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ID Date Authorup Type Category Subject
  6271   Fri Feb 10 15:47:38 2012 ranaUpdatePEMseismic noise back to normal


 Kiwamu and Steve maybe don't know about how to trend seismic noise. If you just take the mean of the time series, you don't prove that the seismic noise got any higher. The STS has a nominally zero DC output, so the long period level shifts that you see tell you just that there was a DC offset.

This is NOT an increase in seismic noise. To see a seismic trend you should plot the trend of the BLRMS channels that we made especially for this purpose.

  6275   Fri Feb 10 23:58:30 2012 ranaUpdatePEMseismic BLRMS loud too



 So, none of our PEM BLRMS channels are recorded as of right now.  All we have for long-term record is the StripTool on the wall.  The 0.1-0.3Hz and 0.3-1 Hz traces both show these weirdo things, but the 1Hz and up BLRMS don't have any unusual noise.

 Seems like a problem to solve on Monday so that we don't end up without trends like this again.

  6289   Thu Feb 16 13:12:30 2012 ranaUpdateLSCsensing matrix of PRMI


I think I have told a lie in the last meeting -- the measured sensing matrix doesn't look similar to what Optickle predicts.

Smells like something is very wrong.

 Those Radar plots are awesome. Even more awesome would be if they were in units of W/m (so that it can be directly compared with Optickle) and so that the numbers are useful even 1 year from now. Otherwise, we will lose the RF transimpedance information and thereby lose everything.

Also, please post the provenance of the counts->V calibration.

  6315   Fri Feb 24 18:37:13 2012 ranaUpdateLSCY arm + PRMI part II


I tried the Yarm + PRMI configuration again.

The PRMI part was locked, but it didn't stay locked during the Y arm was brought to the resonance point.


 Isn't the point that the 11 and 55 MHz signals have the carrier effect, but the 3f signals are better?

  6335   Tue Feb 28 16:44:56 2012 ranaUpdateLSCMICH and PRCL signals in a simulation


 Like I said, this is possible if you fail to set up the OSA to look at the sidebands at BOTH the AS and REFL ports at all times. Don't waste your time - set up an OSA permanently!

  6367   Tue Mar 6 23:14:38 2012 ranaUpdateSUSOptical Lever had bad filters

 We found that that bounce (16.1 Hz) and roll (23.5 Hz) modes on the ITMX were much higher than on the ITMY. After some checking, it seems that the bandstop filters for the

SUSPOS, SUSPIT, SUSYAW, and SUSSIDE loops are set to the correct frequencies. However, the OLPIT and OLYAW had not been set correctly. I have copied the SUS filters into the OL filterbanks and reloaded all the filter banks. Attached are the comparison of old, bad, OL with the SUS ones.

The same cockamamie situation was there for the BS & ITMY as well. Although we still don't have the roll mode frequencies listed in the mechanical resonances wiki, I have guessed that the ITMY roll frequency is the same as the ITMX, since they have nearly the same bounce frequency. OL filters for the BS & ITMY are now at the right frequency (probably). Keiko is on top of fixing things for the other optics.

I think this whole notching adventure was in Leo's hands several months ago, but WE forgot to point him at the OLs in addition to the SUS. I blame Kiwamu 50% for not supervising him and Koji by 45% for not supervising Kiwamu. The other 5% goes to someone else. You know who you are.

Attachment 1: Untitled.png
  6381   Wed Mar 7 21:13:30 2012 ranaUpdateDAQNDS2

 I noticed that NDS2 was not running on mafalda as it should be. Instead, there were a couple of zombie MEDMs using up 99% of the CPU. I killed the zombies and have run the 'build channel list' script. When it finished, I tried to restart the nds server, but got the following error in the log file. Email has been dispatched to JZ.

mafalda:logs>less nds2-mafalda-201203072111.log

Configuring from file: nds2.conf
Allow list: ALL
terminate called after throwing an instance of 'std::runtime_error'
  what():  Insufficient arguments
  6425   Fri Mar 16 16:01:53 2012 ranaUpdateElectronicsREFL165 calibration : measurements

 To characterize the RF V to counts we need to know the state of the whitening filter board. Was the filter on or off ? What was the value of the whitening gain slider?

  6442   Sun Mar 25 20:13:31 2012 ranaHowToSUSOptical Lever Servo Tuning thoughts

To start the optical lever filter design, I looked into the noise on ITMY. It should be similar to the other arm cavity optics since they have the same whitening electronics.

The RED/BLUE are with loops open. The MAGENTA/CYAN with loops closed. Looks good; the bandwidth is a few Hz and there is not much peaking,

To figure out the contribution from the dark noise I misaligned the ITMY until the sum on the QPD went to zero. Then I took the spectra of the OL{1,2,3,4}_OUT signals (they all looked the same).

To normalize them properly I took OL4, multiplied it by 2 to account for the incoherent sum of 4 channels and then divided by the nominal SUM (which was 14685 counts). I've left the OL3 un-normalized to show the ratio.

From this plot it seems that the dark noise is not a problem at any frequency (no need to amplify for the new ADCs).

I'm going to use the open loop spectra to design the optimal feedback control. The file is saved as /users/rana/dtt/ITMY_OL-120325.xml

Attachment 1: Untitled.png
  6463   Wed Mar 28 21:15:53 2012 ranaOmnistructureComputersWireless router for GC

I installed a NETGEAR Wireless Router (WPN824N) today on the 131 network. The admin password for it as well as the wireless access password are in the usual places.

The SSID is 40EARTH. I have set it to allow WPA as well as WPA2 access, so the speed is only 54 Mbps for now. In a year or so, we can turn off the WPA support and up the speed.

  6517   Tue Apr 10 23:56:44 2012 ranaUpdateComputersSensoray

Now that Mike has got the Sensoray working, Jenne/Suresh should grab some new images of the ETM cage as Keiko did so that we can analyze them for another mode matching diagnostic.

  6523   Wed Apr 11 22:48:39 2012 ranaUpdateEnvironmentBLRMS


  6567   Wed Apr 25 18:59:47 2012 ranaUpdatePEMBlue Bird Pre-Amplifier

Usually R is for resistors and D is for diodes. Do you think from the schematic that we should put diodes into the R slots?

  6585   Mon Apr 30 18:46:34 2012 ranaUpdateComputersmegatron

Last week I found that megatron was still off after the power outage. Apparently, the power recovery checklist had not been followed during the recovery.

Please remember to use the checklist and post the checklist results after each power outage. Megatron is now on and functioning.

  6694   Sun May 27 17:19:27 2012 ranaSummaryloreStrawberries

 We have placed some sweet giant strawberries in the fridge; free for eating for anyone working in the lab today or tomorrow:


  6719   Wed May 30 20:12:15 2012 ranaUpdateIOOMC beam spot oscillation

This is a common occurrence when diagnostic scripts are written without the ability to handle exceptions (e.g. ctrl-c, terminal gets closed, etc.).

The first thing to do is make sure that the "new" script you are writing doesn't already exist (hint: look in the old scripts directory).

If you are writing a script that touches things in the interferometer, it must always return the settings to the initial state on abnormal termination:


  6745   Fri Jun 1 19:48:54 2012 ranaUpdateSUSOplevs all different, messed up


 Its a good question, but the answer is yes. At some level all of the OL servos should be different to handle the different mechanical resonances of the suspension as well as the optical table's acoustic noise and the different noise requirements for the difference optical cavities.

However, it would be better to have the same basic structure and then one or two customization filters.

  6785   Thu Jun 7 13:18:42 2012 ranaUpdateSUSPRM is still oscillating

  Set the PRM OL servo gains to zero until someone can take care of this. Turning off the buttons doesn't help anything if people run the alignment scripts.

  6811   Wed Jun 13 02:24:02 2012 ranaUpdateGreen Lockingmy first modescan (sort of)

 That sounds goofy.

With the delay line technique, you can get a linear signal over 50 MHz with no phase shifting. What is with all this I/Q stuff?

  6813   Wed Jun 13 11:10:56 2012 ranaUpdateGreen Lockingmy first modescan (sort of)

You can easily calculate whether or not the coarse readout will work by thinking about the scan resolution you need given the ADC dynamic range and the whitening filter that you use.

  6839   Wed Jun 20 18:00:10 2012 ranaSummaryPSLsummaries

 Nice PSL summaries from LHO:


  6877   Wed Jun 27 10:27:09 2012 ranaSummaryIOOhow to improve mode matching to arms

The MC waist is correct as is the arm RoCs. Most likely the error is in the telescope length or its distance from the MC. Jenne probably has all the numbers and can give us a surface plot showing how the MM degrades as a function of those two parameters.

  6888   Thu Jun 28 15:21:02 2012 ranaUpdateLockingPRMI work started, commissioning plan


 Cycling the vacuum is easy. Why not vent starting Thursday evening and pop the doors on Friday morning? Inspect on Friday and pump on Monday morning.

  6901   Mon Jul 2 00:41:13 2012 ranaSummaryGeneralclipping at BS, my plan


 Start pumping on Monday before Steve goes home.

  6976   Sun Jul 15 16:25:15 2012 ranaUpdateLSCPRMI LSC is making PRM motion worse

As stephanie did a few years ago, the idea should be to match the damping between the DRMI optics so as to minimize the differential motion. No notching is necessary. Read her SURF report about the IMC.


  6993   Thu Jul 19 15:55:21 2012 ranaUpdateComputersused 'aptitude' to install software (TexLive) on rosalba

I used APTITUDE to install texlive-full on rosalba so that I could work on a paper. pdflatex was not found on pianosa, rosalba, megatron, etc. I used this command:

sudo aptitude install texlive-full

While this was installing, I read a bunch of forums which claim that its better to bypass the apt-get and use the 
TexLive installer instead so that we can use its own package updater 'tlmgr'. Otherwise, the standard Ubuntu distributions
are years out of date (e.g. doesn't have RevTex 4.1).

  6994   Fri Jul 20 11:59:27 2012 ranaUpdateComputer Scripts / ProgramsCONLOG not running

WE tried to use the new conlog today and discovered that:

1) No one at the 40m uses conlog because they don't know that it ever ran and don't know how to use regexp.

2) It has not been running since the last time Megatron was rebooted (probably a power outage).

3) We could not get it to run using the instructions that Syracuse left in our wiki.

Emails are flying.

  6995   Fri Jul 20 12:12:25 2012 ranaUpdatePSLPMC problems examined

Jenne, Den, Rana

The PMC transmission has been varying a lot and the MC seems unstable. Superstitious people might blame this on the El-nino or the alignment with Sagitarius, but we are ostensibly scientists.

WE found that the PMC EPICS values had not been toggled since the reboot and so the RF phase and Amplitude were totally wrong (we should replace this with a fixed oscillator box as we did with FSS).

Also, the NPRO SLOW slider was at -2 V which made the mode going into the PMC funny (although the mode was OK this morning before I started playing with the PMC sliders).

Before adjustment, there was a strong correlation between the seismic motions and the PMC reflection. This means that the PMC gain was low and it couldn't stay locked. Now, after fixing the RF and upping the gain slider it looks more stable. Let's watch it for a few days to see if there's an improvement in the trends.

The 10-minute trend of the lat 400 days shows that nothing has changed much this year; its been equally bad for a long while.

Attachment 1: Untitled.png
  7015   Mon Jul 23 21:54:48 2012 ranaUpdatePEMWeather Station Works!

To get the code to run on c1pem1, we had to move the old target back into the /cvs/cds/caltech/target/ directory.  It is in /cvs/cds/caltech/target/c1pem1/.

JoeB had apparently moved it into some other area called 'oldfe' and this was why the weather station has not been running for years.    Joe is at LLO now, but he's not beyond our reach...

Once the code had been moved back I started it up. I also rebooted it from the telnet prompt to ensure that it worked on reboot. It did.

The cable issue that Liz mentions probably happened during the PSL table lifting and cable cleanup. It looks like someone yanked the ethernet cable out of its adapter and broke it...

Attachment 1: Untitled.png
  7034   Wed Jul 25 23:03:22 2012 ranaUpdatedigital noisenotch, lowpass filters

If the problem is the precision in DTT, then why would the noise change when the corner frequency of the filter is changed?

And how about checking for filter noise in the situation we saw online? 4th order low pass at 1 Hz or 8 Hz.

  7039   Thu Jul 26 15:43:03 2012 ranaUpdateLSCmodelled ringdown

You cannot use the digital system for this. You hook up a scope to the transmitted light as well as the incoming light (after the MC, perhaps at IP_POS). Then you acquire the data from both places simultaneously using an ethernet equipped scope. The step response of the PDs used for this has to be calibrated separately.

  7107   Tue Aug 7 16:21:16 2012 ranaUpdateSUSoptical table box wall proposal


 Sanwiched wall as shown: 1" clear acrylic, 2 layers of 0.004" thick "window tint", 1 layer of  0.007" thermashield and  0.125" yellow acrylic

Visibility: 70 %,    Transmission of 1064 nm  2-3 % at 0-50 degrees incident  power density 0.7 W/mm2

Max power 100 mW        

 Good. The power density and max power are not important (especially since you don't define a quantitative way to spec them). We ONLY care about the transmission.

  7110   Tue Aug 7 23:30:58 2012 ranaUpdateEnvironmentNearby EQ

 Just felt an EQ. Impulse moved some vertical blinds by several mm.

Tue Aug 07 23:26:06 2012 

  7112   Tue Aug 7 23:33:44 2012 ranaUpdateSTACISMore noise data

Looks like you're just measuring the ADC noise. You should add ADC noise to your plot. To compare the geophones with the accelerometers, you have to correct for the preamp gain and plot them both in the same units.

To get above the ADC noise you can use an SR560 preamp. (AC Coupled, G = 100)

  7126   Wed Aug 8 22:12:30 2012 ranaConfigurationIOOMC trans optics configured

  The PDA255 is a good ringdown detector - Steve can find one in the 40m if you ask him nicely.

  7183   Tue Aug 14 21:01:51 2012 ranaUpdatePEMBLRMS


I fixed up the seismic.stp file for the StripTool display:

  1. All BLRMS channels now have a y-axis range of 3 decades. So they all are displaying the same relative changes.
  2. So the 0.01-0.1 Hz band which is all over the place is real, sort of. Masha says that it is due to the seismometer signal being dominated by noise below 0.1 Hz. She is going to fix this somehow.
  3. I changed the samping time from 1 sec. to 10 sec. to make the traces less fuzzy.
  4. We (Masha / Liz) should harmonize the colors of this file with what's on the summary pages.
  7187   Wed Aug 15 04:03:55 2012 ranaSummaryLSCY-Arm Locking

0) Did a bunch of alignment to get beams roughly centered on ETMY and ITMY and maximize power. Adjusted the aperture and focus on ETMY camera to get nice image. Camera needs to be screwed in tightly and cables given some real strain relief, Steve.

1) snapshots not working on many MEDM screens. Who's on top of this?

2) save/restore not working for PZT2 sliders

3) changed power and filter triggers on yarm to match xarm

4) yarm filters copied from xarm (need to handtune RGs)

5) DTT wasn't working on rossa. Used the Date/Time GUI to reset the system time to match fb and then it stopped giving 'Test Timed Out'. Jamie check rossa ntpd.

6) Removed the high 3.2 Hz RG filter. We don't have any sharp features like that in the spectrum.
   ---then added it back. The 3.2 Hz comes and goes depending on what Yoichi is doing over in the MC area. Leaving it in by default, but lowering the Q from 2 to 1.5.

7) Attached is the noise spectra, coherence, and loop gain model for this yarm condition. For the plant model, I assume a pendulum (f=1 Hz, Q = 9) and a cavity pole of 1600 Hz. Gain is scaled to set the UGF at 165 Hz (as guessed by looking at the servo gain peaking frequency). This cheezy model doesn't include any of the delays from DAC, AA, or AI. Eric and Sasha should have something more useful for us by Friday.

8) Change the DQ channels: need XARM and YARM IN1 at 16k. e.g. XARM_ERR, etc.

9) To get the DTT plots to make thumbnails in the elog, I print a .ps file and then use 'epstopdf' to make the PDF.

Attachment 1: yArmNoise_120815.png
Attachment 2: yarm.pdf
  7219   Fri Aug 17 14:45:51 2012 ranaUpdateCamerasvideo cameras in the dark

 The problem with the glow on the ETMY face is due to the red light being scattered off of the optical table from the HeNe laser for the OL. Why is the red light hitting the table?

One way to fix the problem for the camera image is to insert a long pass filter (if Steve can find one).

 Edmund Optics: NT62-874

 Edmund Optics: NT65-731

Edmund Optics: NT32-759 

  7238   Tue Aug 21 00:02:05 2012 ranaSummaryComputer Scripts / ProgramsGDS/DTT bug: 10 digit GPS times not accepted

 I've noticed that we're experiencing this bug which was previously seen at LHO. We cannot enter 10 digit GPS times into the time fields for DTT due to a limit in TLGEntry.cc, which Jim Batch fixed in September of last year. Seems like we're running an old version of the GDS tools.

I checked the Lidax tool (which you can get from the GDS Mainmenu). It does, in fact, allow 10 digit entries.

  7239   Tue Aug 21 00:35:25 2012 ranaSummaryIOOVisibilities and Chrome

MC and PMC vis:

MC REFL Unlocked    = 4.4

MC REFL Locked      = 0.67

 1 - Locked/Unlocked = 85%


PMC REFL Unlocked   = 0.270

PMC REFL Locked     = 0.013

 1 - Locked/Unlocked = 95%

I checked (by looking through recent trends) that the zero level is zero on both channels. I tried to do a proper mode scan, but we have lost the PSL fast channels during the upgrade sadly. Also, the DC signal for the PMC REFL needs some gain. Unlocked level should be more like 3-5 V.

Also used the instructions from this page to add Google's sources to rosalba's apt-get list and then installed Chrome.

Attachment 1: Untitled.pdf
  7257   Thu Aug 23 15:35:33 2012 ranaUpdate IMC Ringdown


 It is HIGHLY unlikely that the IMC mirrors are having any effect on the ringdown. The ringdowns take ~20 usec to happen. The mirrors are 0.25 kg and you can calculate that its very hard to get enough force to move them any appreciable distance in that time.

  7258   Thu Aug 23 15:42:48 2012 ranaUpdateSTACISSTACIS signal box made


 I found this entry in the old 40m ilog which describes the STACIS performance. It shows that even though the STACIS is bad for the differential arm motion below 3 Hz. It has quite a big and positive effect at 10-30 Hz. The OSEMs show a bigger effect than what the single arm does. I think this is because the single arm is limited by the MC frequency noise above 10 Hz.

We should figure out how to turn on the STACIS but set the lower UGF to be ~5 Hz.

Attachment 1: vsanni-1107222997.pdf
  7263   Thu Aug 23 22:21:13 2012 ranaConfigurationIOOMCL turned back on

I turned on some filters and gain in the SUS-MC2_MCL filter bank tonight so as suppress the seismic noise influence on MC_F. This may help the MC stay in lock in the daytime.

Koji updated the mcdown and mcup scripts to turn the MCL path on and off and to engage the Boost filters at the right time.

The attached PNG shows the MCL screen with the filters all ON. In this state the crossover frequency is ~45 Hz. MC_F at low frequencies is reduced by more than 10x.

I also think that this may help the X-Arm lock. The number of fringes per second should be 2-3x less.

Attachment 1: mcl-screen.png
Attachment 2: mcf-noise.pdf
  7371   Mon Sep 10 19:04:32 2012 ranaUpdateGeneralplan

 On Friday, Koji and I adjusted the beam pointing into the DRMI using the PZT yaw and found that the beam inside the DRMI (as seen on the AS camera) looked OK (not distorted too much).

So it seems that the issue seen before, namely that the DRMI resonant mode is very strange, is no longer true.

The camera image at the AS port still looks elliptical. So Jenne and Mike have started to make this beam round by adjusting the lenses.

Our plan now is:

1) Fix AS camera optics to get a round beam (single bounce off of ITMY).

2) Flash DRMI to make sure the beam at AS is still round.

3) Using the moveable Watec camera and Sensoray, get images of the spot on all DRMI mirrors with DRMI flashing. Use targets and rulers whenever possible to get quantitative measurements of the beam positions. (i.e. just saying "Oh, its pretty much in the center" is the Mickey Mouse approach to science)

4) Align all pickoff beams in this situation. Make sure there is no in vac clipping. Align IP POS and ANG using this input beam pointing.

5) Pump down.


  7382   Fri Sep 14 00:33:31 2012 ranaUpdatePSLPMC alignment - mystery in reflected power

The PMC reflection made it seem that the beam going into it was misaligned. I went to the table and aligned the input beam to maximize the PMC transmission. I got ~10% improvement.

Just to check if something was loose, I started tapping things upstream of the Faraday. When I tapped the actual PMC body it seemed to get unseated and the reflected (unlocked) power jumped up by more than a factor of two.

I don't understand how this could be. The attached trend of the PMC channels shows that ever since the PSL upgrade, the PMC refl has been at the low level of ~0.3 V, except for a brief phase soon after the upgrade late in 2010 and then also for a few hours early in May of 2012.

If the PMC body actually moved, it seems that the pointing into the MC would also change and I don't see that. So what else can it be? Is there some clipping or dust or a burn spot on the PMC REFL path?

The PMC refl image was lost after the body re-settled itself. Jenne and I re-aligned it and added a 0.5 ND filter to the existing ND in order to account for the higher power. We should hide all of the reflective ND filters and just use absorbtive ND for the cameras to prevent reflections.


This image of the past hour shows the event at just before midnight (0650 UTC) where the PMC reflection goes up from 0.28 to 0.85.

Attachment 1: pmcr.jpg
Attachment 2: e.png
  7385   Fri Sep 14 01:18:51 2012 ranaUpdateCOC2 Layout Changes

After looking at the in-vacuum layout I think we should make two changes during the next vent:

1) Reduce the number of mirrors between the FI and its camera. We install a large silvered mirror in the vacuum flange which holds the Faraday cam (in the inside of the viewport). That points directly at the input to the Faraday. We get to remove all of the steering mirror junk on the IO stack.

2) Take the Faraday output (IFO REFL) out onto the little table holding the BS and PRM Oplevs. We then relocate all 4 of the REFL RFPDs as well as the REFL OSA and the REFL camera onto this table. This will reduce the path length from the FI REFL port to the diodes and reduce the beam clutter on the AS table.

  7389   Fri Sep 14 18:15:43 2012 ranaUpdateASCFirst In Vac Picture


 Looks good. Any way that you can tell in an unambiguous way, where the beam is, is very good. Ideally we want to have1-2 mm accuracy.

  7396   Mon Sep 17 07:57:58 2012 ranaUpdatePEMBS and AS tables for REFL change


 This was in response to my suggestion to move the REFL beam path to the table containing the BS/PRM Oplevs. From this seismic data it is clear that the BS table is no worse than the AS table, so we should plan to make the layout change during the next vent.

  7400   Mon Sep 17 23:58:01 2012 ranaUpdateGeneralLast of In-vac mirror photos taken

 My hope is that the DRMI flashes will be bright enough to see on the PO beams. IF we get 10 mW through the Faraday, you should get some buildup when the carrier resonates in the DRMI.

If the recycling gain is 10 and the pickoff fraction is 100 ppm you ought to get ~10 uW on PO. How much of the recycling cavity power gets out of POP?

  7414   Wed Sep 19 23:17:25 2012 ranaConfigurationPSLAOM installation

Mannasa and Unni and I looked at the RF driver for the AOM. It was fine.

With the ALC input left unconnected, with the power supply set to +28V, it was drawing 0.56 A.

By adjusting the modulation input we were able to get 1.1 Vrms into the scope (terminated at 50 Ohms) after going through 2 10dB attenuators. 11 Vrms into 50 Ohms is 33.8 dBm ~ 2W.

The RF power trimpot on the front of the driver is now adjusted so that -0.31 to 0.69 V takes the driver output from off to 2W output at 80 MHz.


The previous distorted signal that Jan and Manasa saw was at a level of ~100 mVrms, which is ~0.5 mW of power. At this tiny drive level, the internal amplifier is not linear and is mostly putting out a signal at ~160 MHz.


We checked by putting a square wave into the modulation input that the RF power from the driver would indeed shut off with a time scale of ~20 ns. Manasa will add a picture to this entry. We are ready now to calibrate the transmitted power of the AOM v. the modulation input voltage and then to measure the step time of the AOM.

Remember: do NOT believe the spec sheet of whatever PD you are using. All commercial PDs are slower than they advertise. In order to measure a <1 us step time you must use a PD with a >50 MHz 'bandwidth'.

ELOG V3.1.3-