40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
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ID Date Author Type Categorydown Subject
  2082   Wed Jan 25 11:41:55 2017 AidanComputingCymacsPulled old IO chassis and FB0

We want to set up a new Cymacs in the ATF. It would be much cheaper if we don't have to order new ADC and DAC cards.

I pulled the old IO chassis (which contained the old ATF ADC and DAC cards). Unfortunately. they are PCI-X (we think) which will not fit in the PCI-E slots in the new Cymacs. 

We figured we might be able to leave the DAQ cards in the old chassis and continue to it if we can hook it up to a new Cymacs. So we pulled FB0 and extracted the board that expands the BUS out to the IO Chassis (see below). At the moment, we're investigating if this board will work in the new Cymacs. It is, at least, PCI-E.


Attachment 1: IMG_8643.JPG
  2098   Tue May 2 15:31:24 2017 AidanComputingCymacsATF Cymacs FB4 built - only OS and RTSCDS package right now

I've installed Debian 8 on the new ATF Cymacs and called the machine FB4.

Following the instructions on the ATF Wiki, I've installed the ADVLIGORTS-CYMAC package. However, I've not built the framebuilder, RTS or DAQD.


  2302   Mon Mar 11 08:49:11 2019 Aidan, ChubComputingCymacsBuilding FB4 Cymacs

We started migrating equipment for the FB4 Cymacs to the QIL on Friday. See attached list and images.

Attachment 1: IMG_8851.jpg
Attachment 2: IMG_8852.jpg
  2336   Tue May 7 19:39:39 2019 JonLab InfrastructureCymacsUser model set up on QIL cymac

This afternoon I set up a user model on the QIL cymac (fb4), which appears to be running. It required the following steps.

First I created a simple SimuLink model of the signal flow from the one ADC card to the one DAC card (pictured below). The 32 input channels from the ADC are each routed through a standard LIGO filter module (10 IIR filter slots, ramped gain, and test/excitation points). From there the 32 conditioned signals are routed into an output matrix constructing the 16 output signals to the DAC. I saved this model to /opt/rtcds/userapps/local/c4tst.mdl.

Next I compiled the model and installed the build files to the RTS target directories:

$ cd /opt/rtcds/rtscore/release
$ make CC=gcc-4.4 c4tst
$ make CC=gcc-4.4 install-c4tst

Finally I started the new model services and enabled them to auto-start on boot.

$ sudo systemctl start rts@c4tst.target
$ sudo systemctl enable rts@c4tst.target

The cymac I/O has not yet been tested.

Attachment 1: IMG_3278.jpg
  2337   Fri May 10 13:54:28 2019 JonLab InfrastructureCymacsQIL cymac installed in rack, passes loopback testing

After a bit more debugging, Chris and I determined the RTS software was fully functional. At this point I moved all the cymac hardware from underneath the ws2 desk to the neighboring server rack. I permanently mounted the linux machine, fb4, and the anti-alias and anti-image chassis (pictured). Installing fb4 required removing an existing machine, fb1, which Chris and Andrew confirmed is not in current use. For now fb1 is sitting against the wall near the rack, as we may be able to repurpose it. The rest of the hardware is connected temporarily for testing while we await a few remaining cables, etc. (more on this below).

I performed a simple loopback test on the cymac input/output channels. I set a large DC offset (10k counts) in one DAC channel at a time, connected this signal to an input ADC channel, and measured the input channel response. All 16 DAC channels and all 32 ADC channels were confirmed to drive/sense the signal, and in every case the ADC gain was found to be identical: 0.38 counts/count.

There are still a few items to wrap up the installation:

  • [Jon] Create a sitemap MEDM screen
  • [Chub] Two 5' SMB-BNC cables, for connecting the timing reference to the adapter boards. The ones in use now are poor-quality. Chub has already ordered these cables.
  • [Chub] Two backplates for the D060060/D060061 adapter boards, to let them mount in the computer chassis like a PCIe card
  • [Chub] Install a long BNC cable between the cryolab and ATF server racks, for delivering the 10 MHz GPS timing reference. Chub and I walked through the labs this week and determined the cable route and required length.
  • [Chub] +/-15V rackmount power suppy, to replace the bench supply currently power the AA and AI chassis
  • [Chris, Jon] Configure the framebuilder functionality
Attachment 1: IMG_3289.jpg
  2340   Sat May 11 15:47:37 2019 JonLab InfrastructureCymacsMEDM user interface set up on QIL cymac

I created a basic MEDM sitemap modeled after the one the cryolab is running. It is accessed by connecting to fb4 ( and executing the usual command $ sitemap. Eventually the fb4:/opt/rtcds/caltech/c4/medm directory should be shared with all QIL workstations via NFS, so that directly connecting to fb4 is not necessary. The master screen provides full control of the signal routing and conditioning supported by the user model. The 32 input signals from ADC0 are individually conditioned via standard LIGO filter bank modules and routed through an output coupling matrix, which constructs the 16 output signals sent to DAC0.

Attachment 1: Screen_Shot_2019-05-11_at_3.21.07_PM.png
  2342   Wed May 15 19:24:52 2019 JonLab InfrastructureCymacsPermanent cymac hardware installed and tested

[Jon, Chub]

Today Chub brought over the remaining parts for the cymac and we installed them. Specifically:

  • ADC and DAC adapter boards permanently mounted inside the fb4 chassis
  • SRS DS345 function generator mounted on a new shelf installed near the top of the rack
  • New, higher-quality timing cables installed
  • 160' timing cable run from the cryolab to the QIL, to provide a 10 MHz GPS reference signal

Initially I found that no timing signal was reaching the lab. The function generator for the cryolab cymac was also not receiving a signal. I traced the problem back to the RF distribution box in the cryolab, whose power cable appears to have come unplugged. I reconnected it and both labs are now receiving the timing signal.

After installation, I repeated the manual loopback test in #2337 for all ADC and DAC channels. All of the channels still work, and the ADC gain was found to identical to before (0.38 ct/ct). For future reference, the second attachment shows the state of the system overview screens when the cymac is in normal operation. Chris has confirmed that not every indicator light on these screens will turn green. 

The last piece of hardware work is to replace the bench power supply currently powering the AA and AI chassis. Chub and I plan to replace it with two rackmount Sorensenn supplies, one of which is already installed in the rack. Chub is going to procure a second.

Attachment 1: IMG_3300.jpg
Attachment 2: IMG_3299.jpg
  2369   Wed Jul 10 17:37:09 2019 JonComputingCymacsNew QIL workstation

I finally succeeded getting Debian installed on the new workstation with a working network card. I installed Debian 10.0, which was just released last week and will be supported for five years. After installing the OS, I

  • Configured the machine (network interface, user account, etc) following my standard procedure
  • Installed the cds-workstation superpackage following Jamie's instructions.

The user name is controls as usual and it has the standard W. Bridge password. The lscsoft repo for Buster (Debian 10.0) is still missing many packages, so I installed the cds packages for Stretch (Debian 9.9) instead. They seem to be compatible with 10.0 as far as I can tell. The machine is at the same IP as the one it replaced,

To be able to interface with the cymac, there is still an RTS environment (environment variables and an NFS mount) that needs to be set up. I'm looking into what this involves.

Attachment 1: IMG_3493.jpg
  2370   Mon Jul 15 19:02:21 2019 JonComputingCymacsCymac RTS Environment Set Up

Chris and I set up the LIGO RTS environment on the QIL cymac, using code copied from the cryolab cymac. Specifically, the script /opt/rtcds/rtcds-user-env.sh was edited to match the cryolab version and added to the /home/controls/.bashrc file. We also downloaded a copy of the CDS user apps SVN to /opt/rtcds/userapps/release. Tools like dataviewer and ndscope now work on the cymac (fb4:

Our plan is to set up a network drive on a third machine to host the /opt/rtcds directory currently located on the cymac. This way, the directory can be shared with any number of workstations as well as the cymac itself, and the NFS mounts will be unaffected by frequent reboots of the cymac.

I also unsuccessfully attempted to diagnose the race condition that occurs between all the RTS services on boot. Right now the services all start correctly only about 1/3 of the time. I tried setting the order that the services are started and adding a 15-second delay after each service start. However, this did not make things become deterministic.

  2371   Mon Jul 22 18:11:59 2019 JonComputingCymacsNew Monitors for QIL Workstation

Two new 27" LED monitors arrived today for the QIL workstation. I've installed them.

Attachment 1: IMG_3523.jpg
  2397   Tue Aug 13 19:14:04 2019 JonComputingCymacsNFS server set up

I rebuilt one of our old desktop machines to serve as NFS server for the cymac. It is running Debian 10.0 and assigned IP (hostname qil-nfs). I installed a new 2 TB hard drive dedicated to hosting the LIGO RTS software and frame builder archive, which is shared with all other lab machines via NFS.

I have moved the new machine into the server rack and copied the contents of /opt/rtcds on the cymac into the shared location. Functionality like sitemap and the CDS tools can now be run directly from the QIL workstation (plus any other machine on which we add the NFS mount).

Attachment 1: IMG_3587.jpg
  2427   Tue Oct 1 19:25:08 2019 JonComputingCymacsIP address changes

Someone (not me) has recently changed the IP addresses of the lab machines. I see the new assignments are the following: ? QIL Lab fb4 ? QIL Lab qil-nfs ? QIL Lab qil-ws1 ? QIL Lab qil-ws2
  2544   Thu Mar 25 12:28:19 2021 AidanComputingCymacsDAC channels not outputting voltages

Noticed that the DAC channels were not producing a corresponding output in the real world (I changed the Laser Current FM12 value and got not corresponding change on the laser diode driver display).

Sent the following to Chris: "Can you log into the QIL FB4 workstation to see if there is an issue with the DAC? I restarted the C4TST model last week and I don’t seem to have working DAC outputs anymore. The ADC channels still work and the model appears to be running. It just seems that I can’t output any voltages."

After observing that the "DK" (DACKILL) bit in the state word on the IOP status screen was red, the resolution to this was to restart the IOP and TST models.

  2546   Wed Mar 31 11:06:53 2021 AidanComputingCymacsRebuilding the Cymacs software to compile models

[Aidan, Jon, Chris W, Ian]

Summary: We rebuilt the Cymacs C4TST today to get FM31_OUT into frames

Main points: 

  • Had to mount fb4 epics/simLink directory with CDS_PARTS onto QIL-WS2 (only machine with Simulink)
    • Had to make this directory viewable on other machines by editing the /etc/exports file on FB4
    • Had to update the /etc/fstab file on QIL-WS2 to give it the location of the new directory
    • Had to manually mount the directoy on QIL-WS2 to avoid rebooting machine to achieve this (reboot will automatically mount the drive)
  • C4TST model would not compile on FB4. Issue was two-fold:
    • Compilation was done in wrong build directory
    • Compilation was done using sudo
  • To fix this, we had to clean up the compilation files from the failed sudo efforts
    • sudo make clean-c4tst was run (didn't completely solve problem)
    • Removed /usr/share/advligorts/src/src/include/c4tst* using sudo
  • Once the old compiles were cleaned up, we could compile models (not as sudo) in /opt/rtcds/rtbuild/
  • Ran the following commands to manually restart the models (ignore the line numbers)
 1982  sudo /sbin/rmmod c4tst c4iop 
 1983  cd /opt/rtcds/caltech/c4/target/c4iop/scripts/
 1984  ./startupC4rt 
 1985  cd ../../c4tst/scripts/
 1986  ./startupC4rt
 1987  systemctl start rts-awgtpman@c4iop.service
 1988  cd .././../
 1989  ls
 1990  cd gds
 1991  ls
 1992  cd awgtpman_startup/
 1993  ls
 1994  ./awgtpman_c4iop.cmd 
 1995  ./awgtpman_c4tst.cmd 
 1996  systemctl restart daqd@standiop.service
 1997  systemctl
 1998  systemctl status daqd@standiop.service
 1999  systemctl stop daqd@standiop.service
 2000  sudo systemctl restart daqd@standiop.service

  2653   Fri Aug 27 15:33:28 2021 AidanComputingCymacs 

Got the DAC working by reactivating entries in the C4TST_cdsMuxMatrix.

  • FM12-DAC12 = 1 (laser current) works
  • FM13-DAC13 = 1 (bias) works
  • FM15-DAC15 = 1 doesnn't work, No output on BNC at the AI chassis

No problems with channels 12-14. However, channel 15 doesn't output anything at the AI chassis.

Using channel 14 on the AI chassis with FM15 input into it.

  • FM15-DAC14


  2658   Tue Sep 7 08:12:50 2021 AidanComputingCymacs+/-18V power supply to AI/AA chassis was actually +18V, -14.5V


I was working in the QIL on Friday and I heard a clicking sound coming from the rack where the DAQ is installed. It turned out to be the DC power supply for the AI/AA chassis. One of the voltage was floating around from ~14.2V to ~14.8V and the unit was clicking as it did this. Since the AA/AI chassis expect +/-18V which is regulated down to +/-15V, this was, to use the scientific term, bad.

I set the low voltage channel back to 18V. We have noticed previous drifts DAC channels - it's possible this was the cause.


Attachment 1: IMG_4578.jpg
Attachment 2: IMG_4577.jpg
  2660   Tue Sep 7 11:52:40 2021 ranaComputingCymacs+/-18V power supply to AI/AA chassis was actually +18V, -14.5V

We should not have a bench power supply installed permanently. Can you install a Sorensen in that rack or use one of the nearby ones?

  2705   Wed Dec 31 15:59:59 1969 StephenDailyProgressCryo vacuum chamberRadiative Cooling of Si Mass, with worse inner shield inner surface emissivity - retry run was successful

This post will host plots and trends from this radiative cooling run (QIL/2704).

Preliminarily, it looks like the reconfiguration to remove a hardware mistake or two led to a healthier run. The comparison below clarifies the two runs:

  • QIL/2702 - conductive link between inner shield and outer shield (twisted pair from an RTD lead accidentally clamped); possibly another conductive link between outer shield and baseplate (outer shield more wobbly than usual on spacers)
    • this data set should only be used to study the impact of a known conductive link between inner and outer shields.
    • this run demonstrates that there will be more effective, faster cooling if the outer shield is conductively cooled!
  • QIL/2704 - resolved above mistakes!
    • this data set may be used to gain understanding of the impact of emissivity changes to the inner surface of the inner shield.
    • may be compared to QIL/2695, a run that is equivalent except with a higher emissivity inner surface of the inner shield

Run ended with cryocooler shutdown at 12:27 pm (actual duration just under 92 hours). System will warm up with pumps on for the rest of the break, unless I am inspired to come in and run one of the next intended runs discussed in QIL/2704. I did not run any heat input test for this data set, as I am not planning to come in frequently enough to monitor the heating safely.


Attachment 1 compares QIL/2704 (solid) to QIL/2702 (dashed). As expected, the outer shield temperature from the latter run stays warm since the conductive short was resolved. Due to the reduction of the inner shield's thermal load, the inner shield is able to cool faster and plateau at a colder temperature. As Stephen pointed out, however, the test mass is not cooled as efficiently compared to when the outer shield was conductively cooled.

Fitting Results:

Attachment 2 is a current model diagram of the various components being considered, and their thermal couplings. Attachment 3 plots the fitted model (dashed) over the temperature data (solid). The fit parameters were the following emissivities: aluminum foil, rough aluminum, and aquadag. Notes from the fit:

1. With the conductive shorting of the outer shield resolved, the model (which considers only radiative cooling of the OS) is well fit to the OS temperature data

2. The inner shield model is missing some key term(s) affecting its time constant and steady state temperature.

3. The above error propagates to the test mass model (I believe). 

Given these caveats, the fit results are as follows: aquadag e = 0.92, Al foil e = 0.04, rough Al e = 0.19. These all initially seem reasonable, and I'm happy to see that the aquadag emissivity is higher than previously estimated.

Next steps:

1. Separate the cold plate from the inner shield, and model their conductive and radiative link. Also model the radiative link between the cold plate and the test mass.

2. Cover the test mass in foil (to best of our ability) to refine the radiative link between the test mass and inner shield. Doing so will mean both elements have the same emissivity, so there is only one unknown parameter.

Attachment 1: cooldown_12-21_vs_12-10.pdf
Attachment 2: Megastat_Heat_Load_Sketch.png
Attachment 3: 12_21_cooldown_fit.png
  2261   Wed Nov 14 16:49:47 2018 RahulUpdateCryo vacuum chamberassembly

The top (seen with several threaded holes along with 16 through holes) and bottom (only 2 threaded holes for lifting and 16 through holes) plate for the vacuum chamber has arrived and I have moved them into the QIL optical bench/table. Using some aluminum struts/bosch, I am making a simple 3’’ tall spacer on top of which the bottom plater will be resting. After wiping them with solvents, I will start assembling the chamber and the plates.

Attachment 1: Bottom_plate.jpg
Attachment 2: top_plate.jpg
  2267   Tue Dec 4 15:56:29 2018 RahulDailyProgressCryo vacuum chamberO-ring which fits

The viton O-ring shipped by Nor-Cal fits the chamber groove, given below is the correct specification for future reference. I am buying few more for spares.

2-473 Viton , ID 23.940'' OD 24.490'' Width 1/4''

Attachment 1: IMG_0170.jpg
Attachment 2: IMG_0171.jpg
  2269   Wed Dec 5 16:18:50 2018 RahulDailyProgressCryo vacuum chamberbottom plate

Aaron and Rahul - The bottom plate of the chamber was upside down (Gabriele and I did it as we were trying out few things during assembly last week). Now, the bottom plate has been inverted (using crane and trolley) and is ready for the chamber to be brought in. I am giving the chamber and the plates a thorough wipe (speckles of dust easily visible) and the grooves for the O-ring also looks slightly dusty. Probably I should get clean plastic sheets to cover the vessel when the top lid is open.

  2270   Wed Dec 5 16:49:50 2018 RahulDailyProgressCryo vacuum chamberSchematic for the flanges

The vacuum chamber has 12 flanges (four 4-5/8 and eight 2-3/4 flange size). For the pump down test I will attach the pumping station to the 4-5/8 flange and close down the other three flanges with blank flange. Similarly out of the eight smaller flanges (2-3/4 size) five will have Tees (for 2 gauges), up to air valve, two optical windows, cryo-feedthrough and the remaining with blank flanges (or else I can change them with other feedthroughs to test them out for vacuum leakage). Just for information - the pumping station is attached to a reducer which will house the rotary valve. Reducer is requred to match the flange size of the pumps (4-51/2 siz - CF63 size) and the vacuum chamber (4-5/8 size). The rotary valve will be attached to the hose which will then be attached to the flange of the vacuum chamber.

Attachment 1: Schematic_chamber.jpg
  2271   Thu Dec 6 12:44:18 2018 RahulDailyProgressCryo vacuum chamberFabricated parts arrived

Cold plate and the radiation shields have arrived. I will perform a mock assembly of these fabricated parts to check if they are as per our drawings. Next, the outer radiation shields will be shipped for gold plating the outer surface. Rest of the fabricated parts will be cleaned (lots of grease and finger marks visible) and then baked.

Attachment 1: Fabricated_Cold_plate.jpg
  2272   Thu Dec 6 16:49:40 2018 RahulDailyProgressCryo vacuum chamberChamber and bottom plate assembly

The bottom plate and the vacuum chamber (collar) has been assembled – thanks to Aaron for helping me out. The O-ring holds in well in the dovetail groove and makes it really easy (without falling off) to assemble the two components together.

Attachment 1: O-ring_bottom.jpg
Attachment 2: Bottom_collar_assembly.jpg
  2276   Fri Dec 7 16:08:45 2018 RahulDailyProgressCryo vacuum chamberRadiation shields

The cold plate and radiations shields (100K, 50K and bottom 100K shields) are at 40m for cleaning and baking. The outer shields will be cleaned and then sent for gold plating. The inner shield and cold plate be baked after cleaning. 

Attachment 1: shields_1.jpg
Attachment 2: shield_2.jpg
Attachment 3: shields_bottom.jpg
  2278   Tue Dec 11 16:26:07 2018 RahulDailyProgressCryo vacuum chambercleaning of shields and cold plate

The radiation shields and the cold plate have been cleaned twice at the bath at 40m. They are currently undergoing baking for 12 hours, will pick them up on Wed morning once finished.

  2279   Wed Dec 12 14:40:17 2018 RahulDailyProgressCryo vacuum chambercleaning of shields and cold plate

The radiation shields and the cold plate have been cleaned (class B) and baked and can be used in vacuum. I brought them back to the lab and will ship the outer shields for Gold plating.

Attachment 1: IMG_0238.jpg
Attachment 2: IMG_0237.jpg
  2285   Fri Dec 21 15:23:02 2018 RahulDailyProgressCryo vacuum chamberChamber closed for 1st pump down test

The cryo vacuum chamber was closed yesterday (Thursday) for the 1st pump down test. The figure below shows various components which was attached on to the CF flanges. Later I will post the results of the ongoing pump down test.

Attachment 1: Picture1.jpg
Attachment 2: Picture2.jpg
Attachment 3: Picture3.png
Attachment 4: Picture4.jpg
  2288   Fri Dec 21 16:14:42 2018 RahulDailyProgressCryo vacuum chamberPump down results

I switched on the pumping station this morning at 10 am and roughly after 6 hours of pumping the pressure in the vacuum chamber is 8.2*10^-6 Torr. The pressure is being monitored using two gauges (wide range gauge and Ion gauge). However due to some reason the gauge controller is unable to switch on the Ion gauge (there is an inbuilt safety in the controller to protect the low pressure gauge, so this could be one of the reason).


I will keep the pumps running overnight and through out the weekend to monitor the pressure.

Attachment 1: Pressure.jpg
Attachment 2: PLot1_pressure.png
  2364   Tue Jun 18 00:43:17 2019 DuoDailyProgressCryo vacuum chamberChamber Opening

With the help from Chub, we opened the vacuum chamber. The procedures are not complicated. Here are some notes, both about the opening procedures and some other things I learned from Chub.

1) Vent the chamber by opening the venting valve slightly. The venting process needs to be slow - we cover it with a wipe, as shown in the photo 1. We stop opening the valve when we hear the air wheezing.

2) The thing with a screen is a gauge, which gives the pressure inside, but it is not quite working - always showing atmosphere pressure. Chub left me a document on it; I should be able to get it working.

3) We removed the screws of the top chamber. Correct hex keys is necessary - I was going to use one that loosely fits but Chub said it is not good.

4) We lifted the cover of the chamber with the crane and put it besides the chamber. We should release the break of the crane first and then break it again when we land the weight.

5) The pump connection is not very good - leaking oil both into the chamber and onto the floor.

6) The surface under the chamber (shown in photo 2) cover can only be cleaned by dry wipe or alcohol. 

Next I am going to set up the optics, electronics and whatever inside before we close it and pump it down.

Attachment 1: image1.jpeg
Attachment 2: image1.jpeg
  2428   Wed Oct 9 17:40:57 2019 Raymond, Chris, DuoDailyProgressCryo vacuum chamberClosing the vacuum chamber

We closed the chamber without installing the radiation shields or cold plate in order to test the vacuum pressure of the empty system. Upon turning on the backing pump there was a fine oil mist from exhaust port, so the pump was turned off and an oil trap/filter has been purchased. 

It was estimated that 12 inch/pound of torque is required for each of the top plate bolts in order to compress the 75 Shore hardness Viton o-ring by 20% (recommended by O'Hanlon). 


  2429   Thu Oct 10 17:28:33 2019 Raymond, ChrisDailyProgressCryo vacuum chamberRadiation shields unpacked

Today we unpacked the radiation shields and started to puzzle out how to assemble them. Attached are photos of the parts as we guessed they are intended to stack up. We didn't see how the outer shield would be supported and isolated from the cold plate, so we are contacting Rahul to clarify.

One detail not shown in these photos is the rather poor weld quality on the interior of the outer shield.


Attachment 1: IMG_20191010_150645.jpg
Attachment 2: IMG_20191010_150700.jpg
Attachment 3: IMG_20191010_150711.jpg
Attachment 4: IMG_20191010_150757.jpg
Attachment 5: IMG_20191010_150817.jpg
Attachment 6: IMG_20191010_150826.jpg
  2430   Fri Oct 11 17:12:26 2019 Raymond, ChrisDailyProgressCryo vacuum chamberClosing the vacuum chamber

We installed the oil filter/trap on the roughing pump and began pulling a vacuum. This was delayed due to the turbo pump flashing an error message and shutting off automaticallly after failing to spin up within its preset ramp-up time (error message 1221(3)). Upon restarting the system there were no ramp up issues, likely due to the chamber already having pumped down to ~0.5 Torr at the time of restart. Fix: need to increase the turbo pump delay start time, currently at 0 (immediately spins up). After 30 minutes of pumping the pressure reached ~4e-5 Torr in the chamber. (It reached 7e-6 torr after 3 days of pumping.)

We also tested an alternate internal configuration with the unwrapped components (see attached doodle, unlabelled green disc is the cold plate). This has the advantage of thermally isolating the outer radiation shield from the cold plate, but, we found, would slightly misalign the optical input ports. 

Several ant traps were placed around the lab to combat the observed ant problem. 

Attachment 1: IMG_0204.JPG
  2431   Fri Oct 11 17:33:47 2019 ranaDailyProgressCryo vacuum chamberClosing the vacuum chamber

we'll suffer if we use a oil based pump long term - please find and order a dry pump to back this turbo. Not only is it bad for the vac chamber, its bad for other optics in the lab,

  2434   Fri Oct 18 14:44:22 2019 ChrisLab InfrastructureCryo vacuum chamber208V electrical service was installed in the QIL

A historical note - electricians from Facilities visited the lab several weeks ago and installed new electrical service. To do this with a minimum of disruption to the lab, they de-installed some electrical outlets along the south wall and reused the conductors. They also taped up plastic sheeting to the table enclosure to protect the squeezing and laser stabilization experiments.

  2435   Mon Oct 21 17:07:17 2019 ChrisLab InfrastructureCryo vacuum chamberCryo chamber vacuum pressure logging

Ever since the initial pumpdown the pressure in the new cryo chamber has been stuck at ~6e-6 torr, so there's probably a small leak.

Our vacuum gauge controller has a serial communications port, which we can use to log the system pressure to aid in leak hunting. It's connected now to an unused port on fb4. A small python-based epics server queries the pressure gauges and makes the data available as two epics channels, C4:VAC-CRYO_PRES_P1 (wide range gauge) and C4:VAC-CRYO_PRES_P2 (ion gauge). These are recorded by the framebuilder. The script is stored under ~controls/services on fb4 and should start automatically on reboot.

Attachment 1: vac.png
  2440   Tue Nov 5 20:06:36 2019 RaymondUpdateCryo vacuum chamberCooler to tank connection

Attached is a drawing of the first phase (minimal vibration isolation) cryocooler attachment, where the main tank connects via the blue rimmed feedthrough. Boxed/circled components are those that will require custom fabrication:

  1. Copper adaptor from heat station to thermal strap
  2. 5.25" outer diameter 2-153 o-ring connection to conflat adapter (DN75 (4-5/8" outer diameter, 3" tube OD) pictured, but am comparing this with the DN100 (6" OD, 4" tube diameter))
  3. Conflat to ASA o-ring adapter
  4. a + b: Copper adapter from the flat strap connector to the round copper vacuum feedthrough (closeup shown in second figure)

Currently there are only two connections that require viton o-ring rather than conflat connections (cooler to piece 1, piece 3 to HV feedthrough). 

Attachment 1: CoolerCartoon.pdf
Attachment 2: Screen_Shot_2019-11-05_at_20.25.54.png
  2441   Wed Nov 6 17:05:33 2019 RaymondDailyProgressCryo vacuum chamberConflat flange tightening

Tightened all of the vacuum ports on the chamber so that the flange interfaces are all now metal-to-metal, ie full copper gasket compression. All of the ports required at least two star pattern passes before reaching this point, except for the bellows line to the turbo/backing pumps which was already at complete compression. Prior to tighening, the wide range gauge gave a pressure reading of 5.8x10-6 Torr and the ion-gauge showed 5.75x10-6 Torr. After tightening the wide range flange the reading dropped to 5.6x10-6 ; after tightening the ion-gauge flange the gauge reading dropped to 5.69x10-6

For future reference: the 4.625" flanges use 5/16" torx bolts and 1/2" nuts, and the 2.75" flanges use a 1/4" torx bolt and 7/16" nuts. 

  2442   Mon Nov 11 22:19:09 2019 RaymondDailyProgressCryo vacuum chamberChanges to preserve long strap for internal chamber use

I've attached a photo of some changes to the cryocooler-tank connection design. We can save money and space by removing the 45 degree 1.33" conflat ports from the custom CH104 to 6" conflat adapter and using zero length conflat reducers at the unused 4 way cross ports, ie replace the 4-way piece blanks with holes for the vacuum line and gauge. The primary goal for these changes is to shorten the path from the cooler's heat station to the tank so that we keep the long thermal strap for use inside the tank. Also, the height is reduced from 89 cm to 59 cm.

A slightly different cupper adapter is needed to accomodate the thick strap, but no adapter will be needed anymore between the heat station and the thermal strap (same diameter round mates(new holes will need to be drilled though)).

Attachment 1: ShortAdapter.png
  2444   Tue Nov 12 17:44:39 2019 RaymondDailyProgressCryo vacuum chamberTank Update

Last week I moved the upper portion of the crane to the new, bolted crane support stand. Chub removed the wheeled lower section from the lab shortly thereafter. I also re-threaded the nylon lifting strap to remove slack and level the lid a bit better during lifting and moved one of the side tables next to the crane so the lid can be safely lowered after being lifted off the tank (see first photo). 

Opened the tank today to check internal dimensions. It is now closed (top bolts finger tight) but not under vacuum. The diaphragm pump was dispatched today, so will replace the dirty pump and pull vacuum again upon arrival. 

Attached a photo of the baseplate for future drill pattern reference. Note there are three anomalous holes, this is where the PEEK support poles should go. It was discovered today that these holes are 1/4-20 tapped but the PEEK pillars are dirlled/threaded for a smaller bolt.

I've attached a rough cartoon of the cold plate height relative to the optical ports and the tank wall. The outer rad shield is not shown and is slightly misaligned, but it can be easily aligned with a ~1.5 mm shim (better for thermal isolation anyways). 

Attachment 1: IMG_0258.JPG
Attachment 2: IMG_0257.JPG
Attachment 3: IMG_0259.JPG
  2455   Thu Nov 21 21:58:27 2019 RaymondDailyProgressCryo vacuum chamberTank Update

Update of our available electrical feedthroughs:

2 x 19 pin round with corresponding internal connectors and external connectors

2 x 15 D sub 

- re-tapped the PEEK support pieces to 1/4-20 to match the bottom of the tank, added them with vented socket set screws. These will need to be replaced with brass or aluminum to better match thermal contraction (steel screws likely to crack the PEEK upon cooling)

- Drilled holes (attached, highlighted in orange) in the pump station base in order to utilize the more robust shock absorbers that came with the oil pump. 

- Noticed significant flaking of the nuts/bolts when removing the tank lid. Suggested using anit-seize compound on the tank lid bolts but Chris advised against anything lube-like on the system. Just a note to remember to check the integrity of the bolts going forward before tightening the lid to avoid bolt seizing. 

Attachment 1: IMG_0490.JPG
Attachment 2: IMG_0491.JPG
Attachment 3: DiaphragmAdapt.pdf
  2476   Wed Dec 11 15:53:48 2019 Aidan, Chris, RaymondHowtoCryo vacuum chamberProcedure to record photodiode output vs temperature

[Aidan, Chris, Ray]

  1. Add LN2 to cryo-chamber
  2. Turn on heater to 25W
  3. Wait for LN2 to boil off
  4. Turn on the REFPD bias switch, and enable a 200 mV bias on the JPL PD (set C4:TST-FM13_OFFSET to 200)
  5. Switch the readout to the transimpedance amplifier (relay control output from C4:TST-FM15 at 30k ct)
  6. Turn on the laser
    1. Power up the LDC201C and set it for half-power output (50 mA), with the modulation output from C4:TST-FM12 at zero
    2. Set C4:TST-FM12_OFFSET to 1 to go up to full power
  7. Monitor the PD output on oscilloscope and adjust horizontal and vertical alignment of laser beam so that the output of the PD is maximized (also adjust TIA gain if needed so the output is not saturated)
  8. Switch the readout to the Keithley (relay control output from C4:TST-FM15 at zero)
  9. Record bright PD response
    1. Turn on laser (set C4:TST-FM12_OFFSET to 1)
    2. Scan bias voltage and record the PD response using the source meter (scripts are located in $HOME/JPL_PD/scripts on qil-ws1)
      1. ./runsweep.py triggers the Keithley to sweep the bias (range of sweep is defined in the script)
      2. ./getdata.py FILENAME downloads data from the Keithley and writes it to FILENAME
    3. Record REF PD reading
    4. Record RTD resistance
  10. Record dark PD response
    1. Turn off laser (set C4:TST-FM12_OFFSET to -1)
    2. Repeat steps 9-2 through 9-4
  11. Switch the readout to the transimpedance amplifier (relay control output from C4:TST-FM15 at 30k ct)
  12. Measure dark noise vs bias (using either the SR785 or the cymac, TBD)
  13. Wait two minutes and repeat steps 6 through 12 (there is a script ./autorun.sh which continuously repeats steps 9 and 10)
  14. Continue until RTD reaches room temperature (approximately 60-90 minutes).
  2477   Wed Dec 11 19:50:25 2019 ranaHowtoCryo vacuum chamberProcedure to record photodiode output vs temperature

don't we also want to record the dark noise spectrum as a function of T and V_Bias ? I would guess that the dark noise doesn't always scale with dark current at low frequencies since its probably more like a random walk than shot noise.

  2497   Fri Jul 17 15:54:42 2020 StephenLab InfrastructureCryo vacuum chamber 

Torque driver set for QIL setup bolted joints, with range 15 in*oz - 50 in*lb, p/n WIHA 5HYL9, is on order from Grainger, with anticipated delivery in the week of July 20th. Refer to  PO S477925. *update* Tracking Number UPS 1Z19W9330321365493

Cryo connection copper parts PO S475316 will be finished early next week by the machine shop in Torrance, I'll bring them to campus or to Raymond's place (TBD).

  2498   Fri Jul 24 04:46:51 2020 StephenLab InfrastructureCryo vacuum chamber 

Copper parts picked up July 23rd and brought to QIL, now only waiting on PO# S477874 and the pirani gauge from Koji's bulk JPL order


Torque driver set for QIL setup bolted joints, with range 15 in*oz - 50 in*lb, p/n WIHA 5HYL9, is on order from Grainger, with anticipated delivery in the week of July 20th. Refer to  PO S477925. *update* Tracking Number UPS 1Z19W9330321365493

Cryo connection copper parts PO S475316 will be finished early next week by the machine shop in Torrance, I'll bring them to campus or to Raymond's place (TBD).


  2501   Fri Jul 24 07:50:00 2020 RaymondUpdateCryo vacuum chamberPrototype shield panels

Picked up the prototype shield panels from Hamilton Metalcraft 7/22 and brought them to QIL. All of the parts are wrapped by part number and in a bin (see attached photo). There are 6 sets of shield panels, but 2 full sets were removed for coating vendors. One full set is as follows (20 parts total):

Part # Quantity
01 2
02 1
03 4
11 2
12 1
13 2
14 2
031 1
032 1
033 1
131 1
132 1
133 1

All component #'s are preceded by 'D2000298-'. 031, 032, and 033 are 03 panels but with hole variations, same goes for 131, 132, and 133 with respect to panel 13  

Attachment 1: MarinerShieldPrototype_parts.jpg
  2502   Tue Aug 4 17:08:00 2020 RaymondUpdateCryo vacuum chamber19 pin MIL feedthrough and CTC100 wiring

Used the 19-pin MIL feedthrough to run 4 platinum RTD's and a 25 Ω 100 W resistive heater to the cold head. Attachment 1 is the wiring diagram for the feedthrough and the D-sub connector to the CTC-100 temperature sensor. Attachment 2 shows the three RTDs placed on the cold head. It also shows the thermal anchoring of all lead wires. Attachment 3 shows the RTD attached to the cooler below the cold head using cigarette paper and cryo varnish (stored in the flammables cabinet in QIL).

 The Al block is a premade PT-RTD integrated mounting setup, which was placed on some indium sheet bits and clamped down with a screw and belleville washer. The other two cold head sensors are pressure fit to the cold head by a spring loaded mini dog clamps, and one of the two has some indium underneath the RTD to see if there is any value in doing so going forward with these mounting springs. The glued sensor was attached by painting a thin layer of cryo varnish on the cooler, adding a strip of cig paper, layer of varnish, press in sensor, another strip of paper, paint over all of it with a last thin layer of varnish that reaches beyond the bounds of the paper strips. 

Attachment 1: QIL_TempSensor_MIL19pinWiringDiagram.pdf
Attachment 2: external_tank_RTDs_1.pdf
Attachment 3: F6D69C6A-7168-4D06-B02A-E83CE8AFE524_1_105_c.jpeg
  2503   Fri Aug 7 11:50:06 2020 RaymondUpdateCryo vacuum chamberTank pumpdown

The diaphragm pump was turned on earlier this week after finally closing up this external adapter tank. Out of an overabundance of caution the tank and cryocooler are supported by the skycrane and a number of posts to prevent it walking off the foam resting pad once the cryocooler is switched on.

All temperature sensors agree with each other within 0.1 K at room temperature yes

Attachment 1: 6A57C6DF-0B58-413E-B9C0-797B14A10CCF_1_105_c.jpeg
  2504   Fri Aug 14 11:17:04 2020 RaymondUpdateCryo vacuum chamberCooler now operational

Cryopump is up and running. Initial attempts to run the cooler were stymied by an open circuit in the cold head to compressor connection caused by one of the two accessory port fuses (right, circled in attachment 1). The compressor would run but the valve motor wouldn't start in the cooler itself. I extended the spring in the fuse housing (attachment 2) and it seems to have fixed the problem, as now the valve motor starts at the same time the compressor is turned on. Attachment 1 also shows the highly technical cord management procedure done to reduce the trip hazard caused by the compressor power plug. 

User manual recommendations*:

  • Equalization pressure (when not operating): 270-275psi
    • Currently sits at 270psi
  • Operating pressure: 290-330psi
    • Operating at 300psi
  • Insulating vacuum pressure: 1 x 10-3 Torr
    • Vacuum pressure stabilized at 8.5 x 10-1 Torr
      • Edwards diaphragm pump listed ultimate pressure is 1.5 mbar ≈ 1.1 Torr, so either the multirange gauge is malfunctioning or we're getting better backing pressure than expected from the diaphragm pump. A Pirani gauge will be attached to the vacuum space going forward so we'll see how it compares; either way we're above the recommended insulation pressure. The 11" nipple surrounding the coldhead does become cool to the touch during operation, but it does not get cold enough to create condensation.

*Manuals for both the compressor and the cryocooler are linked on the West Bridge wiki manuals page

Attachment 1: IMG-1190.JPG
Attachment 2: IMG-1187.JPG
Attachment 3: IMG-1189.JPG
  2505   Wed Sep 2 08:13:18 2020 StephenDailyProgressCryo vacuum chamberAssembly of QIL Setup and other updates from 2020 Sep 01

2020 Sep 01, StephenA with remote assistance from RaymondR


  • Silicon Mass - Rana had dropped off the Silicon mass in the first room, so I found it when I arrived - thanks!
  • Organization - It was my first time accessing the QIL lab, but everything was pretty well organized and easy to find. All tools for modifications to parts were used in the EE lab which was also well organized. Raymond helped me to figure out where to access things on a few occaisions.
  • Packages - received from Downs Logistics room the Electropolished shield set, a Grainger order with deburring tool and step drill bit, and a McMaster order with a range of bolts - these have all been transported to the lab. Also transported the QIL machined parts that I had received from Machining Solutions to the lab.
    • Koji's Photodiode holders are in the QIL lab ready for pickup.
  • Summary of progress
    • Assembled frame (using torque values from T1100066- #8-32 used 20 in*lb)
    • Assembled brackets to frame
    • Hung silicon mass from music wire
      • Wire is captured under #4-40 SHCS with washers ((using torque values from T1100066- #4-40 used 5 in*lb)
  • Outstanding tasks and questions
    • Did the hang hold?
    • Do we want to have the layered Electropolished and Plain shields during the first installation? Or some sanded state?
    • Assembly requires oversized #8-32 washers which I wasn't able to track down from inventory - these are now on order, along with some more supplies for roughening the surface.

Full Details

  • Assembly work
    • Refer to the DCC - T2000538 - for the videos capturing this assembly effort. I've snagged some screenshots which I've dropped into the attachments.
      • There is a tree catching procedures and other experiment documentation for the QIL Setup at T2000539
  • Issues - there were four issues with the fabricated parts, three of which required small modifications;
    • D2000299-01 small angle rails had threaded holes where there should have been clearance holes for the interface (no issue on big angle rails)
      • modified by drill press to drill out clearance holes at same location
    • D2000308 interface cubes all were threaded only partially through.
      • No action taken, just paid attention and made sure the threads I needed were adequate. Seemed like an offset of only a turn or two, suggesting the CAM program was just a little off (this can happen with tapping, the tap is tapered and the machinist needs to thread deep enough to have the thread major diameter realized through the hole.)
    • D2000307-04 frame upper spacer had threaded holes that were not tapped all the way through.
      • I ran a tap through all of these threads.
    • D2000299-02 large angle rails had threaded holes that didn't pass all of the way through, and we happened to be inserting screws into the wrong side.
      • I ran a screw through these threads, which required a little bit more force than I would have liked, and forcing the screw provided an adequate thread.
        • Note that I anticipate that there will be an issue similar to this, with similar resolution, on the D2000299-01 small angle rails. The shield panels installed on the sides are to be installed from the inside. This can be resolved with a screw coming in from the outside.
    • There was also some inability to access certain screws with the long torque driver, especially if loosening/tightening after putting the frame together.
      • This was managed by use of an L allen key, which of course meant those joints were not torqued to spec. I'm not worried about this compromise.
Attachment 1: photos_cit_qil_lab_cryo_shield_test_assembly_20200901.zip
Attachment 2: T2000538-v1_Part_3_Assembly_of_QIL_Test_Setup_20200901_end_result.jpg
Attachment 3: IMG_7582.JPG
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