Not really true that it passed. That's just an arbitrary margin. Best to throw away all the old wire. We have no quantitative estimate of what the real torque should be. Its just feelings.
The wire will arrive in 1-2 weeks. It is a new production. Brad Snook of Ca Fine Wire was suprised that we are still using the 13 years old wire. Oxidation is an issue with iron contained steel wire.
He would not give me a shelf life time on it. He recommended to check the strenght of it before usage. It passed with safety factor of 2 just recently.
In the future we'll store the new spool in oxigen free nitrogen environment..
My box has been suspended in the PSL using surgical tubing, and it has been connected to C1:PEM-MIC_1 (C17) with a BNC. I made a braided power cable as well but it turned out to be slightly too short... Once this is fixed, everything should be ready and we can see if it's working correctly. I also set up a new tab on the summary pages for this channel:
This data is back from when I had my solderless breadboard running near MC2. I'll add this tab to the real pages once the box is working (which could be a while since I'm gone for a month). Let me know if you see any issues with either the tab or the box/cables.
On the bounce roll balancing:
Recall that back in 2006, the main issue was not with the bounce mode coupling into the OSEMs but instead with too much cross-coupling between the damping loops themselves:
Old elogs from Osamu (reader / readonly). Osamu will be here in a couple weeks and can try to explain what he was doing back then.
The problem was that without a good input matrix, the low frequency motion of the suspension point was dominated by the damping noise rather than the seismic noise. The bounce mode is a nice indicator of whether the OSEM is oriented up/down but its not the most important thing. More important is that the magnet is in the actual LED beam, not just the apparent center of the OSEM.
Then we should be able to fix things by running the diagonalization script and correcting the input matrix (which depends somewhat on the DC alignment).
In November of 2010, Valera Frolov (LLO), investigated our satellite amplifiers and made some recommendations about how to increase the SNR.
In light of the recent issues, we ought to fix up one of the spares into this state and swap it in for the ITMY's funky box.
The sat amp schematic is (D961289). It has several versions. Our spare is labeled as version D (not a choice on the DCC page).
Edit (Sep 6): The purpose of the Radd resistors is to lower the resistance and thus up the current through the LED. The equivalent load becomes 287 Ohms. Presumably, this in series with the LED is what gives the 25 mA stated on the schematic. This implies the LED has an effective resistance of 100 Ohms at this operating point. Why 3 resistors? To distribute the heat load. The 1206 SMD resistors are usually rated for 1/4 W. Better to replace with 287 Ohm metal film resistors rated for 1 W, if Steve can find them online.
The attached PDF shows the output noise of the satellite amp. This was calculated using 'osempd.fil' in the 40m/LISO GitLab repo.
The mean voltage output is ~1 Vdc, which corresponds to a current with a shot noise level of 100 nV/rHz on this plot. So the opamp current noise dominates below 1 Hz as long as the OSEM LED output is indeed quantum limited down to 0.1 Hz. Sounds highly implausible.
To convert into meters, we divide by the OSEM conversion factor of ~1.6 V/mm, so the shot noise equivalent would be ~1e-10 m/rHz above 1 Hz.
After adding the sat amp to the 40m DCC tree (D1600348), I notice that not only is the PD readout not built for low noise, neither is the LED drive. The noise should be dominated by the voltage noise of the LT1031 voltage reference. This has a noise of ~500 nV/rHz at 1 Hz. That corresponds to an equivalent current noise through the LED of 25 mA * (500e-9 / 10) ~ 1 nA/rHz. Or ~45 nV/rHz at the sat amp output. This would be OK as long as everything behaves ideally. BUT, we have thick film (i.e. black surface mount) resistors on the LED drive so we'll have to measure it to make sure.
Also, why is the OSEM LED included in the feedback loop of the driver? It means disconnecting the cable from the sat amp makes the driver go unstable probably. I think one concept is that including the device in the feedback loop makes it so that any EMI picked up in the cabling, etc. gets cancelled out by the opamp. But this then requires that we test each driver to make sure it doesn't oscillate when driving the long cable.
If we have some data with one of the optics clamped and the open light hitting the PD, or with the OSEMs removed and sitting on the table, that would be useful for evaluating the end-to-end noise of the OSEM circuit. It seems like we probably have that due to the vent work, so please post the times here if you have them.
I looked at the PRM free swing spectra. The modes look like they're at the right frequencies, so pointing more and more towards a LED or satellite box issue.
Some of the frequencies have changed between the 2011 in-vac measurement and our 2016 in-air measurement, but that seems within usual parameters.
In the morning, Steve will start opening the north BS door so that we can enter to inspect the PRM LR OSEM.
For the ITMY, I squished together the cables which are in the 'Cable Interface Board' which lives in the rack. This thing takes the 64 pin IDC from the satellite module and converts it into 2 D-sub connectors to go to the PD whitening board and the coil driver board. Lets see if the ITMY OSEM glitches change character overnight.
For the PRM, I aligned it until the arm flashes were maximized and the REFL camera showed a centered spot with dips happening during the arm pops. AS port was more messy since the Michelson alignment wasn't perfect, but the spots were both near the center of the cam and the SRM alignment maximized the wangy fringiness of the image as well as the angry cat meow sounds that the full IFO makes as heard through the DAFI (listening to POX).
On Monday, Osamu should be back and can help with doors and then alignment recovery and locking.
All is not lost. I've stuck and unstuck optics around a half dozen times. Can you please post the zoomed in time series (not trend) from around the time it got stuck? Sometimes the bias sliders have to be toggles to make the bias correct. From the OSEM trend it seems like it got a large Yaw bias. May also try to reseat the satellite box cables and the cable from the coil driver to the cable breakout board in the back of the rack.
susaux is responsible for turning on/off the inputs to the coil driver, but not the actual damping loops. So rebooting susaux only does the same as turning the watchdogs on/off so it shouldn't be a big issue.
Both before and after would be good. We want to see how much bias and how much voltage from the front ends were applied. l1susaux could have put in a huge bias, but NOT a huge force from the damping loops. But I've never seen it put in a huge bias and there's no way to prevent this anyway without disconnecting cables.
I think its much more likely that its a little stuck due to static charge on the rubber EQ stop tips and that we can shake it lose with the damping loops.
Rana suspicious. We had arms locked before pumpdown with beams on Transmon PDs. If they're off now, must be beams are far off on the mirrors. Try A2L to estimate spot positions before walkin the beams too far.
With the WFS and OL, we never have figured out a good way to separate pit and yaw. Need to figure out a reference for up/down and then align everything to it: quad matrix + SUS output matrix
Been non-functional for 3 weeks. Anyone else notice this? images missing since ~Sep 21.
I say just fix the clipping. Don't worry about the PRM OSEM filters. We can do that next time when we put in the ITM baffles. No need for them on this round.
These old specs are not so bad. But we now want to get replacements for the TRX and TRY and PSL viewports that are R <0.1% at 532 and 1064 nm.
I don't know of any issues with keeping BK-7 as the substrate.
I don't think the loss of 25 ppm is outrageous. Its just surprisingly good. The SIS model predicted numbers more like 1 ppm / mirror taking into account just the phase map and not the coating defects.
However, we should take into account the lossed in the DRMI to be more accurate: AR coating reflectivities, scatter loss on those surfaces, as well as possible clipping around BS or some other optics.
We don't need to record any of the AIOut channels, the OL channels (since we record them fast), or the _MEAN channels (I think they must be CALC records or just bogus).
I did apt-get update and then apt-get upgrade on optimus. All systems are nominal.
Indeed. I suggest discussing with Joe B. I believe we should use a dedicated cam network to get the camera signals from the ends and corner all into one machine. Do not use the main CDS FE network for this since it might produce weird collissions. How about make a diagram, post it to elog, and send link to Joe?
It may be a good idea to leave the gigecam interfacing up to a dedicated machine.
In the Generic Pentek interface board, which is used to take in the analog 2-pin LEMO cable from the MC Servo board, there is some analog whitening before the signal is sent into the ADC.
There are jumpers in there to set whether it is 0, 1, or 2 stages of 150:15 (z:p) whitening.
more U4 gain, lesssss U5 gain
Mach Zucker on howto do Ringdowns: https://dcc.ligo.org/LIGO-T900007
As it turns out, its not so old as I thought. Jenne and I reworked these in 2014-2015. The QPD whitening is the same as the IMC WFS whitening so we can just repeat those fixes here for the IMC.
Rana pointed out that this modification (removal of 900Ohm) leave the input impedance as low as 100Ohm.
As OP284 can drive up to 10mA, the input can span only +/-1V with some nonlinearity.
Rather than reinstalling the 900Ohms, Rana will investigate the old-days fix for the whitening filter that may involve the removal of AD602s.
Until the solution is supplied, the IMC WFS project is suspended.
At Hanford, there is this issue with laser jitter turning into an IMC error point noise injection. I wonder if we can try out taking the acoustic band WFS signal and adding it to the MC error point as a digital FF. We could then look at the single arm error signal to see if this makes any improvement. There might be too much digital delay in the WFS signals if the clock rate in the model is too low.
The WFS gains are supposedly maximized already. If we remotely try to increase the gain, the two MAX4106 chips in the RF path will oscillate with each other.
We should insert a bi-directional coupler (if we can find some LEMO to SMA converters) and find out how much actual RF is getting into the demod board.
MC unlocked, Autolocker waiting for c1iool0 EPICS channels to respond. c1iool0 was responding to ping, but not to telnet. Keyed the crate and its coming back now.
There's many mentions of c1iool0 in the recent past, so it seems like its demise must be imminent. Good thing we have an Acromag team on top of things!
Also, the beam on WFS2 is too high and the autolocker is tickling the Input switch on the servo board too much: this is redundant / conflicting with the MC2 tickler.
Dead again. No outputs for the past month. We really need a cron job to check this out rather than wait for someone to look at the web page.
Max tells us that soem conf files were bad and that he did something and now some pages are being made. But the PEM and MEDM pages are bank. Also the ASC tab looks bogus to me.
In this video: https://youtu.be/iphcyNWFD10, the comments focus on the orange crocs, my wrinkled shirt, and the first aid kit.
Manasa pointed me to the CAD drawings in the 40m SVN and I've now uploaded them to the 40m DCC Tree so that EricG and SteveV can convert them into SolidWorks.
Does "done" mean they are OK or they are somehow damaged? Do you mean the workstations or the front end machines?
The computers are all done.
megatron and optimus are not responding to ping commands or ssh -- please power them up if they are off; we need them to get data remotely
This is one of those unsolved door lock acquisition problems. Its been happening for years.
Please ask facilities to increase the strength of the door tensioner so that it closes with more force.
Pages still not working: PEM and MEDM blank.
The attached file is a python notebook that you can use to get data. Minimal syntax.
Minute trend data seems not available using the NDS2 server. Its super slow using dataviewer from the control room.
Did some digging into the NDS2 config on megatron. It hasn't been updated in 2 years.
All of the stuff is run by the user 'nds2mgr'. The CronTab for this user was running all the channel name updates and server restarts at 3 AM each day; I've moved it to 5:05 AM. I don't know the password for this user, so I just did 'sudo su nds2mgr' to become him.
On megatron, in /home/nds2mgr/nds2-megatron/ there is a list of channels and configs. The file for the minute trend (C-M-ChanList.txt), hasn't been updated since Nov-2015. ???
Did we turn off minute trend writing in one of the recent FrameBuilder debug sessions? Seems we only have second trends in 2016. Maybe this explains why its so slow to get minute trends? Dataviewer has to rebuild it from second trend.
controls@nodus|frames > l
drwx------ 2 root root 16384 Jun 8 2009 lost+found/
drwxr-xr-x 2 controls controls 4096 Jul 14 2015 tmp/
-rw-r--r-- 1 controls controls 0 Jul 14 2015 test-file
drwxr-xr-x 5 controls controls 4096 Apr 7 2016 trend/
drwxr-xr-x 4 root root 4096 Apr 11 2016 archive/
drwxr-xr-x 789 controls controls 36864 Jan 13 19:34 full/
controls@nodus|frames > cd trend
controls@nodus|trend > l
drwxr-xr-x 258 controls controls 3342336 Jul 6 2015 minute_raw/
drwxr-xr-x 387 controls controls 36864 Nov 5 2015 minute/
drwxr-xr-x 969 controls controls 36864 Jan 13 19:49 second/
ITMY is not like the others. Real or just OSEM madness?
The "apt-get update" was failing on some machines because it couldn't find the 'Debian squeeze' repos, so I made some changes so that Megatron could be upgraded.
I think Jamie set this up for us a long time ago, but now the LSC has stopped supporting these versions of the software. We're running Ubuntu12 and 'squeeze' is meant to support Ubuntu10. Ubuntu12 (which is what LLO is running) corresponds to 'Debian-wheezy' and Ubuntu14 to 'Debian-Jessie' and Ubuntu16 to 'debian-stretch'.
We should consider upgrading a few of our workstations to Ubuntu 14 LTS to see how painful it is to run our scripts and DTT and DV. Better to upgrade a bit before we are forced to by circumstance.
I followed the instructions from software.ligo.org (https://wiki.ligo.org/DASWG/DebianWheezy) and put the recommended lines into the /etc/apt/sources.list.d/lsc-debian.list file.
but I still got 1 error (previously there were ~7 errors):
W: Failed to fetch http://software.ligo.org/lscsoft/debian/dists/wheezy/Release Unable to find expected entry 'contrib/binary-i386/Packages' in Release file (Wrong sources.list entry or malformed file)
Restarting now to see if things work. If its OK, we ought to change our squeeze lines into wheezy for all workstations so that our LSC software can be upgraded.
Found that the BS whitening was off. Gautam says that "it has always been that way" and "there's nothing in the elog about this" and "I have no special relationship with Putin".
I looked at DV and DTT while turning the OSEM whitening back on. As expected, the sensor noise improved by 10x above 10 Hz. The time series shows no problems - its just less fuzzy now.
All OSEM spectra after the switch show on upper panel of plot. Lower panel shows comparison of BS UL before/after. To rotate the DTT PDF landscape output I typed this:
pdftk BS-white.pdf cat 1N output BSwhite.pdf
"if you see something, do something"
Oot on the streets and in the chat rooms, people often ask, "What is up with the MC_F calibration?".
Not being sure of the wiring in the c1ioo model, I have formed this screencap of today's model and put it here. The MC_LENGTH and MC_FREQ are the filter banks which would calibrate these channels. In the filter banks there were various version of a 'dewhite' filter. They were all approximately z=150, p=15, g =1 @ DC, but with ~1% differences. I don't trust their provenance and so I've enforced symmetry and fixed their names to reflect what they are (150:15). I have also turned on one filter in MC_FREQ so that now the whitening of the Pentek Interface board is compensated.
Why is this TF 1/f? It should be -20 dB/decade if MC_F is in units of Hz* and MCL is a pendulum response. Perhaps its because the combination of the Koji summing box, the Thorlabs HV driver, and the Pomona box forms an additional 1/f ? IF so, this would explain the TF we see. Once we get confirmation from Koji, we can load the TF into the MC_FREQ filter bank and then MC_F will be in units of Hz (as will the summary pages).
(along the way I've also turned off the craaaazzzy servo input enable tickling that gets put in the MC AutoLocker every April Fool's leap year - resist the temptation)
Since we have a frequency counter system here and some oscillators, I wonder if we can just calibrate the MC_L and MC_F directly using a mixer lashed up to one of the counters. If so, and we can get the stabilized laser frequency noise down below 10 mHz/rHz, maybe this is a viable alternative method to the photon calibrators. Counting zero crossings is more honest than counting photons.
I tried to follow these instructions today to make the Simulink Webview accessible:
controls@nodus|public_html > ln -sfn /users/public_html/FE /export/home/
The story is: we currently don't expose the whole /users/public_html folder. Instead, we are symlinking the folders from public_html to /export/home/ on nodus, which is where apache looks for things
So, I fixed the links on the Core Optics page by running:
controls@nodus|~ > ln -sfn /users/public_html/40m_phasemap /export/home/
But...I got a "403 Forbidden" message. What is the secret handshake to get this to work? And why have we added this extra step of security?
Seems like this stops working every ~2 years. Its been busted since early 2016 according to cron, so I fixed up the paths and restored some missing files and committed things to the SVN (with comments!) and now its working and grabbing the Web viewable versions of the front end models. Just need to restore its viewability and then the world can watch our models any time.
Back in 2011, JoeB wrote some entries on how to automatically update the Simulink webview stuff.
Somehow, the cron broke down over the years. I reran the matlab file by hand today and it worked fine, so now you can see the up to date models using the internet.
I suppose before directory listings were turned off we should have fixed the script to make an index.html, but that's how it goes with "up"-grades. How about re-allow directory listing so that our old links for webview work again?
EQ: https://nodus.ligo.caltech.edu:30889/FE is live
Might be. Or it might be in the satellite box cabling. Hard to tell without a tester. I recommend you squish the cables on there and lock the MC and get back to the usual business. I'll check on sat. box with Ben.
Is this sufficient evidence to conclude that the Satellite boxes are to blame? It's hard to explain why the glitches come and go in this fashion, and also the apparent difference in the length of time for which the glitches persist. Here, in almost 24 hours, there is one incidence of glitching, but in yesterday's trend plot, the glitching remains present over several hours... The amplitude of the glitches, and their coincidence in all 5 channels, seems consistent with what we have been seeing though...
"Why does the word wrapping not work in our browsers with ELOG?" I sometimes wonder. Some of the elogs are fine, but often the 40m one has the text run off the page.
I found that this is due to people uploading HUGE images. If you need to do this, just use the shrink feature in the elog compose window so that we only have to see the thumbnail at first. Otherwise your 12 MP images will make it hard to read everyone else's entries.
I think this cron job is running on NODUS (our gateway) instead of our scripts machine:
*/1 * * * * /opt/rtcds/caltech/c1/scripts/Admin/n2Check.sh >> /opt/rtcds/caltech/c1/scripts/Admin/n2Check.log 2>&1
Based on Jenne's chiara disk usage monitoring script, I made a script that checks the N2 pressure, which will send an email to myself, Jenne, Rana, Koji, and Steve, should the pressure fall below 60psi. I also updated the chiara disk checking script to work on the new Nodus setup. I tested the two, only emailing myself, and they appear to work as expected.
The scripts are committed to the svn. Nodus' crontab now includes these two scripts, as well as the crontab backup script. (It occurs to me that the crontab backup script could be a little smarter, only backing it up if a change is made, but the archive is only a few MB, so it's probably not so important...)
moreover this script has a 90MB log file full of not finding its channel
I wish this script was in python instead of BASH and I wish it would run on megatron instead of nodus (why can't megatron send us email too?) and I wish that this log file would get wiped out once in awhile. Currently its been spitting out errors since at least a month ago:
Tue Jan 31 14:10:02 PST 2017 : N2 Pressure:
Channel connect timed out: 'C1:Vac-N2pres' not found.
(standard_in) 1: syntax error
Someone installed "Debian" on allegra. Why? Dataviewer doesn't work on there. Is there some advantage to making this thing have a different OS than the others? Any objections to going back to Ubuntu12?
I think this then allows us to have the low noise OCXO signals everywhere with enough oomph.