model restarts logged for Sat 21/Feb/2015
no restarts reported
model restarts logged for Sun 22/Feb/2015
2015_02_22 03:42 h1fw0
one unexpected restart.
Dan, Sheila
OP Lev Damping on ETMs
We have turned the op lev damping for the ETMs off completely after the interferometer is locked. This is now in the gaurdian. The attached spectra show the witness sensors with oplev damping on (dashed lines) and off (solid lines). We knew these loops were not good, but this clearly shows it. The bottom right plot shows the DHARD WFS error signal with the oplev damping on and off.
DHARD WFS
The DHARD loop, which was designed based on measurements made at a carm offset of about 50 picometers with high op lev damping gain (see alog 16501 comment) , needs to be redesigned to take into account changes in the plant on resoannce and with the op lev damping off or reduced. The attached plots show the change in the transfer function, the first one shows the open loop gain in the situation where the loop was designed, the transfer function on resonance, and a partial measurement of the TF with oplev damping gain reduced. You can see this loop becomes unstable, which explains why we have had to reduce the gain several times in the last few weeks. After turning off the op lev damping, we attempted to take some measurements which could be used to design a new loop, these are shown in the last screen shot and can be found in my directory under /Alingment/DHARD_WFS_NO_OPLEV_WHITE_NOISE.xml While the cohernce is not good at some frequencies, this should be better than what we have now.
Attachments:
1) Spectra showing that op Lev damping was imposing noise, and is now off
2) Swept sine measurements showing that DHARD PIT becomes unstable as we go on resonance and reduce Op Lev gains.
3) swept sine measurements of DHARD Pit plants on resonance and with reduced op lev gain
4) noise injection measurements of DHARD plant with op lev damping off.
Other locking notes from tonight:
- The ETMY violin modes were higher tonight than Friday by a factor of several. I made +/-60deg filters in the ETMY_L2_DAMP_MODE2 filter bank and toyed with the gain and phases. With a gain of 500k and no phase shift the peak height decreased by ~20% in half an hour. So, perhaps some progress.
- On Friday there was some coherence above 100Hz with the OMC ASC loops while the dither was on, I installed some more aggressive butterworth rolloff filters into the dither error signal filter banks. Also I added some poles and zeros to the POSX filter bank to counteract a somewhat poor job of plant inversion for this d.o.f. Tonight the dither alignment was robust, but the IFO itself was quite noisy, so it's not clear whether this was a measureable improvement over Friday.
- Progress was made on the OMC autolocker code. The challenge here is that there is no high-frequency readback of PZT2, only the DC monitor channel is recorded at >16Hz. There is some lag between the PZT2 output and the DC monitor readback, so while the code can find the mode (by sweeping the cavity), the voltage it expects the mode to be at isn't the same as the PZT slider value. This needs some work, more fast DQ channels in the OMC model would be helpful.
We made it to low noise a couple of times, but the pitch motion at the AS port was so bad that the DC lock was not very stable.
J. Kissel
While reducing the EPICs sampling rate, and adjusting the servo PID parameters has killed most coupling to the SEI systems at the end stations, in the DOFs that it does remain, there is still a significant amount of coherence. The table below summarizes the remaining coupling:
Freq Coherence
EX Z L4Cs 0.2 - 1 [Hz] ~0.7
T240s 30-150 [mHz] ~0.85
0.2 - 1 [Hz] ~0.7
RZ L4Cs (none -- sensor noise limited)
T240s 40-150 [mHz] ~0.7
HP L4Cs 30-180 [mHz] ~0.85
0.2-0.8 [Hz] ~0.85
T240s (no such sensor)
EY Z L4Cs 70-150 [mHz] ~0.6
0.2-0.9 [Hz] ~0.9
T240s 60-150 [mHz] ~0.8
200-450 [mHz] ~0.9
0.5-0.9 [Hz] ~0.85
HP L4Cs 20-700 [mHz] ~0.9
T240s (no such sensor)
Indeed the coupling looks strikingly like what's left over in the Beam Splitter. I wonder -- since the differential pressure is being measured by sensors right on BSC2 if the measurement of coherence is better than with the rest of the tanks in the corner. In other words, if you measure the differential pressure noise at the tank where your sensors are, you may get a better measurement of the noise coupling.
The pump pressure noise (or the ADC noise) is significantly larger in amplitude at both end stations, and it even appears as though EY isn't getting any suppression at all. Further, because the "SMOO" low-pass filter has been removed, the noise above 100 [mHz] is larger than before. Looking at the HP ASDs, you can see a clear, order of magnitude reduction in the resulting noise in the platform, but at least EY still looks largely dominated by the pump pressure noise between 0.01 and 1 [Hz].
Looks like there's still some commissioning to do on these end station servos. Booooo.
We'll have measure the voltage input noise on the pressure sensors like we've done with the corner station sensor, to make sure this isn't real pressure noise, and if it isn't -- this gives warrant to accelerate the development of an alternative readout system with lower noise. Further, we'll have to see why EY isn't getting any suppression at all.
Dave, Jeff, Rick, Alexa, Sheila, Elli
This morning we discovered the PSL watchdog had tripped last night aroun 9.40 UTC. Sheila says this was not a flow error, but we don't know what caused the trip. To recover the PSL we did the following steps:
...
-With Rick's help over the phone, we restarted PSL at 12.15 in the fiber room. We then set about waiting an hour for the laser temperature to settle before we turned the PSL watcdogs back on.
-During this hour, we observed an oscillation build up in IMC-MC2_TRANS_SUM_OUTPUT trace. This built up to oscillations between 300-990 counts with a 30 sec period over the hour (see picture). IMC_PWR_IN_OUT16 also oscillating, suggesting a problem downstream of the IMC. (We eventually fixed this by changing the H1:PSL-ISS_REFSIGNAL so that the diffracted power was around 8%.)
-We noticed BS ISI tripped at 6.41 PST and Ham3 ISI triped at 12.06 PT, so we reset these watchdogs.. Big Earthquake at 6am PST which caused the BS trip.
-At this point we turned off IMC WFS by switching H1:IMC-WFS_GAIN from 0.1 to 0, and took the IMC lock guardian from locked to down, and turned off Input 1 on IMC servo board. We cleared the history of the IMC_ASC MC1,MC2,MC3 and PZT loops. As it later turned out, clearing the PZT history was not helpful as clearing this hstory removed a necessary alignment offset.
-We looked at the ISS. Diffracted pw in % ( H1:PSL-ISS_DIFFRACTION_AVG) was also spiking in a saw-toothed wave shape (see picture). We turned off autolock and IMC input power settled down. We reduced H1:PSL-ISS_REFSIGNAL from -2.11V to -2.07V, untill the H1:PSL-ISS_DIFFRACTION_AVG was around 8%. Before this change the diffracted power was getting close to 0%. This changed fixed the strange oscillations we were seeing in IMC-MC2_TRANS_SUM.
-Once the ISS was behaving again, we re-locked theIMC and turned the IMC WFS back on. Because we had cleared the PZT history, turning on the WFS did not bring us back to full IMC power buildup. The beams on WFS-A and WFS-B were not centered, again because the IMC PZT mirror was not correctly aligned. We adjusted PZT H1:IMC-PZT_PIT_OFFSET ( from 2650 to 3535) and H1:IMC-PZT_YAW_OFFSET (from 5774 to 5970) to compensate for the history we cleared. This brought the IMC-IM2_TRANS power back up to its expected value, and WFS-A and WFS_B were again centered.
...
At the end of all this, we think we have recovered the PSL and IMC alignments to where we were at the start.
Dave O, Ellie and Jeff K We noticed this morning that the PSL laser had shut-down. A quick survey of the PSL channels showed that this occurred at 09:34:06 UTC. We phoned Rick S who called Peter K and they agreed that we should restart the laser. Then Rick S talked us through the re-start procedure in the diode room. The laser was re-started around 11.50am PST.
Ellie, Evan and Dave It has been noticed that the H1 Inteferometer has a tendency to spatial mode-hope between TEMOO and TEMO1 modes whilst L1 does not have this tendency. We have been setting up to characterize the SRC cavity length and Gouy phase to see whether it differs from the design settings. To do this we set-up the auxillary laser and improved the focusing of the light onto the high speed 1611 diode of ISCT6 on the OMC_REFl_Air periscope. As a first step we repeated the previous measurement describe in AlOG 16084 with considerably higher signal to noise. With a bright Michelson lock we observed the reflection maximum on the either side of the Michelson. By eyeballing this data we can see that these occurred at -790+/-10 MHz and 905 +/- 10 MHz. Assuming that these are difference because of an offset in lock. The Michelson Reflection Dip is peaked at 847 MHz +/- 7 MHz. This corresponds to a Schnupp Asymetry = 8.9 cm +/- 1mm. A more rigorous analysis of this data will follow.
Here is a simple parabolic fit to the data, which sets the Schnupp asymmetry to 8.7cm (with an error of +/- 0.2mm. This error is calculated using error propagation of least-squares fitting with cross-correlation terms included, but it seems likely this statistical analysis underrepresenting the true error.) The upper- and lower- zero crossings are at 806MHz and 917MHz. Last December we measured Scnipp asymmetry at 9.05cm.
Improvements to this could be made by: -Measureing cable loss/frequency response (the beat note on IOT2R is fed to ISCT6 with a looong cable), -Correcting for photodiode frequency response curve, -Checking if auxiliary laser power has a frequency dependence.
We have removed the 1611 photodiode frequency response from the data and refitted the beat-note minima. We calculate a revised Schnupp asymmetry of 8.9cm (with an error of 0.1mm, which was calculated using least squares fitting error propagation with cross-correlation terms included).
J. Kissel Changing the clock-rate and PID parameters of the corner station's HEPI Pump Servo (LHo aLOG 16796) has removed most of the noise from the corner station SEI systems, while still maintaining a 10 [mHz] UGF loop suppression on the pump pressure (for design, see 16782). Notes on the current impact on chamber performance, compared with what was measured when the problem was initially discovered (LHO aLOG 16239): - The Beam Splitter remains as the worst chamber, with coupling in X, RZ (as measured by the ISI ST1 T240s) and HP (as measured by the HPI L4Cs) between 5-50 [mHz], 5-50 [mHz] and 50-150 [mHz], respectively. Even still, the amplitude of displacement for these DOFs has been reduced by a factor of a few, with the best reduction being RZ from 20-90 [mHz] where the amplitude dropped by a factor of 5 -- should be great for yaw alignment drift of the BS. - For all HAM chambers, any coherence, in any DOF -- except for HP -- has disappeared or, at least it's below the HEPI L4C sensor noise floor. - For the BSCs, all DOFs but for what's mentioned above, show little coherence even with the T240s, indicating we're also not limited by this noise there either. - Of the tanks that still show coherence with HP, their noise amplitude has also reduce by factors of 2 to 3, reducing the coherence by similar factors. HAM2 is the worst offender for HP, with still obvious coherence between 0.1 [Hz] and 1 [Hz]. I think we've got what we can out of the pump servo's stinky computers, tuning the parameters to account for its inherent badness -- and got factors of 2-3 reduction in ISI input noise between 10 [mHz] and 1 [Hz] motion. Any further efforts on improving the remaining coupling should be dedicated to installing a better pressure readout system. For the attached plots, I've focused on the DOFs that still have some coherence, and new information where I've gathered T240 information. For the entire collection of plots showing all DOFs for all tanks, check out .pdf files tagged with the date 2015-02-20 in the /ligo/svncommon/SeiSVN/seismic/HEPI/H1/Common/ folder in the SeiSVN. The DTT template used to make the thousands of plots can be found here: /ligo/svncommon/SeiSVN/seismic/HEPI/H1/Common/2015-02-18_H1HPI_PumpControllerNoise.xml Will post similar results for the ETMs tomorrow -- I expect the same goodness there.
no restarts reported. Conlog frequently changing channels report attached.
I am concluding that the scale factor in the original calibration (alog 16698) was underestimated by a factor of about 2.4 in 2 - 20 Hz frequency band (meaning, the DARM spectra we had collected were too good). This was due to my inaccurate estimation of the ESD actuation response.
For the frequency region above 20 Hz, it has been underestimated by a factor of 3.2 when the PSL power stayed at 2.8 W and the same DARM offset was used. This was due to the inaccuracy in the ESD propagating into the sensing factor and also inaccuracy in the UGF location. I did not try to track how the sensing calibration should have been compensated as a function of the PSL power or the DARM offset (alog 16726).
I have updated the CAL-CS online calibration coefficients accordingly in both the sensing and actuation paths.
Pcal_Y seems to still indicate that the DARM spectrum is consistently too good by 40-65 %.
(ETMX response agreed the sus model by 40 %)
The day before yesterday, I had a chance to repeat the calibration of the ESD response of ETMX by locking the X arm with the IR laser. Comparison with ITMX at 13 Hz gave me an ESD response of 6.32 x 10-16 m/cnts in ETMX at 13 Hz. This is 1.4 times larger than the expected than the suspension model. Since I used alpha of 2.0 x10-10 N/V2 in the model, the measured response corresponds to a slightly larger alpha of 2.8x10-10 N/V2. With the right force coefficient of -124518.4 cnts applied on ETMX, I tested both the linearized actuation and non-linearized. They showed almost same strength in a frequency band of 10 - 59 Hz as expected but with the linearized version somewhat stronger by 3-ish % (see the attached) presumably due to the charge on the test mass.
Since the change between the linearized and non-linerized actuations is so small, I neglected this effect and kept using the transfer coefficient of the non-linarized version at 13 Hz.
(Estimation of the DARM optical gain)
Using the measured data taken by Alexa (alog 16805), I estimated the optical gain of the DC read out to be 9.09x10-7 cnts/m. To get this number, I first extrapolated the ESD response to some frequencies at around 20 Hz. Since the loop shape is already known, fitting of the open loop gives me the optical gain. I did eye-fitting this time. The UGF was at around 23 Hz in this particular data.
Since I was able to lock the interferometer at 2.8 W with the DC read out tonight, I cross-checked the DARM open loop. Running a swept sine, I confirmed that it sill kept the same UGF (see the attached below). Good.
(Comparison with Pcal)
First of all, one thing I have to mention is that, in an alog (alog 16781) describing the comparison between LSC-DARM_IN1 and PCAL is not a fair comparison because we know that LSC_DARM_IN1 was not well-calibrated. I checked the CAL-DELTAL_EXTERNAL_DQ at this particular time, but unfortunately the spectrum did not look reasonable probably because I was in the middle of changing some parameters in the CAL-CS. Instead, I looked into a different lock stretch at Feb-02, 5:13:11 UTC with the same IMC incident power of 2.8 W. The Pcal reported greater displacement by a factor of approximately 4.6 (see the attached below).
If I applied the new accurate sensing calibration, the discrepancy would have been a factor of 1.45 or 45% with the Pcal higher than the DARM spectrum.
To double check it, I checked the Pcal again during one of today's lock stretches at Feb-21, 10:04:05 UTC. One thing we have to pay attention is that the Pcal excitation frequency is now shifted to 540.7 Hz (alog 16815). I used the Pcal calibration formula that Sudartian posted in alog 16718 to get the displacement. The ratio between the Pcal and DARM spectrum was about 1.65 or 65% with the Pcal greater than the DARM spectrum. Even though the ratio is slightly different from 8 days ago or so, it still indicates that the DARM calibration is too good by several 10%.
The other excitation at 36.7 Hz (alog 16815) did not have signal-to-noise ratio more than 2 in the DARM spectrum due to high noise in this frequency region and therefore I did not use it this time. Nevertheless, the Pcal at this frequency was also greater as well. So the relation between Pcal and DARM spectrum is qualitatively consistent.
Here is a fresh DARM spectrum (from 2015-02-26 10:21:50 UTC) compared with the GWINC prediction. Between 1 and 3 kHz (where the spectrum looks reasonably clean and has the right shape for shot noise), the agreement looks good.
GWINC reports 9 Mpc from this measurement.
This is another detail point of this calibration log (for my self-justification).
In the ISC call last Friday, people pointed out that the first Pcal plot (link to the plot ) seemed greater by a factor of 10-ish than the calibrated DARM. Here, I explain that they don't differ by a factor of 10 but a factor of 4.6 as I declared in the original alog.
To be celar, I attach a zoomed version of the previous plot. See below.
Taking the ratio of Pcal/DARM, I again confrimed that the ratio is 4.6185. This is the number I quoted in the original alog. Here, I repeat a conclusion I said in the original alog: since we now know that the DARM calibration was off by a factor of 3.18 on Feb 12th, if we apply this correction the descrepancy between Pcal and DARM would have been a factor of 1.45 or 45 % with the Pcal greater.
Alexa, Sheila, Dan, Evan, Kiwamu
Tonight we have had good locking. The take home message tonight was that our noise changes with aligment, and so we think that we need to spend some time getting some ASC going (or at least a reproducible alingment) before we can make much progress on noise hunting. (see alog 16839)
We moved SR2, the difference between the noise spectrum before and after can probably be explained by the alignment depent noise rather than by reducing the rubbing (see alogs 16831 and 16811). The new positions are shown in the attahed screen shot. The SR3 OPLEV is not alinged any more. If someone wants to use the OpLev over the weekend, you will have to go back to the old alingment of SR2+3.
Turning on the OMC dither alingment improved the spectrum from 20-70 Hz in a way that is reproducble. The main improvement in the noise tonight came from alinging IM4, which resulted in the best spectrum we have had so far around 100 Hz. Note, the attached spectra are not calibrated!
To add to the expanding ecology of H1 noise curves, here is a progression of our 2.8W locks for the past week and a half.
Also tonight Sheila has added the ETMY bounce mode damping to the Guardian with gain of -100. This has been working very well, the bounce mode is the lowest it's ever been.
Just out of curiosity, here is a rough estimate of the calibrated DARM spectrum for the 2.8 W lock. This was done assuming the spectrum is shot-noise limited above 1 kHz (except for the bump).
Alexa, Sheila, Evan, Dan
Peter had noted that our suspension compenstation for the LSC DARM filter was different than the one used at LLO. In his plot LHO#16728 he had actually missed a Lead filter at 200 Hz (FM9) that we turn on once we are on RF DARM. See new sus compenstation comparison plot. Even with this lead filer on, we still do not have as much phase as Livingston.
Today, I loaded LLO's suspension compenstation filter into FM1 of LSC DARM. We tried enaging this for ALS DIFF but immediately saturared L3. Our next plan in attempt to acquire more phase margin is to develop a filter which can be engaged along with the lead filter (FM9) once we are on RF DARM with our original sus compensation filter (FM8), and see if this causes saturation. TBD.
Did you include the stopband (notch) filter for the violin mode fundamentals? If not, perhaps these were saturating L3?
Before tuesday, we had been listening to IFO channels through the computer speakers using z audio. It seems like z audio has disapeared.
Can you be more specific? What's the error message?
Fixed. Somehow the command was acceidentally removed in some recent command parsing restructuring. It should be back to working now.
Several commissioners feel that our new seismic defenses leave H1 insensitive enough to truck traffic that our Hanford site contacts no longer need to email me weekly with reports of their levels of activity. A quick glance at the 1-3Hz seismic trace in the control room will always settle the question of whether the trucks are hauling or not. We've built up a good bank of contacts related to site operations. Feel free to email me any time if you have questions about the possibility of earth-shaking things occurring near LHO.
Dale -- is this a suggestion for a study? D'you have the past ~6 months worth of weekly reports from these contacts? If so, we can corroborate their reports against our seismic data to better quantify that when they say they're doing "X" on site in a given week, then we see "Y" amount of noise in the BLRMS channels (or "Z" amplitude in spectra) at these times of day. This would be a fun DetChar exercise, and prove the point once and for all with a systematic study... I ask because doing the opposite, namely, finding that the IFO is noisey, (asking / being able to prove) whether its because of the ground motion, and then remembering to ask you for "what's going on this week at the Hanford reservation?" is pretty tough. (Unfortunately or thankfully, we don't have LLO's pleasure of proving that loggers surrounding the corner station to our "powerful new seismic defenses," are like mosquitoes are to a brick wall: see LLO aLOG 15797 or LLO aLOG 15634).
The attached PDFs show the resistance measurements for all RHs and the relative resistance vs time for the RHs as 1W is applied to each segment. All segments are operating within nominal parameters.
The resistances for the segments are:
| Segment | Resistance (Ohms) |
| ITMX UPPER | 44.0 |
| ITMX LOWER | 42.4 |
| ITMY UPPER | 40.7 |
| ITMY LOWER | 42.5 |
| ETMX UPPER | 41.9 |
| ETMX LOWER | 41.0 |
| ETMY UPPER | 42.2 |
| ETMY LOWER | 43.6 |
Just for reference, here is the transient thermal lens in ITMX, as measured by the HWS, from this morning's 2W RH test (~1800s of applied power).
A follow-up. The data from the RTD temperature sensors for each RH is plotted in the attaced PDF.
The ETMY and ITMX RH RTDs are non-responsive.
