ER-7 is scheduled for mid-June. There will be a short “annealing” run just before the ER-7 run. Seismic: Running TFs on BS and ITMX. BRS: Software crashes about every two weeks. Ops will check the BRS status daily. CDS: Finished connecting the Dew Point sensors for the 3IFO storage containers. VAC/FMC: HAM6 is still pumping. Hope to transition Ion pump today. Beam Tube cleaning of the X-Arm is 25% complete. There will be a safety meeting at 15:00 in the LSB auditorium. There will be painters on site working in the VPW, LSB, and OSB. PSL: Work continues on the FSS. Comm: Tuning and alignment work on the Mode Cleaner and the HWS.
Koji, Evan, Sheila
Tonight we saw the shelf from 50 up to 100 Hz, however we are back to a range of around 35 Mpc. We saw this last week and hoped that it was related to the HAM6 cleanroom. We have done several things:
The first plot was measured with the injection of 20000cnt@0.2Hz to H1:SUS-OMC_M1_TEST_L_EXC.
The second plot was measured with the injection of 10000cnt@0.2Hz to H1:SUS-OM1_M1_TEST_L_EXC.
Jeff, Sheila
This afternoon during an hour of winds consistently between 20-35 mph, we got a chance to use the three configurations Jeff described in 17729. We hoped to get be able to make a clear statement about whether or not the BRS is helping us on windy days to reduce the motion of the optic, we see a modest improvement with the BRS on, which could also be due to reduced ground motion.
We got at least 15 minutes of data with ALS COMM locked and common tidal runnng to ETMX (ugf set to 0.1 Hz) with three seismic configurations:
The IMC F signal, calibrated in kHz, is a readback of the X arm motion above 0.1 Hz in this configuration, with possible contamination from angular fluctuations. The best performance was measured with the BRS on, where the rms is about 67% of the rms measured with the 90 mHz blends and narrow band sensor correction. From the second screenshot, you can see that the ground motion also dropped when we switched to the BRS sensor correction, the rms of the ground is also about 62% lower for the red traces. The third plot shows X direction GS13s for the three configurations.
The last two attachements are the wind direction ( in degrees from north, this is mostly wind along the Y direction) and speed, and the seismic FOM for today.
What was the status of ITMX? It looks like the rms is limited by the bump at ~50 mHz in figure 1. It is possible that this bump in the ALS signal is coming from the 45 mHz blends at ITMX, though a similar bump in the ETMX GS 13 is also visible, which is a bit odd. With 90 mHz blends, one would expect that the gain peaking would be happenning near 90 mHz.
ITMX was indeed in the nominal configuration, with 45 [mHz] blends and narrow-band, 0.43 [Hz] sensor correction. We'd performed one test once that gave us the superstition that moving blend frequency up on the ITMs made ALS performance worse. I don't think this one test was documented.
Evan, Kiwamu,
We had a difficulty in locking the IMC in this afternoon after the FSS activity (see alog 17875). It turned out that the signal in the IMC trans PD was too low to trigger the IMC-MCL filter. Note that the upper and lower thresholds have been set to 100 and 90 cnts respectively for the nominal 3 W operation. We could have simply increased the output digital gain of this path, but at the same time we noticed that the analog signal was pretty low to begin with. It was about 20 cnts at the ADC when the IMC was locked on a 00-mode. We went to the IOT2L table and checked whether there is a clipping or some stupid things, but we did not find anything obvious. Since I did not like an analog signal to be as low as several counts at the ADC, I decided to crank up the analog gain of the PD (PDA100A) from 0 to 30 dB. Now it detects more than 200 cnts when the IMC is locked on 3 W. Evan then adjusted the digital gain such that it keeps the same conversion. We did not get a chance to subtract the dark offset yet, but the IMC is now locking fine.
Note that it seems that the trans PD has been in this low-ADC counts situation since approximately Feb-25 at which point the signal in IMC-TRANS decreased dramatically for some reason. See the attached trend. Could this be due to the LSC/OMC model split (alog 16893) ????
In an effort to increase the unity gain frequency of the TTFSS, I had tried a higher resonant frequency but
broader notch filter comprising of a 30 uH inductor for L2 and a 1500 pF capacitor for C16. After re-installing
the TTFSS, I found that the frequency no longer locked. Thinking that it was my circuit modification that was
the root cause, I reversed the changes and found that the frequency servo still did not lock.
The error signal was present when the cavity was swept. Each time the servo was engaged it did not lock
as the slow actuator ramp passed the resonance, which to me indicated that there was no feedback. The
problem was traced to the loop switch not engaging, this in turn was a faulty opto-coupler in the FSS fieldbox.
Coincidentally, the same one that Evan and I had switched the other day. Replacing both opto-couplers and
re-engaging the loop switch, the frequency servo locked.
The file M10P5.tif shows the open loop transfer function with the common gain set to -10 dB and the fast gain
set to +5 dB. The presence of the peaks at ~770 kHz and ~1.8 MHz suggest I did not correctly solder in the
two notches.
At the moment the common gain is set to -10 dB and the fast gain to +6 dB. If the loop starts oscillating -
indicated by a wildly oscillating reference cavity transmission of the PZT monitor plot on the MEDM screen
being a solid black, the fast gain needs to be reduced until the oscillation stops and then slowly restored.
The reference cavity transmission was ~1.45 V.
Peter, Rick
I spoke with Evan just to make sure I understood the conversation and implications of this log, and in doing so I've annotated the plot that Peter attached. Hope this helps! The problem is that this 1.8 [MHz] feature has left the FSS is only marginally stable (it works, but it's unclear whether IFO or IMC lock-losses cause (more) oscillations (than usual)). Peter will attack again in the morning.
Pumpdown continues.
An attempt was done today to run the system with only the 500 l/s "main" ion pump (valved out the turbo pump), but the "controller" was not able to "keep up."
So we'll continue to use the turbo pump in parallel with the ion pump, we'll keep this configuration until the pressure is low enough for the controller to support the ion pump demand.
H0:PEM rename to H1:PEM [WP5153, ECR1500016]
Patrick, Jim, Dave:
The EPICS PEM systems which monitor the weather stations and dust monitors had their channel names changed from the prefix H0:PEM- to H1:PEM-.
The DAQ was stopped and the minute trends were offloaded to a temporary location on the SSD raid. A new blank minute trend area was created. The new H1 INI files were loaded and the DAQ was restarted. Later the NDS servers were configured to serve the offloaded minute trends (in their temporary location). Later they will be migrated from SSD to HDD raids.
The EPICS IOCs for Weather and Dust were modfied and restarted. New H1 targets were created, and safe.snap files moved. MEDM screens were modified.
This WP will remain open to cover the remaining DAQ work which is needed.
End Station SUS/SEI upgrade to RCG2.9.1 [WP5154]
Jeff, Jim, Rolf, Dave:
RCG Tag 2.9.1 was installed on h1build. The following models were upgraded to this tag: h1iopsus[ex,ey], h1iopsei[ex,ey], h1susetm[x,y], h1sustms[x,y], h1hpietm[x,y], h1isietm[x,y]. No DAQ restart was required.
This closes WP5154, future WPs will cover upgrading the rest of H1.
3IFO storage environment monitoring
Richard, Filiburto, Dave, Jim:
The EPICS monitoring system for the LVEA 3IFO storage system was started today. The EPICS channels were added to the DAQ.
moved the old H0 dust and weather target directories to target_archive/ so they don't show up in the hourly autoburt backups.
J. Kissel, J. Warner We noticed that the wind / tilt at EX was so large that the peak-to-peak amplitude of tilt as measured by the BRS was surpassing the level at which the BRS's gravitational damper turns on. Since we're trying to get data in these high wind conditions, we've gone to the X end and and turned OFF the gravitational damper from the laptop software. Will turn on again some time soon when it's less windy.
Just a reminder (mostly to myself) -- turning off the gravitational damper, by commenting out its drive signal computation in the laptop's software and then restarting the software, renders the BRS useless for an hour or more because of impulse response of the 1 [mHz] high-pass that's applied to the analog signal. I.e. If you're trying to use the BRS quickly after a software restart -- don't count on it! Post email checking edit: Krishna reminds me that one can reduce the impulse by setting the DC offset compensation to the value record just before killing the software. We (Jim and I) consciously decided that the offset was too small to need updating in the software. We were wrong!
Waiting to clear these until the OMC is shown to be able to handle the changes.
Again there is some 70urad RX (Pitch) and 15urad RZ (Yaw.) Look at the SDF Diff Table (attached) to get an ideal of where to steer if alignment is suspect. Do the Yaw on HEPI though to keep the ISI drive minimal. I suspect the Pitching HEPI will not directly translate to the ISI.
Today's Maintenance Day started with PSL FSS work. Unfortunately, they were not able to complete this work, because they spent a good chunk of the day recovering from the FSS attempt. Due to this work, the PSL PZT Mirror swap was not attempted. Below is a running tally of work.
A while ago I wrote a script to calculate match gains for the BSC FF to match the ISI L4C's to the HEPI L4C's. This was based on Arnaud's script script to compute the match gains for the sensor correction, in alog 16208. The process was much the same, putting the St1 in 750mhz cps blends, turning off feedforward and sensor correction to the ISI and HEPI. I left the ISI's like that for 10 minutes, then calculated the transfer function between the HEPI and ISI L4C's, and took the average between .1 and .4 hz. The transfer functions all look somewhat like the attached one for the BS. Most match gains were are 1 +/-10%, but ETMY and the BS both had one value that was off by about 20%, X for ETMY, Y for the BS. Gains are installed, I'll get some performance data overnight. The script is in the SEISVN under /BSC-ISI/Common/Misc, it's called BSC_FF_gain_matching. You can see what the results look like by running (with the SEI paths loaded) BSC_FF_gain_matching('H1', 'ITMX', 1113079985, 600) and exchanging 'ITMX' for the other chambers.
Since everyone is done at EX and the winds are a blowing, we turned the BRS on and switch to the Mitt_SC.
J. Kissel, K. Izumi Using the same model I described yesterday (see LHO aLOG 17847), I've now compared it against (a) this weekend's measured DARM Open Loop Gain Transfer Functions (OLGTFs), which were taken out to 1 [kHz]: 2015-04-12 Post UIM / TST Crossover Adjustment, Post HAM6 Vent, ESD Linearization OFF, at 10 [W] input power LHO aLOG 17834 2015-04-13 Increase of input power to 15 [W], ESD Linearization OFF LHO aLOG 17835 and (b) The previous measurements shown in LHO aLOG 17847. They've solidified suspicions of we'd just barely begun to see -- there's definitely some funny business going on: - We suspect that the frequency dependence of the sensing function (i.e. optical plant) cannot be simply described by a single-pole filter, but it could also be a flaw in model of the actuation frequency dependence. - The optical gain has significantly reduced from 112e6+/-8% to 75e6+/-4%, even though Evan and Sheila have attempted to compensate for it in the DARM loop digital gain. In the first attachment, I compare all of the measurements against a model with a fixed cavity pole frequency of 389 [Hz], the number calculated to be the ideal from L1 (see LLO aLOG 15923). In the second attachment, I compare all of the measurements against a model where I've adjusted the coupled cavity pole frequency to match the model / measurement discrepancy. From the comparison of these two models, one can see several things: (1) There is a systematic difference in frequency-dependent discrepancy between the earlier, 5-300 [Hz] data and the later, post-HAM6 vent, data. This implies something systematic has changed in the time between 2015-04-06 and 2015-04-12. (2) In order to fit the discrepancy's frequency dependence, I've had to move the DARM coupled cavity pole down to an unrealistically (??) low 320 [Hz] and 290 [Hz] for the earlier and later data, respectively. The ?? is because I'm not sure what is unrealistic. (3) I've used the same time delay for *all* of the data sets. The 40 [us] was chosen *after* I'd shifted the coupled-cavity pole frequency down in order to get the phase to be flat as a function of frequency. We have no reason to suspect that the time delay would have changed over these 5 measurements, so I take this to be the residual unknown timing error (*not* the 93 +/- 30 [us] I'd said in the previous log). There are several things think might be the cause of this (arranged in order of what we think is most likely) - DARM coupled cavity pole is lower than expected because of SRCL offset, low power recycling gain, or IFO alignment - ESD / SUS isn't exactly 1/f^2 at high frequency - Some nasty frequency dependence of the linearization algorithm Kiwamu's hard at work testing the first suspicion. Stay tuned!
Jeff K, Kiwamu,
As Jeff described in the above entry, we noticed that the latest measured DARM open loops behaved as if they got a lower cavity pole (~ 290 Hz). There are several possible reasons for explaining this. This time, we started from study of a SRCL offset which can lower the DARM cavity pole. After the study, we are concluding that the discrepancy is NOT due to a SRCL offset.
(Comparison between model and measurements)
The attached plot below shows a ratio of the zero-SRCL-offset DARM TF and DARM TFs with various SRCL offsets together with the actual data that Jeff posted. The solid curves are made from simulated responses and dots are the measured ones. The numbers in the legend box represent the size of the offsets in the SRCL locking point.
As shown in the plot, the behavior of a rising wing at high frequencies are seen in both the measured data and simulation. However, apparently the measured data do not show a dip at around 200 Hz. As we know, this dip is a particular behavior of a SRCL offset which results in a detuning peak at around the cavity pole.
If we keep increasing the SRCL offset, the location of the cavity pole would become as low as measured one, but at the same time it would also make the dip much deeper. So we think the SRCL offset is NOT the one causing the low cavity pole in DARM.
I'm taking advantage of the PSL down to get some measurments on the BSCs. The measurements require high blends, no sensor correction or feedforward on the ISI. Should take 10 minutes. I will return the platforms to operating states when I have enough data.
This seismometer has given us problems for some time: alogs 15510, 14482, 9727. JeffK may point to others too.
On the attached four plots, there are four successive days, Saturday thru Tuesday at 0100pdt. The lower left panels are the Coherences between the HAM2 & HAM5 (STS-A & C) and the ITMY (STS2.) The Upper Left, Upper Right, and Lower Right panels are the ASDs of the X Y & Z DOFs respectively of STS2 A B & C.
The take away is that in general the character of the ITMY (STS2-B) ground seismometer doesn't change like the other two instruments below 100mhz while the HAM2 & HAM5 instruments change more day to day and mostly look like each other.
Details: The Z DOF is most obvious in that below 50 or 80 mhz, ITMY trends up steeply while the A & C seismos do not. For the Y DOF, the HAM2 (STS2-B) signal seems to be the outlier but the day to day doesn't follow a patten between the instruments so I ... The X DOF is pretty good with the A & C instruments tracking each other pretty closely while the B sensor kinda stays at the same power level, mostly. So, like I say, a Case, maybe.
If I remember right, it sits on some kind of thin plastic or rubber mat, while the others sit directly on the concrete. If possible, it might be useful to make it contact the the concrete floor directly by carving out three holes on the mat.
For convenience: Evidence for low-frequency broken-ness LHO aLOG 15510 LHO aLOG 14482 LHO aLOG 9727 Factor-of-2 drop in X channel gain LHO aLOG 16208 LHO aLOG 16305
J. Kissel, R. Schofield Trying to convince Robert to let us borrow the newly-returned PEM vault STS-2 (S/N 88921) (see when it was removed in LHO aLOG 12931), I tried to show him in more detail with a little less curves on a plot what was wrong with the ITMY, B, Beer Garden STS-2 (S/N 88941). In the process, we not only rediscovered the problem Hugh shows above -- that the Z DOF on ITMY, below 50 [mHz] is just junk, but we also discovered that the Y DOF on the HAM2, A, Input Arm STS-2 (S/N 89922) is also junk. The attached PDFs show 5 days worth of corner station STS2 ASDs and COHs. For HAM2, check out the Y COH .pdf first. We see surprisingly low coherence between HAM2's Y and the other two, where the other two are perfectly coherent with each other. Looking at the ASD, it also shows the HAM2 spectra are consistently discrepant between 500 [mHz] and 3 [Hz], as well as below 0.1 [Hz]. For ITMY, again, check out the Z ASD first. From there, it's obvious that every day, the motion below 50 [mHz] is just junk. This is confirmed by the coherence, which shows that HAM2 is coherent with HAM5 every day, and ITMY is coherent with neither every day. The fact that ITMY and the HAM5, C, Output Arm STS-2 (S/N 100145) are always coherent between ... nope I can't make a consistent story. DOFs are inconsistently coherent, where they should all be perfectly coherent from 1 [Hz] down to 10 [mHz]. We really just need to huddle test all four of the STSs we have available in the corner, 89921 "PEM" Back from Quanterra 89922 Currently STS A 89941 Currently STS B 100145 Currently STS C and confirm -- once and for all -- which channel of whose is busted. Unfortunately, this means a whole lot of cable lugging around the LVEA -- a pretty hefty Tuesday task. Further -- LHO really needs more low-frequency seismometers -- because (a) We're already "temporarily" using a T240 at EX (S/N 531, borrowed fron the ETF at Stanford, originally installed at LHO in Feb 2014, see LHO aLOG 9758, and D1400077) because the project couldn't find enough STS-2s for us. (b) Even *if* we use all 5 in our possession (we have one at ETMY, S/N 89938), we still wouldn't be able to have one fail without significant down time. The lab's STS2/T240 Inventory, E1200068 hasn't been updated since the last time we churned up this subject in Oct 2014. I'm working on updating it myself by beating the streets; stay tuned for a -v15. Devil's advocate (inspired by Robert): Looking at the X DOF, there are days where all corner STSs are perfectly coherent between 60 [mHz] and ~2 [Hz]. Looking at the Y DOF, there are days where ITMY and HAM5 are perfectly coherent between 60 [mHz] and ~3 [Hz]. Looking at the Z DOF, there are days where all corner STSs are perfectly coherent between 60 [mHz] and ~1 [Hz]. The above implies that the corner station ground motion is perfectly coherent between 60 [mHz] and ~1 [Hz]. This implies we could try using a single STS-2 to run sensor correction for all chambers in the corner station. In order of risk of common-mode rejection being compromised: - For the BSCs, in X&Y, we only need a good signal around the first SUS resonances at ~500 [mHz] for DeRosa's narrow-band filter (See figure 3.32 P1500005). - For the HAMs in X&Y, we only need good coherence down to the bottom (frequency) edge of Hua's polyphase FIR bump, at 50 [mHz] (See pg 4 of attachment to SEI aLOG 594) - For all chambers, in Z, we need good coherence down to 10 [mHz], the lower end of the Mittleman's tilt free filter (See pg 5 of SEI aLOG 594) So, *if* we find an STS we like in which off of it's DOFs are performing perfectly (hopefully, presumably it's the one that just came back from Quanterra, S/N 89921), then we might be able to get away with running the entire VEA off of one STS2 (or T240). Maybe.