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ID Date Author Typeup Category Subject
  2269   Thu Feb 7 17:37:48 2019 aaronUpdateCryo Qhard drive failure, reformatting

I reinstalled Debian 8.

On boot, I give controls sudoer privileges and apt-get the debian jessie packages.

Next, I cp -a over the following:

-/opt/* on backup
-/home/controls/* on backup, taking care not to overwrite the other files in cominaux/home/controls
-/home/controls/.config/*, which did not overwrite anything on cominaux
-I do not cp over /home/controls/.dbus, since it already exists on cominaux and looks to have a drive-specific id
-/home/controls/.emacs.d/, which appears to be empty
-/home/controls/.hardinfo/, also empty
-Did not cp /home/controls/.local.share/recently-used.xbel  which was the only file in this directory, and would have overwritten a cominaux file
-/home/controls/.ssh/, except for the file known_hosts which already existed.
-/home/controls/.bashrc, which overwrote the cominaux .bashrc, but I confirmed that the only changes were additional LIGO variable names at the end
-.bash_logout and .profile were unchanged, so I did not cp them
-localhost/ligo, which is a link to a file in rtcds
-the entire /usr/opt/
-/usr/ligo, another link
-/usr/local/lib/*, which did not overwrite anything in cominaux
-/usr/local/lib/liblvrt*, which was everything else in this directory save for the python and R packages, which were already available on cominaux
The only remaining directories to cp are in /etc, and I follow the soft links in the home directory to determine that I want to cp the following (and I do so cp):
-/etc/systemd/system/[CTC100.service, particle.service, SoftIOC.service, vacgauge_MKS901P.service, vacgauge_MKS974B.service]
That's everything I found linked in the home directory to /etc/
I looked for more in the backup /etc/ directory that might need to be copied over, and copied over the following files/folders that didn't exist already on cominaux. If there was already a folder in cominaux:/etc, I didn't copy that over from backup.
-skipped over the lal files
-/etc/request-key.conf (weird, I definitely apt-get with this command for the jessie repo?)
With that I reboot.
  2272   Mon Feb 11 13:56:18 2019 aaronUpdateCryo Qhard drive failure, reformatting

cominaux still boots, so that's good.

I am referencing Chris' log about setting up a new cymac. I couldn't install cdssoft as described by Johannes, and couldn't find instructions on the DAS site. It only has instructions for lscsoft--has cdssoft been packaged together with this now?

I went to setup nfs, but it says it already exists. I reboot anyway to make sure these changes take effect. I added the alias for sitemap as described in Johannes' log.

When I try to use sitemap, it says "medm not found"

I set the default target to 'multi-user' by 'systemctl set-default multi-user.target'

I added 'ALL EXCEPT .caltech.edu' to hosts.deny... hopefully that's the right domain.

I git clone the advligoRTS repo (trunk) in the directory /opt/rtcds/rtscore/, but wasn't sure how to install this.

  2273   Tue Feb 12 14:12:29 2019 aaronUpdateCryo Qhard drive failure, reformatting

Today's the day.

I reboot, cominaux is now booting to the command line, not to a gui, probably because of the new default in systemctl?

I ran apt-get update, since I wasn't sure whether I did the keyring steps in the right order. Followed by 'apt-get install lscsoft-all'. I then reboot cominaux.

I'm still getting a message: "-bash: /opt/rtcds/rtcds-user-env.sh: No such file or directory'.

I tried for a while to find where the cdssoft package is located, but couldn't locate it... I think the things that need to happen are getting the cdssoft packages, and installing advligoRTS.

Following advligoRTS on the git, I moved up directories until I found the CDS software packages wiki and installed cds-release-jessie following the instructions. I then installed the relevant packages

sudo wget -c http://apt.ligo-wa.caltech.edu/debian/pool/jessie/cdssoft-release-jessie/cdssoft-release-jessie_1.3.1_all.deb
sudo dpkg -i cdssoft-release-jessie_1.3.1_all.deb
sudo apt update
sudo apt upgrade
sudo apt install cds-workstation

When there was a conflict with an existing file, I kept the existing file, because these were mostly copied over from cryoaux.

I was having dependency issues when trying to install advligorts-cymac, so I used

sudo aptitude -f install advligorts-cymac

This installed some more packages (advligorts-daqd and advligorts-gpstime-dkms), but not -cymac or -rcg for some reason... the dependency that apt can't find is 'mx'.

I reboot.

I don't know why /opt/rtcds is not mapped from cymac1. I have the line Johannes mentions that needs to be added to fstab; is cymac1 a good alias? Indeed, I can't ssh onto cymac1 from cominaux.

I inadvertently deleted /opt/rtcds/rtcds-user-env.sh from gaston, which mirrored the change to cymac1. So I don't have a copy of that file anymore I think? Might have deleted more, I was trying to rm the directory from cominaux, but I wasn't logged back in. I didn't sudo, so nothing that needed root permission was changed, but for some reason that didn't include the entire directory...

I added the following to cominaux' /etc/hosts/ file:       cymac1       gaston       spirou

# DHCP reservations      redpitaya      prologix      gps

Now I do see rtcds mirrored on cominaux! However, since I deleted the user-env file, it is still missing--I'll have to restore the rtcds directory using the backups for cymac1...

I went into /etc/rsnapshot.conf and saw that the snapshots should be under localhost in /backup/. However, when I ls the files there, I get an Input/Output error. That seems quite bad, searching online points to hardware issues. I'm able to cd into /backup/rsnapshot/daily.0/localhost, but find no files or directories there and can't get into any other snapshots (eg daily.1, weekly.0).


  2274   Wed Feb 13 20:07:38 2019 aaronUpdateCryo Qhard drive failure, reformatting

The reason for the I/O errors is that the backup disk is usually not mounted, I mounted it and now can access what I need. I went into /mnt/rsnapshot/daily.0/localhost/opt and run

cp -Rf rtcds/* /opt/rtcds/

 It takes a while because there are a lot of frames, and I realized I needed sudo permissions for some of this. Instead, I'm going to login as root and instead use:

rsync -avh --delete rtcds/ /opt/rtcds/

 This indeed ran much faster, and since I'm using rsync it doesn't have to re-copy all of the files I just cp'ed over. Even made it verbose and human readable. Success! It's taking a while so I'll return later.

By the way, I see that all of the burt snapshots are saved every hour since at least 2014... is this really necessary? Do we even have hour trends going back that far?

  2275   Thu Feb 14 16:35:51 2019 aaronUpdateCryo Qhard drive failure, reformatting

Looking at the /opt/rtcds/tst/x1/data/burt/ files, I can see that the backup I used was from Jan 25. However, the most recent backup (daily.0) has successfully updated. I'm not sure why this wasn't updating before--perhaps related to the backup drive not being mounted, and those i/o errors I was seeing?

Now that cominaux has the correct user-env file for rtcds (and the rest of that directory), I reboot again with fingers crossed that the services scripts will start. If not I'll do them by hand, and have to figure out where to add the start script.

I run /opt/rtcds/tst/x1/scripts/startALL.sh

I get an error that iocX1.log file doesn't exist, but I am pretty sure I saw it rsync over so I'll have to see why that's happening. I get an error 'Failed to restart mx_crc_only.service' (United mx_crc_only.service failed to load: No such file or directory). Is this related to the error I was getting when trying to download the mx package?
I followed the analogue of the wiki instructions for cds-workstation to try to install some advLigoRTS packages; I followed the line of dependencies, starting with *-cymac*, until I was told I need to install open-mx. This isn't a LIGO package, so I tried 'apt-get install openmx', and was told about a bunch of existing dependencies. I ran 'apt-get -f install', and those dependencies were cleared up, and I was able to install open-mx.

I try running ./startALL.sh again... oh now I get an error that this only runs on cymac1. Of course, this makes more sense now. I navigate to ~/services and run modbusIOC.sh... I'm seeing some channels coming back! I need to run the services script though, not the shell script.

Following Johannes' advice here, I run 'systemctl enable [].service' for all of the user-created services scripts (so not eg diaplsy-manager.service). I reboot. Hmmm for some reason modbusIOC.service wasn't in that systemd/system folder before, so I didn't link it... not sure why this should be? Maybe I just missed it in the backup copy over. I copy it there from ~/services, and repeat the above.

Oddly, the heater channels (which worked when I ran modbusIOC.sh) are not started even on this reboot. I notice that the other .service scripts I enabled appear blue in the services directory, but modbusIOC.service still does not, which means it's not soft linked. So that makes sense, Chris had told me the scripts in /systemd/system/ are soft linked to the home directory. After messing around with the soft links for a while, I finally realized that the right order of operations is:

  • cp service script into /etc/systemd/system/
  • rm the script from the ~/services folder where you want to soft link it.
  • ln -s {full path to service script in systemd} {full path to service script in services}
  • systemctl enable {service script}.service, run this from inside systemd/system/

I tried systemctl start modbusIOC.service, but the heater still doesn't turn on, so I just reboot and see if that does it... nope. Weird. Checking out Johannes' other elog, the modbusIOC script needs procserv, which I see is not in /bin where it belongs. After apt-get installing it, I start the service script and... it works! I've got all the SiQ channels back!

  2276   Wed Feb 20 16:31:10 2019 aaronUpdateCryo QVent for many items

[aaron, ching pin]

We vented today. We pushed the crimp connectors through the heat shield to remove the electrical feedthrough. We confirmed that the 1kOhm RTDs can be held with the clamps from Lakeshore.

We noticed some sticky/slick residue (water on teflon? something else?) on the Teflon cover for the linear actuator when we removed it. It is hard to see in the attached picture, but you can see the dirt sticking onto the residue.


We also replaced the teflon plate with ceramic balls with 3/16 inch diameters, which seem to be a good replacement.

Attachment 1: IMG_20190220_160032.jpg
Attachment 2: Untitled.jpg
  2277   Fri Feb 22 11:52:05 2019 aaronUpdateCryo QVent for many items

[aaron, ching pin]

Aaron stuffed the temperature sensing/control board while Ching Pin worked on the wiring for the 1kOhm RTDs. I've uploaded the plan for the remainder of the vent on the wiki (contains photos of the cryogenics book that I suppose I shouldn't put on the public page). Current plan is to pumpdown on Tuesday.

  2280   Sun Feb 24 17:37:50 2019 aaronUpdateCryo QVent for many items

I added three charcoal getters to the EZ bake oven in the spare room (which was and is unlocked) and am baking with the pump on, heater on at 30%.

I plugged in the new temperature control board, it's drawing 120mA from a lab supply.

  2281   Mon Feb 25 12:52:02 2019 aaron,ching pinUpdateCryo QVent for many items


I soldered the leads to the RTDs following the diagram on the wiki; I then put the RTDs in the bake oven to remain overnight.

[ching pin]


The wires for the feedthough were crimped one the end that connects to the RTDs. They are colour matched to the RTD leads for easier identification and orgainisation.

The heater and its connecting lead wires were prepaired as well, with a measured resistance of 125.8 ohms across the heater itself, and 126.6 ohms across the heater and its connecting lead wires. This ensures that the vast majory of the heat dissapated will do so at the heater. 



The connection to the feedthough previously relied on tiny crimp clips, but as we couldn't find them, we are going to solder them onto the feedthough.

With this wiring replacement, the wires are now all phosphor bronze, with the exception of the ESD ones. 

Attachment 1: IMG_20190225_125401.jpg
Attachment 2: IMG_20190225_125525.jpg
  2283   Tue Feb 26 17:08:59 2019 aaron,ching pinUpdateCryo QVent for many items

Feedthough was soldered, and the wiring replacement completed. We actually found the crimp clips (see previous entry) afterwards. The circults all seem fine, except that the readings from the RTDs go haywire when there is a significant current though the heater, which suggests that the PCB needs to be tweaked. For now however, we can just shutdown the heater whenever we need a RTD reading. Two of the RTDs were clamped via ad hoc methods using aluminum foil and screws, the proper clamps will be sweapped in during the next vent after that have arrived. The RTDs were also not properly calibrated yet, and that will be done next time when we are going to swap to the new clamps. There were also bubbles found in the kapton sandwich for the RTDs, which were supposed to not exist due to the vacuum bake they underwent. This could be a cause of outgassing, we will see what pressures we can reach this cycle.

We also mounted the new heater.

We replaced the silica lens with the sapphire one, and it was quite a bit taller, so we had to do a couple of adjustments to accomodate that, including shifting the ESD.

The wafer used was the same for the previous cycle, visual inspection suggested that it seemed fine.

We started the vacuum and cooldown cycle.


Additional details on wiring: votages are on red and green wires, while current is on gold and black. The ESD is also connected to a gold and black pair, but this pair has both male crimp connectors, for distingishing from the current pair. The heater was connected to a pair of black wires.

The RTDs were kept to the following order: 1. schwarzschild, 2. sphere base, 3. substrate holder

Attachment 1: IMG_20190226_141627.jpg
Attachment 2: IMG_20190226_150214.jpg
Attachment 3: IMG_20190226_151209.jpg
Attachment 4: IMG_20190226_162725.jpg
Attachment 5: IMG_20190226_164518_1.jpg
Attachment 6: IMG_20190226_170130.jpg
  2284   Tue Feb 26 19:38:48 2019 aaronUpdateCryo QVent for many items

I wanted to check on the pressure, but it was reading 0 at the pressure channel, so I thought "I must not have plugged that in".

An hour later, I had indeed plugged in the pressure and have found that there is possibly a hardware issue with the acromag? At least I'm not sure what the software issue would be.

The RTD channels (that is, the AI channels that take DB9 a ttheir input) seem to be working fine, despite a misleading error message in the modbisIOC.log file that says x1adc0 cannot be found (improper IP address seemed to be the cause, but yet it clearly found the adc at some point since these channels are operational). However, the pressure channel (which uses the BNC connectors on the acromag box) is reading 0.

I don't think the problem is software because I can see small changes in the noise near 0 when I eg unplug the BNC, send the signal through a preamplifier before reaching the ADC, etc. However, despite measuring 3-5V at the BNC with a probe, the pressure channel still reads 0V. This is consistent even if I redefine that channel to use a different of ADC ch 0-3 (these are the channels with BNC inputs).

Not sure what's going on. The DAC doesn't seem to have the same problem, I'm able to source 0-10V on the heater channel.

Woah very weird behavior now. When I unplugged the heater from the acromag (DAC1), all of the analog input channels started oscillating. This behavior is not totally repeatable. No idea what's going on.

After plugging/unplugging the BNCs a few times to try to find some repeatable behavior, the pressure channels just started working on their own. I have the heater input BNC plugged in to the temperature control board, but unplugged at the DAC side; this means the heater circuit is seeing a floating voltage at its input, so I'm guessing it's railed somewhere. This would draw down the voltage on the board's supply lines (due to poor trace management), and I suppose has turned off the current supply as a result. When I plug in the heater input, the temperature readouts return to a very noisy 120K (not sure why, the RTDs are at room temperature), and the pressure reading drops. I suppose the temperature control circuit is sourcing some current when it shouldn't be; this is comforting, since it's not an Acromag problem apparently. I talking with Andrew and know the changes I need to make to the board to fix this, but in the meantime I'll just disconnect the RTDs from the acromag.

Since the pressure's now at 1e-4 torr, I'm cooling down.

  2287   Mon Mar 11 10:58:51 2019 aaronUpdateCryo QCooldown

On Saturday, I closed the valve at the cryostat because I was concerned that the pressure is only getting to 1e-5 torr. I noticed that the pressure didn't drop quickly as I would expect for pumping on a closed hose, so I heated the hose over Sunday. Today the pressure is 9e-6 torr inside the hose. I'm letting it cool a bit before opening the valve to the cryostat again, but it seems there's a leak or outgassing somewhere along that line.
I terminated the heater control input on the temperature sensing/control sat box with a 50Ohm terminator and attached a BNC breakout board to the DB9 output so I can see if that noise I was noticing is a result of sending the signal along a long DB9 cable. I still see about 1V rms noise, but now the noise is confined to some large spikes... I'm going to add 90Ohm buffer to the output of the INA and see a large reduction in noise.

+In the meantime, when I open the cryo valve, the pressure inside is about 1e-2 torr, but drops quickly to 1e-5 torr. I fill with nitrogen to begin the cooldown.

I'm going to add a 90Ohm buffer and a 10nF cap to ground to each of the other channels; this will give a ~175kHz low pass filter to each of the outputs. The output LP and an input LP did little to reduce the noise. I'm going to proceed without the RTDs for now, and just check in on their DC level once in a while during the cooldown.

Attachment 1: 9A0C638B-09F2-4E37-8915-6D53A401B124.jpeg
Attachment 2: 31485103-6B21-4BA1-97B7-01771CF50D0E.jpeg
  2288   Mon Mar 11 14:09:03 2019 aaronUpdateCryo QCooldown

I aligned the beam to the QPD, but find I'm unable to excite any of the usual ~2250Hz modes. Is the ESD too far away?

I see a large (10dB above floor) peak ~1500Hz (and multiples) that goes away when I turn off the pump. When I turn off the pump, the pressure slowly rises to ~mtorr. I don't know why the pressure isn't dropping below ~8e-6 torr, even when cold.

I tried exciting a 600Hz mode, but couldn't get it much above background. Then, when I tried using foton from awggui again, I started getting some of what look like seg fault errors and the program would freeze, not sure why. I reboot gaston.

I tried some broadband excitations, but couldn't really identify any modes. I will warm up the cryostat, and in the meantime debug the circuit.

  2325   Mon Apr 8 04:45:55 2019 johannesUpdateLaserCurrent Driver DCC updated
  1. Diode bridge using four 1N004 diodes in series across the laser diode connection to prevent voltage spikes
  2. U9 changed from OP27 to LT1128
  3. Removed M1
  4. Removed R60
  5. Removed C35
  6. Swapped Q2 from 2N6292 to IRF610
  7. Changed R22 with 0 Ohm
  8. Shorted M1 gate and drain with another 0 Ohm
  9. Removed D16 (was protecting M1), as D13 is already protecting Q2 transistor slot

These changes are now reflected in the latest DCC version v7 of the current driver at https://dcc.ligo.org/LIGO-D1200719. The previous topology was preserved, which was achieved by adding the 0-Ohm R63 to bypass the M1 footprint. The v6 circuit can be restored by removing R63 and populating the omitted components as deccribed in v6. The uploads for v7 contain the zipped Altium project, all files required for manufacturing, and the pick&place file for populating by a company.

The IRF 610 N-channel MOSFET that delivers the slow path bias current in the new version was the lightest duty power-MOSFET that was available in the West-Bridge E-shop at the time of tinkering, and was found to work fine for this purpose. There may be more suitable chips available for the 100 mA the driver is designed to deliver.

Attachment 1: schematic_changes.JPG
Attachment 2: diode_protection.JPG
Attachment 3: transistor_swap.JPG
  2377   Tue May 7 23:34:26 2019 aaronUpdateCryoQuick vent, new disk loaded, making it colder


I warmed up the cryostat this afternoon by first softening the vacuum with nitrogen to 1 torr for a few hours. Between 0C and room temperature. I increased the pressure to 100 torr over about an hour, during which I organized a bit--and luckily found some indium wire on Zach's table!

I opened up while flowing nitrogen and removed disk 5, which I returned to the desiccator.

More clamping, indium around the cold window

I removed the cold window. I misremembered, there is actually a snout that extends in both directions from the heat shield. It is black on the inside and shiny on the outside. It had four 2-56 screws fastening it to the shield, which I replaced with longer 2-56 screws that extend beyond the cold window. I clamped the window to the snout with one nut/washer on each screw.

The mirror had some flecks of aluminum on it from where the screws had torn the foil, I cleaned it off by rinsing with methanol.

I made a loop of indium wire, which I then flattened/shaped with some pliers (wrapped in HV foil)and secured with ~1cm square pieces of Kapton tape to the window. I then pressed the window to the snout, and ensured the wire was pressed into the snout. I wrapped four washers in indium foil and tightened them around the window using the a socket wrench bit.

Even though I now have the indium and sufficient force clamping the window to the snout, it's possible there is not enough surface area to provide sufficient conduction. If we find the disk is still too warm and the heat is mostly from the window, it may require some additional design of a window mount.

I also placed some indium around the circumference of the heat shield bottom, which hopefully will may the bottom plate cold.

New disk loaded, cooling

I loaded in disk 8, which was passivated with SiNx ~10nm of SiNx deposited with only high frequency (~10s MHz, rather than kHz for low frequency) plasma excitation.

I checked the electrical connections, wrapped the GeNS in foil, and began pumpdown.


I identified the frequencies of the first three butterfly modes for calibration:

Mode shape Mode number Frequency (Hz) Temperature at RTDs (K) notes
1st butterfly A i=2, j=0 973.49, 976.46 297  
1st butterfly B i=2, j=0 993.43, 1007.13 297

Intermittent peak between these two. 1007 Hz is highest excitation of i=2 j=0 modes

2nd butterfly A i=3, j=0 22212.75, 2229.54, 2246.12 297 2229 is highest peak
2nd butterfly B i=3, j=0 2282.25, 2299.12, 2317.38    
4th butterfly A i=5, j=0 5978.62, 5979.75, 5980.62   5978.6 and 5979.8 are highest peaks
4th butterfly B i=5, j=0 6073.88, 6074.5    

I began the cooldown around 1am 

Attachment 1: wrap.jpg
Attachment 2: ring.jpg
Attachment 3: installed.jpg
Attachment 4: indiumshield.jpg
Attachment 5: fitcheck.heic
  2378   Wed May 8 11:17:40 2019 aaronUpdateCryoQuick vent, new disk loaded, making it colder

Checking the cold(er) eigenfrequencies

I topped off the nitrogen at 11am. It had boiled off, so the temperature at the RTDs was about 136 K, but it is now dropping.

At around 1:30, the RTDs are reading below 100K.

I identified the following modes, choosing the mode that was most excitable of the butterfly modes I measured at room temperature

Mode Room temperature frequency (Hz) Current frequency Current temperature Notes
i=2, j=0 973.49 977.5 173

Though this temperature doesn't agree, note that 150K would correspond to 977.89 Hz.
I'd believe that the uncertainty on the calibration frequency
is large enough to make this up

i=2, j=0 976.46 980.625 166.7  
i=3, j=0 2229.54 2239.75 152  
i=5, j=0 6074 6101.75 154.4













I set up the three moderingers, and raised the disk again so it cools.

  2380   Wed May 8 17:45:29 2019 aaronUpdateCryoQ measurements

Cryostat cold, disk warm, cymac unreliable

Cryostat is cold

The RTDs are reading ~86-87 K.

Beam alignment

The beam was quick to align, but I realized I'd left the beam on the disk during cooldown. If indeed the heat load was primarily from the window, this shouldn't matter.

Finding the modes again

The MRs still contained in band modes, but their frequencies hadn't changed. Since the cryostat is 20 degrees colder, I wonder if that is a real effect, or if the frequency of the excitation just depends on the drive phase. I stepped around the phase a bit, on MR1, but couldn't excite a nearby mode at high Q, so I think the disk temperature really hasn't changed much.

Wed May 8 18:28:55 2019

Looking into 1550nm

I started looking for the datasheets necessary to get this Covega 1550 nm laser (SFL-6881) up and running. Dmass posted the datasheet here.

FE crashing

While I was doing that and not interacting with cymac, the FE crashed. After restarting the FE, it only lasted a few minutes before crashing again.

find_bogus_lengths tells me there are no problems with the minute trends.

I rebooted the IOC using the kill scripts, then startAll. This time it was less than a minute before another crash. The CPU meter on X1SIQ is only hitting ~18 (of 32), so not sure why this is happening. When I tried to shut down the IOC again, cymac froze up and required a hard reboot.

One possibility is, I had several mode objects instantiated in an ipython session. Each mode object calls

RCPID = ezca.Ezca(ifo=none)

and then carries arround RCPID while it exists. I couldn't find anything in Jamie's guardian documentation that suggests this should be a problem, but at some point I was instantiating many RCPID per mode, and the FE were crashing; I wasn't sure if they were related then either.

On reboot, I see white boxes on the DC indicators. The DAQ page is entirely white boxes.

I killed the IOC and ./startAll again...still white boxes. I don't really know what to do with this. I turned everything but the terminal and browser off, and tried a soft reboot of cymac1...

This time I try find_bogus_lengths before starting the models; there were no bad frames. After the start scripts, everything's running again.

Finding modes again

It looks like the temperature is still only 148 K. I'm topping off the nitrogen and will see how cold it gets after prolonged cooldown. In the future, to avoid such a long cooldown time it is necessary to top off the nitrogen a couple hours after the initial fill.   The nitrogen boils off at first, so if you don't top it off the disk won't see a cold environment for long enough.

  2381   Wed May 8 22:14:50 2019 ranaUpdateCryoQ measurements

maybe remove the custom code for T(f) ? I think Duo's imminent python script could handle that asynchronously. In any case, might be worth the test.

  2435   Thu Jun 27 06:20:25 2019 johannesUpdateLaserCryoCavs TF-board Mods

A brief write-up of the modifications to the TF-boards in the CryoCavs experiment from the original :


The first image shows the first filter stage, which has C3 and R4 to provide a bit of phase lead at unity gain. The remaining four filter stages look like the second picture. These are pole-zero pair filters, with the exception of stage one, which has an additional zero-pole combination for the phase lead. In these circuits, R1/R2 controls the gain at DC, and R1*(1/R2+1/R3) controls the gain high frequencies. The transition between these proportional regions is set by C2, which yields the poles and zeros. The transfer function of the CryoLab TF board looks like this:

Attachment 4 contains LTspice models that were used to simulate the above transfer function.


Attachment 3: tf-board_D1700471v2.pdf
Attachment 4: TF-Board.zip
  2438   Mon Jul 1 12:42:27 2019 aaronUpdateLab WorkCryo cleanup, experiments this week

[shubha, anna, aaron]

We gathered this morning to clean up the cryo lab a bit. We spend some time moving optics from the NW cabinet (which will contain optoelectronics and Si fab materials) to the SW optics cabinet.

The FE were down, so I ran killAll. Cymac1 became unresponsive to ssh and commands from the existing session, and I did a hard reboot, then startAll.

The lab should be ready for Shubha to start measuring the laser noise of the green pointer, and I showed him what disk to use to measure temperature as a function of laser power (in air first). The SiQ experiment should be ready for Anna to measure Qs.

Mon Jul 1 17:19:57 2019

Anna and Shubha reported that cymac1 never woke up. I did an Advanced Reboot (unplugged the machine, in addition to rebooting), and monitored the startup directly via VGA.

As had happened once before, cymac1 was getting stuck in emergency boot mode. This had happened once before, I entered the root password, plugged in the external hard drive (this was the backup drive, which cymac1 was searching for during boot), and am now able to finish booting cymac1. Please do not unplug the external hard drive behind cymac1. We will make the backup drive internal when we reorganize the rack.

  2453   Thu Jul 11 10:39:21 2019 aaronUpdateQryoCold Qs

[anna, aaron]

Thu Jul 11 10:39:36 2019 we filled the nitrogen.

  2489   Fri Aug 16 13:19:42 2019 aaronUpdateQryoTopped off lN2

Yesterday Anna measured some disk eigenfrequencies at room temperature, then we cooled down.

I topped off the nitrogen at Fri Aug 16 13:20:15 2019 . Temperatures were still above 200K at the RTDs (nitrogen had boiled off this morning), so it's going to take some time to cool still.

  2490   Mon Aug 19 17:13:17 2019 aaronUpdatestuff happensLeak valve not operable

I disconnected the SS-8BS leak valve from the shutoff valve so I could bake it, but found an unpleasant surprise. The photos probably tell it best. The labelled parts in attachment 1 are:

There was a glass sleeve of some kind inside the valve, shattered; I can't find mention of it on the elog, but maybe I don't know what it was used for in the past?

  2535   Thu Jul 16 11:27:18 2020 aaronUpdateLab WorkReopening cryo lab

Notice of lab entry

Date of entry: 17 July 2020
time of entry:  13:00 PT
time of exit:    18:00 PT
Date of entry: 17 July 2020
time of entry:  13:10 PT
time of exit:    17:25 PT
Purpose: I will begin the reopening procedures outlined in previous elogs (2534, 2533). I'll also try to locate at least one Wilcoxon accelerometer and an M2 ISS readout board. I'll enter the EE shop to move one solder station from EE to cryo lab. 

That's probably all that's necessary for a typical lab entry, though more details always good. Here's what I'll be doing and a couple checklists for COVID procedures.

Planned activities
  1. Go to cryo lab and do a quick survey for PPE. I will pick up 2 sets of PPE, cleaning supplies, and signage from Downs 318 for cryo (one personal set per person). For list of PPE and other supplies, see the PSOMA hardware inventory (under Procurement on the wiki).
  2. Follow the applicable steps in the "back to lab" checklist in prior elog.
  3. ​ ​Put together personal tool cart and workstation, labeling
  4. Check / repair HEPA filter
    1. connection to wall
    2. check filter specification against requirements. air scrubbing reference. Calculator for acceptable person-time limits for shared rooms (currently not applicable, since cryo will be one person per day occupancy). Aerosol guidelines reference.
    3. See if particle counter still logging.
    4. Air flow meter measuring flow at filter, around filter, at the door, at the opening in the ceiling near NW corner.
  5. Set up in/out box bins for materials / tools entering and exiting cryo lab.
  6. Locate seismometer and circuit.
  7. Transport 1 solder station from EE shop to cryo
  8. Check inventory in cryo lab against the PSOMA hardware list
  9. Make sure cymac and the fe are running.
Before checklist

During checklist

  • Physically distanced at all times, following one-way signage around campus, wearing a face covering. I'll need to use elevators for a while, and will keep those single occupancy.
  • Wearing mask always and washing hands as appropriate.
  • On arrival, wipe down door knobs, keyboard, mouse, knobs, any frequently touched surface. 
  • No more than 1 person in the cryo lab per day, stay more then 6' from others.
  • Update other lab members of activity on the elog. The remote lab member is a 'virtual buddy'.

After checklist

  • complete elog, close work permit
  • Sanitize shared surfaces
  • Dof PPE except for face mask
  2537   Fri Jul 17 13:15:03 2020 aaronUpdateLab WorkReopening cryo lab

TLDR: I sealed the leaks around the HEPA filter. I did an inventory of PPE and cleaning supplies in cryo, and separated two sets of personal PPE for Shruti and myself from the common supply. I did not receive PPE or cleaning supplies from Downs or 40m, but have inquired after both. Any anticipated work not explicitly mentioned here was not done; I tried to take care, but still strongly suggest that Shruti wipe down anything I placed in your personal supplies, just in case.

Next steps: See prior elog


After clearing the temperature check at home, still showing no symptoms, and starting the daily log in the reporting app, I head to West Bridge.

I entered the lab at 13:10 PT, using the N (olive walk) entrance to W Bridge. I am wearing a disposable mask, applied hand sanitizer on entering the lab, and don nitrile gloves. I locate the ISO and Kim wipes and wipe down

  • personal devices
  • glasses
  • keyboard, mouse, spirou workstation
  • door handles
  • Orange-brown lab chair
  • Common cabinet handles
  • label maker

Existing PPE and cleaning supplies in cryo

I located the following in the cryo lab, and am storing all PPE in the staging area at the entrance.

  • 4x laser glasses suitable for 1550nm. 2 are over-glasses, 2 are not, and I've labeled the glasses and storage cubby for myself and Shruti to have one of each.
  • 4x laser glasses for 1064. 2 are labeled '40m' and will be placed clean in the outbox for pickup with the circuit, the other 2 are also in labeled cubbies.
  • 1 pair of lN2 safety googles, 1 pair of ordinary sunglasses. These are not in regular use, and can be used occasionally with proper cleaning.
  • Limited supply of blue shoe covers (1 package)
  • 56 boxes of small dry Kim wipes, 4 box supply of large dry Kim wipes
  • 1 box of large nitrile gloves, nearly depleted
  • 2 Kimtech lens cleaning stations (34623; need to check whether this is just anti fog or also EPA approved sanitizing spray)
  • Various Tyvek coveralls (PN IC 182 BWH SM 00250C) size small to XL
  • 2 polyester lab coats (M, L)
  • Variety of Single-wrapped latex gloves, size 7, 8, 8.5, 9, 
  • hair nets
  • sleeve covers
  • 1 Willson face shield
  • disposable frocks size S 
  • limited supply of shop wipes
  • 1 package pre-wetted polyester wipes
  • dust catcher floor mats

Personal tools and PPE

Any tool I used that we have multiple copies of, I labeled "[aaron/shruti]" and set aside one copy for me and one for Shruti. My tools are on the blue cart holding Spirou. Shruti's are on the tan cart formerly holding screws and power supples (which I moved onto the remaining cart, the work bench, and the middle optics bench). Personal toolkit currently includes:

  • scissors
  • large flat head screwdriver
  • glasses cleaning station
  • dry kim wipes
  • small IPA spritz bottle 

Personal PPE are in clear bins labeled "Shruti" or "Aaron" and with the box contents. Currently each set includes

  • 2 disposable (but multi use) frocks
  • 2 disposable (but multi use) coveralls
  • 1 washable lab coat (where to launder?)
  • several pairs of AccuTech ultra-clean latex gloves
  • several hair nets
  • several blue shoe covers
  • several white sleeve covers

The remaining PPE are in clear boxes near the entrance labeled "common" and with the box contents. Extra AccuTech gloves and a few more coveralls are on the shelf below the HEPA filter.

Any tool with only one copy, I am noting here for a future order. I sanitized these tools before and after use. Common tools will remain in the tall blue Crafsman tool box.

  • label maker. The batteries were badly corroded (we usually run on power supply), I set them aside for disposal.
  • ladder

HEPA filter

The model of the HEPA filter is not visible from the exterior, and I will have to look up its cleaning schedule. The tape sealing the edges of the filter does not adhere to the textured paint surrounding part of the filter [attachment 1] . The smooth paint on the far wall appears to support adequate adhesion. To create a seal on the textured surface, I first cleared the supplies from the shelf under the filter and pealed back the non-adhering tape. I applied rubber cement to the sticky side of the tape, and held the tape in position for drying using the small boxes of Kim wipes from before. I applied rubber cement along the entire edge wherever there was textured paint, but not on the region with smooth paint. Air flow through the filter was noticeably increased following this procedure and seal was intact after a few hours, though I did not make a quantitative measurement. 

Stopped by Downs

at 1500 I exited the lab to use the restroom, eat, and pick up PPE from Downs 318. I swapped gloves on exit, and resanitized my hands after using the restroom in W Bridge basement, which is designated for our lab's use. After eating, I entered Downs and took the elevator to the 3rd floor, but was not able to access room 318 for PPE. I emailed Chub and Calum (listed contacts for Thomas lab) to coordinate a pickup at a later date. Specifically, I am requesting:

  • Nitrile gloves, M and S
  • 4 cloth face coverings, 2 for me and 2 for Shruti
  • Cleanroom masks (can also obtain from 40m PPE supply)
  • Beard covers (can also obtain from 40m PPE)
  • IPA wipes (some available in 40m supply)
  • disposable frocks size M (available at 40m)
  • 2x Disinfectant spray can
  • 2x hand sanitizer
  • 2x face shield
  • 2x no touch tools
  • 2x door adapter
  • 2x shop safety glasses
  • Signage
  • Borrow air flow meter if available 
  • anti-fog disinfecting wipes for glasses (is this the same as the Kimtech station?)


  • I found one function generator (SRS DS345) plugged into a power strip that was not connected to power. I've plugged it in to the wall and labelled it "check battery"


At 17:15, I begin wiping down the common tools and surfaces I used and exit at 17:25, upon which I disinfect hands again.

Attachment 1: tape_before.pdf
Attachment 2: glasses.pdf
  2538   Mon Jul 20 08:59:02 2020 shrutiUpdateLab WorkAt cryo lab

Notice of lab entry:

After going over the checklist outlined in the previous elogs by Aaron, I completed everything relevant in the one labelled 'before', 'lab entry'.

Entry ~08:30, Will be here until ~17:30, with a break for lunch and a meeting (12:00-14:30)

Purpose: To give myself a lab tour, clean up the area around the workstation I'd be using, arrange and label tools, record part numbers of components for the PSOMA experiment

I also went in to the EE shop to get a solder station and related implements that I could find more than one of. I've placed this on the table to the south of the cryo Q experiment, after clearing up the space and placing the boxes below the table (see pictures).

Attachment 1: FFDA12DE-AD53-4751-96C5-7AA726F4BC51.jpeg
Attachment 2: 332F07DE-A250-44A6-BA28-5A0DF65207E9.jpeg
  2539   Tue Jul 21 14:03:33 2020 shrutiUpdateLab WorkAt cryo lab

Notice of lab entry: ~13:45. Expect to be here until around 17:00.

Liz dropped off PPE that was collected from the 40m (Thanks Liz!), this included two sets each of items as marked on the safety tab of PSOMA inventory doc. Also, see Attachment 1. I have removed one set of items and placed them on the tan cart that I use. Aaron's set is still in the box by the door; while I have worn gloves and tried not to touch those items, please assume that I have.

I think I have located the PD readout circuits requested by Gautam, which was in Johannes' setup. See Attachment 2,3,4; the DCC number of 2 checks out. I have placed them in a box in the area near the entrance marked by a red square. Other items labeled with '40m' are also in that box.

Attachment 1: 156CA9F4-5287-4222-9C45-5ACA006DFEDC.jpeg
Attachment 2: 64F84876-1D78-427F-B272-5584D0D7AC2C.jpeg
Attachment 3: B56E1C6B-C039-4E7E-85F1-AEFE8FA1BEAB.jpeg
Attachment 4: D540AD24-6D44-447C-B87F-B6CCD01D9521.jpeg
  2540   Fri Jul 24 15:59:12 2020 aaronUpdateLab Workcryo open

Notice of lab entry


Date of entry: 23 July 2020
time of entry:  15:15 PT
time of exit:    18:09 PT

Purpose: finish up the steps outlined above (2533)

[note: date is correct, I needed to remake the entries for July 23 but the content of 2541 is nearly identical. I had a backup.]

  2541   Fri Jul 24 16:12:13 2020 aaronUpdateLab Workcryo open

entered W Bridge 264

I stopped by my office (W Bridge 364E) to pick up the new workstation computer and a mini monitor that might be handy. Stayed < 15 min and wore fresh gloves, mask, etc; also recorded entry by door.

I entered the lab around 3:15pm and wiped down the common surfaces. I sanitized and sorted my set of PPE from the box Liz dropped off -- thank you!

We should try not to bring cardboard Into the lab, and remove any cardboard we find. I got rid of a couple boxes.

lab temperature is high

The thermostat is doing its usual thing. It is set to 'cool,' but despite the temperature reading 71.2 F at the thermostat, the temperature at the particle counter is 80F and it feels warm. When I try to lower the set point, the thermostat requests a password. I found online that the default password for is 9995. The thermostat seems to accept the password but won't let me change the setpoint.

The rubber cement at one corner of the HEPA filter delaminated, but the edge held by the kim wipes set in place. I reapplied glue and fixed the tape more securely, and noticed improved air flow through the filter again. The lab temperature also improved a bit -- the leak seems directs cold air down to the floor, while the filter sends cool air across the top of the room.

misc reopening steps

These cover most of the recommended reopening steps. I'll do some general cleaning and organization, and make some new signage, then will call it 'reopen.' 

  • ran the sink hot and cold for about 10 min. There are no noticeable leaks or dampness under the sink, along the edges of the lab, or in any of the major cabinets in the lab.
  • Valved off the cryo Q vacuum and turned off the pump. Pressure reached 2e-3 torr in ~3 hours
  • strain relieved cables of spirou workstation, moved the station, ethernet, etc closer to PSOMA electronics rack
  • checked level of compressed He (1900 psi) and N2 (we don't have a cylinder). I will coordinate with Chub to get an N2 delivery
  • Added isopropyl, methanol, other solvents to the PSOMA inventory
  • Confirmed that our fire extinguisher still has pressure. Where is our eye wash and emergency shower station?  There's one on the basement level, is there one in the subbasement?
  • Not sure about sprinklers, gas, and vacuum utilities. I checked the utility with a yellow valve at NE corner of the lab, but opening the valve releases neither gas nor vacuum. I did not touch the sprinkler system, and did not test the compressed gas tubing (such as for the optics benches).
  • Laser 'in use' lkight at the lab entrance is functioning.
  • Checked that the hot plate (1) and variac cables were not under stress or damaged

exit lab Thu Jul 23 18:09:38 2020

  2542   Sun Jul 26 20:37:50 2020 aaronUpdate  

Notice of lab entry


Date of entry: 27 July 2020
time of entry:  11:30 
time of exit:    19:00


Purpose: PSOMA hardware inventory, find out what we can turn on

  2543   Mon Jul 27 12:11:49 2020 aaronUpdateLab WorkSimplifying W optic bench

PSOMA hardware inventory

I located the materials for stage 1 PSOMA on the West optics table. I recorded what we have in the hardware inventory, and what we don't have is flagged for purchase. I start by cleaning up the electronics rack, removing anything I think is not in use.

Electronics rack

  • Both laser current drivers are D1500207
  • The E laser has a TED 200 C temp controller. The W laser is not plugged in to TEC, but there is a spare ITC 502 combination controller on the rack, and cryo cavs has a additional ITC 510.
  • There are three universal PDH servo boxes on the W rack: 1x D0901351 and 2x D1700219-v1. All of the boxes need lids and proper rack mount hardware.
    • Innards
      • Inside the *1351, the board matches the front panel DCC number (serial number 1437)
      • Both the *0219 have matching boards: D1700192-v2, D1700195-v2, D1799182-v2, D1700131-v2
  • Power supplies
    • The +- 15V power strip is currently unplugged. I don't see a low noise DC supply on this rack, but there is a Tenma 72-6615 on the ground. The closed-ring connector of the power strip is incompatible with this supply, so likely it was powered off of something else.
    • There's a NewFocus 1901 +- 15V supply on the W table itself. I think this should be located not on the table? The outputs are 0.1 A max to banana, plus 2x 0.3A max to a coax cable. The NewFocus was only supplying the PDs on the table. 
    • Cryo cavs has a dedicated rack for its power supplies (2x Sorensen DCS33-33E), separated from the laser control and PDH electronics. Is this an important choice, and should we also move our power supplies?
    • On the bottom of the rack, there's a Mech-Tronics NIM power supply. Seems out of use, only a PD power supply and readout board is plugged in, but this has no corresponding PD. 
    • I found on the elog that Chris moved the two Sorensens from the cryo cantilevers (W) rack to the cryoaux (central, rolling) rack after the supplies Johannes bought in 2017 died (fans not running). Do these usually die right after their 2 year warranty expires, or were we especially hard on them?
      • sidenote, great to see a potential solution to cryo lab timing woes, and that the overheated Sorensens were causing cominaux hard drive failures. Thanks Chris!
      • I've added 2x Sorensen supplies to our purchase list for PSOMA
    • For now, I moved all existing power supplies onto the electronics rack, and power the strip with the Tenma. In the future, we can discuss a remote location for power supplies, and will buy 2x additional Sorensens.
  • Misc
    • a bunch of old and open circuit boards, in cases compatible with the NIM supply. One power amp II; one PDH2 servo board (D1100996); 2 channel low noise amplifier (contains D1101396-v2 and another hand made board); a general filter board claiming to be from the gyro experiment. 
    • There were a few loose minicircuits components connected to the OCXO preamp (D1500064). These were providing 33.59 and 32.7 MHz modulation to Zach's experiments. I removed these from the preamp so we can give them a more permanent box later.

W optics bench

  • vacuum pump
    • I don't see the pumping station that used to be by the W optics bench. I don't remember using it elsewhere, and don't find any elog mentioning it being borrowed or moved. Has anyone seen this pump? It's one of the HiCube all-in-ones; it should have LIGO property tag C21832.
    • Similarly, what happened to the IR labs cryostat that housed the cantilever Q measurement (property tag)? I see maybe the glint of a cantilever in the short gryo vacuum can, and I have the cantilever Q HV driver and feedthrough, but no cryostat.
  • Photodiodes
    • PDA50B (Ge, 800-1800 nm)
    • 2x PDA255
    • Found 2 loose (unmounted) photodiodes wrapped in foil near the "optical contact razorblade test" setup (SE corner of W table).
    • NewFocus 1811, 1611
    • 1 home brewed QPD and breakout board, (PN on the circuit board is 10-00146 rev 1)
  • Put away or onto the workbench any loose optics, unused optomechanics, and most cables. Anything that wasn't a stock part I placed in a clear plastic box labeled 'Cryo Cantilevers' in the projects cabinet (2-part wooden cabinet on S wall). Stock parts went into the respective optics cabinets.


  • The lab temperature is still way too high. The temperature at the particle counter is reading 78, the thermostat still reads 71 F. The filter is not leaking substantially.j
  • Got the speaker working -- there was an aux adapter in the headphone port, so system was confused
  • Raymond requested a CF16 blank. I couldn't find one, but gave him a CF40-to-CF25 adapter that had a CF25 blank epoxied onto it, along with a CF16 to CF40 adapter and some gaskets. Here was the disinfection procedure for sending these items to QIL:
    1. Found a large plastic bag and disinfected inside and out with Phenomenal (TM) spray
    2. Disinfected the unpackaged UHV components with 70% isopropyl alcohol and a Kim wipe, wrapped them in foil, and placed in the disinfected bag
    3. Disinfect the outside of the bag with Phenomenal spray and leave outside the door to cryo for same-day pickup.
  • noted that pressure in cryo Q vacuum is 24 utorr after about a day valved off
  • Emailed Jordan and Liz about anemometer, to measure air flow in cryo. If we can compute the time for air to circulate through the cryo lab, we can reduce the length of time between lab entries (currently Shruti and I are leaving 1 day between our lab uses). 
  • Starting piling up seemingly unused components from W table onto the S workbench. These need a new home.
  • Found some historical documents, sticky notes from Zach. Took photos of these just in case (attached, later) and placed along with the miscellany on the workbench.
  • Checked with other W Bridge lab users before entering EE shop at 3:30pm. Disinfected surfaces I touched before and after use. I retrieved 3x 9V rechargeable batteries for the cryo lab multimeters.
  • Found a cardboard boxed fiber polarization controller (FPC032), which I placed in the NW optics cabinet sans box. Is this safe for storage (attachment 3)? What about things like Kim wipes, are those an acceptable amount of cardboard, or should they be eliminated?
  • Moved any cantilevers, etc into the silicon storage cabinet (NW corner cabinet)
  2544   Tue Jul 28 13:33:06 2020 aaronUpdateLab WorkRio laser

Notice of lab entry


Date of entry: 28 July 2020
time of entry:  15:00 
time of exit:    19:30
Purpose: Turn on the Rio laser, find what we need for beam profiling, do some cleaning (mop, putting away stuff from the workbenches, etc)
  2545   Tue Jul 28 16:13:56 2020 aaronUpdateLab WorkAir flow measurement


  • I propose we continue scheduling cryo lab use with one individual using the lab per day, and announcing who will be in lab the day before.
    • If needed, this analysis suggests we could schedule two people to use the lab during the same day, but not at the same time. (of course, we are not yet cleared for shared use of the lab)
  • Use the air scrubber near the workstations, or wherever in the lab has stagnant air and prolonged use
  • Increase air circulation in the lab
    • I can order fans this week.
    • Can we open an additional port for air flow out (and possibly in) to the lab? What's behind the old cryo access in the NW corner, could we put a vent for out flow?
    • Change the HEPA filter
  • Before returning the anemometer, perhaps should measure air flow in the interior of the lab.
  • Check out the new cryo lab group and repo(s) on the github!

Cryo lab air flow

Liz dropped off an air scrubber (Medify Airx MA-40) and an anemometer (Digi-sense 20250-15) today. I'm using the instructions on the DCC to measure the air flow and assess the occupancy limits of the cryo lab. I calculate an acceptable amount of time between lab uses, and for two people to occupy the cryo lab simultaneously. For these calculations, I use a conservative threshold of P<1% for the acceptable probability that a second person becomes infected, given one infected lab occupant who sheds virus at 10 nL/min. I measured the dimensions of the lab at about 30x20x10' (l, w, h), for a 6000 ft^3 volume. I expect that's a high estimate, as it doesn't account for things like the awkward geometry of the staircase, volume of lab equipment, or stagnant air inside cabinets.

I measured the air flow at 20 points in a grid covering the surface of the HEPA filter. I also confirmed that there is no measurable air flow into the lab other than at the HEPA filter (eg, at the hole in the ceiling in the NW corner of the lab, or where the RF timing sígnal is sent through wall to Crackle lab). The average air flow through the HEPA filter is 200 CFM (cubic ft / min).
The flow is highest near the edges of the filter--does this indicate it is nearing the end of its life (it's been at least a year since replacement)? The flow is mostly above 200 CFM, but varies from 100-300 CFM across position and time.


The first row is the minimum number of minutes to wait between when a (presumably infected) person exits the lab, and when a (presumably uninfected) person can enter the lab to maintain a <1% probability of new infection through aerosolized spread. The second row is the maximum number of person-hours the second and further (presumably uninfected) users can collectively spend in the lab with one presumably infected user, while still keeping a <1% probability of observing any areosolized spread. I don't have Spirou online currently, but I'll eventually put the calculation notebook in a shared folder accessible to the new cryo lab environment repo. Update: it's here.
Configuration cloth mask, no scrubber cloth mask, with scrubber N95+, no scrubber N95+,with Scrubber 
Minimum time between occupants (min) 17 7 0 0
Maximum person-hours of shared occupancy (person-hour) 0.004 0.008 0.08 0.15

These results are consistent with what I see for similar types of rooms in the LIGO spreadsheet.

Under an air flow model assuming perfect distribution of air from HVAC and HEPA scrubber throughout the lab, and very conservative requirements for probability of spreading COVID assuming a single lab user is infected, 

  1. Within 6 minutes of an infected user exiting lab, an uninfected person can enter and expect a tolerably low concentration of aerosolized virus.
  2. Within 10 minutes of one infected and one uninfected person working in the lab 6'+ apart with N95 or better masks, the viral load to an uninfected at-risk person may be intolerably high

Furthermore, the air in the lab Is not perfectly distributed. The air intake is several feet from the outflow, both near the door. The primary heat sources are the electronics racks along the N and NW sides of the room. The gradient from 71.1 F at the thermostat to 78 F at the cryocavs rack is uncomfortable to work in and bad for the electronics and optics. It's also too stagnant for the viral load conditions assumed in Evans P2000189 to apply. 

We are not currently cleared for 2+ people to use the lab. This analysis suggests to me that before doing so, we should improve the air flow conditions in the lab. And, even under optimal conditions we may minimize the total time with multiple people in the lab simultaneously.

Rio laser

I disconnected the oscillator, PDH boxes, and laser drivers from the power strip, and powered the strip with the Tenma supply. I had the ground and negative pins switched at first, careful of this -- ground is black, negative is green on this cable.

I plugged in the electronics, but only turned on DC power to the laser driver. I just left them on long enough to confirm a bright green (on viewcard) beam spot for both lasers -- we're in business!

Turned off the lasers, disinfected the common surfaces and objects.

PS, the anti-fog wipes work wonders. My goggles went from fogging in seconds to no fog at all.

  2550   Wed Aug 5 19:03:56 2020 aaronUpdateLab WorkNotice of lab entry

Notice of lab entry

Date of entry: 7 Aug 2020
time of entry:  11:00 
time of exit:   
edit: postponed this work from 6 Aug to 7 Aug.

Purpose: Measure optical table dimensions, start to assess what we need for an enclosure. Set up EOM/EOAM to take some transfer functions. Set up realtime model. Figure out why particle counter isn't logging to frames. Turn on the HEPA for cryo cavs table.

  2551   Fri Aug 7 11:35:09 2020 aaronUpdateLab Worklab work

Entered the lab at 11:00 am. The lab is far too hot (78F) and humid (45%)! 

Inventoried available photodiodes in the cryo lab, on the PSOMA wiki.

Fri Aug 7 12:55:53 2020
Facilities came to check the fire alarm. I let them in with shoe covers, they held a magnet up to the fire alarm and left. Total operation took less than 5 min.
[lunch and a couple meetings 1 - 3]

Pretty tired honestly, I submitted an order for a few things we want in the lab, such as:

  • 2x "ultra quiet" fans to circulate air
  • longer ethernet cable for reaching far end of PSOMA table
  • headset web cam so we can take video while doing lab activities
  • more plastic storage bins
  • food and water for our emergency kit

The PSOMA optics table is from TMC vibration control (TMC 784-29701-01). I sent them an inquiry for the datasheet, and also asked whether they sell clean enclosures or have application notes that might help us put one together. Also talked with Arian Jadbabaie a bit about the Hutzler lab enclosures, and got some photos.

Exit ~430 pm

  2554   Tue Aug 18 15:05:33 2020 aaronUpdateLab Worknotice of lab entry

Notice of lab entry

Date of entry: 18 Aug 2020
time of entry: 2pm
time of exit:   11pm

Purpose: Inventory lens supply, identify some combination of optics that will let us mode match to our ring cavity. Picked up some books on silicon from the library.

  2555   Tue Aug 18 21:35:49 2020 aaronUpdateLab Worknotice of lab entry
I'm taking inventory of our optics supply, in between figuring out what's wrong with the temperature log channels.

The inventory is in Clickup, which is a new organizational tool I'm trying out. There' an easy csv export, so I can get it elsewhere if/when we want. We have a wide variety of lenses:

Focal length (mm) 25.4 38.1 100 103.22 154.82 200 225 250 258.04 309.65 412.86 500 850
Quantity @ 1550nm 1 4 2 7 2 2 6 2 1 3 12 1 2

I found fewer curved mirrors, but there were a couple.

Steps I took for the temperature sensor:

1. Tried to see what's the temperature by reading the current temperature in ndscope or dataviewer. In dataviewer, go to 'Signal' tab, and enter the channel name or find it on the list of slow channels. For ndscope...

nsdscope X1:AUX-LAB_TEMP_F 

No data appears on either. I restart cymac1, which seemed frozen, but still nothing.

2. What's going on with these channels?

$ caget X1:AUX-LAB_TEMP_F
X1:AUX-LAB_TEMP_F     -459.7
$ caget X1:AUX-LAB_TEMP_K
X1:AUX-LAB_TEMP_K     -0.0166677

Looks like the channel is reading zero.

3. I traced the cable from the particle counter and found that it sends data to cominaux, the common auxiliary machine for the lab.

ssh cominauxThat's a little surprising to me, because
cd ~/services/modbusIOC/
less CRYOXT.db

This is the database file that defines the channels on cominaux. I search for 'LAB_TEMP_F' and find the epics record for the temperature channels. The epics records are all "calc" records, and the temperature in Kelvin is taken from X1:AUX-ACROXT_AI_15. This corresponds to channel 15 of the acromag slow ADC.

$ caget X1:AUX-ACROXT_AI_15
X1:AUX-ACROXT_AI_15     -0.0003333

 That's starting to make sense, the cable from the particle counter didn't go to the acromag ADC. Starting from the ADC channel 15, I traced the cable back to what used to be the AD590 temperature transducer.

4. Where did the IC temperature sensor go? Searching the elog and my dusty memory... neither readily recalls where it went. Let's get another one, they are cheap and easy to use.

  2556   Wed Aug 19 12:11:47 2020 aaronUpdateLab WorkNotice of entry

Notice of lab entry

Date of entry: 18 Aug 2020

time of entry: 12pm
time of exit:  
Purpose: Identify some combination of optics that will let us mode match to our ring cavity, set up PDH locking with the existing ~33 MHz modulation.
  2557   Wed Aug 19 12:15:40 2020 aaronUpdateLab WorkNotice of entry

The cameras were unfortunately lost in the mail, but we can use my laptop or other camera. Ended up leaving to do a couple comsol things that needed completing today.

  2558   Mon Aug 24 13:21:40 2020 aaronUpdateLab Worknotice of entry

Notice of lab entry

Date of entry: 24 Aug 2020

time of entry: 12pm
time of exit:  
Purpose: stage 1 cavity setup
  2559   Mon Aug 24 13:22:32 2020 aaronUpdateLab WorkalaPSOMA

Did some mode matching, see the git.

  2561   Tue Aug 25 13:42:40 2020 aaronUpdateLab Workoptics setup

setting up PSOMA beam path

I took some photos of the existing layout. I'll just take apart the E beam path, and leave the W path unchanged for now as reference.

I moved the E fiber output coupler closer to the edge of the table, to make this path easier to reach.

Hopped around on the laser hysterisis curve for a minute. To optimize the temperature,

  1. Started with TEC on near room temperature, then turned on the laser driver with the current set to maximize power on the meter (S122C)
  2. increased the temperature setpoint (decrease resistance setpoint) slowly until the laser power starts to decrease.
  3. Turn off the laser driver. Decrease temperature setpoint to just below the maximum power setpoint.
  4. Turn on the laser driver. Total power is now 4.6mW, compared to ~2mW with TEC off.
  2562   Wed Aug 26 12:12:22 2020 aaronUpdateLab Workoptics setup
  • aligned beam along the NS axis using two irises and the existing 2x f=100 lenses from the E path.
    • HWP->steering mirror-> 90-10 BS -> iris -> lens -> lens -> iris -> PD
    • all transmitted beams dumped
  • Mounted a 1'' x 1m FL Si mirror in a polaris mount. Made a ring cavity with that and 2x mirrors coated for 45 deg.


Can anyone tell me the specs / history of some of the custom optics in cryo? I'm mounting the 1m Coastline mirror and will start with that in the PSOMA cavity.

  • Laseroptik 1'' mirrors. Batch # 19028Kel. Part(?) numbers L-13997, L-13998. (these are in red boxes cases w clear lid)
  • Coastline Optics 1.0''x0.25'' FS substrates. Coated for 1550nm at 45 degrees. (these are in stacks cylindrical clear cases, and include some witness and rejected samples)
  • Coastline optics 1'' silicon substrate, 1 meter focal length. SN 1.0-Si-1.0M
  • Photon Laseroptik 1'' FS substrates (~50), labeled 75S308926. Also labeled with a wedge angle or what looks like a focal length (no unit)
  • Two stacks from Gooch & Housego, taped in bubble wrap with the data sheet. These are coated for 1550nm, transmission ~1% S and ~5% P at 45 deg.
  2564   Fri Aug 28 16:59:59 2020 aaronUpdateLab Workoptics setup

I measured the transmission of the Coastline 1m mirror at 180. ppm (S122C).

Alignment procedure while setting location of optics:

  1. use 2x irises to constrain a beam path at the locations of the eventual MZ input BS and the cavity BS.
  2. Place the first (R~1) flat mirror at 45 degrees centered on the beam line. Use this mirror to steer into an iris at the location of the cavity's curved mirror.
  3. Use steering optics to direct the eventual transmission beam into the trans mon PD (PDA 20CS)
  4. Place the curved mirror at near normal incidence. Use this mirror to steer the beam through irises at the location of the MZ output BS and cavity BS.
  5. Use steering mirrors to send the beam to the refl PD (PDA255).
  6. Place the cavity BS and steer the reflected beam to the refl PD.

Alignment procedure subsequently:

  1. Misalign the cavity BS
  2. Use the cavity mirrors to steer the circulated reflection into refl PD.
  3. Use cavity BS to align prompt reflection into refl PD.


  2565   Mon Aug 31 10:00:25 2020 aaronUpdateLab Workoptics setup

Here's the layout.

Some easy things that should be changed:

  • Transmission through the cavity end mirror should go to a steering mirror before PDA20CS
  • Should clamp the cables (eg power to PDA255) with something soft so they stay in place and aren't strained
  • Need to dump the reflection from transmon PD. Do we really need to dump transmission through mirrors with frosted backs?
Attachment 1: 200828_layout.jpg
  2566   Wed Sep 2 16:19:57 2020 shrutiUpdateLab Worklab entry, information gathering

Notice of lab entry: 20 Sep 2020   evening

Fiber modulators on the table :

1. Intensity modulators (BW: up to 12 GHz) MXAN-LN-10

2. EOM phase modulators (BW: up to 150 MHz) MPX-LN-01

Dimensions of vacuum cans mentioned in attachments.

Attachment 1: 7BA40146-4F86-4819-8D6C-FFDC8F246E50.jpeg
Attachment 2: 129FE089-1E57-4E6D-9E77-F80F8E124CD1.jpeg
  2575   Fri Oct 23 19:06:05 2020 gautamUpdateEquipment LoanTwo resonant RFPDs ---> 40m

I was in the Cryo lab between 1215-1230 this afternoon. I removed two resonant RFPDs from what was Johannes' setup (encircled in Attachment #1). I also brought a SR554 preamplifier to the 40m.

I was wearing the usual PPE (gloves, face mask) while I was in the lab.

Attachment 1: IMG_8903.JPG
  2581   Wed Nov 18 08:24:02 2020 shrutiUpdatePSOMAtemp control and transverse beam profiles

D [in.]

West laser (X) [um]  West laser (Y) [um] East laser (X) [um] East laser (Y) [um]
2 327.2, 336.5 332.0, 340.9 327.1, 332.8 330.0, 335.2
3 358.2, 269.6 363.4, 374.7    
4 420.4, 439.3 417.8, 439.8    
5 511.7, 549.2 510.2, 549.9 527.6, 550.7 519.6, 540.4
6 642.8, 688.0 630.6, 674.9    
7 766.4, 807.9 754.6, 801.4 778.0, 848.3 716.0, 782.7
8 891.1, 932.6 894.7, 942.1    
9 974.3, 1023.1 943.9, 1000.6    
10 1142.6, 1193.9 1152.7, 1203.5 1092.2, 1159.7 1040.6, 1103.4


This is the data using the Data Ray Beam'R2 profiler with the InGaAs window. Attachment 1 contains images of each of those profiles.

D: distance from fiber launcher in inches; The two values in each of the cells are [Clip 13.5%, 4 sigma] respectively, i.e., the method used to calculate the beam widths.

The previous measurement using a razor blade refers to 'sigma' which I believe explains why these values are 4 times larger.

These profiles were taken with temperature stabilized such that the powers were ~1 mW.

East laser set to 8.070 k Ohm, West laser set to 9.065 k Ohm. I don't understand why there is such a difference.


Other updates:

I had hooked up the ITC 502 combi controller to the west Rio laser and used only its temperature controller. (I believe both the thermistors that measure the diode temperatures are TH-20k Ohm.)

Both the PID controllers work satisfactorily: the TED 200 C with the east laser stabilizes to within few Ohms of the setpoint thermistor resistance within some seconds;

the ITC 502 stabilizes at a similar rate but at an offset of ~10 Ohms despite the integrator being set to maximum. I fiddled around with the P and I settings a little but realized that this configuration seemed optimal.


To measure these profiles at different distances I moved the fiber launcher head and then replaced it back to its original position, roughly.

Attachment 1: beamprofdata.zip
  2582   Thu Nov 19 11:23:44 2020 shrutiUpdateLab Workpsoma locking

Attachment 1: An updated version of the diagram in elog 2577 where the path lengths to the beat beam-splitter are identical. The fiber launchers and some components have been moved around, but everything after PO1.1 along the beam has been retained as before.

Attachment 2: Retaining the same configuration to the beat BS, the cavity with Mach-Zehnder interferometer has been added. Also the path lengths to the MZ input BS along both laser beam paths have the same length. Except for the ring cavity, the Mach-Zehnder is also balanced.

Attachment 3: Updates pertaining to the current setup

  • Work in progress to achieve the configuration in Attachment 1.
  • I have switched the two PDs so the beat can be measured with the Newfocus 1611 (has a larger BW) and the noise measurement with the east laser can be done with the Newfocus 1811.
  • I removed the 10/90 pick-off circled in green, so that would have to be added to the path to continue the noise measurement.


Attachment 1: PLL_FS_sym.pdf
Attachment 2: MZ_PLL_FS_sym.pdf
Attachment 3: NewBeat.pdf
  2585   Tue Nov 24 10:16:04 2020 shrutiUpdateLab Workpsoma locking


- Found a suitable power cable M-M for the New Focus 0901 power supply on the east table (I did not realize yesterday that these were the same cables). Then I checked the voltage on the pins and they were fine.

- Using the New Focus 1611 (1 GHz PD) powered by the New Focus 0901 +-15 V / 0.3 A max. power supply, I tried finding the beat note. I looked at the RF output on a HP 8560 E spectrum analyzer and the DC output on an oscilloscope.

The DC output ranged from 500 mV to over 1 V as I scanned the temperature of one or both lasers.

- When the east laser temperature read roughly 8.34 kOhm and west was 9.04 kOhm I saw a pattern as in Attachment 2.

Changing the temperature slightly did cause the peaks to shift about, and further when I changed the polarization of the east laser using the HWP the height of the peaks varied. They also disappeared when either of the beams were blocked.

The estimated peak power in the taller peaks is ~0.1 µW from the plot.

- I also tried scanning the temperature of both lasers again to possibly find a single peak. No luck yet.

Today, I didn't check the alignment very carefully and I probably have to tune it further after the changes that Aaron and I made over the past few days.

The next step is to do the phase-locking.



Attachment 1: BeatSetup.pdf
Attachment 2: BeatOrNot.pdf
ELOG V3.1.3-