40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
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ID Date Author Typeup Category Subject
  9022   Sun Aug 18 17:56:16 2013 ranaSummaryCDSMEDM Screen CPU Usages

I noticed at LLO (?) that the LSC screen there uses up ~25-30% of the CPU time on a single core for the control room iMac workstations - this seems excessive.

Here is an accounting of CPU usage percentages for some of our screens:


Screen Name CPU (%)

These were measured using the program 'glances' on rosalba. MEDM running with only the sitemap used up 0.9% of a CPU. With the screens running, the fluctuation from sample to sample could be ~ +/- 0.5%. While the LSC screen seems to be the biggest pig, it is only big in comparison to small pigs. Certainly this pig has gotten bigger after getting sent to Louisiana.

Attachment 1: obama1404_666531c.jpg
  9042   Tue Aug 20 16:23:41 2013 ranaSummaryGeneral/home/cds nearly full

/home/cds is >98% full - below are some of the usage numbers:

controls@rosalba:/users/OLD 0$ du -h --max-depth=1
42M    ./katrin
1.5M    ./ben
2.4M    ./sanjit
569M    ./waldman
328M    ./sonia
3.6G    ./lsinger
44M    ./dbusby
105M    ./dbarron
21M    ./manuel
709M    ./yaakov
46M    ./rodionov
240M    ./ishwita
2.7G    ./clara
56M    ./gopal
290M    ./mashaB
87M    ./varvella
5.6M    ./Sascha
2.9G    ./ryan
190M    ./nancy
3.5G    ./john
269M    ./elizabeth.davison
165M    ./jweiner
460K    ./mjones
49M    ./stephanie
52M    ./mohana
56M    ./noriyasu
38M    ./mjenson
76M    ./sballmer
224M    ./kirk
812K    ./bonnie
33M    ./janosch
16M    ./kevin
122M    ./dblair
2.6G    ./mirko
389M    ./keenan
195M    ./tf
150M    ./littlezach
193M    ./jmiller
1.8G    ./ting
131M    ./dmalling
842M    ./sharmila
1.4G    ./caryn
12G    ./rward
4.1M    ./jay
443M    ./emintun
184M    ./katharine
76K    ./nick
804K    ./nicole.ing
14M    ./jenny
542M    ./vsanni
45M    ./peter
7.8G    ./miyakawa
4.8M    ./channa
4.0K    ./frank
9.9G    ./razib
35M    ./amin
361M    ./sharon
62M    ./bram
3.9M    ./volodya
7.9M    ./larisa
301M    ./sasha
33M    ./eric.hendries
18M    ./vuk
101M    ./huan
1.8M    ./sonali
453M    ./megan
43M    ./Royal
5.4G    ./ayaka
19M    ./mott
518M    ./justing
501M    ./avi
173M    ./kakeru
3.9G    ./alberto
41M    ./paul.fulda
59M    ./elena
67G    .

controls@rosalba:/opt/rtcds/userapps 0$ du -h --max-depth=1
1.4G    ./tags
13M    ./trunk.bak
40K    ./.svn
3.0G    ./trunk
174M    ./trunk.bak2
4.2G    ./branches
8.7G    .

linux1:cds>nice du -h --max-depth=1
du: `./llo/chans/daq/archive': Permission denied
du: `./llo/chans/daq/old': Permission denied
707M    ./llo
9.7M    ./mit~
752K    ./raidwebFirmware
462M    ./epics
2.1G    ./tmp
1.5G    ./gds
76M    ./project
9.1G    ./ligo
449G    ./rtcds
3.3G    ./apps
20K    ./.kde
512K    ./cdscfg
1.4M    ./.Trash-controls
5.8M    ./scripts
20K    ./.TemporaryItems
964G    ./caltech
71M    ./bin
16K    ./.Trash-1001
4.5G    ./rtapps
564M    ./src
11M    ./vw
3.8M    ./dvSave
460M    ./lho
1.2G    ./data
1.5T    .

  9044   Wed Aug 21 00:18:03 2013 MasayukiSummaryGreen LockingX-arm PDH OLTF measurement

[Manasa Masayuki]
Today we measured the openloop transfer function of the PDH green lock of the x-arm.

Edit //manasa// The excitation was given from SR785 source. SR560 was used as the summing node at the PDH servo box output where the loop was broken to measure the OLTF. The SR785 was used to measure the frequency response (CH2/CH1; CH1 A SR560 output and CH2 A PDH servo output) in sweptsine mode.

We measured with two different servo gain. We started with the servo gain of 3 and at that gain the UGF was 1.5 kHz and the phase margin was 50 degree. After that we increase the servo gain to 5.5 and at that gain the UGF was 6.2 kHz and the phase margin was 55 degree. In all the measurement we use the source amplitude of 1.0 mV for all frequencies (from 100 Hz to 100 kHz). We could not increase the gain and also the source amplitude any more because the green was kicked out of lock.

Next work list
1. In the earlier measurements we found the UGF of the PDH green lock of the x-arm as 10 kHz and the phase margin as 45 degree, so we will investigate what has changed from these measurements.elog 4490

2. We will measure the power spectrum of the error signal and the feedback signal.

3. We will calibrate the above signals to compare with ALS out of loop noise.

netgpib was taking forever to transfer data. So the measurements are just photos of the display.

attachment1 - servo gain 3


attachment2 - servo gain 5.5


  9045   Wed Aug 21 17:42:03 2013 ranaSummaryGeneral/home/cds nearly full

One of the reasons that our disk is getting full is due to the scripts_archive directory. A backup script runs on op340m and makes a tar.bz2 file of the scripts directory and puts it in scripts_archive every morning at 6 AM.

On Oct 7, 2011, Koji fixed this script to point at our new scripts directory instead of the old /cvs/cds/caltech/scripts directory. Since then, however, no one has fixed the exclude file to NOT back up the junk that's in that directory. Its a 1.6 GB directory so its full of it.

I've deleted a bunch of junk from the scripts directory: this directory is for scripts, not for your personal home movies or junk data files. Put those in your USER directory. Put temporary data files in /tmp/. I've also added a few more patterns to the exclude file so that less .mpg, .png, .pdf, .dat, etc get stored every day. The new daily .tar.bz2 file wil be ~25 MB instead of 770 MB.

(also fixed the backup script to use 'env' to setup the perl environment and removed the hard-coded path to tar)

  9047   Wed Aug 21 19:37:25 2013 MasayukiSummaryGreen LockingX-arm PDH OLTF measurement

[Manasa, Masyauki]

Today we measured OLTF of PDH green lock of x-arm again. In the previous measurement the excitation signal was injected at the PDH servo box output(elog 9044), but in this measurement we changed the injection point to the RFPD mixer output (just before the servo input).

We measured the OLTF with the servo gain of 6.5 and source amplitude of 5 mV for all frequency band. The measured UGF was 11 kHz and the phase margin was 48 degree.

Next that measurement, we tried to measure the power spectrum density of the error signal and feedback signal. But the alignment was not so good, so we aligned the green light injection point. Tomorrow we will continue the alignment and will measure the PSD.

attatchment1 - OLTF of PDH green lock with servo gain of 6.5


  9054   Thu Aug 22 20:25:28 2013 MasayukiSummaryGreen LockingY-arm PDH OLTF measurement

[Manasa, Masayuki]
We measured the the openloop transfer function of the PDH green lock of the y-arm.The measurement setup was same as yesterday's measurement.elog 9047

In this measurement, the servo gain was 7 and the source amplitude for the excitation was 1 mV. As you can see in below figure, the measured UGF was 15 kHz and the phase margin was 45 degree.

attatchment1 - OLTF with servo gain of 7


  9089   Fri Aug 30 01:01:28 2013 rana, nicSummaryComputer Scripts / ProgramsaLIGO Noise Budget code installed and running

Chris Wipf has been developing a new Noise Budget code that allows us to use our existing Simulink models to handle all of the noise transfer functions. This is mainly by being clever about avoiding the numerical pitfalls that we encounter when doing linearization of Simulink models (e.g. linmod or linmod2).


In this model, the optical plant is done with analytic TFs using the formulae from the Sigg Frequency Response doc. The big Orange block has just the DAC and some simple pendulum TFs. The upper section contains the simulated digital system: input matrix, digital filter TFs, and output matrix. The digital filters are just based on my memory of iLIGO. The CARM path is made to be fast to approximate the high gain of the Common Mode servo. Without this high gain the PRC optical plant is unstable due to the right half plane zeros. This simple model is used just so that we could see the NB work on a multi-loop system. For the next steps of getting it to work for the 40m, we will use the Optickle TFs instead of analytic functions and also load the digital filters directly from the FOTON files. For the LLO DRMI, we'll add some simplified version of the SUS Simulink models for triples and quads.


Yesterday, Nic and I took my old iLIGO IFOmodel.mdl Simulink model and added the new NB hooks that allowed us to use the new code. The screenshot below is from a run of this code:

1) Figure 1 shows the DARM Noise budget. So far we have included shot noise in DARM, CARM, MICH, & PRC. Radiation pressure noise on the ITMs and ETMs. Coating thermal noise on all mirrors.

2) Figure 2 shows the breakdown of how each of the shot noises at each port couple to the DARM readout. The RED trace is the AS port DC readout shot noise. The GREEN trace is the MICH shot noise feeding through the MICH loop and being mostly cancelled by the scalar MICHdamp feedforward path.

3) Figure 3 shows that we've set the coating thermal noise to be equal on all 4 TMs.

4) Figure 78754 is a set of Bode plots of the open loop gains of the 4 LSC loops (inferred from the closed loop TF). Also plotted is the residual MICH2DARM TF (with the MICHdamp cancellation path ON).

5) Figure 9911123 are the step responses of the LSC loops: step inserted at the error point and response measured just after the excitation point.

The editor window on the left shows how simple the NB code is to use once the Simulink model has had all the hooks added to it.

Attachment 1: NBplots.png
  9123   Wed Sep 11 23:34:37 2013 MasayukiSummaryGreen LockingALS locking in both arms

[manasa, masayuki]

We locked the XARM and YARM with using ALS control loop and we succeeded to lock stably both arms. The performance of the ALS was tested with a measurement of the calibrated error signal. (attachment 1)

- red and blue : the in-loop noise of ALS of each arm.

- green and purple:Stability of the beat-note frequency with the MC and the arm freely running.


In the high frequency region, YARM has larger noise than XARM, and these noises were not there in previous measurements by Koji and Manasa (elog8865). You can see that in both of in-loop noise and free running noise. These noises may be caused by the Green PDH servo or hte phase tracker servo or any other electrical staff. We will start noise budget of these servo.

At higher frequency than UGF of ASL control loop, the loop does not suppress the noises at all, but the inloop and free running noise are not equivalent. I have no idea about that so far.




Attachment 1: noise.pdf
  9124   Wed Sep 11 23:43:10 2013 KojiSummaryGreen LockingALS locking in both arms

What was the beat freq for each arm?
The HF noise level depends on the frequency of the beat note.
As the BBPD has the freq dependent noise level. (See this entry)

  9125   Thu Sep 12 00:07:26 2013 MasayukiSummaryGreen LockingALS locking in both arms


What was the beat freq for each arm?
The HF noise level depends on the frequency of the beat note.
As the BBPD has the freq dependent noise level. (See this entry)

 I'm not sure about the actual number of the beat frequency, but the beat frequency was almost same in both arms. And I took this measurement sometimes with slightly different beat frequency but the noise level didn't change so much.

  9147   Fri Sep 20 20:14:52 2013 ranaSummaryGeneral/home/cds nearly full


One of the reasons that our disk is getting full is due to the scripts_archive directory. A backup script runs on op340m and makes a tar.bz2 file of the scripts directory and puts it in scripts_archive every morning at 6 AM.

On Oct 7, 2011, Koji fixed this script to point at our new scripts directory instead of the old /cvs/cds/caltech/scripts directory. Since then, however, no one has fixed the exclude file to NOT back up the junk that's in that directory. Its a 1.6 GB directory so its full of it.

I've deleted a bunch of junk from the scripts directory: this directory is for scripts, not for your personal home movies or junk data files. Put those in your USER directory. Put temporary data files in /tmp/. I've also added a few more patterns to the exclude file so that less .mpg, .png, .pdf, .dat, etc get stored every day. The new daily .tar.bz2 file wil be ~25 MB instead of 770 MB.

(also fixed the backup script to use 'env' to setup the perl environment and removed the hard-coded path to tar)

 OUr disk was getting full again. Turned out my "fix" to 25 MB was only a fix to 250 MB. Since we were getting disk full warnings on our Ubuntu workstations, I deleted some COMSOL.dmg files from users/zach/ and then started deleting every other tarball from the scripts_archive directory. ~221 GB are now free. Still need to fix the exclude file for scripts better.

  9156   Tue Sep 24 20:43:45 2013 masayukiSummarySUSoptical levers centering

I centered optical levers of ITMX,BS,ETMY. I also change the position of optical levers of ITMX, ETMY, ITMY, BS on Friday night(9/21), of ITMX, ETMY, BS on Monday night. Both are around 6:00 ~ 7:00.But centering on Monday was totally wrong, because I centered with not good IFO alignment.

The attachment is the 5 days trend of the opt lev of ITMX. First gap is alignment on Friday and Second gap is the alignment on Monday. Now I centered after  locking the FPMI.

The attachment 2 is the last 6 hours data.  The gap on 9/25 00:00 and 1:30(UTC)  is because the alignment of the cavity and the last gap is because of  centering of the optical lever.

Attachment 1: Screenshot-Untitled_Window.png
Attachment 2: Screenshot-Untitled_Window-1.png
  9158   Wed Sep 25 08:11:01 2013 MasayukiSummaryLSCLSC calibration screen


  The real time calibration system is not correct in high frequency.

The attachment are the plot of two free running noise. Blue curve is the plot of noise calibrated with OLTF. Green one is the just fft analysed signal of the real time calibration system output. You can see the ripple in high frequency region in green curve. That is because the anti-aliasing filter and digital anti-aliasing filter. I assume the sensitivity of MI as constant but Rana mentioned that we should take these filters into account.

modeled OLTF and sensitivity H
 I put the AA filter and DAA filter effects into matlab calibration script. The attachment 2 is the modeled sensitivity of the MICH. You can find each filter properties in  elog#8555 (analog AA filter) and in elog#3961. I estimate the H gain by measuring the fringe. The attachment 3 is the plot of fringe and I averaged with green points. The actual number is 3.48e7 count/m

attachment 2: the sensitivitiy of MICH


 attachment 3: fringe of the MICH


I modeled OLTF with this H and the fitted into the measurement data. That is in attachment 4. In this OLTF I also included the DAI filter and AI filter, and ' sample and hold circuit' of DAC TF . These are  mentioned in two references. Additionally I added the time delay 309.6 us.  Yuta mentioned that in C1SUS has 125us time delay. In MICH control we have also C1LSC , so I think this time delay is reasonable. I compensated the error signal with these OLTF and MICH sensitivity.

attachment 4: OLTF of the MICH control


You can see that the ripple is gone in blue curve and after 5 kHz the curve is flat.

Next step

I'm trying to put the inverted AA filter and DAA filter in C1CAL_INCV servo. But the ploblem is the difference of sampling frequency, so I couldn't fix yet. One possibility is putting approximated filter. I hope I will find some good way to design these filters.



Other thing

I esitimated the FPMI noise propagated from the residual noise of IR PDH control of both ARMS. I will summarize and write these staff in this afternoon.

Attachment 1: plot.pdf
  9161   Wed Sep 25 23:15:11 2013 MasayukiSummaryGreen LockingFPMI noise caused by ARM locking
I measured some error signal, OLTFs and responses for FPMI noise estimation. Especially we are interested in the noise from in-loop noise of ALS Green PDH control. The strategy and
1) Purpose
 Estimation of the FPMI phase shift noise caused by in-loop noise of Green PDH control. 
2) What we should figure out
 For that estimation we have to figure out the transfer function from the cavity length change to the phase shift which is measured by MICH.
3) Strategy
 I attached the block diagram of  our interferometer. Our goal is to find the transfer function H_L-l and to calibrate the out of loop noise of interferometer with that TF and error signal of the PDH control.
 H,A and F mean the sensitivity, actuator response and servo filter for each control loop. L_xarm is the disturbance of the cavity length and l- is the differencial motion of the interferometer
We can get this H_L-l from measurement of the response from calibrated ETM actuation to the MICH error signal. You can get the formula for calculating H_L-l with simple calculation and that is
             1 + G_mich       1 + G_xarm      V_mi  
H_L-l = ---------------  -----------------  ------------
              H_mich             A_etmx         V_excetm
where the each G is OLTF and V_mi/Vexcetm is the response from the ETM actuation to the MICH error signal.
And then  the FPMI noise in the unit of meter / rHz is
N_fpmi = l_dis + ------------ Vx
This second term is what we are interested in.
To estimate these noises
i) We can calibrate the actuators of  ITMX, ITMY and BS with using the MICH as sensor. So we can calibrate the arm error signals by  excitation of arm length using ITMs actuator.
ii) If we know the TFs of arms, we can calibrate the ETMX and ETMY actuators.
iii) We should know the response from ETMX or ETMY actuating to error signal of mich.
iv) Also we should calibrate the error signal of MICH in FPMI locking(H_mich). We can do that by exciting the BS.

Then we can estimate the noises.

In next entry, I will write about measurement.


  9162   Wed Sep 25 23:59:29 2013 MasayukiSummaryGreen LockingFPMI noise caused by ARM locking


Measurement with ARMs

i) By locking the MICH with AS55Q signal I measured the actuator response of ITMX ITMY BS for calibration of each actuator. This measurement was done at the same time with elog#9158. The actuator response was
BS : 2.2347e-8 / f^2 [m/count]

ITMX: 5.0843e-9 /f^2 [m/count]

ITMY: 4.9677e-9 / f^2 [m/count]

ii)By locking the Arms for IR with POX,POY. I measured the OLTF and the response from ITM actuation to POX and POY signal. Attachment 1,2 are the plots of fitted OLTF , the measured OLTF, and residual function (model - measure)/model and the attachment 3,4 are the response of each arm. I fitted the three parameters. Those are the gain, time-delay and cavitypole. Each fitted parameter is
timedelay:-282.09 usec, cavity pole : 2872.0 Hz
timedelay:-283.84 usec, cavity pole : 2939.9 Hz
The cavity pole seems higher than privious measurement (In 2009). Actually the residual function are increase at the higher frequency region than 1kHz, so I guess the fitting is not so good.One possibility is that in the region where cavity pole effect increase we has not much data.
With fitted OLTF and actuator response I calibrated the H_xarm and H_yarm.
Hxarm : 2.9796 e11 [count / m]
Hyarm : 6.1394 e11 [count / m]
iii) After that I measured the response from ETM actuation to POX and POY signal to calibrate the ETM actuator. The response of each actuator is
ETMX:1.2040e-8 / f^2 [m/count]

ETMY:1.4262e-8 / f^2 [m/count]
iv) I calibrated the error signal with OLTF and Hxarm,Hyarm. The result is in Attachment 5

 In high frequency region there is the difference between xarm and yarm. These difference are already there in error signal. I'm not sure where these noise comes from. We will make measurement with Green PDH from tomorrow, so  we can also check with those measurement.

In other region the two noises are very close and also very similar to the plot of the seismic motion in the control room (attached on the front of TV screen).

Attachment 1: XARM_OLTF.pdf
Attachment 2: YARM_OLTF.pdf
Attachment 3: XARM_ITMXresponse.png
Attachment 4: YARM_ITMYresponse.png
Attachment 5: free_running.pdf
  9163   Thu Sep 26 01:49:28 2013 MasayukiSummaryGreen LockingFPMI noise caused by ARM locking


 Measurement with FPMI

i)By locking the FPMI with AS55Q and arms using POX,POY we measured  the OLTF on AS55Q, the response from BS actuation to error signal on AS55Q  for H_mich. The fitted,  measured OLTF and the residual function is in attachment1. I fitted two parameters and they are time-delay and the gain. The time delay is -275 usec. The time delay in three different control are almost same. The response from BS to AS55Q is in attachment 2.

With these two measuremets, I calclated the H_mich in FPMI. This H_mich should be different from simple MI because the cavity  refrectivity is different from the front mirror. Acrually it changed and the value was
Hmich = 4.4026e7

ii) I excited the ETMX and ETMY and measure the response from actuation to the error signal of MICH on AS55Q. The response is in attachment 3 and 4. from these result I calculated the H_L-l by using the formula as I mentioned. The value was
H_Lx-l = 175.7650 (XARM)
H_Ly-l = 169.8451 (YARM)

iii) I measured the error signal of MICH and XARM and YARM and with measured H_L-l, I estimated the FPMI noise caused by ARM locking. You can see in the higher frequency region than 10 Hz is dominated by noise caused by ARM control in-loop noises. 150 Hz and 220Hz are the UGF of each arms, so the two peaks are caused by arm control. You can see the small difference between FPMI noise and  noise from arms. There are two possibilities, one is that these measurement is not same time measurement so they should have small difference. and  other possibility is the error of the caliculation. But I think it doesn't look so bad estimation.


Next step

We will do same measurement with lock the arms the ALS system on tomorrow. Then we will check the PDH servo or other noise source and investigate the ALS system

Attachment 1: MICH_OLTF.pdf
Attachment 2: BS-RS55Q.png
Attachment 3: ETMX-RS55.png
Attachment 4: ETMY-RS55.png
Attachment 5: plot.pdf
  9182   Tue Oct 1 14:12:22 2013 ranaSummaryCDSsvndumpfilter on linux1 makes NFS slow

 Yesterday and this morning's slow NFS disk access was caused by 'svndumpfilter' being run at linux1 to carve out the Noise Budget directory. It is being moved to another server; I think the disk access is back to normal speed now.

  9184   Tue Oct 1 19:42:19 2013 ranaSummaryCDSmegatron upgrade

Max and I started upgrading megatron to Ubuntu 12.NN today. We were having some troubles with getting latest python code to run to support the Summary pages stuff.

Its also a nice test to see what CDS tools fail on there, before we upgrade the workstations to Ubuntu 12.

Since its Linux, none of the usual upgrading commands worked, but after an hour or so of reading forums we were able to delete some packages and all the 3rd party packages and get the upgrade to go ahead. We'll have to re-install the LSC, GDS, LAL repos to get it back into shape and get NDS2 working. The upgrade is running in a 'screen' command on there.

Wed Oct 02 14:50:16 2013 

Update #1: The upgrade asks a couple dozen questions so it doesn't proceed by itself. I've been checking in to the 'screen' every couple hours to type in 'Yes' to let it keep going.

Update #2: It finished a few hours ago:

controls@megatron:~ 0$ uname -a
Linux megatron 3.2.0-54-generic #82-Ubuntu SMP Tue Sep 10 20:08:42 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux
controls@megatron:~ 0$ date
Wed Oct  2 18:33:41 PDT 2013

  9191   Thu Oct 3 02:43:34 2013 rana, jenneSummaryLSCPRMI: comparison of 1f and 3f signals w/ calibration

The attached plot shows the spectra of all the REFL signals with the PRMI SB lock.

We excited the ITMY_LSC with 3000 counts. We used the Masayuki calibration of ITMY (5 nm / count * (1/f^2)) to estimate this peak in the REFL spectra.

To correctly scale the REFL spectra we account for the fact that the DTT BW was "0.187 Hz" and we turn off the "Bin" radio box before measuring the peak height with the cursor.

Since the ITMY motion is 3000 * 5e-9 / (580.1 Hz)^2 = 44.6 pm_peak, we want the DTT spectrum of the REFL spectra to report that too.

i.e. to convert from peak height to meters_peak, we use this formula:

meters_peak = peak_height * sqrt(BW) * sqrt(2)

I *think* that since the line shows up in multiple bins of the PSD, we should probably integrate a ~0.5 Hz band around the peak, but not sure. Need to check calibration by examining the time series, but this is pretty close.

Mystery: why are the REFL_I 3f signals nearly as good in SNR as the 1f signals? The modelling shows that the optical gain should be ~30-100x less. Can it be that our 1f electronics are that bad?

Bonus: notice how we have cleverly used the comb of bounce frequencies around the calibration line to determine that REFL11 is clipping!

Attachment 1: REFL_signals_CalLinesLinedUp.pdf
  9205   Sun Oct 6 17:05:49 2013 ranaSummaryIOOMC ASC problems

MC unlocked over the weekend and also got severely mis-aligned. It all started around midnight on Saturday.

At first I thought that this was due to the MCS CPU meter being railed at 60 us, so I deleted a bunch of filters in MC1,2,3 that are unused and left over from Den's quantization noise investigations. This reduced the CPU load somewhat, but didn't make any real improvements. Turning on the ASC filter banks in the MC SUS still mis-aligned the MC.

With the MC WFS and MC ASS turned off, there is still some digital junk coming in and misaligning things. Plot attached.

Similar stuff coming in on ITMX, but not ITMY.

Tried restarting various FEs, but there was no effect. Also tried rebooting c1lsc, c1ioo, & c1sus. Finally did 'shutdown -r now' on all 5 computers on the CDS overview screen and simultaneously (almost) pressed the reset button on the RFM switch above the old c1pem crate. Everything came back OK except for c1oaf (I had to manually button his BURT button) and now the ASC inputs on all the SUS are zero when they should be and MC is well locked and aligned.

Rob and I used to do this trick when he thought that a cosmic ray had corrupted a bit in the RFM network.

Attachment 1: mcasc.pdf
  9207   Sun Oct 6 20:55:08 2013 ranaSummaryASCMC WFS Limits set based on 40 days of trends

MC3 watchdog gets tripped sometimes when lock is lost. I noticed that there were no limits set in the MC WFS drive. The attached plot shows that over 40 days, the OUT16 channels from the WFS don't exceed 1000 counts. So I've set the limit to be 2000 in all 6 of the MC ASCPIT/YAW filter banks. Please don't turn them off.

OUT16 is really not the right way to measure this, but for some reason, we don't have any DQ channels from the MC WFS screen ??? So we're not able to measure the trend of the high frequency drive signal.

So I added the WFS(1,2)_I_(PIT,YAW)_OUT_DQ and WFS(1,2)_(PIT,YAW)_OUT_DQ channels to the c1ioo.mdl at 2048 Hz. I used Jamie's excellent 'rtcds' utility to build and install:

1) after making the edits to c1ioo.mdl I saved the file/

2) sshing to c1ioo

3) rtcds stop c1ioo

4) rtcds make c1ioo

5) rtcds install c1ioo

6) rtcds start c1ioo

7) telnet fb 8087

8) daqd> shutdown

That seemed to do it OK.

Unfortunately, all of the instructions that we have in the Wiki for adding channels and model building are misleading and don't mention any of this. There are a few different methods listed which all instruct us to do the whole make and make install business in a bunch of non existent directories.

Attachment 1: mcwrfs_trend.png
  9216   Mon Oct 7 18:32:01 2013 John ZweizigSummaryComputer Scripts / Programsnds2 installed, restarted

The upgrade of megatron broke the nds2 service. I have fixed things by

  1) installing the latest version of framecpp (1.19.32) from the lsc debian repository (this was necessary because I couldn't link to the existing version)

  2) built nds2-server-0.5.11 and installed it in the system directories (/usr/bin)

  3) there were a few scripts/links/etc that didn't seem to be set up correctly and I fixed them to correspond with my preious message.

 nds2 is now running and the channel list should be updated regularly and the service restarted as appropriate.


  9218   Mon Oct 7 18:39:29 2013 JenneSummaryLSCPRMI: REFL11 beam realigned


Bonus: notice how we have cleverly used the comb of bounce frequencies around the calibration line to determine that REFL11 is clipping!

 Rana and I noticed last week that it looked like the REFL11 beam was clipping.  This afternoon, I locked the PRMI with REFL 165 I&Q, and checked the REFL 11 path.  The beam looks fine through all of the optics going to the diode, so I just realigned the beam onto the diode using the itty bitty steering mirror.  I have not yet checked the change (hopefully improvement) in the REFL11 spectrum.

  9324   Thu Oct 31 21:22:00 2013 rana, kojiSummaryIOOmodulation beat note in MC servo

I hooked up the 4395 to the MC servo board test out (TP2A) and looked at the spectrum using our new SPAG4395.py script. We noticed a huge peak at ~3.8 MHz and correctly guessed that it was due to the beat between the MC modulation frequency 29.5 MHz and 3*f1 (~33 MHz).

So we tuned the Marconi for the main mod. from 11065910 to 11066099 Hz and saw the beat note disappear (to within the 1 Hz tuning precision of our Marconi).

New MC length tuning method! Alert the LA Times!


My conjecture is that this temperature dependent mismatch between the modulation frequency (f1) and the MC length  is what leads sometimes to our nasty saturating PC DRIVE signal. TBD.

  9326   Fri Nov 1 17:01:46 2013 GabrieleSummaryLSCSimulation of REFL_3f signal when the arms come in

 I simulated how the 3f signal is affected by the resonance condition of the arms.

To keep it simple, I only simulated a double cavity. The attached plot shows the result. In x there is the arm cavity detuning from resonance (in log scale to show what happens close to the 0 value). In the y axis there is the PRC detuning. So every vertical slice of the upper plot gives a PDH signal for a given arm detuning. The bottom plot shows the power build up inside the arm, which is dominated by the carrier.


The 3f signal is not perturbed in any significant way by the arm resonance condition. This is good and what we expected.

However, in this simulation I had to ensure that the 1f sidebands are not perfectly anti-resonant inside the arms. They are indeed quite far away from resonance. If the modulation frequency is chosen in order to make the 1f sidebands exactly ant-resonant, the 2f will be resonant. This screws up the signal: REFL_3f is made of two contributions of equal amplitude, one on the PRC sidebands resonance and the other on the PRC carrier resonance. When the arm tuning goes to zero, these two cancels out and there is no more PDH...


However, this is a limit case, since the frequency show match perfectly. If the modulation frequency is few arm line widths away from perfect anti-resonance, we have no problem.

  9327   Fri Nov 1 17:44:06 2013 KojiSummaryLSCSimulation of REFL_3f signal when the arms come in

Yes, the resonance of the 2nd-order sidebands to the IFO screws up the 3f scheme.

2f (~22MHz) and 10f (~110MHz) are at x 5.6 and x 27.9 FSR from the carrier, so that's not the case.

Could we also see how much gain fluctuation of the 3f signals we would experience when the arm comes into the resonance?

  9332   Sun Nov 3 00:05:52 2013 CharlesSummaryISSISS Update - Bout' time

Right near the end of summer, I had an ISS board that was nominally working, but had a few problems I couldn't really sort out. Since I've been back, I've spent a lot of time just replacing parts, trying different circuit topologies and generally attempting to make the board function as I hoped it might in all those design stages. Below is a brief list of some of the problems I've been fixing as well as the first good characterization of the board transfer function that I've been able to get.

We'll start with some of the simple problems and proceed to more complicated ones.

  • The 5V reference I was using to obtain an error signal from some arbitrary DC photodiode readout was only producing ~2.5 V. 
    • Turns out I just need a FET type op-amp for the Sallen-Key Filter that I was using to clean up any noise in the reference output, as the leakage current in a AD829 was causing a significant voltage drop. I put in an OPA140 and everything worked marvelously.
  • The way I set up input grounding (i.e. send a ~0 amplitude signal through the board as an input) passed a few Amps through one of my chips causing it to burn out rather fantastically.
    • There isn't a good way to fix this on the current board (besides just getting rid of the functionality altogether) so my solution so far has just been to redesign that particular sub-system/feature and when we implement the second version of the ISS, the input grounding will be done correctly
  • One of the ICs I'm using, specifically the AD8436 RMS-to-DC converter, causes some super strange oscillations in -5V power line. When this chip is soldered onto the board, the -5V supply jumps between -3V and -10V rather sporadically and the DC power-supply used to provide that -5V says that board is drawing ~600 mA on that particular power line.
    • To date, I don't really have any idea what's going with this chip, and I've tried a lot of things to remedy the problem. My first thought was that I had some sort of short somewhere so I took the chip off the board, cleaned up all the excess solder and flux around the chip's footprint and then meticulously soldered a new chip on (when I say meticulously, it took over an hour to solder 20 little feet. I really really didn't want to short anything accidentally as the chip only comes in a package with ridicously small spacing between the leads). Lo and behold, nothing happened. I still saw the same oscillations in power supply and the board was still drawing between >500 mA on that line. Just to be sure, I soldered on a third chip taking the same amount of care and had the same problems.
    • I went over the schematic in Altium that we used to order the board, and unless the manufacturer made a mistake somewhere, there aren't any incorrectly routed signals would cause, say, two active devices to try setting the voltage of a particular node to different values.
    • I got some QSOP-to-DIP package converters so that I could mess around with the AD8436 on a breadboard to make sure it functioned correctly. I set up an identical circuit to the one on the PCB and didn't see any oscillations in the power supply, both for +-5V and +-15V as the chip can handle both supply voltages. I'm not really sure how to interpret this...
    • I'm still actively trying to figure this particular problem out, but I'm shooting in the dark at this point. 
  • Initial attempts to measure the transfer-function of the board were wrought with failure.
    • I figured out, with Nic's help, that the board needs the 'loop closed' with a significant broadband attenuator (to simulate the plant optics discussed in elog 9331) in order to not have constant railing of the high gain op-amp filter stages. Even after I did this, the measured transfer functions were not at all consistent with simulation. I wasn't sure if it was just a part issue, a design issue or a misunderstanding/bad data collection on my part so I just redesigned the whole servo and stuffed the board with entirely new components from around the 40m. Turns out the newly designed servo behaved more properly, as I will show below.

The above list encompasses all the issues I've had in making the ISS board function correctly. No other major problems exist to my knowledge.

I was able to measure both the open- and closed-loop transfer functions of the servo with the SR785. The results are shown below.


The transfer function with the boosts on caps at a particular value set by op-amp railing, i.e. below 100 Hz, the op-amps are already putting out their max voltage. This is the usual physical limitation when measuring the transfer function of an integrator. We can also see that the measured phase follows the simulated phase above ~300 Hz. The 'phase matching' at low frequency is again do to the op-amp railing in the servo output..

The closed-loop gain is shown below,


The measured closed-loop gain with the boosts on again matches the LISO simulation quite well except at low frequency where we are limited by op-amp railing. We compare the measured closed-loop transfer function to the desired noise suppression stipulated in my previous elog 9331,


 And we might hopefully conclude that my servo functions as desired. One should note that the op-amp railing seen in these measurements is not indicative of limitations we might face in some application of the ISS for the following reason. These transfer functions were measured with a 100 mV excitation signal (it is necessary to keep this signal amplitude large enough so that the inherent signal-to-noise ratio of the excitation source is large enough for accurate measurement) which leads to somewhat prompt railing of the op-amps. When the ISS operates to actually stabilize a laser, the input error signal will be much smaller (on the order of a few 10's of mV or less) and will decrease significantly assuming correct operation of the ISS. This means we won't see the same type of gain limitations.


What now, you ask?

Aside from the problem with the AD8436 chip, the ISS board seems to be functioning correctly. The transfer functions we have measured are correct to within the component tolerances and all of the various subsystems are behaving as they were designed to. Moving toward the goal of having this system work in situ for the CTN experiment, I need to do the following things,

  • Design a housing for the board -> order said housing and the front panel previously designed
  • Make sure the power supply daughter PCB boards are compatible with the ISS board and can provide power correctly
  • Talk to Evan and Tara about integrating the ISS with their experiment and make sure my board can do everything it needs to in that context.

So close, or so I say all the time 


  9337   Mon Nov 4 14:11:23 2013 GabrieleSummaryLSCSimulation of REFL_3f signal when the arms come in


Yes, the resonance of the 2nd-order sidebands to the IFO screws up the 3f scheme.

2f (~22MHz) and 10f (~110MHz) are at x 5.6 and x 27.9 FSR from the carrier, so that's not the case.

Could we also see how much gain fluctuation of the 3f signals we would experience when the arm comes into the resonance?

 From the simulation there is no visible change in the gain.

  9430   Wed Nov 27 18:31:26 2013 KojiSummaryLSCAdittion of the ALS error signals to the LSC input matrix

The Phase tracker outputs (= ALS X/Y error signals) are now conveyed to the LSC model.

Their entry points at the LSC model are C1:LSC-ALSX_IN1 and C1:LSC-ALSY_IN1.
They are connected to the signal matrix (28th and 29th signals) via signal conditioning filters (C1:LSC-ALSX and C1:LSC-ALSY).

The main LSC screen has not been updated. The conventional ALS servos are still remains as they were.

This renovation required the recompilation of c1als, c1rfm, and c1lsc. Two PCIe-RFM bridge paths were added resulting in
increase of the c1rfm timing budget from 38 to 44.

  9440   Wed Dec 4 15:43:13 2013 JenneSummaryLSCPut LSC DAQ channels back

Last week, Koji cleaned up the LSC model to make it much more readable, while he was working on piping the ALS signals to the LSC model.  However, somehow the DAQ Channels block got deleted before the model was committed to the svn.  Since there were 2 months between svn checkins for c1lsc.mdl, it's possible that someone had the model open just to look at, and the block got deleted, and that's the version that Koji started with. 

Anyhow, thankfully we have the svn, so Koji and I found that the DAQ Channels block was (as expected) in the previously checked-in version of the LSC model.  I put a copy of the old model onto my desktop, opened it up, copied the DAQ Channels block, and then pasted it into the new cleaned-up version of the model.  (Jamie - is there a way to conveniently download a previous version through the web interface?)

I have checked it in, compiled and restarted the lsc model.  The _DQ channels are back now.

  9476   Sun Dec 15 20:37:41 2013 ranaSummaryTreasureThere is a Wagonga in the container that Steve does not believe in

From Linda and Bram:

Attachment 1: WagSu.pdf
Attachment 2: Wagonga.jpg
Attachment 3: MandehlingMedStrong.jpg
  9490   Wed Dec 18 17:28:50 2013 GabrieleSummaryLSCEstimate of the PRC length error


Looking back at what I did in april (see log #8411) I realized that it is possible to get an estimate of how much the PRC length is wrong looking at the splitting of the sideband resonant peak as visible in the POP_110_I signal. With the help of Jenne the PRMI was aligned and left swinging. The first plot shows a typical example of the peak splitting of 55MHz sidebands. This is much larger than what was observed in April.

When the sidebands resonate inside the PRC they get a differential dephasing given by 

dPhi = 4*pi*f_mod/c * dL

where dL is the cavity length error with respect to the one that makes the sidebands perfectly resonant when the arms are not there. This is not exactly the error we are interested in, since we should take into account the shift from anti-resonance of the SBs in the arm cavities.

Nevertheless, I can measure the splitting of the peak in units of the peaks full width at half maximum (FWHM). I did this fitting few peaks with the sum of two Airy peaks. Here is an example of the result


The average splitting is 1.8 times the FWHM. Knowing the PRC finesse, one can determine the length error:

dL = c / (4 * f_mod * Finesse) * (dPhi / FWHM)

Assuming a finesse of 60, I get a length error of 4 cm.

To get another estimate, we kicked the PRM in order to get some almost linear sweeps of the PRC length. Here is one of the best results:


The distance between consecutive peaks is the free spectral range (FSR) of the PRC cavity. Again, I can measure the peak splitting in units of the FSR and determine the length error:

dL = c / (4 * f_mod) * (dPhi / FSR)

The result is again a length error of 4 cm.


An error of 4 cm seems pretty big. Therefore I set up a quick simulation with MIST to check if this makes sense. Indeed, if I simulate a PRMI with the 40m parameters and move the PRC length from the optimal one, I get the following result for POP_110_I, which is consistent with the measurement.



 Therefore, we can quite confidently assume that the PRC is off by 4 cm with respect to the position that would make the 55 MHz sideband resonant without arms. Unfortunately, it is not possible with this technique to infere the direction of the error.







Attachment 3: pop110_vs_dL.png
  9493   Thu Dec 19 12:51:57 2013 JenneSummaryLSCEstimate of the sign of the PRC length error

My hunch is that the PRC is SHORT by a few cm, not long. 

In my Optickle simulation, the sidebands are not perfectly co-resonating in the PRMI when the arms are not locked.  See Fig 1, which is the fields in the PRMI using the design PRC length.  If I add 5cm to the PRC length, I get Fig 2, where the peaks are about the same separation, but the upper and lower sidebands have swapped sides of the 0 mark.  However, if I remove 5cm from the PRC length, I get Fig 3, where the peaks are much farther apart than in Fig 1.  This case looks more similar to the data that Gabriele plotted in his elog entry, where the peaks are separated by at least a linewidth.  This is not at all conclusive, but it's a guess for which direction we need to move.  Obviously doing an actual measurement will be better. 

My tummy feelings also agree with this simulation:  When we flipped PR3 (the only optic change in the PRC since Gabriele and I measured the 55MHz peak separation in April), since the HR side of the optic is now at the back, we had to push the whole suspension cage forward to get the beam aligned to the Yarm.  Conversely, however, transmitting through the glass substrate adds to the optical path length.  So, my tummy feelings may be wrong.

Figure 1, PRC at design length, PRMI sweep:


Figure 2, PRC 5cm longer than design length:


Figure 3, PRC 5cm shorter than design length:



  9495   Thu Dec 19 18:33:25 2013 GabrieleSummaryLSCEstimate of the sign of the PRC length error

Maybe I'm getting confused, but I still believe there is no way to decide the direction from yesterday's measurement.

Let's say for example that the arm sideband detuning from antiresonance is equivalent to a PRC length change of +1cm away from the position of ideal resonance of the sidebands without arms. Then we can get a measured separation of the sidebands, without arms, corresponding to 5cm both if the PRC is off by +4cm or by -6cm...

  9498   Fri Dec 20 00:16:39 2013 KojiSummaryCDSRCG parsing bug?

A while ago, I noticed that the most significant bits of the LSC whitening DOs are not toggling.
I track this issue down and found what is happening. I need experts' help.

To illuminate the issue, terminators are connected to Bit15 of the Bit2Word blocks in the LSC model (attached screen shots).

The corresponding source file is found in c1lsc.c at the following location.
The last channels of the Bit2Word are connected to lsc_cm_slow (the filter module).
This is the source of the issue. This wrong assignment of the connections
can't be changed by connecting Go-From tags to the chennels.


3881// Bit2Word:  LSC_cdsBit2Word1                                                                                                              
3883double ins[16] = {
3884        lsc_as110_logicaloperator4,
3885        lsc_as110_logicaloperator1,
3886        lsc_refl11_logicaloperator4,
3887        lsc_refl11_logicaloperator1,
3888        lsc_pox11_logicaloperator4,
3889        lsc_pox11_logicaloperator1,
3890        lsc_poy11_logicaloperator4,
3891        lsc_poy11_logicaloperator1,
3892        lsc_refl33_logicaloperator4,
3893        lsc_refl33_logicaloperator1,
3894        lsc_pop22_logicaloperator4,
3895        lsc_pop22_logicaloperator1,
3896        lsc_pop110_logicaloperator4,
3897        lsc_pop110_logicaloperator1,
3898        lsc_as165_logicaloperator4,
3899        lsc_cm_slow
3901lsc_cdsbit2word1 = 0;
3902for (ii = 0; ii < 16; ii++)
3904if (ins[ii]) {
3905lsc_cdsbit2word1 += powers_of_2[ii];

3946// Bit2Word:  LSC_cdsBit2Word2                                                                                                              
3948double ins[16] = {                                                                                                                          
3949        lsc_as55_logicaloperator4,                                                                                                          
3950        lsc_as55_logicaloperator1,                                                                                                          
3951        lsc_refl55_logicaloperator4,                                                                                                        
3952        lsc_refl55_logicaloperator1,                                                                                                        
3953        lsc_pop55_logicaloperator4,                                                                                                         
3954        lsc_pop55_logicaloperator1,                                                                                                         
3955        lsc_refl165_logicaloperator4,                                                                                                       
3956        lsc_refl165_logicaloperator1,                                                                                                       
3957        lsc_logicaloperator_cm_ctrl,                                                                                                        
3958        ground,                                                                                                                             
3959        ground,                                                                                                                             
3960        lsc_logicaloperator_popdc,                                                                                                          
3961        lsc_logicaloperator_poydc,                                                                                                          
3962        lsc_logicaloperator_poxdc,                                                                                                          
3963        lsc_logicaloperator_refldc,                                                                                                         
3964        lsc_cm_slow                                                                                                                         
3966lsc_cdsbit2word2 = 0;                                                                                                                       
3967for (ii = 0; ii < 16; ii++)                                                                                                                 
3969if (ins[ii]) {                                                                                                                              
3970lsc_cdsbit2word2 += powers_of_2[ii];


Attachment 1: Bit2Word1.png
Attachment 2: Bit2Word2.png
  9503   Fri Dec 20 11:40:13 2013 JamieSummaryCDSRCG parsing bug?

I submitted a bug report for this:


However, given how old our RCG version is (2.5 vs. 2.8 current deployed at the sites) I don't think we're going to see any traction on this.  Even if this is still a bug in 2.8, they'll only fix it in 2.8.  There's no way they're going to make a bug fix release for 2.5.

We need to upgrade.

  9505   Fri Dec 20 18:00:02 2013 KojiSummaryCDSRCG parsing bug?

The bug is still there but the incorrect bits are now overridden.

Attachment 1: Screenshot-c1lsc-LSC.png
  9511   Tue Dec 31 23:19:58 2013 KojiSummaryGenerallinux1 RAID crash & recovery

Dec 22 between 6AM and 7AM, physical or logical failure has occure on the 4th disk in the RAID array on linux1.
This caused the RAID disk fell into the readonly mode. All of the hosts dependent on linux1 via NFS were affected by the incident.

Today the system has been recovered. The failed filesystem was restored by copying all of the files (1.3TB total) on the RAID to a 2TB SATA disk.
The depending hosts were restarted and we recovered elog/wiki access as well as the interferometer control system.

Recovery process

o Recover the access to linux1

- Connect an LCD display on the host. The keyboard is already connected and on the machine.
- One can login to linux1 from one of the virtual consoles, which can be switched by Alt+1/2/3 ...etc
- The device file of the RAID is /dev/sda1
- The boot didn't go straightforward as mounting of the disks accoding to /dev/fstab doesn't go well.
- The 40m root password was used to login with the filesystem recovery mode.
- Use the following command to make the editing of /etc/fstab available

# mount -o rw, remount /

- In order to make the normal reboot successfull, the line for the RAID in /etc/fstab needed to be commented out.

o Connect the external disk on linux1

- Brought a spare 2TB SATA disk from rossa.
- Connect the disk via an USB-SATA enclosure (dev/sdd1)
- Mount the 2TB disk on /tmpdisk
- Run the following command for the duplication

# rsync -aHuv --progress /home/ /tmpdisk/ >/rsync_KA_20131229_0230.log

- Because of the slow SCSI I/F, the copy rate was limited to ~6MB/s. The copy started on 27th and finished 31st.

o Restart linux1

- It was found that linux1 couldn't boot if the USB drive is connected.
- The machine has two SATA ports. These two are used for another RAID array that is not actually used. (/oldhome)
- linux1 was pulled out from the shelf in order to remove the two SATA disks.
- The 2TB disk was installed on the SATA port0.
- Restart linux1 but didn't start as the new disk is recognized as the boot disk.
- The BIOS setting was changed so that the 80GB PATA disk is recognized as the boot disk.
- The boot process fell into the filesystem recovery mode again. /etc/fstab was modified as follows.

/dev/VolGroup00/LogVol00 /                ext3    defaults        1 1
LABEL=/boot              /boot            ext3    defaults        1 2
devpts                   /dev/pts         devpts  gid=5,mode=620  0 0
tmpfs                    /dev/shm         tmpfs   defaults        0 0
proc                     /proc            proc    defaults        0 0
sysfs                    /sys             sysfs   defaults        0 0
/dev/VolGroup00/LogVol01 swap             swap    defaults        0 0
#/dev/md0                 /oldhome         ext3    defaults        0 1
/dev/sda1                /home            ext3    defaults        0 1
#/dev/sdb1                /tmpraid         ext3    defaults        0 1

- Another reboot make the operating system launched as usual.

o What's happen to the RAID?

- Hot removal of the disk #4.
- Hot plug of the disk #4.
- Disk #4 started to get rebuilt -> ~3hours rebuilding done
- This made the system marked as "clean". Now the raid (/dev/sdb1) can be mounted as usual.

o Nodus

- Root password of nodus is not known.
- Connect an LCD monitor and a Sun keyboard on nodus.
- Type Stop-A. This leads the nodus transition to the monitor mode.
- Type sync.
- This leads the system rebooted.

  9512   Wed Jan 1 15:01:29 2014 KojiSummaryGeneralIFO recovery

IFO restart after the recovery of linux1

Machine recovery in the following order
- Start fb
- Start the following machines: mafalda, megatron, op340m
- Start c1ioo, c1lsc, c1sus, c1iscex, c1iscey

CDS recovery / burtrestore

- Confirm all of the RT systems are running in "green". If not, restart corresponding model.
- c1iscaux, ciscaux2 didn't have response (white boxes). Went to the LCS digital rack and power cycled these targets
- burtrestore: The snapshots at Dec 19 05:07 were used. For c1iscaux and c1iscaux2 the snapshots at Dec 22 05:07 were used.

fast machines

slow machines


IFO recovery

- Reload watchdogs => restore sus damping
- MC misaligned but TEM00 was locked
- Gave a small touch on MC2 yaw => IMC almost aligned
- Autolocker wasn't running => Manually launched rather than wait for an hour for cron to launch it
- PMC was largely misaligned. => Aligned on the PSL table (PSLTRANS 0.640->0.753)
- IFO X/Y arm locked and aligned with ASS.
- PRMI mode: manually aligned PRM. The PRMIsb momentally locked.

  9513   Thu Jan 2 10:15:20 2014 JamieSummaryGenerallinux1 RAID crash & recovery

Well done Koji!  I'm very impressed with the sysadmin skillz.

  9516   Fri Jan 3 11:18:41 2014 SteveSummaryVACpower supply replaced with a short vent




 The temperature went down to room temp with temporary fan in the back. Voltage and current are stable.

Regardless, it will be replaced early next week.

Koji, Steve

 It was a bad experience again with our vacuum system.  The valves went crazy as we rebooted the computer. This was required for the swap in of a good 24V power supply.

The IFO was vented to 27 Torr through the annuloses, VA6, V7, Maglev,VM2 and VM1 (VC2 was open too)

I just opened the PSL shutter after a 4 hours pumpdown.

Condition: annuloses are not pumped, the IFO and the RGA are pumped as Atm2 shows

I will be here tomorrow morning to switch over to vacuum normal. 

More details later



 Events of the power supply swap:

1, Tested 24V DC ps from Todd

2, Closed V1, VM1 and all annulos valves to create safety net for the reboot. Turbo pumps left on running.

3, Turned computer off

4, Swap power supplies and turned it on

5, Turning the power on of c1vac2 created caos switching of valves. This resulted in a air vent as shown below.

6, VM1 was jammed and it was unable to close. The IOO beam shutter closed and the IFO was venting with air for a few minutes. Maglev did an emergency shut down. TP2's V4 and TP3' V5 closed. RP1 and RP3                           roughing         pumps turned on, their hose was not connected as usual. The RGA shut down to protect itself.

7, Closed annulos valves, stoped the vent at P1 27 torr as the vacuum control was  manually recovered

8, The Maglev and the annuloses were roughed out 500 mtorr . The Maglev was restarted.

9, The IFO pump down followed std procedure from 27 torr. VM1 was moving again as the pressure differential was removed from it.


 Remember: next time at atm .....rough down the cryo volume from 27 torr !

Attachment 1: rebootVENT.png
  9517   Fri Jan 3 15:19:39 2014 ranaSummaryPSLPSL pointing monitoring

 This is a 10-minute trend of the last 60 days of the pointing of the PSL beam.

The main fluctuation seems to be at the ~30 day time scale (not 24 hour) and its all in the vertical direction; the horizontal drift is ~10x less (as long as we believe there is no calibration error).

So what's causing all of this vertical shift? And why is there not just as much horizontal??

Attachment 1: PSL_pointing_2013.png
  9518   Fri Jan 3 18:21:45 2014 ranaSummaryPSLPSL pointing monitoring


 I went to the PSL table to re-align the input pointing to the IMC. After trying to optimize the pointing into the PMC and not succeeding I also then touched the wrong mirror and messed up our IOO QPD reference pointing.

The IMC is locking again, but I'll have to fix the pointing on Monday.

  9519   Mon Jan 6 16:30:31 2014 JenneSummaryPSLPSL pointing monitoring

I'm not sure which pointing Rana wanted to fix today, but here's a measurement of the MC spots.  They actually look pretty good.  There is some room for improvement, but not a lot, so I'm leaving it alone for now, while I play with other things in the IFO.

spot positions in mm (MC1,2,3 pit MC1,2,3 yaw):
[0.63368182839757914, 1.3004245778952557, 0.33621668795755993, -1.5585578137597658, -3.1344594013487286, -1.0533063060089816]


  9520   Mon Jan 6 16:32:40 2014 KojiSummaryGenerallinux1 RAID crash & recovery

Since this configuration change, the daily backup was speeded up by factor of more than two.
It was really limited by the bandwidth of the RAID array.


rsync.backup start: 2013-12-20-05:00:00, end: 2013-12-20-07:04:28, errcode 0
rsync.backup start: 2014-01-05-05:00:00, end: 2014-01-05-05:55:04, errcode 0

(The daily backup starts from 5:00)

  9537   Wed Jan 8 13:01:48 2014 GabrieleSummaryLSCEffect of PRC length mismatch on error signals

I ran a simulation of a double cavity with a PRC length mismatched w.r.t. the modulation frequency. I summarized the results in the attached PDF. I think it would be important to have a cross check of the results.

In brief:

A mismatch between PRC length and modulation frequency do have an effect on error signals

Multiple zeros appear in REFL_3f/PRCL that can be removed by careful tuning of the demodulation phase (however, the shape of the signal makes difficult to understand which phase is good…)

No visible effect on REFL_1f/CARM

But a large PRCL signal appears in REFL_1f_I, which is used to control CARM. This is not good.

A mismatch of the order of 0.5 cm has a small effect.






Attachment 1: REFL_vs_PRClength.pdf
REFL_vs_PRClength.pdf REFL_vs_PRClength.pdf REFL_vs_PRClength.pdf REFL_vs_PRClength.pdf REFL_vs_PRClength.pdf REFL_vs_PRClength.pdf REFL_vs_PRClength.pdf REFL_vs_PRClength.pdf
  9539   Wed Jan 8 16:08:52 2014 ericqSummaryLSCEffect of PRC length mismatch on error signals


So, we want an relatively quick measurement of the PRC length error (with sign!) at the order of .5 centimeter or so. Rana suggested the "demodulation phase method," i.e. lock the simple Michelson, measure what demodulation phase brings the 1F signal entirely within the phase quadrature, then lock the PRMI and measure the demodulation phase again. This tells you something about the length of the PRC. 

Gabriele and I worked through a simulation using MIST to determine how to actually do this. We simulated the case of injecting a line at 1kHz in the laser frequency via the laser's PZT and looking at the transfer function of the 1kHz signal to the I and Q at the 1F AS demodulated signal when locked. (Michelson locked on the dark fringe, PRC locked on 11MHz sideband) With the I and Q in hand, we can measure some demodulation phase angle that would bring everything into I. 

When the PRC length is in the ideal location, the demodulation phases in the two cases are the just about the same. Sweeping the length of the PRC around the ideal length gives us a monotonic function in the difference in the demodulation phases:


So, with this simulation, we should be able to calibrate a measured difference in demod phase into the length error of the cavity! We will proceed and report...

  9541   Wed Jan 8 19:05:30 2014 GabrieleSummaryLSCEffect of PRC length mismatch on error signals

 [Gabriele, EricQ]

Actually it is difficult to see any laser frequency line in the dark fringe signal, since the Schnupp asymmetry is small. It is much better to use a differential MICH excitation which gives a better signal at the dark port.

We repeated the simulation explained before. We can use both the AS55 or the AS11 signals, bout the first one has a limited linear range and the expected 4cm value is very close to saturation.


  9544   Thu Jan 9 17:58:31 2014 ericqSummaryLSCEffect of PRC length mismatch on error signals

[ericq, Gabriele, Manasa]

 We wanted to perform the PRC length measurement today with an AS11 signal, but such a signal didn't exist. So, we have temporarily connected the AS110 PD signal (which is some Thorlabs PD, and not a resonant one) into the REFL11 demod board. 

We then proceeded with the goal of locking the PRC with REFL165. A few parameters that were changed along the way as we aligned and locked things:

  • the XARM gain was increased from 0.4 to 0.5 to help it acquire lock
  • the MICH gain was decreased from -10 to -5 since there was some gain peaking in its servo output
  • the REFL165 demodulation phase was changed from 155 to 122, to place a PRCL excitation entirely within I (we did this while locked on the carrier)

Sadly, in the end, we couldn't lock the PRC on a sideband in a stable manner. The alignment would drift faster than we could optimize the alignment and gains for the PRC. I.e. we would lock the PRC on the carrier, align PRM (and maybe touch ITMX) to maximize POPDC, switch to sideband locking, try to lock, and things would start looking misaligned. Switching back to carrier locking, the beam spots on REFL (for example) would have moved.

Manasa noted the MC_TRANS_Y has been substantially drifting along with small drift in MC_TRANS_P as well. So we need to fix the source of the mode cleaner beam drifting if we want to make this measurement. 

  9546   Fri Jan 10 15:31:07 2014 ranaSummaryLSCEffect of PRC length mismatch on error signals


 Its very doubtful that the MC yaw drift matters for the IFO. That's just a qualitative correlation; the numbers don't hang together.

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