEM vs. Optical Lever story. - This could explain why some of the violin mode coupling has changed. - This could explain a relative misalignment that is described by what we see in the OSEM vs. Optical Lever story. - This should show up as a change in resonance frequencies in top-to-top TFs, in especially the rotational DOFS. (4) Some EQ stops are now rubbing. - The top-to-top mass transfer functions essentially rule this out. ETMX and ITMY TF have some niggling features, we'll go back to it for more precise measurements. (5) Optical levers are untrustworthy because they have moved. - We’ve ruled this out because restoring optics to their optical lever values after the EQ have made the interferometer go, and we’ve checked spot positions on optics once the IFO is going and they’re in the same place as before. More ideas / comments / questions welcome!
(6) TOP Mass Flags have gotten bumped
- This could explain some of the discrepancy between optical levers and the TOP stage OSEMs.
- This could explain why we need more torque at the top mass to make the test mass realigned.
- In top-to-top mass transfer functions,
- A flag move that caused rubbing would clearly show up as distorted top-to-top mass transfer functions (we don't see this)
- A flag move without causing new rubbing may cause a small change in moment of inertia, affecting resonant frequencies (we don't see this)
- A flag move without causing new rubbing may cause a small change in off-diagonal transfer functions (L to P, or V to L, etc) (we don't see this, see LHO aLOG 37848)
- This could not explain why some of the violin mode coupling has changed.
TITLE: 07/28 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 54Mpc
INCOMING OPERATOR: Jim
SHIFT SUMMARY:
H1 locked for just over 13hrs and has been at a fairly flat 55Mpc. Winds & EQ were minimal over the shift.
Nothing to report other than H1 locked for ~9.5hrs & useism continues to dip even lower.
TITLE: 07/28 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 54Mpc
OUTGOING OPERATOR: Ed
CURRENT ENVIRONMENT:
Wind: 7mph Gusts, 5mph 5min avg
Primary useism: 0.01 μm/s
Secondary useism: 0.05 μm/s
(4) EQs seen in the last 24hrs, but now the winds have just died down and useism is still low.
QUICK SUMMARY:
Current lock is almost 5hrs long.
I walked toward the Control Room to the howls of coyotes just before midnight; they didn't return my howls.
Just performed an OSB walkthrough, nothing to report.
Seismon-5-Event:
Sheila, with many conversations with Keita, Jeff K, and others
We have several reasons to believe that something changed in our suspensions durring the Montana EQ. (See alog from Beverly Berger and Josh Smith, (37775) which got us started looking at this, and Cheyl's log about the large triples, (37674). We are still looking at some of the data from alignment sensors, but here arer some things we can say:
There is more to be done checked on here, for example, checking if this has happened at any other times during the run (I checked one large EQ, I see no shifts like this), checking yaw (which has much smaller shifts than pitch), checking the triples, and looking at the alignments of the reaction chains. Can we interpret the information we have to make a gues aout what might have changed in the suspension? Wire slipping or some kind of damage to the prisms are some things we have been thinking about.
Hysteresis is a possibility here. We discovered on the LASTI quad during one of the early builds that these suspensions have significant hysteresis in pitch. That is, if you tip the stages a given amount, they will not come back all the way, leaving you with a pitch offset. The attached plot shows a measurement of this effect from LASTI, showing a pretty standard looking hysteresis plot. We learned that you can 'undo' any offsets by getting the pendulum swinging, and letting it slowly damp itself. The slower the ringdown, the closer it returns to its nominal 'equilibrium' position.
The offsets you see here don't look any bigger than what we saw there, though granted we were trying to measure the effect, so pushed it pretty far. Then again, we didn't have any major earthquakes either.
There were many documents written to investigate what we saw at LASTI. Mark Barton's document, T0900103, includes a list of most if not all of them.
So it could be that this earthquake induced some hysteresis offset, or perhaps there was an offset already and the swinging motion from the earthquake removed it. Anyway, try swinging the pendulum in pitch with some large *but safe* amplitude, and you should return to the nominal 'equilibrium' position, if it isn't already there.
Looking at Beverly log (37775) that shows DC changes in the pitch offset across the earthquake time. Are the changes in the pitch in the lower masses compatible with the reported change at the top mass?
Here are some additional plots, for those who are interested in what happens to the osems between the reaction mass and the top mass. I also have plots that show torque applied to the reaction mass vs measured pitch, these aren't very useful because we don't change the torque applied to the reaction mass, but they do show that there were similar shifts in the reaction chain. In order to interpret the data from the L1 and L2 osems we will need to account for shifts in the reaction chain.
Posting a jpeg version of the LASTI hysteresis plot above, since the pdf was causing issues.
Also, here is a summary of the procedure I used to make the plot way back in 2008:
"These data points are separate pushes and releases. The procedure was to put the top mass on its stops with the rest of the chain suspended. Note, the quad was on the test stand outside the chamber at the time. Then the top mass stops were used to tip the top mass some amount in pitch. The angle of the test mass, with the top mass still tipped, was measured with either an autocollimator or optical lever. That test mass angle is the X axis in the plot, called ‘Input Pitch’. Then the top mass was released slowly to avoid oscillation, and the test mass pitch angle was recorded again. That value is the Y axis, called ‘Output pitch’. This process was repeated for successively larger and larger Input pitch values, until I was afraid to tip the suspension any more. I then started to tip the suspension in the other direction until I was again afraid to tip the suspension any more. And finally, to close the hysteresis loop, I repeated some of the data points along the original tipping direction."
J. Kissel I'm behind on my documentation as I slow process all the data that I'm collecting these days. This aLOG is to document that on this past Tuesday (2017-07-25) I took standard top-to-top mass transfer functions for the Triple SUS (BS, HLTS, and HSTS; 10 SUS in total), as I've done for the QUADs (see LHO aLOG 37689 and associated comments). I saw no evidence of rubbing during the act of measurement, but I'd like to confirm with a thorough comparison. As such, I'll post comparisons against previous measurements, other suspensions, and the appropriate model in due time. This leaves: 3 doubles, 9 singles. Data is stored and committed here: /ligo/svncommon/SusSVN/sus/trunk/BSFM/H1/BS/SAGM1/Data/ 2017-07-25_1501_H1SUSBS_M1_WhiteNoise_L_0p01to50Hz.xml 2017-07-25_1501_H1SUSBS_M1_WhiteNoise_P_0p01to50Hz.xml 2017-07-25_1501_H1SUSBS_M1_WhiteNoise_R_0p01to50Hz.xml 2017-07-25_1501_H1SUSBS_M1_WhiteNoise_T_0p01to50Hz.xml 2017-07-25_1501_H1SUSBS_M1_WhiteNoise_V_0p01to50Hz.xml 2017-07-25_1501_H1SUSBS_M1_WhiteNoise_Y_0p01to50Hz.xml /ligo/svncommon/SusSVN/sus/trunk/HLTS/H1/PR3/SAGM1/Data/ 2017-07-25_1507_H1SUSPR3_WhiteNoise_L_0p01to50Hz.xml 2017-07-25_1507_H1SUSPR3_WhiteNoise_P_0p01to50Hz.xml 2017-07-25_1507_H1SUSPR3_WhiteNoise_R_0p01to50Hz.xml 2017-07-25_1507_H1SUSPR3_WhiteNoise_T_0p01to50Hz.xml 2017-07-25_1507_H1SUSPR3_WhiteNoise_V_0p01to50Hz.xml 2017-07-25_1507_H1SUSPR3_WhiteNoise_Y_0p01to50Hz.xml /ligo/svncommon/SusSVN/sus/trunk/HLTS/H1/SR3/SAGM1/Data/ 2017-07-25_H1SUSSR3_M1_WhiteNoise_L_0p01to50Hz.xml 2017-07-25_H1SUSSR3_M1_WhiteNoise_P_0p01to50Hz.xml 2017-07-25_H1SUSSR3_M1_WhiteNoise_R_0p01to50Hz.xml 2017-07-25_H1SUSSR3_M1_WhiteNoise_T_0p01to50Hz.xml 2017-07-25_H1SUSSR3_M1_WhiteNoise_V_0p01to50Hz.xml 2017-07-25_H1SUSSR3_M1_WhiteNoise_Y_0p01to50Hz.xml /ligo/svncommon/SusSVN/sus/trunk/HSTS/H1/ PR2/SAGM1/Data/2017-07-25_1607_H1SUSPR2_M1_WhiteNoise_L_0p01to50Hz.xml PR2/SAGM1/Data/2017-07-25_1607_H1SUSPR2_M1_WhiteNoise_P_0p01to50Hz.xml PR2/SAGM1/Data/2017-07-25_1607_H1SUSPR2_M1_WhiteNoise_R_0p01to50Hz.xml PR2/SAGM1/Data/2017-07-25_1607_H1SUSPR2_M1_WhiteNoise_T_0p01to50Hz.xml PR2/SAGM1/Data/2017-07-25_1607_H1SUSPR2_M1_WhiteNoise_V_0p01to50Hz.xml PR2/SAGM1/Data/2017-07-25_1607_H1SUSPR2_M1_WhiteNoise_Y_0p01to50Hz.xml PRM/SAGM1/Data/2017-07-25_1607_H1SUSPRM_M1_WhiteNoise_L_0p03to50Hz.xml PRM/SAGM1/Data/2017-07-25_1607_H1SUSPRM_M1_WhiteNoise_P_0p01to50Hz.xml PRM/SAGM1/Data/2017-07-25_1607_H1SUSPRM_M1_WhiteNoise_R_0p01to50Hz.xml PRM/SAGM1/Data/2017-07-25_1607_H1SUSPRM_M1_WhiteNoise_T_0p01to50Hz.xml PRM/SAGM1/Data/2017-07-25_1607_H1SUSPRM_M1_WhiteNoise_V_0p01to50Hz.xml PRM/SAGM1/Data/2017-07-25_1607_H1SUSPRM_M1_WhiteNoise_Y_0p01to50Hz.xml SR2/SAGM1/Data/2017-07-25_1715_H1SUSSR2_M1_WhiteNoise_L_0p01to50Hz.xml SR2/SAGM1/Data/2017-07-25_1715_H1SUSSR2_M1_WhiteNoise_P_0p01to50Hz.xml SR2/SAGM1/Data/2017-07-25_1715_H1SUSSR2_M1_WhiteNoise_R_0p01to50Hz.xml SR2/SAGM1/Data/2017-07-25_1715_H1SUSSR2_M1_WhiteNoise_T_0p01to50Hz.xml SR2/SAGM1/Data/2017-07-25_1715_H1SUSSR2_M1_WhiteNoise_V_0p01to50Hz.xml SR2/SAGM1/Data/2017-07-25_1715_H1SUSSR2_M1_WhiteNoise_Y_0p01to50Hz.xml SRM/SAGM1/Data/2017-07-25_1814_H1SUSSRM_M1_WhiteNoise_L_0p01to50Hz.xml SRM/SAGM1/Data/2017-07-25_1814_H1SUSSRM_M1_WhiteNoise_P_0p01to50Hz.xml SRM/SAGM1/Data/2017-07-25_1814_H1SUSSRM_M1_WhiteNoise_R_0p01to50Hz.xml SRM/SAGM1/Data/2017-07-25_1814_H1SUSSRM_M1_WhiteNoise_T_0p01to50Hz.xml SRM/SAGM1/Data/2017-07-25_1814_H1SUSSRM_M1_WhiteNoise_V_0p01to50Hz.xml SRM/SAGM1/Data/2017-07-25_1814_H1SUSSRM_M1_WhiteNoise_Y_0p01to50Hz.xml
More detailed plots of BS, compared against previous measurements and model. We see perfect agreement with model and previous measurement, so this SUS is definitely clear of rubbing.
More detailed plots if PR3 and SR3. Both are clear of rubbing. The new measurements agree with old measurements of the same suspension, the model, and other suspensions of its type. PR3's L2L transfer function shows "extra" unmodeled resonances that were not there before, but they line up directly with the Y modes. This is likely that, during the measurement the Y modes got rung up, and the power is so large that it surpasses the balance the of the sensors, so they're not subtracted well. I can confirm that these frequencies are incoherent with the excitation, and we've seen such inconsequential cross coupling before. Nothing about which to be alarmed.
More detailed plots of PRM, SRM, and SR2 compared against previous measurements and model. We see good agreement with model and previous measurement, so these SUS are clear of rubbing. There is a subtle drop in response scale factor for all of these suspensions (and in retrospect it's seen on the other SUS types too), and I suspect this is a result of the OSEMs LEDs slowly loosing current over the series of measurements, see attached 4 year trends.
While PR2 shows all resonances are in the right place, there is a suspicious drop in scale for the L and Y DOFs with respect to prior measurements. However, this is the first measurement where we've measured the response with the nominal alignment offsets needed to run the IFO (!!). These DOFs (L and Y) have the LF and RT OSEM sensor / actuators in common (see E1100109 for top mass OSEM layout), so I checked the OSEM sensors, an indeed the LF OSEM sensor is on the very edge of its range at ~1400 [ct] out of 32000 (or 15000 [ct] if it were perfectly centered). I'll confirm that the suspension is free and OK tomorrow by retaking the measurements at a variety of alignment offsets. I really do suspect we're OK, and the measurement is just pushing the OSEM flag past its "closed light" voltage and the excitation is becoming non-linear, therefore reducing the linear response. I attach the transfer function data and a 4 year trend of the LF and RT OSEM values to show that we've been operating like this for years, and there's been no significan change after the Jul 6th EQ.
I'd forgotten to post about the OMCS data I took on 2017-07-25 as well.
The data lives here:
/ligo/svncommon/SusSVN/sus/trunk/OMCS/H1/OMC/SAGM1/Data/
2017-07-25_1812_H1SUSOMC_M1_WhiteNoise_L_0p02to50Hz.xml
2017-07-25_1812_H1SUSOMC_M1_WhiteNoise_P_0p02to50Hz.xml
2017-07-25_1812_H1SUSOMC_M1_WhiteNoise_R_0p02to50Hz.xml
2017-07-25_1812_H1SUSOMC_M1_WhiteNoise_T_0p02to50Hz.xml
2017-07-25_1812_H1SUSOMC_M1_WhiteNoise_V_0p02to50Hz.xml
2017-07-25_1812_H1SUSOMC_M1_WhiteNoise_Y_0p02to50Hz.xml
Detailed plots now attached, and they show that OMC is clear of rubbing; the data looks as it has for past few years, and what difference we see between LHO and LLO are the lower-stage Pitch modes which are arbitrarily influence by ISC electronics cabling running down the chain (as we see for the reaction masses on the QUADs).
J. Kissel
Still hunting for what's limiting our range, we took Valera's suggestion to drive stage 2 (ST2) the test masses' BSC-ISIs to check for, among other mechanisms,
(a) scattered light problems,
(b) charge coupling issues, or
(c) mechanical shorting / rubbing
The measurements indicate that ETMX and ITMY are the worst offenders, in that their ambient noise falls as ~1/f^{1/2} between 10 and 100 Hz, with some resonant features at 70 and 92 Hz. The features are presumably the first few cage bending modes, for which we have Vibration Absorbers that have already knocked down the Q of the ~70 Hz modes, thankfully.
I've used the measurements to "calibrate" the error point of the ISI's ST2 Isolation Loops, and project the ambient noise to equivalent DARM displacement noise (a.k.a. primitive noise budgeting), see first attachment.
Each come within a factor of 3-5 at their worst parts during ambient conditions; too close for comfort.
Also, of course, there should be no such coupling at all if the cage were properly isolated from the suspension, and this appears to be a straight-forward linear coupling.
Note that the precision of the projection is not great -- I did not try hard to get it right. There are addendum plots that show the residual between model and measurement.
I don't think this is a / the limiting source now, since there is little coherence during ambient conditions, but this will certainly be a problem in the future if the coupling remains this bad for ETMX and ITMY. It definitely deserves a more careful calibration, further study with other degrees of freedom, and mapping out a broader frequency band. Perhaps we should check the coherence with these ST2 ISI channels after Jenne's subtraction of jitter (see LHO aLOG 37590) -- though the slope doesn't quite match up (from eye-ball memory).
ITMX's coupling is about 1/2 as bad, and ETMY does not show any visible signs of bad coupling at this excitation level (which is damning evidence that it's related to charge, since ETMY has the largest effective bias voltage at the moment).
%%%%%%% Details %%%%%%%%
Measurement Technique (all while in nominal low noise):
- choose obvious, simply to imagine coupling degrees of freedom: the longitudinal axis for the optics in the arm cavity (X for ETMX and ITMX, Y for ETMY and ITMY)
- measure ambient error signals in those directions using DTT.
- In the same DTT template, create a band-passed excitation where you suspect you're having problems (10-100 Hz), shape it to look roughly like that ambient spectra you see. I used
ellip("BandPass",4,1,40,10,100)zpk([0.1],[1; 10],1,"n")gain(0.159461)gain(1e-4)
copied and pasted to the 4 excitation banks (thanks Daniel!) so that I can pick and chose what I'm driving, and with what amplitude.
- Grab a bunch of relevant response signals; the excitations, the error signals, the calibrated displacement (the pre-calibrated SUSPOINT signals are especially nice -- though the suffer from spectral leakage up to above 10 Hz).
- Slowly creep up the drive (I started with 0.001 [ct] to be extra careful) until you start to see hints of something / coherence.
- In case the coupling is non-linear, record the results at three different drive levels (I chose factors of three, 500 ct, 1500 ct, and 4500 ct, filtered by the above band-pass.)
Analysis Techniques
- Remember, to calibrate DELTA L EXTERNAL, one must apply the transfer function from
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/H1/Scripts/ControlRoomCalib/caldeltal_calib.txt
i.e. copy and paste that file into the "Trans. Func." tab of the calibration for the channel, after creating a new entry called (whatever) with units "m".
- For calibrated transfer functions of ISI displacement in local meters to DELTA L in global differential arm meters, just plot transfer functions between SUSPOINT motion (which comes pre-calibrated) and DELTA L EXT.
- Store the transfer function between the ISI ST2 ISO error point and DELTA L EXT for the loudest injection
- For "good enough" calibration of the error point, make a foton filter (in some junk file) that looks like the transfer function of error point to DELTA L EXT, and install into DTT calibration for that channel. Guess the gain that makes the driven error-point spectra line up well with the DELTA L spectra. For ETMX this was
foton design: resgain(70 Hz, Q=8, h=8) * resgain(92 Hz, Q=30, h=10) * zpk(100,1,1)
equiv zeros and poles: z=[10.6082+/-i*69.1915, 3.42911+/-i*91.9361, 100], p = [4.2232+/-i*69.8725, 1.08438+/-i*91.9936, 1], g = 1
dtt calibration:
Gain: 1e-14 [m/ct]
Poles: 4.2232 69.8725, 1.08438 91.9936, 1
Zeros: 10.6082 69.1915, 3.42911 91.9361, 100
For ITMY this was the same thing, but without the 92 Hz resonant feature:
foton design: resgain(70 Hz, Q=8, h=8) * zpk(100,1,1)
equiv zeros and poles: z=[10.6082+/-i*69.1915, 100], p = [4.2232+/-i*69.8725, 1], g = 1
dtt calibration:
Gain: 1e-14 [m/ct]
Poles: 4.2232 69.8725, 1
Zeros: 10.6082 69.1915, 100
This calibrates the channel, regardless of if there's excitation or not (assuming all linearity and good coherent original transfer function) --- in the region where your transfer function is valid, then this will calibrate the ambient noise.
Since I didn't take enough data to really fill out the transfer function, I only bother to do this in the 10-100 Hz, and did it rather quickly -- only looking for factors of ~2 precision for this initial assessment.
So as to not confuse the main point of the aLOG, I'll attach supporting plots as a comment to this log.
I attach support plots that show
For each test mass: The DELTA L EXTERNAL spectra during excitations, along with calibrated displacement of each excitation, the resulting transfer function, and coherence.
For those who may have to repeat the measurement, I attach screenshots of the DTT configuration and what channels I used explicitly. The template's too big to attach, but it lives in
/ligo/home/jeffrey.kissel/2017-07-242017-07-24_BSCISI_ST2_BB_Injections.xml
Also, shown for ETMX and ITMY, the projected ST2 Error Point both under excitation and during ambient conditions, with the residual transfer function shown below to expose how poor the calibration is.
Jeff and I added his data to the simple noise budget. We are still using a pre-EQ darm noise in this plot, and you can see that the couplings he found explain some of our unexplained noise around 60-70 Hz.
Adding a couple plots to show that ETMX ST2 coherence to CAL_DELTAL has changed, but measured motion doesn't seem to have changed. First plot is the coherence for 500 averages from the long lock on June 22, 2017 from 18:00 UTC on (in blue) to a similar window from the lock last night (red). The lump at 70-ish hz in red is new, not visible in the pink trace from June. Second plot shows the ST1 L4Cs and ST2 GS13s (both in meters) for the same periods (the June measurement is red and blue, last night are green and brown). The ST2 motion especially is nearly identical around the lump at 70 hz. Talking to Sheila, this maybe implies that scatter at EX is worse now than before.
I looked at all of the other BSCs as well for the lock segment last night, but none of the them showed the same coherence as ETMX.
For the record, here are two alogs from LLO on tests we've done:
BSC injections before O2 (when we found the problem with ITMY). We plan to repeat these before the end of the run.
O2 HAM injections (all clear to at least x10 above ambient).
If we are making a budget of the stage 2 motion to DARM then we should take into account the rotation motion also, since the bottom of the cage has ~2 meter lever arm
For off-site interested parties, I've committed the above template to the seismic repository here:
/ligo/svncommon/SeiSVN/seismic/BSC-ISI/H1/Common/Data/2017-07-24_BSCISI_ST2_BB_Injections.xml
and corresponding key to all of the 100+ references in the template (as well as documentation of measurement times) is in the same location, with a similar name:
/ligo/svncommon/SeiSVN/seismic/BSC-ISI/H1/Common/Data/2017-07-24_BSCISI_ST2_BB_Injections_ReferenceNotes.txt
I've replotted some of Jeff's data for the stage to beam direction drive to Darm and added a plot from Ryan and Valera's (24820) similar data.
There are the four stage 2 motion to Darm transfer functions from H1 (I made the ETMY data dotted because it has no coherence)
There is a 1/f^2 line (light blue) which is what you might expect for the coupling from a charged path on the test mass to a moving charge (not quite a matching slope, but the transfer function phases all look like 0 degrees)
I wasn't able to recover transfer functions from the LLO data so I plotted the amplitude ratio for the one platform where there is excess signal in Darm (ITMY in green). The vertical black lines mark the limits of where there is excess signal and where you can believe that we have a decent estimate of the transfer function. The sensitivity on the other LLO chambers is much less (at least a factor of 5)
One more plug for a rotation measurement, a good measurement of the rotation to Darm transfer function on ETMX and/or ITMY would let us do some geometry to guess at the height of the coupling location (again assuming a point like integration between the cage and the suspension cage)
J. Kissel
Performed same check on ETMs as I did yesterday on ITMs with standard Top Mass to Top Mass transfer functions.
I similarly attach sneak peak screenshotss of fully processed data, but having watched the TFs go by,
The ETMs are clear of rubbing.
Left to do: all 10 of the triples, 3 doubles, and if we really care, the 9 singles.
(PS, we should get these as reference anyways, in prep for the up-coming vent)
Please ignore the difference with the black references on the reaction chains -- to save time, rather than figure out good templates for the ETMs, I copied over the ITM template and replaced the characters ITM with ETM. We know that ITM reaction chains have different resonance shapes and frequencies that the ETM reaction chains. From years of staring at these, I can tell they're fine. Again, will process these later to show how they really compare what's expected.
The main chains between ETMs and ITMs are identical, so their comparison can be treated as legit.
Data is stored and committed to svn here:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGM0/Data/
2017-07-21_2004_H1SUSETMX_M0_WhiteNoise_L_0p01to50Hz.xml
2017-07-21_2004_H1SUSETMX_M0_WhiteNoise_P_0p01to50Hz.xml
2017-07-21_2004_H1SUSETMX_M0_WhiteNoise_R_0p01to50Hz.xml
2017-07-21_2004_H1SUSETMX_M0_WhiteNoise_T_0p01to50Hz.xml
2017-07-21_2004_H1SUSETMX_M0_WhiteNoise_V_0p01to50Hz.xml
2017-07-21_2004_H1SUSETMX_M0_WhiteNoise_Y_0p01to50Hz.xml
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMX/SAGR0/Data/
2017-07-21_2051_H1SUSETMX_R0_WhiteNoise_L_0p01to50Hz.xml
2017-07-21_2051_H1SUSETMX_R0_WhiteNoise_P_0p01to50Hz.xml
2017-07-21_2051_H1SUSETMX_R0_WhiteNoise_R_0p01to50Hz.xml
2017-07-21_2051_H1SUSETMX_R0_WhiteNoise_T_0p01to50Hz.xml
2017-07-21_2051_H1SUSETMX_R0_WhiteNoise_V_0p01to50Hz.xml
2017-07-21_2051_H1SUSETMX_R0_WhiteNoise_Y_0p01to50Hz.xml
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMY/SAGM0/Data/
2017-07-21_2005_H1SUSETMY_M0_WhiteNoise_L_0p01to50Hz.xml
2017-07-21_2005_H1SUSETMY_M0_WhiteNoise_P_0p01to50Hz.xml
2017-07-21_2005_H1SUSETMY_M0_WhiteNoise_R_0p01to50Hz.xml
2017-07-21_2005_H1SUSETMY_M0_WhiteNoise_T_0p01to50Hz.xml
2017-07-21_2005_H1SUSETMY_M0_WhiteNoise_V_0p01to50Hz.xml
2017-07-21_2005_H1SUSETMY_M0_WhiteNoise_Y_0p01to50Hz.xml
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/ETMY/SAGR0/Data/
2017-07-21_2055_H1SUSETMY_R0_WhiteNoise_L_0p01to50Hz.xml
2017-07-21_2055_H1SUSETMY_R0_WhiteNoise_P_0p01to50Hz.xml
2017-07-21_2055_H1SUSETMY_R0_WhiteNoise_R_0p01to50Hz.xml
2017-07-21_2055_H1SUSETMY_R0_WhiteNoise_T_0p01to50Hz.xml
2017-07-21_2055_H1SUSETMY_R0_WhiteNoise_V_0p01to50Hz.xml
2017-07-21_2055_H1SUSETMY_R0_WhiteNoise_Y_0p01to50Hz.xml
More detailed plots of ITMX, compared against previous measurements and model. Both Main and Reaction chains show expected dynamics and are clear of rubbing.
More detailed plots of ITMY, compared against previous measurements and model. The reaction chain checks out OK. This latest main chain's data set (2017-07-20) resolution is at 0.02 Hz instead of the previous measurement which was at the standard 0.01 Hz -- so it *looks* like some resonances are truncated, but upon close inspection, they're just not resolving the resonance. Not sure what happened during the (main chain) pitch measurement at high frequency, but this behavior has been present in the 2017-04-25 and 2017-01-17 data sets. The last clean undamped data set is way back in 2014-10-28; there is a 2.5 year gap in the data for this chain... so difficult to say. From my experience, I propose is that the main chain is OK too, given that data points surrounding the resonances match up nicely for all other DOFs. However, while I finish out the single / double rubbing checks (or during yet another earthquake) I'll remeasure the main chain with a high resolution and focus on getting a good pitch measurement.
More detailed plots of ETMX. I'm 10% suspicious about the main chain (M0) and reaction (R0) chain showing their first two L 2 L resonances a little stunted since these were last measured on 2014-12-22, but this may just be due to lack of coherence. But, as with ITMY above, the data points surrounding the resonances all line up nicely. My yellow flag trigger is twitchy, likely because this is the suspension with one of the worst BSC ISI ST2 longitudinal coupling (see LHO aLOG 37752). All other dynamics check out... Further investigation is needed here (sheesh).
More detailed plots of ETMY, compared against previous measurements and model. Both Main and Reaction chains show expected dynamics and are clear of rubbing.
Because we're also considering TOP Mass flags moving around (not big enough to cause rubbing, but enough to cause (a) a moment of inertia change and therefore resonant frequency change, or (b) a change in cross-coupling to non-diagonal response to diagonal drive, e.g. L to P, or V to L, etc), I also post the individual transfer functions for each QUAD, and a previous measurement against which to compare. I've taken a look through all of these, and they don't show much difference. If anything, the new transfer functions just show a more coherent TF because I've improved the drive parameters to get better SNR. Cross-coupling plots start on pg 7 of each attachment.