40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
 Cryo Lab eLog, Page 1 of 58 Not logged in
ID Date Author Type Category Subject
537   Fri Jul 27 16:40:02 2012 Mike J.ComputingVacuumws1...

Can no longer log into ws1 as controls, need to log in as root then su to controls in terminal. May need formatting.

545   Thu Aug 2 17:16:14 2012 Mike J.ComputingGeneralws1 specs

ws1 has:

2.60 GHz Pentium4 Processor

1.5GB RAM

40.0 GB HDD

DVD-ROM Drive

Dysfunctional Floppy Disk Drive

Integrated Graphics

Integrated Audio

Nifty Dell Optiplex GX270 Case

2208   Sun Nov 18 21:11:39 2018 ranaComputingGeneralworkstation gaston upgrades

Did some apt-get install/upgrades: chromium, pdftk, okular. Other stuff surely got upgraded.

Also did 'gsettings set org.gnome.shell.overrides edge-tiling false' at the terminal to stop that annoying thing where the window automatically maximizes if you drag it to the top of the screen.

This is just another reason to use SL instead of dweebian.

318   Sun Oct 23 23:32:41 2011 neat freakUpdateCleanlinessworking on a dump...

don't know how other people can work in an environment like this. Currently it looks like the situation is out of control and the lab transforms into a dump as foreseen in post 218, some people work on that intensively. After one of the tables and desks didn't have a single square inch to work on anymore people started taking over the workbench and the other desk!  Looks like we have to start daily cleaning from now on...

Oh, if you miss equipment in the EE shop check the crackle area. Chances are excellent to find what you are looking for, but you might have to dig a little bit.

As we have to give a plan to the PMA people by EOB this Tuesday for the cabinet and desk installation, we will toss everything which will be left on the desks by Tuesday afternoon. If you want to save something then move it ...

Attachment 8: 8.jpg
484   Wed May 23 14:32:41 2012 FrankCryostatLab Workwiring to cold plate

I turned out that running individual wires with connectors attached from the RT connector to the cold plate is basically impossible with those twisty wires after you have a couple in there already. So beginning of this week i got some insulating braid from Rich to make running the wires down the skinny tube from the outside to the cold plate easier. To get the wires into the braid they gave me a skinny aluminum tube which you put in first and then the wires through. But it turned out to be not to work for us:

• the inner diameter is too small once you have a single cable already through the thing
• It also turned out that the braid is NOT vacuum compatible

So today i got some of the good stuff from one of the broken and rejected aLIGO cables. This PEEK braid is slightly larger in diameter if you squeeze it to a tube.
So the current idea is

1. cut it to length first, in compressed state (the final length we need, to not make it longer than required to keep the process easy
2. clean the thing
3. compress the whole thing in length, which in principal makes a large diameter hose
4. use some Kapton tape to fix it in compressed state
5. put the wires with connectors attached through
6. expand the whole thing to make it thin again

We also have to test if a second assembly fits down to the cold plate as the PEEK braid is a little thicker than i thought (the cross section area is small enough that two will fit, but i don't know for sure if two times the diameter will fit through the thinnest part of the connection to the cold plate - have to measure

288   Sat Aug 20 00:56:04 2011 FrankElectronicsDrawingswiring diagram

here a first version of the wiring including everything from the sensors to the front of the breakout box:

17   Wed Oct 13 00:18:27 2010 FrankLaserDrawingswiki page for optical setups updated
• As we started calling the first cryo setup version 1.0 i had started the numbering for the first setups 0.x, which, after talking to Dmass, was probably a stupid idea.
• i started renumbering the setups, starting with v1.0 for the Al-spacer setup and subsequently v2.0 for the dual FS-cavity setup...
• i've also added a schematic for the Al-spacer setup and updated the description for each experiment.
• so i've updated the page for the optical setups on the wiki. The page looks different but has almost the same content as before...
2745   Thu May 20 13:32:11 2021 aaronComputingstuff happenswhere's the x1cry medm master?

I went digging for what TEC settings Johannes had been using for those lasers, and what x1cry channels I might use to measure their PV curve to get a current noise.

Strangely, I can't find the x1cry medm master files. I recently copied over these files into the x1oma medm directory, then made some modifications (rm'ed some files unnecessary for x1oma). I'm seeing those modifications reflected in the medm/x1cry/master directory, as well as medm/x1oma/master. Here's my bash history

cp -r x1cry/master x1oma/master
cd x1oma/master

I might not have actually lost data, since it looks like x1cry/master contained the actual master crymaster.adl, plus several backups. However, any changes I make in x1cry/master (eg, renaming the file) are reflected not only in x1oma/master, but also in the backups in medm/archives/x1cry_*/master. The files I'm working on are not linked, and the archives certainly shouldn't be affected by updates to the main files, so I don't know why this should happen.

Ah, I didn't realize x1cry/master was linked to some other directory. Now x1oma/master is linked to its own directory.

2742   Fri May 14 13:27:42 2021 aaronLab InfrastructureGeneralwhat's up with nodus proxy errors?

I'm getting frequent proxy errors when uploading pdfs to the elog. Started yesterday, continuing today. Error message below.

Proxy Error

The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request GET /Cryo_Lab/.

Reason: Error reading from remote server

1772   Tue Oct 17 22:14:47 2017 johannesNoise HuntingTransfer Functionswhat's in the box

Beat noise did not change with the addition of remote controls and turning off the RF board and Arduino.

For a beat noise measurement I usually lock the cavities with the boosts off and lowered gain. I then increase the loop gain until the error signal spectrum shows minimal noise, and finally add the boosts. I then go back to the loop gains and confirm that the beat noise is also minimal, if not I tweak the loop gain again. Generally I can make these statements:

1. The problem seems to be the east loop. Because:
• I can move the west loop gain up and down a bit with no change to the beat noise
• However, for the east loop decreasing or increasing the loop gain pretty much immediately affects the noise level
• The east servo is the first unit we had, although the two I'm using are supposed to be nominally identical.
2. The problem is not just the lack of loop gain - in both boxes the turning the third boost on or off does not affect the beat noise level

I tried a new twist today - I deliberately reduced the loop gain with boost3 off, bringing up the noise level. The thought was that if this is noise coming in pre-servo, then switching on boost3 will push the level down again - which it didn't. The beat noise was also unaffected by boost3, and I had to instead increase the VGA gain to bring the beat noise down.

This confirms again that we're not loop gain limited in the traditional sense, but indicates that what is causing this is between the VGA and the boost stages. I just realized I should have done the same thing with boost1, which sits right behind the VGA, so I can narrow it down even further. I have measured the VGA's output noise to be ~200 nV/rtHz, just like stated in its datasheet, and that wouldn't be enough to cause the level we're stuck at.

The next thing is to modify the transfer function board to our need. For this I started by repeating ringdown measurements, for the first time with the new servos:

 Cavity West East 1/e time constant 1.86 us 2.01 us round-trip loss 364 ppm 337 ppm Finesse 17250 18620 Cavity Pole 42.8 kHz 39.6kHz

Currently all five boost stages are identical: pole-zero pairs at 1kHz and 6kHz, respectively.

My plan to modify the TF board is the following:

1. Measure closed loop transfer function (haven't actually done this with the new servos yet)
2. Obtain model for plant
3. Match the zero of the first boost to the cavity pole
4. Iteratively improve other boost stages for best results

I've also been thinking if there could be a problem with the demodulation. The wenzel box gives us ~15.5 dBm of local oscillator power. Before, to use the phase shifter I had to attenuate that by ~20dB for its input, and afterwards it was amplified to 17dBm for the level 17 mixer. Since the RF board is no longer powered, I used cabling to get the LO phase right. In=lock there is a lot of signal coming out of the east RFPD, with a 20dB directional coupler I can see up to 100-200mVpp signals at the modulation frequency - this means that even in-lock there are up to 1-2Vpp going into the mixer due to unsupressed high frequency noise, which can drive the mixer into saturation if we're not careful.

Attachment 1: cavity_ringdown_20171017.tar.gz
Attachment 2: cavity_ringdowns_20171017.pdf
1997   Mon Apr 2 23:54:38 2018 johannesDailyProgressBeat Spectrumwest PDH servo repair, west current driver repair, fast trans beat PD install

I recovered the alignment of both beams and found the transmission beat. Because I'm not using an amplified detector the signal is very small (about -20dBm) and requires an amplifier which I will install tomorrow. Since the cold beat is just below 290 MHz I will use a Mini Circuits ZFL-500LN or equivalent.

West PDH Servo

Symptom: Output was sitting at negative rail, first noticed from the saturation LED indicator. Was not responding to turning servo on/off.

Solution: Traced to part U22 (HA-5002 buffer IC). Input was correctly sitting at zero, with output railing. Replaced with spare part -> fixed problem

West Current Driver

Symptom: There were two things that have been bugging me since I had made the changes documented in elog 1934 that I only saw in the west current driver:

1. The dial settings to get the nominal 96mA output current requested by the west laser (documented in elog 1621) had changed. With the fine dial at 5.0 the coarse dial used to be at ~4.3 but now had to be set at ~3.4. The changes I made had nothing to do with the setpoint, so this was a little weird but I didn't investigate it further. The total current monitor connector was still reporting the current correctly.
2. When locking the west cavity, I consistenly observed a slow drift in the control signal away from 0. In the past with warm cavities there would be a consistent drift to positive voltages from the cavities warming up due to the absorbed laser power after turning them on. This was different. The drift velocity scaled with the level of the voltage, as if something is slowly integrating the feedback signal. The feedback to the diode laser temperature was nulling the current control signal, so it was never an issue, just strange.

Solution: The reference voltage on the coarse and fine dials was 12V instead of 10V, which is why the dial settings were off. I traced the signal chain of the 10V reference and found that Q4, which is a PNP General Purpose Amplifier 2N2907, was putting out 12V instead of acting as a buffer for the 10V. I replaced the part, which restored the dial settings. After putting all electronics back in their place I don't see any more drifting of the control signal.

Transmission Beat PD

Lacking a NewFocus 1611 for the transmission beat, I grabbed an ET-3010 from the 40m. I have been using an ET-3000A, which is a fast, amplified InGaAs detector with a transimpedance gain of 450 V/A. The ET-3010 is just biased, not amplified, and battery powered, although wall-power is available to order.

While looking through the optics cabinet in the cryo lab I found a detector I was not familiar with: a Newport 818-BB-30. It looks almost identical to the ET3010, and the insides are virtually the same. The 818-BB-30 has a bandwidth of 2GHz when terminated into 50 Ohms and is biased at 6V by two 3V flat lithium batteries. I placed it in the setup and got a beat with ~50% visibility, which has to be improved by tweaking the distance to the beam splitted of the two optical paths. I plan to use a 50Ohm mini circuits amplifier, which will attach directly to the biased PD's output connector.

1966   Wed Mar 7 21:25:10 2018 aaronUpdateDAQweird beep

I heard a beep coming from somewhere to the right of the desk station, and just afterwards all ADC channels I was looking at read zero briefly, before returning to normal. Not sure what this was, maybe related to the fb issue earlier this week? There doesn't seem to be any problem with grabbing data from these times, just sent the channels to zero...

I've seen it happen five+ times over the last hour or so. The channels are off for about 6 seconds.

1967   Thu Mar 8 09:52:58 2018 johannesUpdateDAQweird beep

The beep is a warning sound from my laser temperature controllers that the thermistor reading of the laser package is outside some tolerance range of its setpoint. They have their internal offset setting, and the fast DAC provides a correction that I use for relieving the current-feedback in the PDH stabilization. When you restart the DAC process or models that voltage jumps and instantaneously moves the setpoint, and the controller's internal feedback loop is too slow (only couple Hz bandwidth) to respond. While the lasers are off, this is without consequence, and if they're on it will kick them out of lock but not do any damage. Still, if you plan on doing some DAQ work or have to restart cymac or the models, as a precaution please turn off my lasers.

If you didn't restart anything, it's still highly likely that it is related to the glitch in the ADC/DAC that you're describing. I know of no other device but the temperature controllers in that area that would issue an audio warning.

 Quote: I heard a beep coming from somewhere to the right of the desk station, and just afterwards all ADC channels I was looking at read zero briefly, before returning to normal. Not sure what this was, maybe related to the fb issue earlier this week? There doesn't seem to be any problem with grabbing data from these times, just sent the channels to zero... I've seen it happen five+ times over the last hour or so. The channels are off for about 6 seconds.

1968   Thu Mar 8 10:10:19 2018 aaronUpdateDAQweird beep

I didn't restart anything yesterday or the day before, but it is possible that the ADC interruption is occuring slightly before the 'beep', which could mean that there is some interruption occurring that then resets your setpoint and causes the beep.

1765   Mon Oct 16 14:46:41 2017 aaron, brittanyNotesCryo Qweekly game plan

Brittany and Aaron came up with our game plan for the week.

Here is what Aaron's up to this week:

1. Temperature Control
1. Control Circuit (hardware; first half of week)
1. Build new readout circuit (monday), with 3 instrumentation amplifiers, REF200 in 'lower noise' configuration, and the same heater as before
2. Characterize noise from the new circuit. I need to figure out how to use a current preamp to measure the noise from the current source.
2. Control loop (software; second half of week)
1. Check out Andrew's PID loop at the 40m wiki, ask Andrew about how it works.
2. Set this up at the cryo lab
3. Check out Nick's Q measurement modules (this will probably push into next)
1. Find documentation on the elog, wikis, etc
2. Get the module to work in the cryo lab (ie without modifications), try it out on an excited disk and see if we can measure Q.
3. Modify this script to get us the extra pieces that we need (not sure what is already implemented, so not sure what else is needed. We want to observe multiple frequencies, continuously measure their Q values, and use one in the frequency stabilized loop in (2))
2. Modeling.
1. What constraint can we place on phi?
1. Make a MC to construct confidence intervals with Feldman Cousins
2. In conjunction with the ipynb for the MC, I'll make the notebook pedagogical mostly for myself but also to use in journal club
2. Temperature dependence of eigenfrequencies (probably will not have progress this week)
1. Need to confirm that model and measured eigenfrequencies agree, which means we need to be in 'measuring mode' again. Therefore, probably this will happen when we are testing the temperature control stuff in a frequency stabilized loop.
3. Dilution Factor Study
1. Run many models to explore the space of disk parameters, asking for the dilution factor each time at several frequencies. This will be used to give physical meaning to curves on the phi constraint vs bare Q plots in (1). (that is, the plots in (1) will have a different line for each dilution factor, but we would like to know what sets of choices of disk parameters gives us each of those dilution factors).

Green means should happen this week, yellow will be started but may or may not be completed depending on what is prioritized, whatever the third color is will probably not see much progress.

------------------------------------------------

Here's what Brittany's up to this week

I will be traveling to the SACNAS conference from Wed through the weekend. I’ll keep this short and hopefully over ambitious

‘Getting Cold and Staying Cold’

• Goal of this : iterate on a method for cooling down the disk quicker and decreasing the thermal load within the cryostat
• Check out status of Nalu to see if I could use it to test cooling tests
• Roam around to see if there is any mylar around otherwise order some

‘Getting all dem frequencies’

• Goal of this : Use Gabriele’s Matlab scripts to analyze multiple frequencies at the same time
• Make sure I have all the proper packages installed on my computer
• Download files from measurements we took with Gabriele a while ago
• Read through scripts to make sure I understand them (take notes this time!)
• Make progress on trying to run them with some datas

‘A Q-phi story’

• Goal of this : Work towards a plot that one is able to read off what upper limits one can place on the loss angle given the measured Q
• Try a different way of plotting Q_bare vs. Phi_relation (Aaron started on this and is going a different path. We will see where will converge)
• Open up a python notebook and put in equations
• See how far I get and what the problem is
• Be a cool kid and upload it to GitHub

‘Manuscriptin’

•  Move the draft that I have on GitHub on to overleaf  (https://nodus.ligo.caltech.edu:8081/Cryo_Lab/1769)
• Continue to write some more words to this thing
1766   Mon Oct 16 17:58:55 2017 brittanyNotesCryo Qweekly game plan

Eric G. suggested to Rana to acquire some fused silica samples from Gabriele and put it in to our set-up. We should be able to get Q ~1e7 and this could help us iterate at room temperature.

We will add this in to our list for the week and early next week.

'Fused Silica Q'

• Acquire an uncoated fused silica disk from Gabriele (https://nodus.ligo.caltech.edu:8081/Cryo_Lab/1768)
• Install it in to our setup
• Work on getting a Q measurement from it

 Quote: Brittany and Aaron came up with our game plan for the week. Here is what Aaron's up to this week: Temperature Control Control Circuit (hardware; first half of week) Build new readout circuit (monday), with 3 instrumentation amplifiers, REF200 in 'lower noise' configuration, and the same heater as before Characterize noise from the new circuit. I need to figure out how to use a current preamp to measure the noise from the current source. Control loop (software; second half of week) Check out Andrew's PID loop at the 40m wiki, ask Andrew about how it works. Set this up at the cryo lab Check out Nick's Q measurement modules (this will probably push into next) Find documentation on the elog, wikis, etc Get the module to work in the cryo lab (ie without modifications), try it out on an excited disk and see if we can measure Q. Modify this script to get us the extra pieces that we need (not sure what is already implemented, so not sure what else is needed. We want to observe multiple frequencies, continuously measure their Q values, and use one in the frequency stabilized loop in (2)) Modeling. What constraint can we place on phi? Make a MC to construct confidence intervals with Feldman Cousins In conjunction with the ipynb for the MC, I'll make the notebook pedagogical mostly for myself but also to use in journal club Temperature dependence of eigenfrequencies (probably will not have progress this week) Need to confirm that model and measured eigenfrequencies agree, which means we need to be in 'measuring mode' again. Therefore, probably this will happen when we are testing the temperature control stuff in a frequency stabilized loop. Dilution Factor Study Run many models to explore the space of disk parameters, asking for the dilution factor each time at several frequencies. This will be used to give physical meaning to curves on the phi constraint vs bare Q plots in (1). (that is, the plots in (1) will have a different line for each dilution factor, but we would like to know what sets of choices of disk parameters gives us each of those dilution factors). Green means should happen this week, yellow will be started but may or may not be completed depending on what is prioritized, whatever the third color is will probably not see much progress. ------------------------------------------------ Here's what Brittany's up to this week I will be traveling to the SACNAS conference from Wed through the weekend. I’ll keep this short and hopefully over ambitious   ‘Getting Cold and Staying Cold’ Goal of this : iterate on a method for cooling down the disk quicker and decreasing the thermal load within the cryostat Check out status of Nalu to see if I could use it to test cooling tests  Roam around to see if there is any mylar around otherwise order some   ‘Getting all dem frequencies’ Goal of this : Use Gabriele’s Matlab scripts to analyze multiple frequencies at the same time Make sure I have all the proper packages installed on my computer Download files from measurements we took with Gabriele a while ago Read through scripts to make sure I understand them (take notes this time!)   ‘A Q-phi story’ Goal of this : Work towards a plot that one is able to read off what upper limits one can place on the loss angle given the measured Q Try a different way of plotting Q_bare vs. Phi_relation (Aaron started on this and is going a different path. We will see where will converge) Open up a python notebook and put in equations See how far I get and what the problem is Be a cool kid and upload it to GitHub   ‘Manuscriptin’ Move the draft that I have on GitHub on to overleaf  Continue to write some more words to this thing

1791   Tue Oct 24 17:45:39 2017 brittany, aaronNotesCryo Qweekly game plan

Here is the game plan for the rest of the week from cryoQ world

Here's what Brittany's up to this week

i was overly ambitious last week and didn't have enough time before the conference to get through it all, so of this is repeats may look familiar.

' hooray for 300K'

• Goal of this : Iterate on systematics of the setup using fused silica (that we can compare to Gabiele's measurements)
• Lower disk and make Q measurements
• Try the dttRana technique for getting measurements (based off of aaron's notes since i didn't write any when he showed us)
• Make a few measurements

‘Getting Cold and Staying Cold’

• Goal of this : iterate on a method for cooling down the disk quicker and decreasing the thermal load within the cryostat
• Try to get get the screw out of one of the holes
• Close up the cryostat and turn on the pump (if we are not using if for the other cryostat)
• Think through a staged double aluminum shield for reducing the heatload (after our convo with Rana, mylar outgasses too much)
• Sketch out a setup that will be used to test out a cool down idea
• Go look for the things to make that idea happen

‘Getting all dem frequencies’

• Goal of this : Learn how to use Gabriele's new python script for analyzing all the data at the same time
• Read through gabriele's new script​
• Work on reading in a data file
• See if I can make a plot

‘A Q-phi story’

•     Goal of this : Work towards a plot that one is able to read off what upper limits one can place on the loss angle given the measured Q
•     Try a different way of plotting Q_bare vs. Phi_relation (Aaron started on this and is going a different path. We will see where will converge)
•     Open up a python notebook and put in equations
•     See how far I get and what the problem is
•     Be a cool kid and upload it to GitHub

‘Manuscriptin’

• Open up the overleaf draft
• Pick a topic
• Write some words
• Start the bibliography file
• Begin putting relevant papers in there

Here's what Aaron's up to this week

Editing his NSF proposal that's due on Friday

Temperature Control

1. Temperature Control Circuit (hardware)
1. Look at the data taken on Friday of noise from this circuit.
2. Temperature Control loop (software)
1. Check out Andrew's PID loop at the 40m wiki, ask Andrew about how it works.
2. Set this up at the cryo lab
3. Check out Nick's Q measurement modules
1. Find documentation on the elog, wikis, etc
2. Get the module to work in the cryo lab (ie without modifications), try it out on an excited disk and see if we can measure Q.
3. Modify this script to get us the extra pieces that we need (not sure what is already implemented, so not sure what else is needed. We want to observe multiple frequencies, continuously measure their Q values, and use one in the frequency stabilized loop in (2))
4. ​Miscellany
1. ​Followup again on the Millitnow quote for RTD mounts
2. Email Keithley about their box, also there are 2 other boxes to troubleshoot in the lab
3.

1. Modeling.
1. What constraint can we place on phi?
1. Make a MC to construct confidence intervals with Feldman Cousins
2. In conjunction with the ipynb for the MC, I'll make the notebook pedagogical mostly for myself but also to use in journal club
2. Temperature dependence of eigenfrequencies (probably will not have progress this week)
1. Need to confirm that model and measured eigenfrequencies agree, which means we need to be in 'measuring mode' again. Therefore, probably this will happen when we are testing the temperature control stuff in a frequency stabilized loop.
3. Dilution Factor Study
1. Run many models to explore the space of disk parameters, asking for the dilution factor each time at several frequencies. This will be used to give physical meaning to curves on the phi constraint vs bare Q plots in (1). (that is, the plots in (1) will have a different line for each dilution factor, but we would like to know what sets of choices of disk parameters gives us each of those dilution factors).
2640   Thu Feb 11 14:44:41 2021 aaronComputingDAQwake up spirou

enter Thu Feb 11 14:44:53 2021

I wanted to access some files on spirou remotely, but it does not wake from sleep on ssh. I found this entry on Debian wiki describing how to enable wake on lan. I followed the steps and confirmed they 'worked' in the manner described on the wiki, but putting spirou to sleep and logging on from gaston returns 'no route to host'. ssh to spirou.local works when spirou is awake, but returns varying errors ('connection timed out' or 'name or service not known', or even elog fragments followed by syntax error) when spirou is asleep.

For now, I've just set spirou to never suspend itself, which will use a bit more power but allow remote work before I figure this out later.

Exit Thu Feb 11 15:42:09 2021

NOVA wafers are here and on the VIP desk in Koji's office.

ZK: Wafers unpacked and stored in 050.

610   Wed Nov 21 17:00:57 2012 ranaCryostatOpticsviewports

ISI, a subset of MDC, seems to have kind of cryostat viewport ability that we want.

ISI Viewport Webpage

611   Tue Nov 27 22:11:11 2012 DmassCryostatOpticsviewports

 Quote: ISI, a subset of MDC, seems to have kind of cryostat viewport ability that we want. ISI Viewport Webpage

We didn't go for these on the first go-round because using aluminum in the cold stage stopped us from using conflat as a flange (we wanted to the high thermal conductivity of Al, but we inherit its softness to get that, so we went with a custom flange). We did get the windows we eventually used from MDC/ISI though. As a reminder, the workflow was:

1. Get Sapphire from Meller
2. MDC/ISI brazes weldable stainless adapter to Window with Kovar
3. Coaters coat the windows
4. Precision welds flange to stainless adapter.

The Mickey Mousery of the process seems to be welding the thing after it is coated. IF we don't think of something more clever, we might want to consider doing:

1. Make a one-piece flange which interfaces with existing cryostat indium seal based on what MDC/ISI used
• (have to check materials, and whether you can braze aluminum to sapphire, I expect Warren knows the answer to this)
2. Have MDC/ISI braze the window to the flange
3. CLEAN THE BEEJEEBUS OUT OF THE ASSEMBLY
4. Coat it
5. Clean it more

That lets do nothing violent to the window after we have it coated.

612   Wed Nov 28 08:31:20 2012 SteveCryostatOpticsviewports

 Quote: ISI, a subset of MDC, seems to have kind of cryostat viewport ability that we want. ISI Viewport Webpage

These viewports have no wedge

2781   Tue Jul 13 12:00:36 2021 aaronUpdateControl Systemventing cantilevers cryostat

[aaron, shruti]

morning

Shruti and I opened up the cantilevers cryostat. Vacuum wasn't fully vented despite the valve being fully open, due to the foil covering the open valve sealing against the flange while venting. The cryostat popped rather than lifted open. The damage is at least:

• All three steel wires between the blade springs and optical platform snapped
• both cantilevers broke and the mirrors detached from the cantilevers
• there's a knick on the inner edge of the sealing surface we were opening, and a couple radial scratches visible.

Overall pretty disastrous. We'll have to investigate the full extent of the damage this afternoon, and first order of business will be cleaning out the broken Si fragments and evaluating the vacuum pressure.

Afternoon

We removed the silicon cantilever from the bottom of the cryostat with teflon-tipped foreceps, and stored them in a wafer casette. We also cleaned and regreased the o-ring with Krytox lubricant (we couldn't find the cryo lab's Apiezon N grease, must have been lent).

We pumped down the cryostat, but the roughing pump wasn't able to reach a low enough pressure to switch on the turbo. We also valved off the cryostat from the rest of the system, and pumped down on the hose + gauge + up-to-air valve (closed). The turbo was able to spin up to 90 krpm, but the pressure leveled out a several 100 uTorr. Pumpdown curves are in attachment 2.

The second pumpdown curve (pumping on just the hose and pressure gauge) suggests the pumping station needs some maintenance. I've seen this behavior before from a faulty KF flange connection, or when some condensation had built up in the roughing pump line. There is a procedure in the HiCube manual for flushing this line, I'll dig it up from my old elogs. However, the pumpdown on the cryostat suggests an even more severe leak in the cryostat itself, since the turbo wasn't even able to spin up and the curve appears leak-limited well above 1 torr. This is consistent with the visible damage to the mating surface in attachment 1. I suspect we need to send the cryostat to be reground and polished.

Attachment 1: EA078826-F058-4029-BE52-0A0534AF5180.jpeg
Attachment 2: Screenshot_from_2021-07-13_16-25-28.png
2787   Tue Aug 10 17:23:39 2021 aaronDailyProgressVacuumventing cantilevers cryostat

[aaron, shruti]

Today we are testing the pumping station while pumping on just some blanked off Ts and the vacuum gauge. Last time, we pumped on the vacuum hose leading to the closed Key valve at the cryostat, and observed the pressure level off near mtorr, before eventually reaching only several utorr. The turbo should really have no trouble getting to utorr pumping on just hose sections, so we'll try to observe some better pumping action today.

• Powered on acromag chassis and set up pressure gauge on just the turbo pump as in attachment 1
• Noticed that at atmosphere, the gauge reads 744 torr, but the epics channel reports 722 torr.
• Pumped down on the blanked off system, and again observed the pressure level off at 20-30 utorr after 10 min. If we let it continue, perhaps would reach a similar pressure of several utorr. The discontinuity around 10 mtorr is due to the gauge changing modes.
• Vented the system by valving off the turbo then using the up-to-air valve go to atmosphere. You'll note the vent looks a little faster than intended; the valve had been too zealously tightened.
• Following the instructions in the HiCube Eco manual for troubleshooting a pump that does not reach desired final pressures or takes a long time to get there, we suspect either condensation has built up in the gas ballast line or the gas ballast line has been left open. Aaron went through these troubleshooting steps back in 2019 a couple times. We need to open then close the gas ballast line.
• Following the manual and my procedures from 2019, we first closed the red vent valve on the side of the turbo and confirmed that the black vent valve is also closed
• Next, we went turn Vent Mode on. We found vent mode was already on, which could explain the mediocre vacuum pressures.
• Just in case, we pumped down again on the same system in attachment 1, this time with the red valve on the turbo closed, and held vacuum for 20 minutes.
• Turned off the pump, and wait for the turbo to spin down. After the pump reaches 0 rpm, go up to air (this time, we didn't valve off the turbo and opened the up-to-air valve more slowly).
• Change the valve mode setting to 'auto'
• Pump down once more to see if it made any difference.
• We recorded the pressure during the above operations, see attachment 2. A zoomed in view of the last two pumpdowns is in attachment 3. The final pumpdown was moderately faster, and we've left the pump on to see what final pressure it achieves overnight. Note that we did not re-open the red valve at the side of the turbo; we suspect we probably should have, but aren't sure exactly why. We can try another pumpdown with it open tomorrow.
• In my previous elog (2289), I noted that our roughing pump appears to have a manually actuated valve on the gas ballast line, and ended up opening and closing that valve. We didn't quite get to try that today, but have noted it for the future.
Attachment 1: 10CC78ED-EC51-4F10-8CBB-9ED236746501.jpeg
Attachment 2: Screenshot_from_2021-08-10_19-13-12.png
Attachment 3: Screenshot_from_2021-08-10_19-14-19.png
2789   Wed Aug 11 13:21:23 2021 aaronDailyProgressVacuumventing cantilevers cryostat

The cantilevers cryostat vacuum line [edit: Aaron (May 2022) suspects I was pumping on the vacuum line only, not the chamber, as indicated in the previous log] has only reached 7 utorr (the reading on the gauge matches epics) after pumping overnight. I'm going to try manually actuating the gas ballast valve in case our roughing pump is manual-only.

1. Turned off the pumping station, and wait for turbo to spin down before venting up to air.
2. Manually move the roughing pump's gas ballast valve from the 'open' to the 'closed' position, as in figure 2 of the MVP 015-2 manual (roughing pump). I spent some time digging through the HiPace 80 (turbo pump) manual and figuring out how the venting valve on the side of the turbo works.
3. Turn on the pumping station and observe the pumpdown. The result is in attachment 1.

After closing the gas ballast valve, the pressure drops below 7 utorr in under 30 minutes and is approaching 1 utorr. That's not the best I've seen from this pump, but should be good enough to continue diagnosing the cryostat.

To that end, I'm installing a new 2-270 Viton o-ring on the cantilever cryostat (needs name).

1. Clean the new o-ring with isopropyl alcohol and a lint-free wipe
2. Grease the new o-ring with Krytox, and place on a fresh sheet of HV aluminum foil
3. Use the crane to open the cryosta at the midsection. The screws have already been removed.
4. Install the o-ring and close the cryostat, tightening the bolts in a star pattern
• I couldn't get the o-ring to stay in the inverted groove. I found Zach mention he taped some L-brackets to hold it in place, but couldn't find L-brackets nor could get our Kapton tape to stick to the cryostat with the weight of the o-ring. Will try it again with two people.
Attachment 1: Screenshot_from_2021-08-12_14-57-42.png
2791   Thu Aug 12 15:03:32 2021 shrutiDailyProgressVacuumventing cantilevers cryostat

[aaron, shruti]

We repeated steps 1-4 in elog 2789 and, with two people, managed to get the o-ring to stay in place while lowering.

• Before pumping down the cryostat, we decided to pump down everything until the valve to the cryostat (by closing the valve to the cryostat), as a check. In around 6 min the pressure dropped to 100 utorr and kept decreasing to tens of utorr slowly. After 60 min we stopped this experiment.
• We then opened the valve to the cryostat and began pumping down, the pump stopped automatically after around 10 min. This is the first kink in curve in Attachment 1. At this lower pressure, we decided to restart the pump anyway. Even though the turbo came up to 90000 rpm pretty quickly, the lowest pressure achieved after an hour was not lower than 400 utorr.
• Thinking that the low rate may be because the long tube that connects the cryostat to the pump was of a small diameter, we decided to change the setup to one with the larger diameter. Attachment 2 has the final setup.
• Then starting again at atmosphere, we began pumping down again. It does seem to go faster, although the pump did stop once and had to be restarted. I think we plan to leave it pumping overnight.
Attachment 1: Screenshot_from_2021-08-12_17-51-06.png
Attachment 2: 885A9694-996E-499E-BDCC-FB550338561F.jpeg
2792   Mon Aug 16 18:48:37 2021 ranaDailyProgressVacuumventing cantilevers cryostat

could the pumpdown plot be made so that the units are visible? Maybe use dataviewer or python?

2159   Sat Sep 8 02:45:04 2018 johannesElectronicsDigital PLLvalon testing

Luis and I took a shot at quantifying the noise of the Valon 3010 programmable frequency dividers today. The setup we used was the following:

A Marconi generated signal was split and put in two separate dividers, whose RF output "DIV1" was then fed to the Red Pitaya phasemeter. We used physically different units because the three channels share the same input amplifier and comparator. This drawing from the spec sheet illustrates this:

We added attenuation and subsequent amplification and lowered the input power to the divider, the frequency, and the divide-by setting. In the final configuration the Marconi generated a -4 dBm 961 MHz signal which was attenuated to -34 dBm and then amplified and split, giving about -17 dBm as input to the divider (specs are -20dBm to +20 dBm) which was set to divide by a ratio of 32. The 5dBm square wave output was 30 MHz bandpass filtered using mini circuits filter to suppress the harmonics, and filled the RP ADC dynamic range to ~50%, so we did not add any amplifiers after the dividers. We used Marconi frequency and divider settings compatible with the bandpass filter.

The noise plot for the final measurement is attached, in units of Hz/rtHz as well as rad/rtHz. It looked virtually the same for every combination we tried. The differential trace shows that below ~100 Hz this measurement is limited by the internal resolution of the RP (the frequency estimate of the PLL is streamed to the workstation with 32 bit precision to the work station at 200kS/s, which corresponds to a frequency noise floor of ~64 uHz/rtHz). Above 1kHz, at roughly 0.24 urad/rtHz  the measured phase noise is slightly higher than the theoretical ADC noise inferred by Vineeth's measurement from long ago (70 nV/rtHz).

Things we didn't test are

• more noisy signals. we attenuated and amplified to worsen the SNR, a low SNR PD signal will be noisier.
• moving frequencies during measurement.

What we can extract from this measurement is that

1. The precision achievable with the RP in  a differential measurement is
$\sqrt{\left(64\,\mu\mathrm{rad}/\sqrt{\mathrm{Hz}}\times\frac{1\,\mathrm{Hz}}{f}\right)^2+\left(70\,\mathrm{nrad}/\sqrt{\mathrm{Hz}}\times\frac{V_\mathrm{ref}}{A}\right)^2}$, where V_ref = 1 V is the reference voltage of the RP (+/- 1V input range) and A is the amplitude of the digitized signal
2. Based on the measurement, the phase noise added by the divider is less than
$\sqrt{\left(64\,\mu\mathrm{rad}/\sqrt{\mathrm{Hz}}\times\frac{1\,\mathrm{Hz}}{f}\right)^2+\left(0.24\,\mu\mathrm{rad}/\sqrt{\mathrm{Hz}}\right)^2}$
3. A single channel beat frequency measurement will still be limited by the blue trace (clock noise of the RP crystal oscillator?), which is an order of magnitude higher than the differential noise. Between 10 Hz and 3 kHz this is (partly well) below 1 mHz/rtHz, so sufficient for the SiFi measurement IF the divider ratio is not too high, since dividing the beat frequency also means dividing the differential frequency noise of the two lasers that are beat.
Attachment 1: setup.pdf
Attachment 2: valon.JPG
Attachment 3: rp_valon_961MHz_div32_2units_-34dBm_amp_to_-17dBm_f.pdf
Attachment 4: rp_valon_961MHz_div32_2units_-34dBm_amp_to_-17dBm_p.pdf
226   Thu Jul 7 02:08:50 2011 FrankCryostatVacuumvacuum schematic

here the first draft of the vacuum schematic including all important features. The valve for the insulating vacuum comes with the cryostat and is welded to it. The rest is standard KF25 equipment.

1825   Mon Nov 13 11:37:22 2017 brittanyDailyProgressCryo Qvacuum leak sleuthing

Episode 1

I thought I would try potentially targetted approach that would help me determine the size of the leak (rather than opening it up and just bolting it all together with new Orings and hoping it will be fine)

• I remember figuring out the size of a vacuum leak with Steve Meyer on the Holometer though unsucessfully found the relation I was looking for while I was roaming the internets
• Most of what I found basically said it's "hard" to determine the size of a leak
• I like this resource out of the random other things I found : https://www3.nd.edu/~nsl/Lectures/urls/LEYBOLD_FUNDAMENTALS.pdf

On Friday, I turned off the pump and recorded the pressure over time. (Old school style not with data logging since our pressure gauge doesn't talk to the DAQ)

• Below is a plot of this
• I put the ipython notebook in the github repo for anyone to enjoy (Qryo/Cryo_Analysis/code/Vacuum.ipynb)

Turns out we have a leaky system

• Leak rate = Q = 1.65e-2 mbar*l/s == 12.4 Torr*cm^3/s (l is liter)
• In the vacuum technology manual they have some rules of thumb for leak rate
• < 1e-6mbar*l/s - equipment is very tight
• ~1e-5 mbar*l/s- sufficiently tight
• >1e-4 mbar*l/s - leaky
• Seeing as though we are ~100 times worse than that the final conclusion is that it is leaky

Turns out this was not nearly as fruitful as I had hoped. If anyone has this calculation I am thinking of to get the size of the leak that would be great.

Now, I am going to take out the guts of the cryostat, close it up and check for leaks just on the cryojacket. (and hope it will be fine. or order new things)

Attachment 1: Vacuum.pdf
1827   Mon Nov 13 14:55:16 2017 brittanyDailyProgressCryo Qvacuum leak sleuthing

Episode 2

I opened up the cryostat

I want to take everything out for two reasons - 1) I want to get the cryojacket + oring + screw system to reach the 1e-6 ish Torr level 2) this way we can bake our parts and do some more thorough cleaning.

• There was a weird smell coming out of the cryostat when I opened it back up to atmosphere. Perhaps this is a clue of sorts
• Screws seemed fine at the top and bottom parts of the jacket (tops tighter than the bottom for obvious reasons). There was some white stuff that came off the screws maybe left over nitrogen junk? Worth cleaning.
• The fused silica disk was in good condition when I took it out. I put it back in the case and managed to catch it when it fell out of the case since the thing didn't lock very well. Now there is likely a smudge (I did have purple gloves on so does not fully have all my DNA on it). uughhhhh. hopefully this doesn't mess up the Q measurements that much.
• I like to forget about the wires between the feedthrough and the inside. So this is a longer process than I gave it time today. I unscrewed the ESD and messaged Aaron about what would be the best place to snip the wires that would be easy to reconnect later (and have the least future headache). We decided a little downstream from the feedthrough should be fine.

Will continue this path manana

 Quote: Episode 1 I thought I would try potentially targetted approach that would help me determine the size of the leak (rather than opening it up and just bolting it all together with new Orings and hoping it will be fine) I remember figuring out the size of a vacuum leak with Steve Meyer on the Holometer though unsucessfully found the relation I was looking for while I was roaming the internets Most of what I found basically said it's "hard" to determine the size of a leak I like this resource out of the random other things I found : https://www3.nd.edu/~nsl/Lectures/urls/LEYBOLD_FUNDAMENTALS.pdf On Friday, I turned off the pump and recorded the pressure over time. (Old school style not with data logging since our pressure gauge doesn't talk to the DAQ) Below is a plot of this I put the ipython notebook in the github repo for anyone to enjoy (Qryo/Cryo_Analysis/code/Vacuum.ipynb) Turns out we have a leaky system  Leak rate = Q = 1.65e-2 mbar*l/s == 12.4 Torr*cm^3/s (l is liter) In the vacuum technology manual they have some rules of thumb for leak rate < 1e-6mbar*l/s - equipment is very tight ~1e-5 mbar*l/s- sufficiently tight >1e-4 mbar*l/s - leaky  Seeing as though we are ~100 times worse than that the final conclusion is that it is leaky Turns out this was not nearly as fruitful as I had hoped. If anyone has this calculation I am thinking of to get the size of the leak that would be great. Now, I am going to take out the guts of the cryostat, close it up and check for leaks just on the cryojacket. (and hope it will be fine. or order new things)

1831   Tue Nov 14 09:38:15 2017 brittanyDailyProgressCryo Qvacuum leak sleuthing

Episode 3 - Orings + Screws

I want to focus on the seals first before addressing the cleanliness of the insides

This morning, I did this :

• Wiped down the inside of the cryostat with ISO
•   we may need to clean this a lot better because the old mylar is flaking off
• Cleaned the Oring around the feedthrough port
• Replaced the 4-40 screws at the feedthrough port
• Opened one of the other blank ports and it didn’t look as though it had much stuff so I decided against opening them all up for now
• I didn’t clean the Oring around the window — I think that will need to be cleaned
• Swap out the bottom plate for a blank from a different cryostat
• Cleaned the Oring around there
• Wanted to swap out the top for a blank but we don’t have one
• I cleaned the pod-space ship top of the cryostat and stuck that on the top
• I wiped down the insides of that but there are some little particles floating in there. It's hard to clean under the peak of the cone

At 8:25 - I turned on the pump and over the next ~2 minutes it quickly got down to ~1e0 Torr. Ill check on it again later

My suspicion on the leak origin has to do with how many times we need to access the vacuum (i.e. opening and closing different ports). This invites the opportunity to pick up a bunch of particles to hang out in the Orings and potentially screwing up our seals.

Quote:

Episode 2

I opened up the cryostat

I want to take everything out for two reasons - 1) I want to get the cryojacket + oring + screw system to reach the 1e-6 ish Torr level 2) this way we can bake our parts and do some more thorough cleaning.

• There was a weird smell coming out of the cryostat when I opened it back up to atmosphere. Perhaps this is a clue of sorts
• Screws seemed fine at the top and bottom parts of the jacket (tops tighter than the bottom for obvious reasons). There was some white stuff that came off the screws maybe left over nitrogen junk? Worth cleaning.
• The fused silica disk was in good condition when I took it out. I put it back in the case and managed to catch it when it fell out of the case since the thing didn't lock very well. Now there is likely a smudge (I did have purple gloves on so does not fully have all my DNA on it). uughhhhh. hopefully this doesn't mess up the Q measurements that much.
• I like to forget about the wires between the feedthrough and the inside. So this is a longer process than I gave it time today. I unscrewed the ESD and messaged Aaron about what would be the best place to snip the wires that would be easy to reconnect later (and have the least future headache). We decided a little downstream from the feedthrough should be fine.

Will continue this path manana

 Quote: Episode 1 I thought I would try potentially targetted approach that would help me determine the size of the leak (rather than opening it up and just bolting it all together with new Orings and hoping it will be fine) I remember figuring out the size of a vacuum leak with Steve Meyer on the Holometer though unsucessfully found the relation I was looking for while I was roaming the internets Most of what I found basically said it's "hard" to determine the size of a leak I like this resource out of the random other things I found : https://www3.nd.edu/~nsl/Lectures/urls/LEYBOLD_FUNDAMENTALS.pdf On Friday, I turned off the pump and recorded the pressure over time. (Old school style not with data logging since our pressure gauge doesn't talk to the DAQ) Below is a plot of this I put the ipython notebook in the github repo for anyone to enjoy (Qryo/Cryo_Analysis/code/Vacuum.ipynb) Turns out we have a leaky system  Leak rate = Q = 1.65e-2 mbar*l/s == 12.4 Torr*cm^3/s (l is liter) In the vacuum technology manual they have some rules of thumb for leak rate < 1e-6mbar*l/s - equipment is very tight ~1e-5 mbar*l/s- sufficiently tight >1e-4 mbar*l/s - leaky  Seeing as though we are ~100 times worse than that the final conclusion is that it is leaky Turns out this was not nearly as fruitful as I had hoped. If anyone has this calculation I am thinking of to get the size of the leak that would be great. Now, I am going to take out the guts of the cryostat, close it up and check for leaks just on the cryojacket. (and hope it will be fine. or order new things)

274   Thu Aug 4 00:05:25 2011 FrankNotesVacuumvacuum gauges connector pinout and calibration data

361   Tue Nov 15 22:29:17 2011 FrankComputingSensorsvacuum gauge script crashed

the script for one of the sensors crashed with an exception while converting the string read from the device to a number:

Traceback (most recent call last):
File "vacgauge_MKS974B-v0.1.py", line 110, in read_device
ValueError: invalid literal for float(): 3.452E-

For some unknown reason the splitting of the text string went wrong and the exponent got lost. Will add some more debugging and restart the script.
Current version of the script is started in /caltech/scripts/python/dist.  Scripts are creating a log-file with date and time followed by the name of the script (e.g. 20111115_224556_vacgauge_MKS974B.log) in the same folder.
Logfile contains detailed information about each reading from the device and individual steps of the conversion:

example log file:
Tue, 15 Nov 2011 22:45:56 INFO     Starting vacuum gauge application for MKS974B
Tue, 15 Nov 2011 22:45:56 INFO     Opened serial port for vacuum gauge MKS974B: /dev/ttyUSB0
Tue, 15 Nov 2011 22:45:56 INFO     Thread successfully started
Tue, 15 Nov 2011 22:45:58 INFO     channel: C5:VAC-P2_PRESSURE command: @253PR4?;FF response: @253ACK6.905E-5;FF result: 6.905E-5
Tue, 15 Nov 2011 22:45:58 INFO     channel: C5:VAC-P2_PR1 command: @253PR1?;FF response: @253ACK6.00E-5;FF result: 6.00E-5
Tue, 15 Nov 2011 22:45:58 INFO     channel: C5:VAC-P2_PR2 command: @253PR2?;FF response: @253ACK-7.47E+2;FF result: -7.47E+2
Tue, 15 Nov 2011 22:45:58 INFO     channel: C5:VAC-P2_PR4 command: @253PR4?;FF response: @253ACK6.905E-5;FF result: 6.905E-5
Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_PR5 command: @253PR5?;FF response: @253ACK6.90E-5;FF result: 6.90E-5
Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_TEMP command: @253TEM?;FF response: @253ACK1.91E+1;FF result: 1.91E+1
Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_TIME command: @253TIM?;FF response: @253ACK2005;FF result: 2005
Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_SP1 command: @253SP1?;FF response: @253ACK1.00E+0;FF result: 1.00E+0
Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_SP2 command: @253SP2?;FF response: @253ACK1.00E+0;FF result: 1.00E+0
Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_SP3 command: @253SP3?;FF response: @253ACK1.00E+0;FF result: 1.00E+0
Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_SH1 command: @253SH1?;FF response: @253ACK1.10E+0;FF result: 1.10E+0
Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_SH2 command: @253SH2?;FF response: @253ACK1.10E+0;FF result: 1.10E+0
Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SH3 command: @253SH3?;FF response: @253ACK1.10E+0;FF result: 1.10E+0
Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SS1 command: @253SS1?;FF response: @253ACKCLEAR;FF result: CLEAR
Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SS2 command: @253SS2?;FF response: @253ACKCLEAR;FF result: CLEAR
Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SS3 command: @253SS3?;FF response: @253ACKCLEAR;FF result: CLEAR
Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_EN1 command: @253EN1?;FF response: @253ACKOFF;FF result: OFF
Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_EN2 command: @253EN2?;FF response: @253ACKOFF;FF result: OFF
Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_EN3 command: @253EN3?;FF response: @253ACKOFF;FF result: OFF
Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SD1 command: @253SD1?;FF response: @253ACKBELOW;FF result: BELOW
Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SD2 command: @253SD2?;FF response: @253ACKBELOW;FF result: BELOW
Tue, 15 Nov 2011 22:46:01 INFO     channel: C5:VAC-P2_SD3 command: @253SD3?;FF response: @253ACKBELOW;FF result: BELOW

362   Tue Nov 15 23:34:02 2011 FrankComputingSensorsvacuum gauge script crashed

problem located: the response read from the device is missing one character at the end: @253ACK6.00E-5;F instead of @253ACK6.00E-5;FF. As i'm simply deleting the last three characters i delete the exponent in that case. But i don't know why i get one character less in some very rare cases and only from that device. Will add a better sanity check if the received string is actually valid before i try converting it.

 Quote: the script for one of the sensors crashed with an exception while converting the string read from the device to a number: Unhandled exception in thread started by Traceback (most recent call last):   File "vacgauge_MKS974B-v0.1.py", line 110, in read_device ValueError: invalid literal for float(): 3.452E- For some unknown reason the splitting of the text string went wrong and the exponent got lost. Will add some more debugging and restart the script. Current version of the script is started in /caltech/scripts/python/dist.  Scripts are creating a log-file with date and time followed by the name of the script (e.g. 20111115_224556_vacgauge_MKS974B.log) in the same folder. Logfile contains detailed information about each reading from the device and individual steps of the conversion: example log file: Tue, 15 Nov 2011 22:45:56 INFO     Starting vacuum gauge application for MKS974B Tue, 15 Nov 2011 22:45:56 INFO     Opened serial port for vacuum gauge MKS974B: /dev/ttyUSB0 Tue, 15 Nov 2011 22:45:56 INFO     Thread successfully started Tue, 15 Nov 2011 22:45:58 INFO     channel: C5:VAC-P2_PRESSURE command: @253PR4?;FF response: @253ACK6.905E-5;FF result: 6.905E-5 Tue, 15 Nov 2011 22:45:58 INFO     channel: C5:VAC-P2_PR1 command: @253PR1?;FF response: @253ACK6.00E-5;FF result: 6.00E-5 Tue, 15 Nov 2011 22:45:58 INFO     channel: C5:VAC-P2_PR2 command: @253PR2?;FF response: @253ACK-7.47E+2;FF result: -7.47E+2 Tue, 15 Nov 2011 22:45:58 INFO     channel: C5:VAC-P2_PR4 command: @253PR4?;FF response: @253ACK6.905E-5;FF result: 6.905E-5 Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_PR5 command: @253PR5?;FF response: @253ACK6.90E-5;FF result: 6.90E-5 Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_TEMP command: @253TEM?;FF response: @253ACK1.91E+1;FF result: 1.91E+1 Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_TIME command: @253TIM?;FF response: @253ACK2005;FF result: 2005 Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_SP1 command: @253SP1?;FF response: @253ACK1.00E+0;FF result: 1.00E+0 Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_SP2 command: @253SP2?;FF response: @253ACK1.00E+0;FF result: 1.00E+0 Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_SP3 command: @253SP3?;FF response: @253ACK1.00E+0;FF result: 1.00E+0 Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_SH1 command: @253SH1?;FF response: @253ACK1.10E+0;FF result: 1.10E+0 Tue, 15 Nov 2011 22:45:59 INFO     channel: C5:VAC-P2_SH2 command: @253SH2?;FF response: @253ACK1.10E+0;FF result: 1.10E+0 Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SH3 command: @253SH3?;FF response: @253ACK1.10E+0;FF result: 1.10E+0 Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SS1 command: @253SS1?;FF response: @253ACKCLEAR;FF result: CLEAR Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SS2 command: @253SS2?;FF response: @253ACKCLEAR;FF result: CLEAR Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SS3 command: @253SS3?;FF response: @253ACKCLEAR;FF result: CLEAR Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_EN1 command: @253EN1?;FF response: @253ACKOFF;FF result: OFF Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_EN2 command: @253EN2?;FF response: @253ACKOFF;FF result: OFF Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_EN3 command: @253EN3?;FF response: @253ACKOFF;FF result: OFF Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SD1 command: @253SD1?;FF response: @253ACKBELOW;FF result: BELOW Tue, 15 Nov 2011 22:46:00 INFO     channel: C5:VAC-P2_SD2 command: @253SD2?;FF response: @253ACKBELOW;FF result: BELOW Tue, 15 Nov 2011 22:46:01 INFO     channel: C5:VAC-P2_SD3 command: @253SD3?;FF response: @253ACKBELOW;FF result: BELOW

364   Wed Nov 16 22:48:46 2011 FrankComputingSensorsvacuum gauge script crashed

after fixing the problem with parsing the response from the gauges i had more crashes without any error messages.

i monitored what's going on and realized that the script was accumulating a lot of memory, about 1Meg per few seconds. After using about 1.5G of ram it crashed. I've debugged the code and found out that calling the CA put command from the python-epics module to fast (every 100ms) the function does not release all of it's memory and the python garbage collector does not catch it either. If one calls it every minute or so everything is OK. As we would like to have a relative fast update for temp sensors etc.

i tried different things to fix that problem. One solution which seems to work now is to use the subprocess module and call the caput command in a classic way.  After monitoring the code for a few hours i could not observe any increase in memory consumption.

Current script version is v0.3. Code has been updated on framebuilder and svn.

184   Sat Jun 4 15:19:31 2011 FrankThings to BuyVacuumvacuum gauge

we need to buy some vacuum gauges to measure the pressure in the experimental chamber and the isolating chamber for the cryostat.
As we want to use exchange gas for cooling the cavity we first have to pump both chambers, refill the experimental chamber with some gas and then pump it again later after cooling.
So i think what we want is two vacuum gauges, one for each volume. The flanges on the chamber are KF25, so i would go for KF25 flanges on the gauges as well to simplify connections/adapters.

The next question is how much range do we need. I think we don't need a full range gauge going from atm to 10-9 Torr or so. They are expensive, ~$2k each, depending on brand and interfaces they are coming with, and usually they need an additional display unit to read the value. Less range should be fine for us. So i browsed the web for a while and checked what is sold these days and i found a nice device from MKS, which is a combination of two transducers, covering atm to 10-5 Torr. It comes with local display, RS232 port, analog output, 3 programmable relay outputs etc, everything for less than$600.  Shall we go for two of it?

1996   Mon Apr 2 14:57:03 2018 brittany, aaronDailyProgressCryo Qvacuum baseline testing

Plumbing

• Gauge only (Pressure @ End : 1e-8 Torr)
• Started : 2:51pm (Brittany)
• Ended:  10:05pm (18:04:03:05:06:39 UTC or 1206767215 GPS) (Aaron)
• Pressure when pump turned off: <1e-8torr!!!!
• Notes :
• File is 180402_pumpdown_GaugeOnly
• Aaron is very happy that the pump is not broken. The gauge bottoms out at 1e-8 torr, and the pressure trend indicates it could go lower.
• Dataset
• Saved - 18:04:03:05:06:39 and 8 hrs before it (Brittany)
• File pathway ~/git/Qryo/CryoQ_Analysis/data/VacuumBaseline/180403_GaugeOnly.dat (Brittany)
• *Don't forget to push datasets to the git repo from gaston*
• +Hose (Pressure @ End 4.380e-7 Torr)
• Started: 10:16pm (near 18:04:03:05:17:00 UTC, 1206767836 GPS) (Aaron)
• Ended : 9:02am (Tue Apr  3 09:02:03 PDT 2018, 1522771321 UTC) (Brittany)
• Oops okay I am sure a more helpful time is the one from dataviewer
• This is from ~9:55am = 18:04:03:16:50:26 1206809442, so the one above is like an hour before this
• Notes :
• I flushed the hose out with nitrogen before adding it to the system. I am using the 26'' hose with no steel sheath. (Aaron)
• I used the command 'date' and 'date +%s' to generate the timestamp, maybe we should standardize how we get this time stamp :) (Brittany)
• Dataset :
• Saved 18:04:03:16:50:26 and 14 hrs before it  (Brittany)
• +T and blank (Pressure @ End 2.3e-6 torr)
• Started : 9:16am (Tue Apr  3 09:16:24 PDT 2018 1522772191 UTC) (Brittany)
• ~9:55am = 18:04:03:16:50:26 1206809442, to help searching for the dataviewer
• Ended : ~5:00 pm = (Tue Apr 3 18:04:04:00:00:46 UTC, 1206835262 GPS) (Aaron)
• Notes :
• I cleaned out the T with iso and had to do a little bit of cleaning. There was some brownish colored junk that came out from inside. This potentially could have been a suspect in the pressure. We will see (Brittany)
• +PumpValve (Pressure @ End 1.775e-6)
• Started : 5:11pm (Tue Apr 3 18:04:04:00:11:21 UTC, 1206835897 GPS) (Aaron)
• Ended : 11:35am (Wednesday Apr 4 18:04:04:1jacket + single tank w/ conical top + bottom with linear actuator8:35:43 UTC, 1206906129 GPS) (Brittany)
• Notes :
• I cleaned the valve with Isopro, it seemed pretty clean already. I also cleaned the additional o-ring added to the system, which also looked pretty clean already. (Aaron)
• Because it seemed that either the T or blank we introduced in the last step increased the pressure out of proportion with its size, I am looking into (Aaron)
• +Cryostat Valve (Pressure @ End 1.654e-6)
• Started : 11:47am (18:04:04:18:51:43 UTC 1206902827 GPS) (Brittany)
• Ended : 10:40am (18:04:05:17:39:58 UTC 1206985214 GPS) (Brittany)
• Notes :
• I am going to keep this valve closed off for this test. I am not sure how to test it otherwise. We don't have a blank for the inside of this part. This is the last stage in plumbing before the cryostat. So in the next test, it will also be testing going through the gauge (Brittany)
• Accidentally turned it off before I read the final pressure, so there is a teeny blip at the end for like 20 seconds (Brittany)
• ​​+PumpT (Pressure end @ 1.69e1-6 Torr)
• Started : 10:55am (18:04:05:17:54:29 UTC 1206986085 GPS) (Brittany)
• Ended : 1:58pm (18:04:06:20:58:42 UTC 1207083538 GPS) (Brittany)
• Notes :
• I realized that we needed to add a T that vents to air to protect the gauge. I added this after the pump and before the pump valve (Brittany)

Cryostat

• jacket + blank on top + bottom with linear actuator (Pressure end @ 4e-6 torr)
• Started : 2:18pm (18:04:06:21:17:33 UTC 1207084669 GPS) (Brittany)
• Ended :  3:45pm (18:04:09:22:48:39 UTC, 1207349335 GPS) (Aaron)
• Notes :
• The electrical feedthrough is one that is a blank (Brittany)
• I cleaned off the window from a fingerprint twice (Brittany)
• Turns out it is easy to add when you attaching the window
• I gave the inside of the jacket an iso wipe down (Brittany
• The oring on the bottom flange was fully of speckles of foil that rain down from above. We need to be ultra careful about inspecting this before buttoning up (Brittany)
• jacket + single tank w/ conical top + bottom with linear actuator (Pressure end @ 1.061e-4 torr)
• Started : 4:20pm (18:04:09:23:19:52 UTC, 1207351208 GPS) (Aaron)
• Ended : 3:11pm (18:04:10:22:10:34 UTC, 1207433450 GPS) (Brittany)
• Notes :
• I removed the aluminum foil and scrubbed off the varnish with acetone from the top of this tank, and cleaned the large o-ring with the iso pro on lint free wipe and vacuum grease (Aaron)
• Aaron and Brittany chatted and it may be exposing the aluminimum and the residual varnish maybe be the culprit. Path forward try a different tank, clean that one and try again (Brittany)
• I did an iso leak check aroud the large and top o-ring with no obvious change in pressure (Brittany)
• Well if varnish was the problem before the problem now is that the entire tank is kinked over to one side. This is probably my fault because I though the tank had come back up to atmosphere because of what it read on the gauge. However i heard clank when i got the top open and now the tank is cocked over to the side. I will look in to ordering a new tank tomorrow. ugh (Brittany)

1853   Tue Dec 5 17:41:59 2017 BrittanyDailyProgressCryo Qvacuum + 2in fused silica disks

2inch fused silica disks have arrived to Caltech!

• We plan on working with Gabriele this week to have the measurements done in his lab to compare with ours

Started putting the vacuum back together @ 40m

• Putting together our disk loader was a little trick though it’s mostly come together

Seeing how low the pump is going

• Rustled up a kf25 blank (we should get some more for cryolab since we don’t have any spares)
• Took apart our tube and gauge and noticed how dirty our orings are
• Wiped things down and decided to just see how low our pump and gauge can go
• The gauge is still shedding random piece of metal
• Does anyone know why it does this?
• It was all over the oring that connects it (see picture)
• I cleaned it off and put it back together (I figured we got to 1e-5 before with this and maybe it’s not super terrible. It would be useful to know if this is a bad practice for subbasement standards)
• Hooked up gauge + pump and turned it on. It was at 3.4e-5 after a few minutes
• Left the pump on to see how low it can go

Attachment 1: bottomOfGauge.jpg
Attachment 2: Oring_metalFilings.jpg
1856   Tue Dec 12 20:25:18 2017 ranaDailyProgressCryo Qvacuum

and then what happened?

 Quote: Left the pump on to see how low it can go

201   Fri Jun 17 23:21:58 2011 FrankCryostatDrawingsvaccum system

here a picture of what i think the vacuum system could look like. There is a flex hose missing from the valve on top of the 6-way cross to the tee attached to the other valve (the valve for the outer insulating vacuum).
There are two gauges, one for the insulating vacuum (down to 10-5 Torr), mounted on a tee, which we don't need (the tee) but i wanted to see if there is enough space to add one just in case we want to add another feedthrough over there.
The other is a better model which can measure down to 10-8 Torr. There are also two 24pin connectors on the cross and an open port for the needle valve for the exchange gas. The two open ports are connected to the LN2 reservoir.

Will add the schematic for it later.

206   Wed Jun 22 10:22:54 2011 FrankUpdateVacuumvaccum pump station shipping date changed

i got confirmation that the pump including all options and adapter will be shipped August 5. They don't have any in stock at the moment.
I hope it won't delay anything as the cryostat will be delivered first week of August as well.

Will update the project file on the svn.

182   Sat Jun 4 12:32:41 2011 FrankNotesPurchasesvaccum pump station

- personal notes-

Vacuum pump station

HiCube 80 Eco, DN 63 CF-F, with DCU 002    (PM S03 556http://www.pfeiffer-vacuum.com/productPdfs/PMS03556.en.pdf

additional options we might wanna have:

http://www.pfeiffer-vacuum.com/products/turbopumps/hipace-tm-series/hipace-tm-10-800/hipace-80/onlinecatalog.action?detailPdoId=4511

• TVV 001 fore-vacuum safety valve (PMZ01206)
• Splinter screen for Turbopumps, DN 63 CF-F flange (PM016312)
• Vent Valve, G-1/8 connection w/ M8 plugin cable for HiPace 80  (PMZ01290)

Requested a quote on Friday

2863   Wed Mar 9 14:20:26 2022 aaronDailyProgressElectronicsupdates to fiber patch cables, realignment, N laser in path, relock
• Replaced the patch cable carrying PSOMA South laser from the fiber box to the table with 2x P3-1550PM-FC-10 cables (one for S, one for N), and wrapped them in the protective cable cover. Clamped the cables with rubber on the table and fastened the flexible cable wrap to the optical table and enclosure. Then had to slightly realign the fiber launch until the 00 mode locks again.
• Also replaced the 10 dB attenuator at the LB box input with a 6 dB attenuator, to make up for the 50-50 RF power splitter I introduced before the PDH mixers yesterday
• Completed the N laser path: 90% of pickoff BS to N EOM, then to [10% path of a 90-10 fiber splitter... asking around for a 50-50 splitter, unless I'm missing something the 10% path doesn't even register
• cleaned any fiber tips before connecting
• clamped with rubber the EOM
• Found a 90-10 splitter off the shelf, but we're out of spare fiber component mounting trays so I left it in the plastic packaging and secured with Kapton tape
• Locking activities
• Reducing the laser power (due to the RF power splitter, and the fiber splitter that mixes N and S beams) obviously pushes us to higher open loop gains... but we're close to the phase margin, so that doesn't come easily
• I added Shruti's loop compensating filter box before the LB servo input, which allowed me to increase the LB servo gain knob to 6.2 (up from 5.3, on a log scale) before the loop oscillates... although, there's still not enough gain to completely suppress the 40 Hz oscillation from the cantilever's fundamental mode. I also removed the 6 dB attenuator and incidentally swapped from (-B) input to (+A) input on the LB box.
• It's probably also worth improving the mode matching again. A couple times I locked on to a 1-0 mode.
• Also played around with the LFGL but noticed no qualitative difference in the system (especially REFL DC) with LFGL off or on.
• Plan is to use the Moku Lab as a PID controller lieu of a second LB servo box. However, turning on the N laser doesn't even register on the REFL photodiode... this is surprising, the PD should definitely be sensitive enough to see the N laser even at 10% of full power (should be 400 uW).
• Is this an alignment issue? Wrong part of the laser's T-I curve? Something wrong earlier in one of the fiber components (seems likely)? I couldn't locate the Thorlabs power meter, so had trouble testing these. Has anyone borrowed it? Might just be looking in the wrong places, but usually it's on the optics table.
• Misc
• The second oscilloscope on the optics table was making an annoying switching sound, so I turned it off.
•
115   Mon Mar 28 12:38:15 2011 FrankUpdateCavityupdated refcav drawings

made some slight changes to the spacer drawing. updated files below:

221   Thu Jun 30 13:18:40 2011 Dmass, FrankUpdateCavityupdated mirror quotes

we talked to a couple of vendors today and relaxed the specs a little bit. Four of them will quote us within the next 24h.

Specs are now:
Silicon mirror, 1m cc, 30min wedge
L/10 @ 1.5um
SD20-10 both sides
<3nm rms
(annulus only if possible on short time scale)

2388   Sun May 12 17:49:52 2019 ranaMiscGeneralupdate Wiki

https://nodus.ligo.caltech.edu:30889/CryoWiki/doku.php?id=projects:cryoq

1. Should separate Qryo stuff from the CryoCav and SiFi stuff in the wiki.
2. make Qryo list for June-July
1. more robust timing electronics
1. cabling: use high quality cables (never use L-Com); SMA preferred
2. put SRS clock generator somewhere secure; outside of rack, someplace its not getting bumped all the time.
3. strain relieve cables going into FE computer.
2. rational approach to sample rates, # of DQ channels, AA/AI corner frequencies
4. Lab Maintenance
5. Better sensor of disk modes?
1. Where is the QPD noise budget?
2. bi-refringence seems to have low SNR
3. QPD sensor moves a lot during cool-down
4. Can we use ESD as dual-duty capacitive sensor?
6. Closed cycle cooler for Qryo?
1. can stay cold longer
2. too much vibrations?
7. Do we need to isolate pump vibrations more?
1. put some weights on the roughing pump
2. move Turbo somewhere else? tradeoff vibrations vs. pump speed
8. Hang more Pomona cable holders (Orange, Black, and Blue)
9. Many cables in Qryo are too tight. Connectors under strain, moving around the lab will break things.
270   Sat Jul 30 01:14:23 2011 FrankUpdateCryoupdate
• the machine shop fixed the problem with the feedthrough connectors. Picked them up and also got DI water from the 40m to clean the parts downstairs.
Bob is pretty busy with ALigo stuff and the parts are very tiny but totaly covered with oil. So i will use our ultrasonic bath in the PSL lab  to clean them.

• Will then assemble and test the feedthroughs. Have to either get our pump back from Vladimir or could also wait for our new pump which should be delivered beginning next week.
Have to make some cables for the vacuum gauges anyway so once i have everything ready i will see which way to go.

• Will get a first cryo sensor ready on the weekend. Have to borrow a small dewar for the 40m as we still didn't get our own. However we have all our other safety equipment by now

• Tested the cryo temp controller the last couple of days to get familiar with the interface. Seems to be OK so far, don't need a manual to set everything up (which is good). Will try to hook it up to the network and access it from remote to see how to communicate with it. Even it is recording everything to a local USB stick we would like to read/ write values using Epics( or our RT control system later).

• We also might get our radiation shields next week. I've seen parts of it already so they might be able to finish them next week. Have to finalize the order for the heater. Have to come up with a good estimate for the heating power we need to pick a good value for the resistance to not choose a totally stupid one. We have the choice of 6 to 12 values from 10Ohms to 500Ohms depending on the size we choose.

1526   Fri Feb 24 20:25:59 2017 brittanyDailyProgressCryo Qupdate

I spent some time figuring out where and how the mount for the periscope will be in the version of the machined GeNS that we hope to get sent out soon. I decided to go with a design very similar to the way the mirrror is currently mounted in the JaNS. It is this neatly machined piece of metal that looks like the shape of lipstick that is screwed in to the bottom plate. It has a shield around it to absorb the reflections. I have not added my changes to the dcc and will do that some time early next week. I need a little more time to find this weird optic to get and get the dimensions correct.

Earlier today, I checked the vacuum and the pressure had gone down to 7.2e-5 (with the pump still on)

2678   Tue Mar 9 13:57:38 2021 aaronDailyProgress update

enter Tue Mar 9 13:57:31 2021

• picked up a fiber microscope and cleaner from Aidan's office
• I'd like to record data with cymac1 to assist in the 'coherent 3 corner hat' measurement. To that end, I'm setting up the x1oma model (again).
• Not much success

exit Tue Mar 9 16:42:41 2021

ELOG V3.1.3-