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ID Date Authorup Type Category Subject
  14324   Thu Nov 29 17:46:43 2018 gautamUpdateGeneralSome to-dos

[koji, gautam, jon, steve]

  • We suspect analog voltage from N2 pressure gauge is connected to interfacing Omega controller with the 'wrong' polarity (i.e pressure is rising over ~4 days and then rapidly falling instead of the other way around). This should be fixed.
  • N2 check script logic doesn't seem robust. Indeed, it has not been sending out warning emails (threshold is set to 60 psi, it has certainly gone below this threshold even with the "wrong" polarity pressure gauge hookup). Probably the 40m list is rejecting the email because controls isn't a part of the 40m group.
  • Old frames have to be re-integrated from JETSTOR to the new FB in order to have long timescale lookback.
  • N2 cylinder pressure gauges (at the cylinder end) need a power supply - @ Steve, has this been purchased? If not, perhaps @ Chub can order it.
  • MEDM vacuum screen should be updated to have gate valves be a different color to the spring-loaded valves. Manual valve between TP1 and V1 should also be added.
  • P2, P3 and P4 aren't returning sensible values (they should all be reading ~760torr as is P1). @ Steve, any idea if these gauges are broken?
  • Hornet gauges (CC and Pirani) should be hooked up to the new vacuum system.
  • add slow channels of   foreline pressures of TP2 & 3   and    C1:Vac-IG1_status_pressure
  14326   Fri Nov 30 19:37:47 2018 gautamUpdateLSCLSC feedforward block diagram

I wanted to set up an RTCDS model to understand this problem better. Attachment #1 is the simulink diagram of the signal flow. The idea will be to put in the appropriate filter shapes into the various filter blocks denoting the DARM and auxiliary DoF plants, controllers and actuators, and then use awggui / diaggui to inject some noises and see if in this idealized model I can achieve good subtraction. Then we can build up to applying a time varying cross coupling between DARM and the vertex DoF, and see how good the adaptive FF works. Still need to setup some MEDM screens to make working with the test system easier.

I figured c1omc would be the least invasive model to set this upon without risking losing any of our IR/green alignment references. Compile and install went smooth, see Attachment #2. The c1omc model was clocking 4us before, now it's using 7us.

Attachment #3 shows the top level of the OMC model, while Attachment #4 shows the MEDM screen.

* Note to self: when closing a loop inside the realtime model, there has to be a delay block somewhere in the loop, else a compilation error is thrown.

Attachment 1: LSC_FF_tester.png
LSC_FF_tester.png
Attachment 2: Screenshot_from_2018-11-30_19-41-07.png
Screenshot_from_2018-11-30_19-41-07.png
Attachment 3: Screenshot_from_2018-12-10_15-31-23.png
Screenshot_from_2018-12-10_15-31-23.png
Attachment 4: SimLSC.png
SimLSC.png
  14328   Sun Dec 2 17:26:58 2018 gautamUpdateIMCIMC ringdown fitting

Recently we wondered at the meeting what the IMC round trip loss was. I had done several ringdowns in the winter of 2017, but because the incident light on the cavity wasn't being extinguished completely (the AOM 0th order beam is used), the full Isogaio et. al. analysis could not be applied (there were FSS induced features in the reflection ringdown signal). Nevertheless, I fitted the transmission ringdowns. They looked like clean exponentials, and judging by the reflection signals (see previous elogs in this thread), the first ~20us of data is a clean exponential, so I figured we may get some rough value of the loss by just fitting the transmission data. 

The fitted storage time is 60.8 \pm 2.7 \mu s.However, this number isn't commensurate with the 40m IMC spec of a critically coupled cavity with 2000ppm transmissivity for the input and output couplers.

Attachment #1: Expected storage time for a lossless cavity, with round-trip length ~27m. MC2 is assumed to be perfectly reflecting. The IMC length is known to better than 100 Hz uncertainty because the marconi RF modulation signal is set accordingly. For the 40m spec, I would expect storage times of ~40 usec, but I measure almost 30% longer, at ~60 usec.

Attachment #2: Fits and residuals from the 10 datasets I had collected. This isn't a super informative plot because there are 10 datasets and fits, but to eye, the fits are good, and the diagonal elements of the covariance matrix output by scipy's curve_fit back this up. The function used to fit the t > 0 portions of these signals (because the light was extinguished at t=0 by actuating on the AOM) is \text{Transmission} = Ae^{-\frac{2t}{\tau_{\mathrm{storage}}}}, where A and tau are the fitted parameters. In the residuals, the same artefacts visible in the reflection signal are seen.

Attachment #3: Scatter plot of the data. Width of circles are proportional to fit error on individual measurements (i just scaled the marker size arbitrarily to be able to visually see the difference in uncertainty, the width doesn't exactly indicate the error), while the dahsed lines are the global mean and +/- 1 sigma levels.

Attachment #4: Cavity pole measurement. Using this, I get an estimate of the loss that is a much more believable 300 \pm 20\, \mathrm{ppm}.

Attachment 1: tauTheoretical.pdf
tauTheoretical.pdf
Attachment 2: ringdownFit.pdf
ringdownFit.pdf
Attachment 3: ringdownScatter.pdf
ringdownScatter.pdf
Attachment 4: cavPole.pdf
cavPole.pdf
  14331   Tue Dec 4 18:24:05 2018 gautamOmnistructureGeneralN2 line disconnected

[jon, gautam]

In the latest installment in this puzzler: turns out that maybe the trend of the "N2 pressure" channel increasing over the ~3 day timescale it takes a cylinder of N2 to run out is real, and is a feature of the way our two N2 cylinder lines/regulators are setup (for the automatic switching between cylinders when one runs out). In order to test this hypothesis, we'd like to have the line pressure be 0 initially, and then just have 1 cylinder hooked up. When we went into the drill-press area, we heard a hiss, turns out that one of the cylinders is leaking (to be fair, this was labelled, but i thought it isn't great to have a higher N2 concentration in an enclosed space). Since we don't need any actuation ability, I valved off the leaky cylinder, and disconnected the other properly functioning one. Attachment #1 shows the current state.

Attachment 1: IMG_7195.JPG
IMG_7195.JPG
  14334   Fri Dec 7 12:51:06 2018 gautamUpdateIMCIMC ringdown fitting

I started putting together some code to implement some ideas we discussed at the Tuesday meeting here. Pipeline isn't setup yet, but i think it's commented okay so if people want to play around with it, the code lives on the 40m gitlab

Model parameters:

  • T+ --- average transmission of MC1 and MC3.
  • T- --- difference in transmission between MC1 and MC3 (this basis is used rather than T1 and T3, because the assumption is that since they were coated in the same coating run, the difference in transmission should be small, even if there is considerable uncertainty in the actual average transmission number.
  • T2 --- MC2 transmission.
  • Lrt --- Round trip loss in the cavity.
  • "sigma" --- a nuisance parameter quantifying the error in the time domain ringdown data.

Simulation:

  • Using these model parameters, calculate some simulated time-domain ringdowns. Optionally, add some noise (assumed Gaussian).
  • Try and back out the true values of the model parameters using emcee - priors were assumed to be uniformly distributed, with a +/- 20% uncertainty around the central value.
  • For a first test, see if there is any improvement in the parameter estimation uncertainty using only transmission ringdown vs both transmission and reflection.

Initial results and conclusions:

  • Attachment #1 - Simulated time series used for this study. The "fit" trace is computed using the median values from the monte-carlo.
  • Attachment #2 - Corner plots showing the distribution of the estimated parameter values, using only transmission ringdown. The "true" values are indicated using the thick blue lines.
  • Attachment #3 - Corner plots showing the distribution of the estimated parameter values, using both transmission and reflection ringdowns.
  • The overall approach seems to work okay. There seems to be only marginal improvement in the uncertainty in estimated parameters using both ringdown signals, at least in the simulation.
  • However, everything seems pretty sensitive to the way the likelihood and priors are coded up - need to explore this a bit more.

Next steps:

  • Add more simulated measurements, see if we can constrain these parameters more tightly. 
  • Use linear error analysis to see if that tells us which measurements we should do, without having to go through the emcee.

There still seems to be some data quality issues with the ringdown data I have, so I don't think we really gain anything from running this analysis on the data I have already collected - but in the future, we can do the ringdown with complete extinguishing of the input light, and repeat the analysis.

As for whether we should clean the IMC mirrors - I'm going to see how much power comes out at the REFL port (with PRM aligned) this afternoon, and compare to the input power. This technique suffers from uncertainty in the Faraday insertion loss, isolation and IMC parameters, but I am hoping we can at least set a bound on what the IMC loss is.

Attachment 1: time_reflAndTrans.pdf
time_reflAndTrans.pdf
Attachment 2: corner_transOnly.pdf
corner_transOnly.pdf
Attachment 3: corner_reflAndTrans.pdf
corner_reflAndTrans.pdf
  14335   Fri Dec 7 17:04:18 2018 gautamUpdateIOOIMC transmission
  • Power just before PSL shutter on PSL table = 97 +/- 1 mW. Systematic error unknown.
  • Power from IFO REFL on AP table = 40 +/- 1 mW. Systematic error unknown.

Both were measured using the FieldMate power meter. I was hesitant to use the Ophir power meter as there is a label on it that warns against exceeding 100 mW. I can't find anything in the elog/wiki about the measured inesrtion loss / isolation of the input faraday, but this seems like a pretty low amount of light to get back from PRM. The IMC visibility using the MC_REFL DC values is ~87%. Assuming perfect transmission of the 87% of the 97mW that's coupled into the IMC, and assuming a further 5% loss between the Faraday rejected port and the AP table, the Faraday insertion loss would be ~30%. Realistically, the IMC transmission is lower. There is also some part of the light picked off for IPPOS. Judging by the shape of the REFL spot on the camera, it doesn't look clipped to me.

Either way, seems like we are only getting ~half of the 1W we send in on the back of PRM. So maybe it's worth it to investigate the situation in the IOO chamber during this vent.


c1pslc1susaux,c1iool0,caux  crates were keyed. Also, the physical shutter on the PSL NPRO, which was closed last Monday for the Sundance crew filming, was opened and the PMC was locked. PMC remains locked, but there is no light going into the IMC.

  14339   Mon Dec 10 15:53:16 2018 gautamUpdateLSCSwept-sine measurement with DTT

Disclaimer: This is almost certainly some user error on my part.

I've been trying to get this running for a couple of days, but am struggling to understand some behavior I've been seeing with DTT.

Test:

I wanted to measure some transfer functions in the simulated model I set up.

  • To start with, I put a pendulum (f0 = 1Hz, Q=5) TF into one of the filter modules
  • Isolated it from the other interconnections (by turning off the MEDM ON/OFF switches).
  • Set up a DTT swept-sine measurement
    • EXC channel was C1:OMC-TST_AUX_A_EXC
    • Monitored channels were C1:OMC-TST_AUX_A_IN2 and C1:OMC-TST_AUX_A_OUT.
    • Transfer function being measured was C1:OMC-TST_AUX_A_OUT/C1:OMC-TST_AUX_A_IN2.
    • Coherence between the excitation and output were also monitored.
  • Sweep parameters:
    • Measurement band was 0.1 - 900 Hz
    • Logarithmic, downward.
    • Excitation amplitude = 1ct, waveform = "Sine"

Unexplained behavior:

  • The transfer function measurement fails with a "Synchronization error", at ~15 Hz.
    • I don't know what is special about this frequency, but it fails repeatedly at the same point in the measurement.
  • Coherence is not 1 always
    • Why should the coherence deviate from 1 since everything is simulated? I think numerical noise would manifest when the gain of the filter is small (i.e. high frequencies for the pendulum), but the measurement and coherence seem fine down to a few tens of Hz.

To see if this is just a feature in the simulated model, I tried measuring the "plant" filter in the C1:LSC-PRCL filter bank (which is also just a pendulum TF), and run into the same error. I also tried running the DTT template on donatella (Ubuntu12) and pianosa (SL7), and get the same error, so this must be something I'm doing wrong with the way the measurement is being run / setup. I couldn't find any mention of similar problems in the SimPlant elogs I looked through, does anyone have an idea as to what's going on here?

* I can't get the "import" feature of DTT to work - I go through the GUI prompts to import an ASCII txt file exported from FOTON but nothing selectable shows up in DTT once the import dialog closes (which I presume means that the import was successful). Are we using an outdated version of DTT (GDS-2.15.1)?  But Attachment #1 shows the measured part of the pendulum TF, and is consistent with what is expected until the measurement terminates with a synchronization error.


the import problem is fixed - when importing, you have to give names to the two channels that define the TF you're importing (these can be arbitrary since the ASCII file doesn't have any channel name information). once i did that, the import works. you can see that while the measurement ran, the foton TF matches the DTT measured counterpart.


11 Dec 2pm: After discussing with Jamie and Gabriele, I also tried changing the # of points, start frequency etc, but run into the same error (though admittedly I only tried 4 combinations of these, so not exhaustive).

Attachment 1: SimTF.pdf
SimTF.pdf
  14344   Tue Dec 11 14:33:29 2018 gautamUpdateCDSNDScope

NDscope is now running on pianosa. To be really useful, we need the templates, so I've made /users/Templates/NDScope_templates where these will be stored. Perhaps someone can write a parser to convert dataviewer .xml to something ndscope can understand. To get it installed, I had to run:

sudo yum install ndscope
sudo yum install python34-gpstime
sudo yum install python34-dateutil
sudo yum install python34-requests

 I also changed the pythonpath variable to include the python3.4 site-packages library in .bashrc

Quote:

https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=44971

Let's install Jamie's new Data Viewer

Attachment 1: ndscope.png
ndscope.png
  14345   Tue Dec 11 18:20:59 2018 gautamUpdateOptical LeversBS/PRM HeNe is dead

I found that the BS/PRM OL SUM channels were reading close to 0. So I went to the optical table, and found that there was no beam from the HeNe. I tried power-cycling the controller, there was no effect. From the trend data, it looks like there was a slow decay over ~400000 seconds (~ 5 days) and then an abrupt shutoff. This is not ideal, because we would have liked to use the Oplevs as a DC alignment reference during the ventnoI plan to use the AS camera to recover some sort of good Michelson alignment, and then if we want to, we can switch out the HeNe.

*How can I export PDF from NDscope?

Attachment 1: BSOL_dead.png
BSOL_dead.png
  14349   Thu Dec 13 01:26:34 2018 gautamUpdateGeneralPower Outage recovery

[koji, gautam]

After several combinations of soft/hard reboots for FB, FEs and expansion chassis, we managed to recover the nominal RTCDS status post power outage. The final reboots were undertaken by the rebootC1LSC.sh script while we went to Hotel Constance. Upon returning, Koji found all the lights to be green. Some remarks:

  1. It seems that we need to first turn on FB
    • Manually start the open-mx and mx services using
      sudo systemctl start open-mx.service 
      sudo systemctl start mx.service
    • Check that the system time returned by gpstime matches the gpstime reported by internet sources.
    • Manually start the daqd processes using
      sudo systemctl start daqd_*
  2. Then fully power cycle (including all front and rear panel power switches/cables) the FEs and the expansion chassis.
    • This seems to be a necessary step for models run on c1sus (as reported by the CDS MEDM screen) to pick up the correct system time (the FE itself seems to pick up the correct time, not sure what's going on here).
    • This was necessary to clear 0x4000 errors.
  3. Power on the expansion chassis.
  4. Power on the FE.
  5. Start the RTCDS models in the usual way
    • For some reason, there is a 1 second mismatch between the gpstime returned on the MEDM screen for a particular CDS model status, and that in the terminal for the host machine.
    • This in itself doesn't seem to cause any timing errors. But see remark about c1sus above in #2.

The PSL (Edwin) remains in an interlock-triggered state. We are not sure what is causing this, but the laser cannot be powered on until this is resolved.

  14351   Thu Dec 13 12:06:35 2018 gautamUpdateGeneralPower Outage recovery

I did a walkaround and checked the status of all the interlock switches I could find based on the SOP and interlock wiring diagram, but the PSL remains interlocked. I don't want to futz around with AC power lines so I will wait for Koji before debugging further. All the "Danger" signs at the VEA entry points aren't on, suggesting to me that the problem lies pretty far upstream in the wiring, possibly at the AC line input? The Red lights around the PSL enclosure, which are supposed to signal if the enclosure doors are not properly closed, also do not turn on, supporting this hypothesis...

I confirmed that there is nothing wrong with the laser itself - i manually shorted the interlock pins on the rear of the controller and the laser turned on fine, but I am not comfortable operating in this hacky way so I have restored the interlock connections until we decide the next course of action...

Quote:
 

The PSL (Edwin) remains in an interlock-triggered state. We are not sure what is causing this, but the laser cannot be powered on until this is resolved.

  14352   Thu Dec 13 18:12:47 2018 gautamUpdateIOOND filter on AS camera changed

In order to see the AS beam a bit more clearly in our low-power config, I swapped out the ND=1.0 filter on the AS camera for ND=0.5.

  14356   Thu Dec 13 22:56:28 2018 gautamUpdateCDSFrames

[koji, gautam]

We looked into the /frames situation a bit tonight. Here is a summary:

  1. We have already lost some second trend data since the new FB has been running from ~August 2017.
  2. The minute trend data is still safe from that period, we believe.
  3. The Jetstor has ~2TB of trend data in the /frames/trend folder.
    • This is a combination of "second", "minute_raw" and "minute".
    • It is not clear to us what the distinction is between "minute_raw" and "minute", except that the latter seems to go back farther in time than the former.
    • Even so, the minute trend folder from October 2011 is empty - how did we manage to get the long term trend data?? From the folder volumes, it appears that the oldest available trend data is from ~July 24 2015.

Plan of action:

  1. The wiper script needs to be tweaked a bit to allow more storage for the minute trends (which we presumably want to keep for long term).
  2. We need to clear up some space on FB1 to transfer the old trend data from Jetstor to FB1.
  3. We need to revive the data backup via LDAS. Also summary pages.

BTW - the last chiara (shared drive) backup was October 16 6 am. dmesg showed a bunch of errors, Koji is now running fsck in a tmux session on chiara, let's see if that repairs the errors. We missed the opportunity to swap in the 4TB backup disk, so we will do this at the next opportunity.

  14362   Sat Dec 15 20:04:03 2018 gautamUpdateIOOTT1/TT2 stepping

I'm running a script that moves TT1 and TT2 randomly in some restricted P/Y space to try and find an alignment that gets some light onto the TRY PD. Test started at gpstime 1228967990, should be done in a few hours. The IMC has to remain locked for the duration of this test. I will close the PSL shutter once the test is done. Not sure if the light level transmitted through the ITM, which I estimate to be ~30uW, will be enough to show up on the TRY PD, but worth a shot I figure.

Test was completed and PSL shutter was closed at 1228977122.

  14366   Wed Dec 19 00:12:46 2018 gautamUpdateOMC40m OMC DCC node

I made a node to collect drawings/schematics for the 40m OMC, added the length drive for now. We should collect other stuff (TT drivers, AA/AI, mechanical drawings etc) there as well for easy reference.

Some numbers FTR:

  • OMC length PZT capacitance was measured to be 209 nF.
  • Series resistance in HV path of OMC lenght PZT driver is 10 kohms, so this creates a LP with corner 1/2/pi/10kohm/200nF ~80 Hz.
  • Per Rob's thesis, the length PZT has DC actuation coefficient of 8.3 nm/V, ∼ 2 µm range. 
  14368   Wed Dec 19 15:15:56 2018 gautamUpdateIOOTT1/TT2 stepping

I removed the ND filter from the ETMYT camera to facilitate searching for a TRY beam. This should be replaced before we go back to high power.

  14369   Wed Dec 19 19:51:19 2018 gautamUpdateGeneralPumpdown prep

[Koji, gautam]

Summary:

We are ready to put the heavy doors back on the chambers and do some test pumpdowns tomorrow morning if Jon gives us the go-ahead. Also, Koji made the OMC resonate some of the AUX beam light we send into ityes

Details:

  1. EY work:
    • IMC was locked, and we attempted to locate the beam with an IR card inside the chamber.
    • Koji found that the beam was too high, we were over-shooting the entire black-glass baffle on the EY table.
    • So I moved the TTs to try and center the beam through the aperture of aforementioned baffle.
    • Once this was done, we found that the beam was misaligned in yaw by ~1-inch in transmission on the EY optics table (there was an iris in place marking the cavity transmission axis). This explains why I couldn't find any TRY flashes while moving the TTs around.
    • We hypothesize that without the 2 degree ETM wedge in place, there isn't a compatible axis for the ITM transmission to also make it through the EY baffle and transmission iris. Over ~1m, the 2 degree wedge makes roughly 1.4 inch translation in yaw, so this seems to be a plausible hypothesis.
    • The ETMY suspension was moved from the mini-cleanroom setup back into the EY vacuum chamber. Two clamps (finger tightened only) hold it in place on the NE edge of the optical table. We decided that this is a better resting palce for the cage over the holidays than an in-air cleanroom.
  2. OMC chamber work:
    • While we were in clean garb, we decided to also investigate the OMC situation a bit.
    • It quickly became apparent that it was hopeless for me to work in chamber in the tightly confined IOO chamber. So Koji went in to have a look.
    • Koji will post the detailed alignment procedure - but after some alignment of the AUX laser input beam axis using in air steering mirrors and Koji's expert tweaking of the pointing into the OMC, we observed some resonances of the OMC.
    • Attachment #1 shows the full-range triangle ramp applied to the OMC length PZT (top row) and the OMC REFL signal (bottom row), measured using a PDA520 (chosen for its large active area) connected to a scope (AC-coupled, 1Mohm impedance, averaged to make the dips more prominent).
    • The OMC transmission was also (barely) visible on an IR card.
    • So the OMC length PZT seems capable of sweeping the length of the cavity. Based on the size of the dips we saw, the MM into the cavity is sub 1-percent.
    • The transmission PDs didn't output any measurable signal - but I'm not sure that the satellite box / readout electronics have been carefully characterized on the electroncis bench, so that will have to be done first.
    • We replaced the copper cover of the OMC (finger tightened for now) in case we do any test pumpdowns tomorrow. HV supply has been turned off, and the AUX laser has been reverted to standby mode.
Attachment 1: OMCscan.pdf
OMCscan.pdf
  14370   Wed Dec 19 21:14:50 2018 gautamUpdateVACPumpdown tomorrow

I just spoke to Jon who asked me to make this elog - we will be ready to test one or more parts of the pumpdown procedure tomorrow (12/20), so we should proceed as planned to put the heavy doors back on EY and OMC chambers at 9am tomorrow morning. Jon will circulate a more detailed procedure about the pumpdown steps later today evening.

  14373   Thu Dec 20 10:28:43 2018 gautamUpdateVACHeavy doors back on for pumpdown 82

[Chub, Koji, Gautam]

We replaced the EY and IOO chamber heavy doors by 10:10 am PST. Torquing was done first oen round at 25 ft-lb, next at 45 ft-lb (we trust the calibration on the torque wrench, but how reliable is this? And how important are these numbers in ensuring a smooth pumpdown?). All went smooth. The interior of the IOO chamber was found to be dirty when Koji ran a wipe along some surfaces.

For this pumpdown, we aren't so concerned with having the IFO in an operating state as we will certainly vent it again early next year. So we didn't follow the full close-up checklist.

Jon and Chub and Koji are working on starting the pumpdown now... In order to not have to wear laser safety goggles while we closed doors and pumped down, I turned off all the 1064nm lasers in the lab.

  14374   Thu Dec 20 17:17:41 2018 gautamUpdateCDSLogging of new Vacuum channels

Added the following channels to C0EDCU.ini:

[C1:Vac-P1b_pressure]
units=torr
[C1:Vac-PRP_pressure]
units=torr
[C1:Vac-PTP2_pressure]
units=torr
[C1:Vac-PTP3_pressure]
units=torr
[C1:Vac-TP2_rot]
units=kRPM
[C1:Vac-TP3_rot]
units=kRPM

Also modified the old P1 channel to

[C1:Vac-P1a_pressure]
units=torr

Unfortunately, we realized too late that we don't have these channels in the frames, so we don't have the data from this test pumpdown logged, but we will have future stuff. I say we should also log diagnostics from the pumps, such as temperature, current etc. After making the changes, I restarted the daqd processes.


Things to add to ASA wiki page once the wiki comes back online:

  1. What is the safe way to clean the cryo pump if we want to use it again?
  2. What are safe conditions to turn the RGA on?
  14376   Fri Dec 21 11:11:51 2018 gautamUpdateCDSLogging of new Vacuum channels

The N2 pressure channel name was also wrong in C0EDCU.ini, so I updated it this morning to the correct name and units:

[C1:Vac-N2_pressure]
units=psi

Now it too is being recorded to frames.

  14377   Fri Dec 21 11:13:13 2018 gautamOmnistructureVACN2 line valved off

Per the discussion yesterday, I valved off the N2 line in the drill press room at 11 am PST today morning so as to avoid any accidental software induced gate-valve actuation during the holidays. The line pressure is steadily dropping...

Attachment #1 shows that while the main volume pressure was stable overnight, the the pumpspool pressure has been steadily rising. I think this is to be expected as the turbo pumps aren't running and the valves can't preserve the <1mtorr pressure over long timescales?

Attachment #2 shows the current VacOverview MEDM screen status.

Attachment 1: VacGauges.png
VacGauges.png
Attachment 2: Screenshot_from_2018-12-21_13-02-06.png
Screenshot_from_2018-12-21_13-02-06.png
  14380   Thu Jan 3 15:08:37 2019 gautamOmnistructureVACVac status unknown

Larry W came by the 40m, and reported that there was a campus-wide power glitch (he was here to check if our networking infrastructure was affected). I thought I'd check the status of the vacuum.

  • Attachment #1 is a screenshot of the Vac overview MEDM screen. Clearly something has gone wrong with the modbus process(es). Only the PTP2 and PTP3 gauges seem to be communicative.
  • Attachment #2 shows the minute trend of the pressure gauges for a 12 day period - it looks like there is some issue with the frame builder clock, perhaps this issue resurfaced? But checking the system time on FB doesn't suggest anything is wrong.. I double checked with dataviewer as well that the trends don't exist... But checking the status of the individual daqd processes indeed showed that the dates were off by 1 year, so I just restarted all of them and now the time seems correct. How can we fix this problem more permanently? Also, the P1b readout looks suspicious - why are there periods where it seems like we are reading values better than the LSB of the device?

I decided to check the systemctl process status on c1vac:

controls@c1vac:~$ sudo systemctl status modbusIOC.service
● modbusIOC.service - ModbusIOC Service via procServ
   Loaded: loaded (/etc/systemd/system/modbusIOC.service; enabled)
   Active: active (running) since Thu 2019-01-03 14:53:49 PST; 11min ago
 Main PID: 16533 (procServ)
   CGroup: /system.slice/modbusIOC.service
           ├─16533 /usr/bin/procServ -f -L /opt/target/modbusIOC.log -p /run/...
           ├─16534 /opt/epics/modules/modbus/bin/linux-x86_64/modbusApp /opt/...
           └─16582 caRepeater

Jan 03 14:53:49 c1vac systemd[1]: Started ModbusIOC Service via procServ.

Warning: Unit file changed on disk, 'systemctl daemon-reload' recommended.

So something did happen today that required restart of the modbus processes. But clearly not everything has come back up gracefully. A few lines of dmesg (there are many more segfaults):

[1706033.718061] python[23971]: segfault at 8 ip 000000000049b37d sp 00007fbae2b5fa10 error 4 in python2.7[400000+31d000]
[1706252.225984] python[24183]: segfault at 8 ip 000000000049b37d sp 00007fd3fa365a10 error 4 in python2.7[400000+31d000]
[1720961.451787] systemd-udevd[4076]: starting version 215
[1782064.269844] audit: type=1702 audit(1546540443.159:38): op=linkat ppid=21820 pid=22823 auid=4294967295 uid=1000 gid=1000 euid=1000 suid=1000 fsuid=1000 egid=1000 sgid=1000 fsgid=1000 tty=pts0 ses=4294967295 comm="git" exe="/usr/bin/git" res=0
[1782064.269866] audit: type=1302 audit(1546540443.159:39): item=0 name="/cvs/cds/caltech/target/c1vac/.git/objects/85/tmp_obj_uAXhPg" inode=173019272 dev=00:21 mode=0100444 ouid=1001 ogid=1001 rdev=00:00 nametype=NORMAL
[1782064.365240] audit: type=1702 audit(1546540443.255:40): op=linkat ppid=21820 pid=22823 auid=4294967295 uid=1000 gid=1000 euid=1000 suid=1000 fsuid=1000 egid=1000 sgid=1000 fsgid=1000 tty=pts0 ses=4294967295 comm="git" exe="/usr/bin/git" res=0
[1782064.365271] audit: type=1302 audit(1546540443.255:41): item=0 name="/cvs/cds/caltech/target/c1vac/.git/objects/58/tmp_obj_KekHsn" inode=173019274 dev=00:21 mode=0100444 ouid=1001 ogid=1001 rdev=00:00 nametype=NORMAL
[1782064.460620] audit: type=1702 audit(1546540443.347:42): op=linkat ppid=21820 pid=22823 auid=4294967295 uid=1000 gid=1000 euid=1000 suid=1000 fsuid=1000 egid=1000 sgid=1000 fsgid=1000 tty=pts0 ses=4294967295 comm="git" exe="/usr/bin/git" res=0
[1782064.460652] audit: type=1302 audit(1546540443.347:43): item=0 name="/cvs/cds/caltech/target/c1vac/.git/objects/cb/tmp_obj_q62Pdr" inode=173019276 dev=00:21 mode=0100444 ouid=1001 ogid=1001 rdev=00:00 nametype=NORMAL
[1782064.545449] audit: type=1702 audit(1546540443.435:44): op=linkat ppid=21820 pid=22823 auid=4294967295 uid=1000 gid=1000 euid=1000 suid=1000 fsuid=1000 egid=1000 sgid=1000 fsgid=1000 tty=pts0 ses=4294967295 comm="git" exe="/usr/bin/git" res=0
[1782064.545480] audit: type=1302 audit(1546540443.435:45): item=0 name="/cvs/cds/caltech/target/c1vac/.git/objects/e3/tmp_obj_gPI4qy" inode=173019277 dev=00:21 mode=0100444 ouid=1001 ogid=1001 rdev=00:00 nametype=NORMAL
[1782064.640756] audit: type=1702 audit(1546540443.527:46): op=linkat ppid=21820 pid=22823 auid=4294967295 uid=1000 gid=1000 euid=1000 suid=1000 fsuid=1000 egid=1000 sgid=1000 fsgid=1000 tty=pts0 ses=4294967295 comm="git" exe="/usr/bin/git" res=0
[1783440.878997] systemd[1]: Unit serial_TP3.service entered failed state.
[1784682.147280] systemd[1]: Unit serial_TP2.service entered failed state.
[1786407.752386] systemd[1]: Unit serial_MKS937b.service entered failed state.
[1792371.508317] systemd[1]: serial_GP316a.service failed to run 'start' task: No such file or directory
[1795550.281623] systemd[1]: Unit serial_GP316b.service entered failed state.
[1796216.213269] systemd[1]: Unit serial_TP3.service entered failed state.
[1796518.976841] systemd[1]: Unit serial_GP307.service entered failed state.
[1796670.328649] systemd[1]: serial_Hornet.service failed to run 'start' task: No such file or directory
[1797723.446084] systemd[1]: Unit serial_MKS937b.service entered failed state.

 

I don't know enough about the new system so I'm leaving this for Jon to debug. Attachment #3 shows that the analog readout of the P1 pressure gauge suggests that the IFO is still under vacuum, so no random valve openings were effected (as expected, since we valved off the N2 line for this very purpose).

Attachment 1: Screenshot_from_2019-01-03_15-19-51.png
Screenshot_from_2019-01-03_15-19-51.png
Attachment 2: Screenshot_from_2019-01-03_15-14-14.png
Screenshot_from_2019-01-03_15-14-14.png
Attachment 3: 997B13A9-CAAF-409C-A6C2-00414D30A141.jpeg
997B13A9-CAAF-409C-A6C2-00414D30A141.jpeg
  14386   Fri Jan 4 17:43:24 2019 gautamUpdateCDSTiming issues

[J Hanks (remote), koji, gautam]

Summary:

The problem stems from the way GPS timing signals are handled by the FEs and FB. We effected a partial fix:

  • Now, old frame data is no longer being overwritten
  • For the channels that are indeed being recorded now, the correct time stamp is being applied so they can be found in /frames by looking for the appropriate gpstime.

Details:

  • The usual FE/FB power cycling did not fix the problem.
  • The gps time used by FB and associated RT processes may be found by using  cat /proc/gps (i.e. this is different from the system time found by using date, or gpstime).
  • This was off by 2 years.
  • The way this worked up till now was by adding a fixed offset to this time.
    • This offset can be found as a line saying set symm_gps_offset=31622382 in daqdrc.fw (for example)
    • There were similar lines in daqdrc.rcv and daqdrc.dc - however, they were not all the same offset! We couldn't figure out why.
    • All these files live in /opt/rtcds/caltech/c1/target/daqd/.

Changes effected:

  1. First, we tried changing the offset in the daqdrc.fw file only.
    • Incremented it by 24*60*60*365 = number of seconds in a year with no leap seconds/days.
    • This did not fix the problem.
  2. So J Hanks decided to rebuild the Spectracom driver - these commands may not be comprehensive, but I think I got everything).
    • The relevant file is spectracomGPS.c (made a copy of /usr/src/symmetricom-3.3~rc1, called symmetricom-3.3~rc1-patched, this file is in /usr/src/symmetricom-3.3~rc1-patched/include/drv)
    • Added the following lines:
      /* 2018 had no leap seconds or leap days, so adjust for that */
             pHardware->gpsOffset += 31536000;
    • re-built and installed the modified symmetricom driver.
    • Checked that cat /proc/gps now yields the correct time.
    • Reset the gps time offsets in daqdrc.fw, daqdrc.rcv and daqdrc.dc to 0
    • With these steps, the frames were being written to /frames with the correct timestamp.
  3. Next, we checked the timing on the FEs
    • Basically, J Hanks rebuilt the version of the symmetricom driver that is used by the rtcds models to mimic the changes made for FB.
    • This did the trick for c1lsc and c1ioo - cat /proc/gps now returns the correct time on those FEs.
    • However, c1sus remains problematic (it initially reported a GPS time from 2 years ago, and even after the re-installed driver, is 4 days behind) - he suspects that this is because c1sus is the only FE with a Symmetricom/Spectracom card installed in the I/O chassis. So c1sus reports a gpstime that is ~4 days behind the "correct" gpstime.
    • He is going to check with Rolf/other CDS experts to figure out if it's okay for us to simply remove the card and run the models, or if we need to take other steps.
    • As part of this work, the c1x02 IOP model was recompiled, re-installed and re-started.

The realtime models were not restarted (although all the vertex FEs are running) - we can regroup next week and decide what is the correct course of action.

Quote:
 
  • Attachment #2 shows the minute trend of the pressure gauges for a 12 day period - it looks like there is some issue with the frame builder clock, perhaps this issue resurfaced? But checking the system time on FB doesn't suggest anything is wrong.. I double checked with dataviewer as well that the trends don't exist... But checking the status of the individual daqd processes indeed showed that the dates were off by 1 year, so I just restarted all of them and now the time seems correct. How can we fix this problem more permanently? Also, the P1b readout looks suspicious - why are there periods where it seems like we are reading values better than the LSB of the device?
  14389   Tue Jan 8 10:27:27 2019 gautamUpdateGeneralNear-term in-chamber work

Here is a list of tasks I think we should prioritize for the next two weeks. The idea is to get back to the previous state of being able to do single arm, PRMI-on-carrier and DRMI locking, before making further changes.

Once the new folding mirrors arrive, I'd like to modify the SRC length to allow locking in the signal-recycled config as opposed to RSE. Still need to do the detailed layout, but I think the in-vacuum layout will work. In that case, I'd like to also move the OMC and OMMT to the IY table, and also move the in-air AS photodiodes to the IY in-air optical table. This is why I've omitted the OMC alignment from this near-term list, but if we want to not move the OMC, then we probably should add alignment of the AS beam to the OMC to this list.

List of in-chamber tasks for 1/2019

Chamber Task(s)
EY
  • Clean ETMY optic and suspension
  • Put ETMY suspension back in place, recover Y-arm cavity alignment
  • Remove any residual hardware from unused heater setup
  • Restore parabolic heater setup, center radiation pattern as best as possible on ETMY
  • Check beam position on IPANG steering mirror
IY
  • Clean ITMY optic and suspension cage
  • Restore ITMY suspension, recover Y arm cavity alignment.
  • Check position of AS beam on OM1/OM2
BS/PRM (if we decide to open it)
  • Replace BS/PRM Oplev HeNe, bring the beam in and out of vacuum with beam well centerd on in-vacuum mirrors (can take this opportunity to fix the in-air layout as well to minimize un-necessary steering mirrors)
  • Check position of AS beam on OM3/OM4, adjust if necessary
  • Check position of IPPOS and IPANG beams on their respective steering optics
OMC (if we decide to open it)
  • Check position of AS beam on OM5/OM6
  • Ensure AS beam exits the vacuum cleanly
  14391   Wed Jan 9 11:07:09 2019 gautamUpdateVACNew Vac channel logging

Looks like I didn't restart all the daqd processes last night, so the data was not in fact being recorded to frames. I just restarted everything, and looks like the data for the last 3 minutes are being recorded yes. Is it reasonable that the TP1 current channel is reporting 0.75A of current draw now, when the pump is off? Also the temperature readback of TP3 seems a lot jumpier than that of TP2, probably has to do with the old controller having fewer ADC bits or something, but perhaps the SMOO needs to be adjusted.

Quote:
 

Gautam and I updated the framebuilder config file, adding the newly-added channels to the list of those to be logged.

Attachment 1: Screenshot_from_2019-01-09_11-08-28.png
Screenshot_from_2019-01-09_11-08-28.png
  14392   Wed Jan 9 11:33:35 2019 gautamUpdateCDSTiming issues still persist

Summary:

The gps time mismatch between /proc/gps and gpstime seems to be resolved. However, the 0x4000 DC errors still persist. It is not clear to me why.

Details:

On the phone with J Hanks on Friday, he reminded me that c1sus seems to be the only machine with an IRIG-B timing card installed. I can't find the elog but I remembered that Jamie, ericq and I had done this work in 2016 (?), and I also remembered Jamie saying it wasn't working exactly as expected. Since the DAQ was working fine before this card was installed, and since there are no problems with the recording of channels from the other four FE machines without this card installed, I decided to simply pull out the card from the expansion chassis. The card has been stored in the CDS/FE cabinet along the Y arm for now. There was also a cable that interfaces to the card which brings over the 1pps from the GPS unit, which has also been stored in the CDS/FE cabinet.

This seems to have resolved the mismatch between the gpstime reported by cat /proc/gps and the gpstime commands - Attachment #1 (the <1 second mismatch is presumably due to the deadtime between commands). However, the 0x4000 DC errors still persist. I'll try the full power cycle of FEs and FB which has fixed this kind of error in the past, but apart from that, I'm out of ideas.

Update 1215:

Following the instructions in this elog did not fix the problem. The problem seems to be with the daqd_fw service, which reports the following:

controls@fb1:~ 0$ sudo systemctl status daqd_fw.service 
● daqd_fw.service - Advanced LIGO RTS daqd frame writer
   Loaded: loaded (/etc/systemd/system/daqd_fw.service; enabled)
   Active: failed (Result: start-limit) since Wed 2019-01-09 12:17:12 PST; 2min 0s ago
  Process: 2120 ExecStart=/usr/bin/daqd_fw -c /opt/rtcds/caltech/c1/target/daqd/daqdrc.fw (code=killed, signal=ABRT)
 Main PID: 2120 (code=killed, signal=ABRT)

Jan 09 12:17:12 fb1 systemd[1]: Unit daqd_fw.service entered failed state.
Jan 09 12:17:12 fb1 systemd[1]: daqd_fw.service holdoff time over, scheduling restart.
Jan 09 12:17:12 fb1 systemd[1]: Stopping Advanced LIGO RTS daqd frame writer...
Jan 09 12:17:12 fb1 systemd[1]: Starting Advanced LIGO RTS daqd frame writer...
Jan 09 12:17:12 fb1 systemd[1]: daqd_fw.service start request repeated too quickly, refusing to start.
Jan 09 12:17:12 fb1 systemd[1]: Failed to start Advanced LIGO RTS daqd frame writer.
Jan 09 12:17:12 fb1 systemd[1]: Unit daqd_fw.service entered failed state.
                                                     

Update 1530:

The frame-writer error was tracked down to a C0EDCU issue. Jon told me that the Hornet CC1 pressure gauge channel was renamed to . C1:Vac-CC1_pressure, and I made the change in the C0EDCU file. However, it returns a value of 9990000000.0, which the frame writer is not happy about... Keeping the old channel name makes the frame-writer run again (although the actual data is bunk).

Update 1755:

J Hanks suggested adding a 1 second offset to the daqdrc config files. This has now fixed the 0x4000 errors, and we are back to the "nominal" RTCDS status screen now - Attachment #2.

Attachment 1: gpstimeSync.png
gpstimeSync.png
Attachment 2: Screenshot_from_2019-01-09_17-56-58.png
Screenshot_from_2019-01-09_17-56-58.png
  14394   Thu Jan 10 10:23:46 2019 gautamUpdateVACovernight leak rate

Overnight, the pressure increased from 247 uTorr to 264 uTorr over a period of 30000 seconds. Assuming an IFO volume of 33,000 liters, this corresponds to an average leak rate of ~20 uTorr L / s. It'd be interesting to see how this compares with the spec'd leak rates of the Viton O-ring seals and valves/ outgassing rates. The two channels in the screenshot are monitoring the same pressure from the same sensor, top pane is a digital readout while the bottom is a calibrated analog readout that is subsequently digitized into the CDS system.

Quote:
 

We allowed the pumpdown to continue until reaching 9e-4 torr in the main volume. At this point we valved off the main volume, valved off TP2 and TP3, and then shut down all turbo pumps/dry pumps. We will continue pumping tomorrow under the supervision of an operator. If the system continues to perform problem-free, we will likely leave the turbos pumping on the main volume and annuli after tomorrow.

Attachment 1: OvernightLeak.png
OvernightLeak.png
  14397   Fri Jan 11 16:38:57 2019 gautamUpdateGeneralSome alignment checks

The pumpdown seems to be progressing smoothly, so I think we are going to stick with the plan decided on Wednesday, and vent the IFO on Monday at 8am. I decided to do some checks of the IFO alignment.

I turned on the PSL again (so goggles are advisable again inside the VEA until this work is done), re-locked the PMC, and opened the PSL shutter into the vacuum (still low power 100 mW beam going into vacuum). The IMC alignment required minor tweaking, but I recovered ~1300 cts transmission which is what it was --> so we didn't macroscopically change the input pointing into the IMC while working on the IOO table.

Centering the ITMY oplev spot, there is a spot on the AS camera roughly centered on the control room monitor, so the TT pointing must also be pretty close.

Then I centered the ITMY oplev spot to check how well-aligned or otherwise the Michelson was - the BS has no Oplev so there was considerable angular motion of the Michelson spot, but it looked like on average, it was swinging around through a well aligned place. I saved the slow bias voltages for the ITMs and BS in this config.

Then I re-aligned ETMX and checked the green transmission - it was okay, ~0.3, and I was able to increase it to ~0.4 using the EX green PZT mirrors. So far so good.

Finally, I tried to lock the X-arm on IR - after zeroing the offsets on the transmission QPD, there seems to be a few flashes as the cavity swings through resonances, but no discernible PDH error signal. Moreover the input pointing of the IR into the X arm is controlled by the BS which is swinging around all over the place right now, so perhaps locking is hopeless, but the overall alignment of the IFO seems not too bad. Once ETMY is cleaned and put back in place, perhaps the Y arm can be locked.

I shuttered the PSL and inserted a manual beam block, and also turned off the EX laser so that we can vent on Monday without laser goggles.

*Not directly related to this work: we still have to implement the vacuum interlock condition that closes the PSL shutter in the event of a vacuum failure. It's probably fine now while the PSL power is attenuated, but once we have the high power beam going in, it'd be a good to revert to the old standard.

Attachment 1: pd82.png
pd82.png
Attachment 2: LSC_X.png
LSC_X.png
  14398   Mon Jan 14 10:06:53 2019 gautamUpdateVACVent 82 complete

[chub, gautam]

  • IFO pressure was ~2e-4 torr when we started, on account of the interlock code closing all valves because the N2 line pressure dropped below threshold (<65 psi)
  • Chub fixed the problem on the regulator in the drill-press area where the N2 tanks are, the N2 line is now at ~75 psi so that we have the ability to actuate valves if we so desire
  • We decided that there is no need to vent the pumpspool this time - avoiding an unnecessary turbo landing, so the pumpspool is completely valved off from the main volume and TPs 1-3 are left running
  • Went through the pre-vent checklist:
    • Chub measured particle count, deemed it to be okay (I think we should re-locate the particle counter to near 1X8 because that is where the air enters the IFO anyways, and that way, we can hook it up to the serial device server and have a computerized record of this number as we had in the past, instead of writing it down in a notebook)
    • Checked that the PSL was manually blocked from entering the IFO
    • Walked through the lab, visually inspected Jam Nuts and window covers, all was deemed okay
  • Moved 2 tanks of N2 into the lab on account of the rain
  • Started the vent at ~930am PST
    • There were a couple of short bursty increases in the pressure as we figured out the right valve settings but on average, things are rising at approx the same rate as we had in vent 81...
    • There was a rattling noise coming from the drypump that is the forepump for TP2 (Agilent) - turned out to be the plastic shell/casing on the drypump, moreover, the TP2 diagnostics (temperature, current etc) are all normal.
    • The CC1 gauge (Hornet) is supposed to have an auto-shutoff of its High Voltage when the pressure exceeds 10 mTorr, but it was reporting pressures in the 1 mTorr range even when the adjacent Pirani was at 25 torr. To avoid risk of damage, we manually turned the HV off. There needs to be a python script that can be executed to transition control between the remote and local control modes for the hornet, we had to Power Cycle the gauge because it wouldn't give us local control over the HV.
    • Transitioned from N2 to dry air at P1a=25 torr. We had some trouble finding the correct regulator (left-handed thread) for the dry air cylinders, it was stored in a cabinet labelled green optics no
    • Disconnected dry air from VV1 intake once P1b reached 700 torr, to let lab air flow into the IFO and avoid overpressuring.
    • VA* and VAV* valves were opened so as to vent the annuli as we anticipate multiple chamber openings for this vent.

As of 8pm local time, the IFO seems to have equilibriated to atmospheric pressure (I don't hear the hiss of in-rushing air near 1X8 and P1a reports 760 torr). The pumpspool looks healthy and there are no signs in the TP diagnostics channels that anything bad happened to the pumps. Chub is working on getting the N2 setup more robust, we plan to take the EY door off at 9am tomorrow morning with Bob's help.

* I took this opportunity to follow instructions on pg 29 of the manual and set the calibration for the SuperBee pirani gauge to 760 torr so that it is in better agreement with our existing P1a Pirani gauge. The correction was ~8% (820-->760).

Attachment 1: Vent82Summary.png
Vent82Summary.png
  14399   Tue Jan 15 10:52:38 2019 gautamUpdateSUSEY door opened

[chub, bob, gautam]

We took the heavy door off the EY chamber at ~930am.

Chamber work:

  • ETMY suspension cage was returned to its nominal position.
  • Unused hardware from the annular heater setup was removed.
  • The unused heater had its leads snipped close to the heater crimp point, and the exposed part of the bare wires was covered with Kapton tape (we should remove the source leads as well in air to avoid any accidental shorting)

Waiting for the table to level off now. Plan for later today / tomorrow is as follows:

  1. Lock the Y arm, recover good cavity alignment.
  2. Position parabolic heater such that clipping issue is resolved.
  3. Move optic to edge of table for FC cleaning
  4. Clean optic
  5. Return suspension cage to nominal position.
  14400   Tue Jan 15 15:27:36 2019 gautamUpdateGeneralLasers and other stuff turned back on

VEA is now a laser hazard area as usual, several 1064nm lasers in the lab have been turned back on. Apart from this

  • the IFR was reset to the nominal modulation settings of +13dBm output at 11.066209 MHz (this has to be done manually following each power failure).
  • The temeprature control unit for the EY doubling oven PID control was turned back on.
  • The EY Oplev HeNe was turned back on.
  • EY green PZT HV Kepco was turned back on.
  14401   Tue Jan 15 15:49:47 2019 gautamUpdateSUSEY door opened

While restoring OSEMs on ETMY, I noticed that the open voltages for the UR and LL OSEMs had significantly (>30%) changed from their values from ~2 years ago. The fact that it only occurred in 2 coils seemed to rule out gradual wear and tear, so I looked up the trends from Nov 25 - Nov 28 (Sundance visited on Nov 26 which is when we removed the cage). Not surprisingly, these are the exact two OSEMs that show a decrease in sensor voltage when the OSEMs were pulled out. I suspect that when I placed them in their little Al foil boats, I shorted out some contacts on the rear (this is reminiscent of the problem we had on PRM in 2016). I hope the problem is with the current buffer IC in the satellite box and not the physical diode, I'll test with the tester box and evaluate the problem further.


Chamber work by Chub and gautam:

  1. Table leveling was checked with a clean spirit level
    • Leveling was substantially off in two orthogonal directions, along the beam axis as well as perpendicular to it.
    • We moved almost all the weights available on the table.
    • Managed to get the leveling correct to within 1 tick on the level.
    • We are not too worried about this for now, the final leveling will be after heater repositioning, ETMY cleaning etc.
  2. ETMY OSEM re-insertion
    • OSEMs were re-inserted till their mean voltage was ~ half the open values.
    • Local damping seems to work just fine.
Attachment 1: EY_OSEMs.png
EY_OSEMs.png
  14402   Tue Jan 15 18:16:00 2019 gautamUpdateOptical LeversETMY Oplev HeNe needs replacement

Perhaps the ETMY Oplev HeNe is also giving up - the power has fallen by ~30% over 1 year (Attachment #2), nearly twice as much as ETMX but the RIN spectrum (Attachment #1, didn't even need to rotate it!) certainly seems suspicious. Some "nominal" RIN levels for HeNes can be found earlier in this thread. I can't close any of the EY Oplev loops in this condition. I'll double check to make sure I'm routing the right beam onto the QPD, but if the problem persists, I'll replace the HeNe. ITMX HeNe also looks to be near EOL.

Quote:

Finally I reallized what is killing the ETMY oplev laser. Wrong  power supply, it  was driving the HeNe laser by 600V higher voltage than recommended. Power supply 101T-2300Vdc replaced by 101T-1700Vdc ( Uniphase model 1201-1, sn 2712420 )

The laser head 1103P, sn P947049 lived for 120 days and it was replaced by sn P964431   New laser output 2.8 mW,  quadrant sum 19,750 counts

Attachment 1: OLRIN.pdf
OLRIN.pdf
Attachment 2: OLsums.png
OLsums.png
  14403   Wed Jan 16 16:25:25 2019 gautamUpdateSUSYarm locked

[chub, gautam]

Summary:

Y arm was locked at low power in air.

Details:

  1. ITMY chamber door was removed at ~10am with Bob's help.
  2. ETMY table leveling was found to have drifted significantly (3 ticks on the spirit level, while it was more or less level yesterday, should look up the calib of the spirit level into mrad). Chub moved some weights around on the table, we will check the leveling again tomorrow.
  3. IMC was locked.
  4. TT2 and brass alignemnt tool was used to center beam on ETMY.
  5. TT1 and brass alignment tool was used to center beam on ITMY. We had to do a c1susaux reboot to be able to move ITMY. Usual precautions were taken to avoid ITMX getting stuck.
  6. ETMY was used to make return beam from the ETM overlap with the in-going beam near ITMY, using a holey IR card.
  7. At this point, I was confident we would see IR flashes so I decided to do the fine alignment in the control room.

We are operating with 1/10th the input power we normally have, so we expect the IR transmission of the Y arm to max out at 1 when well aligned. However, it is hovering around 0.05 right now, and the dominant source of instability is the angular motion of ETMY due to the Oplev loop being non-functional. I am hesitant to do in-chamber work without an extra pair of eyes/hands around, so I'll defer that for tomorrow morning when Chub gets in. With the cavity axis well defined, I plan to align the green beam to this axis, and use the two to confirm that we are well clear of the Parabola.

* Paola, our vertex laptop, and indeed, most of the laptops inside the VEA, are not ideal to work on this kind of alignmment procedure, it would be good to set up some workstations on which we can easily interact with multiple MEDM screens,

Attachment 1: Yarm_locked.png
Yarm_locked.png
  14404   Fri Jan 18 12:52:07 2019 gautamUpdateOptical LeversBS/PRM Oplev HeNe replaced

I replaced the BS/PRM Oplev HeNe with one of the heads from the SP table where Steve was setting up the OL RIN/pointing noise experiment. The old one was dead. The new one outputs 3.2 mW of power, I've labelled it with this number, serial number and date of replacement. The beam comes out of the vacuum chamber for both the BS and PRM, and the RIN spectra (Attachment #1) look alright. The calibration into urad and loop gains possibly have to be tweaked. Since the beam comes out of vacuum, I say that we shouldn't open the BS/PRM chamber for this vent - we don't have a proper plan for the in-air layout yet, so we can add this to the list of to-dos for the next vent.

I think we are down to our last spare HeNe head in the lab - @Chub, please look into ordering some more, the ITMX HeNe is going to need replacement soon.

Attachment 1: OLRIN_20190118.pdf
OLRIN_20190118.pdf
  14405   Fri Jan 18 15:34:37 2019 gautamUpdateThermal CompensationElliptical reflector part number

Nobody documented this, but here is the part number with mechanical drawings of the elliptical reflector installed at EY: Optiforms E180. Heater is from Induceramics, but I can't find the exact part which matches the dimensions of the heater we have (diameter = 3.8mm, length = 30mm), perhaps it's a custom part?

The geometry dictates that if we want the heater to be at one focus and the ETM to be at the other, the separation has to be 7.1 inches. It certainly wasn't arranged this way before. It seems unrealistic to do this without clipping the main beam, I propose we leave sufficient clearane between the main beam and the reflector, and accept the reduced heating efficiency. 

Thanks to Steve for digging this up from his secret stash.

  14406   Fri Jan 18 17:44:14 2019 gautamUpdateVACPumping on RGA volume

Steve came by the lab today, and looked at the status of the upgraded vacuum system. He recommended pumping on the RGA volume, since it has not been pumped on for ~3 months on account of the vacuum upgrade. The procedure (so we may script this operation in the future) was:

  1. Start with the pumpspool completely isolated from the main IFO volume.
  2. Open V5, pump down the section between V5 and VM3. Keep an eye on PTP3.
  3. Open VM3, keep an eye on P4. It was reporting ~10 mtorr, went to "LO".
  4. Close VM3 and V5, transition pumping of the RGA volume to TP1 which is backed by TP2 (we had to open V4 as all valves were closed due to an N2 pressure drop event).
  5. Open VM2.
  6. Watch CC4.

CC4 pressure has been steadily falling. Steve recommends leaving things in this state over the weekend. He recommends also turning the RGA unit on so that the temperature rises and there is a bakeout of the RGA. The temperature may be read off manually using a probe attached to it.

Attachment 1: CC4.png
CC4.png
  14407   Fri Jan 18 21:34:18 2019 gautamUpdateSUSUnused optic on EY table

Does anyone know what the purpose of the indicated optic in Attachment #1 is? Can we remove it? It will allow a little more space around the elliptical reflector...

Attachment 1: IMG_5408.JPG
IMG_5408.JPG
  14409   Sat Jan 19 15:33:18 2019 gautamUpdateSUSETMY OSEMs faulty

After diagnosis with the tester box, as I suspected, the fully open DC voltages on the two problematic channels, LL and UR, were restored once I replaced the LM6321 ICs in those two channel paths. However, I've been puzzled by the inability to turn on the Oplev loops on ETMY. Furthermore, the DC bias voltages required to get ETMY to line up with the cavity axis seemed excessively large, particularly since we seemed to have improved the table levelling.

I suspected that the problem with the OSEMs hasn't been fully resolved, so on Thursday night, I turned off the ETMY watchdog, kicked the optic, and let it ringdown. Then I looked at the time-series (Attachment #1) and spectra (Attachment #2) of the ringdowns. Clearly, the LL channel seems to saturate at the lower end at ~440 counts. Moreover, in the time domain, it looks like the other channels see the ringdown cleanly, but I don't see the various suspension eigenmodes in any of the sensor signals. I confirmed that all the magnets are still attached to the optic, and that the EQ stops are well clear of the optic, so I'm inclined to think that this behavior is due to an electrical fault rather than a mechanical one.

For now, I'll start by repeating the ringdown with a switched out Satellite Box (SRM) and see if that fixes the problem. 

Quote:

While restoring OSEMs on ETMY, I noticed that the open voltages for the UR and LL OSEMs had significantly (>30%) changed from their values from ~2 years ago. The fact that it only occurred in 2 coils seemed to rule out gradual wear and tear, so I looked up the trends from Nov 25 - Nov 28 (Sundance visited on Nov 26 which is when we removed the cage). Not surprisingly, these are the exact two OSEMs that show a decrease in sensor voltage when the OSEMs were pulled out. I suspect that when I placed them in their little Al foil boats, I shorted out some contacts on the rear (this is reminiscent of the problem we had on PRM in 2016). I hope the problem is with the current buffer IC in the satellite box and not the physical diode, I'll test with the tester box and evaluate the problem further.

Attachment 1: Screen_Shot_2019-01-19_at_3.32.35_PM.png
Screen_Shot_2019-01-19_at_3.32.35_PM.png
Attachment 2: ETMY_sensors_1231832635.pdf
ETMY_sensors_1231832635.pdf
  14411   Tue Jan 22 20:36:53 2019 gautamUpdateSUSETMY OSEMs faulty

Short update on latest Satellite box woes.

  1. I checked the resistance of all 5 OSEM coils on ETMY using a DB25 breakout board and a multimeter - all were between 16-17 ohms (mesured from the cable to the Vacuum flange), which I think is consistent with the expected value.
  2. Checked the bias voltage (aka slow path) from the coil driver board was reaching the coils
    • The voltages were indeed being sent out of the coil driver board - I confirmed by driving a slow sine wave and measuring at the output of the coil driver board, with all the fast outputs disabled.
    • The voltage is arriving at the 64 pin IDC connector at the Satellite box - Chub and I verified this using some mini-grabbers and leads from wirewound resistors (we don't have a breakout board for this kind of connector, would be handy to get some!)
    • However, the voltages are not being sent out through the DB25 connectors on the side of the Satellite box, at least for the LL and UR channels. UL seems to work okay.
    • This behavior is consistent with the observation that we had to apply way larger bias voltages to get the cavity axis to line up than was the nominal values - if one or more coils weren't getting their signals, it would also explain the large PIT->YAW coupling I observed using the Oplev spot and the slow bias alignment EPICS sliders.
    • This behavior is puzzling - the Sat box is just supposed to be a feed-through for the coil driver signals, and we measured resistances between the 64 pin IDC connector and the corresponding DB25 pins, and measured in the range of 0.2-0.3 ohms. However, the voltage fails to make it through - not sure what's going on here.. We will investigate further on the electronics bench.

What's more - I did some Sat box switcheroo, swapping the SRM and ETM boxes back and forth in combination with the tester box. In the process, I seem to have broken the SRM sat box - all the shadow sensors are reporting close to 0 volts, and this was confirmed to be an electronic problem as opposed to some magnet skullduggery using the tester box. Once we get to the bottom of the ETMY sat box, we will look at SRM. This is more or less the last thing to look at for this vent - once we are happy the cavity axis can be recovered reliably, we can freeze the position of the elliptical reflector and begin the F.C.ing.

  14412   Tue Jan 22 20:45:21 2019 gautamUpdateVACNew N2 setup

The N2 ran out this weekend (again no reminder email, but I haven't found the time to setup the Python mailer yet). So all the valves Steve and I had opened, closed (rightly so, that's what the interlocks are supposed to do). Chub will post an elog about the new N2 valve setup in the Drill-press room, but we now have sufficient line pressure in the N2 line again. So Chub and I re-opened the valves to keep pumping on the RGA.

  14413   Wed Jan 23 12:39:18 2019 gautamUpdateSUSEY chamber work

While Chub is making new cables for the EY satellite box...

  1. I removed the unused optic on the NW corner of the EY table. It is stored in a clean Al-foil lined plastic box, and will be moved to the clean hardware section of the lab (along the South arm, south of MC2 chamber).
  2. Checked table leveling - Attachment #1, looked good, and has been stable over the weekend.
  3. I moved the two oversized washers on the reflector, which I believe are only used because the screw is long and wouldn't go in all the way otherwise. As shown in Attachment #2, this reduces the risk of clipping the main IFO beam axis.
  4. Yesterday, I pulled up the 40m CAD drawing, and played around with a rectangular box that approximates the extents of the elliptical reflector, to see what would be a good place to put it. I chose to go ahead with Attachment #3. Also shown is the eventually realized layout. Note that we'd actually like the dimension marked ~7.6 inches to be more like 7.1 inches, so the optic is actually ~0.5 inch ahead of the second focus of the ellipse, but I think this is good enough. 
  5. Attachment #4 shows the view of the optic as seen from the aperture on the back of the elliptical reflector. Looks good to me.
  6. Having positioned the reflector, I then inserted the heater into the aperture such that it is ~2/3rds the way in, which was the best position found by Annalisa last summer. I then ran 0.9 A of current through the heater for ~ 5 minutes. Attachment #5 shows the optic as seen with the FLIR with no heating, and after 5 minutes of heating. I'd say this is pretty unambiguous evidence that we are indeed heating the mirror. The gradient shown is significantly less pronounced than in Annalisa's simulations (~3K as opposed to 10K), but maybe the FLIR calibration isn't so great.
  7. For completeness, Attachment #6 shows the leveling of the table after this work. Nothing has chanegd significantly.

While the position of the reflector could possibly be optimized further, since we are already seeing a temperature gradient on the optic, I propose pushing on with other vent activities. I'm almost certain the current positioning places the optic closer to the second focus, and we already saw shifts of the HOM resonances with the old configuration, so I'd say we run with this and revisit if needed.

If Chub gives the Sat. Box the green flag, we will work on F.C.ing the mirrors in the evening, with the aim of closing up tomorrow/Friday. 

All raw images in this elog have been uploaded to the 40m google photos.

Attachment 1: leveling.pdf
leveling.pdf
Attachment 2: IMG_5930.jpg
IMG_5930.jpg
Attachment 3: Ellipse_layout.pdf
Ellipse_layout.pdf
Attachment 4: IMG_5932.jpg
IMG_5932.jpg
Attachment 5: hotMirror.pdf
hotMirror.pdf
Attachment 6: EY_leveling_after.pdf
EY_leveling_after.pdf
  14414   Wed Jan 23 18:11:56 2019 gautamUpdateElectronicsEthernet Power Strip IP conflict

For the last week, I noticed that I was unable to turn the EY chamber illuminator on using the remote python scripts. This was turning out to be really annoying, having to turn the light on/off manually. Today, I looked into the problem and found that there is a conflict in the IP addresses of the EY Ethernet Strip (which Chas assigned a static IP but did not include detailed procedures forno) and the vertex area laptop, paola. The failure of the python control of the power strip coincided exactly with when Chub and I turned on paola for working at the IY chamber - but how was I supposed to know these events are correlated? I tried shutting down paola , power cycling the Ethernet power strip, and restarting the bind9 services on chiara, but remote control of the ethernet power strip remains elusive. I suspect reconfiguring the static IP for the Ethernet switch will require some serial port enabled device...

  14415   Wed Jan 23 23:12:44 2019 gautamUpdateSUSPrep for FC cleaning

In preparation for the FC cleaning, I did the following:

  1. Set up mini-cleanroom at EY - this consists of the mobile HEPA unit put up against the chamber door, with films draped around the setup.
  2. After double-checking the table leveling, I EQ-stopped ETMY and moved it to the NE corner of the EY table, where it will be cleaned.
  3. Checked leveling of IY table - see Attachment #1.
  4. Took pictures of IY table, OSEM arrangement on ITMY.
  5. EQ-stopped ITMY and SRM.
  6. Removed the face OSEMs from ITMY (this required clipping off the copper wire used to hold the OSEM wires against the suspension cage). The side OSEM has not yet been removed because I left the allen key that is compatible with that particular screw inside the EY chamber. 
  7. To position ITMY at the edge of the IY table where we can easily clean it, we will need to move the OSEM cabling tower as we did last time. I've taken photos of its current position for now.

Tomorrow, I will start with the cleaning of ETMY HR. While the FC is drying, I will position ITMY at the edge of the IY cable for cleaning (Chub will setup the mini-cleanroom at the IY table). The plan is to clean both HR surfaces and have the optics back in place by tomorrow evening. By my count, we have done everything listed in the IY and EY chambers. I'd like to minimize the time between cleaning and pumpdown, so if all goes well (Sat Box problems notwithstanding), we will check the table leveling on Friday morning, and put on the heavy doors and at least rough the main volume down to 1 torr on Friday.

Attachment 1: IY_level_before.pdf
IY_level_before.pdf
  14416   Thu Jan 24 15:32:31 2019 gautamUpdateSUSY arm cavity side first contact applied

EY:

  • A clean cart was setup adjacent to the HEPA-enclosed mini cleanroom area (it cannot be inside the mini cleanroom, because of lack of space). 
  • The FC tools (first contact, acetone, beakers, brushes, PEEK mesh, clean scissors, clean tweezers, Canon camera, green flashlight) were laid out on this cart for easy access.
  • I inspected the optic - the barrel had a few specks of dust, and the outer 1.5" annular region of the HR face looked to have some streak marks
    • I was advised not to pre-wipe the HR side with any solvents
    • The FC was only applied to the centran ~1-1.5" of the optic
  • After applying the FC, I spent a few minutes inspecting the status of the OSEMs 
    • Three out of the four face OSEMs, as well as the side OSEM, did not have a filter in
    • I inserted filters into them.
  • Closed up the chamber with light door, left HEPA unit on and the mini cleanroom setup intact for now. We will dismantle everything after the pumpdown.

IY:

  • Similar setup to EY was implemented
  • Removed side OSEM from ITMY.
  • Double-checked that EQ stops were engaged.
  • Moved the OSEM cable tower to free up some space for accommodating ITMY.
  • Undid the clamps of ITMY, moved it to the NE corner of the IY table.
  • Inspected the optic - it was much cleaner than the 2016 inspection, although the barrel did have some specks of dust.
  • Once again, I applied first contact to the central ~1.5" of the HR surface.
  • Checked status of filters on OSEMs - this time, only the UL coil required a filter.
    • Attachment #3 shows the sensor voltage DC level before and after the insertion of the filter. There is ~0.1% change.
    • The filters were found in a box that suggests they were made in 2002 - but Steve tells me that it is just stored in a box with that label, and that since there are >100 filters inside that box, he thinks they are the new ones we procured in 2016. The coating specs and type of glass used are different between the two versions.

The attached photo shows the two optics with FC applied.

My original plan was to attempt to close up tomorrow. However, we are still struggling with Satellite box issues. So rather than rush it, we will attempt to recover the Y arm cavity alignment on Monday, satellite box permitting. The main motivation is to reduce the deadtime between peeling off the F.C and starting the pumpdown. We will start working on recovering the cavity alignment once the Sat box issues are solved.

Attachment 1: Yarm_FC.pdf
Yarm_FC.pdf
Attachment 2: OSEMfilter.png
OSEMfilter.png
  14417   Thu Jan 24 22:55:50 2019 gautamUpdateElectronicsSatellite box S/N 102 investigation

I had taken Satellite box S/N 102, from the SRM suspension, down to the Y-end as part of debugging. However, at some point, I stopped getting readbacks from the shadow sensor PDs, even with the Sat. Box tester hooked up (so as to rule out anything funky with the actual OSEMs). Today evening, I did a more systematic investigation. Schematic with component references is here.

  1. Used mini-grabbers and a bench power supply to connect +/-24V to C57 and C58.
  2. Checked that all ICs were getting +/- 15 V to the supply pins.
  3. Debugged individual channels, checking voltages at various nodes
    • Found that the "PD K" bias voltage was anomalosly low.
    • Found that the inverting input of U3C wasn't ground.
    • The above findings are summarized in Attachment #2.
    • This suggested something was wrong with the Quad OpAmp LT1125 IC, so I elected to switch it out.
    • During the desoldering process, the pads for the "NC" pins came off (Attachment #1) - this has happened to me before on these old boards. I don't think I applied excess heat during the desoldering (I used 650F).
    • Replaced the IC, and measured the expected 10V at the "PD K" node.
  4. I then connected the tester box and verified all the shadow sensor channels (LED + PD) work as expected, using the front panel J3 and the "octopus cable".
  5. It remains to verify that the coil driver signals get correctly routed through the Satellite box before giving this box a pass certification.

The question remains as to what caused this failure mode - I can't think of why that particular IC was damaged during the Satellite box swapping process - is this indicative of some problem elsewhere in the ETMY OSEM/coil driver electronics chain?

Attachment 1: IMG_7294.JPG
IMG_7294.JPG
Attachment 2: D961289-B2.pdf
D961289-B2.pdf
  14418   Fri Jan 25 12:49:53 2019 gautamUpdateElectronicsEthernet Power Strip IP conflict resolved

To avoid the annoying excercise of having to manually toggle the illuminators, I solved the IP conflict. Made a wiki page for the ethernet power strips since the documentation was woeful (the way the power strips are mounted in the racks, you can't even see the manufacturer/model/make). All chamber illuminators can now be turned on/off by the MEDM scripts yes. Note that there is a web interface available too, which can be useful in case of some python socket issues. The main lesson is: avoid using the "reset" button on the power strips, it destroys the static IP config.


Unrelated to this work: The EY laptop, asia, won't boot up anymore, with a "Fan Error" message being the red flag. I've temporarily recommissioned the vacuum rack laptop, belladonna, to be the EY machine for this vent. Can we get 3 netbooks that actually work and don't need to be tethered to a power strip for the VEA?

  14419   Fri Jan 25 16:14:51 2019 gautamUpdateVACVacuum interlock code, N2 warning

I reset the remote of this git repo to the 40m version instead of Jon's personal one, to ensure consistency between what's on the vacuum machine and in the git repo. There is now a N2 checker python mailer that will email the 40m list if all the tank pressures are below 600 PSI (>12 hours left for someone to react before the main N2 line pressure drops and the interlocks kick in). For now, the script just runs as a cron job every 3 hours, but perhaps we should integrate it with the interlock process?

Quote:

All the python code running on c1vac is archived to the git repo: 

https://git.ligo.org/40m/vacpython

  14421   Tue Jan 29 17:19:16 2019 gautamUpdateElectronicsSatellite box S/N 105 repaired

[chub, koji, gautam]

Attachment #1 shows the signal routing near the Satellite box. Somehow, the female 64 pin IDC connector that brings the signals from the coil driver board wasn't mating well with the mail connector on the Satellite box front panel. This is a connector specific problem - plugging the female end into one of the male connectors inside the Satellite box yielded signal continuity. The problem was resolved by re-making both connections -by driving the EPICS bias slider through its full range, we were able to see the full voltage swing at the DB connectors going to the flange

This kind of flakiness could be all around the lab, and could be responsible for many of the suspension "mysteries". To re-iterate, the problem seems to be the way the female sockets of the connector mates with the male pins - while the actual crimping points may look secure, there may not be signal continuity.

Now that this problem is resolved, tomorrow we will recover the cavity alignment and possibly start a pumpdown.


Unrelated to this work - the spare satellite box (S/N #100), which had a note on it that said "low voltages", was tested. The "low voltages" referred to the OSEM shadow sensor voltages being low when the LED was completely unobscured. The reason was that the mod to increase the drive current to 25 mA had not yet been implemented on this unit. I added the appropriate 806 ohm resistors, and verified that the voltages were correct, so now we have a working spare. It is stored in the "photodiode" cabinet along the east arm, together with the tester boxes. 

Attachment 1: IMG_7301.JPG
IMG_7301.JPG
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