It took several extra hours to get the beam aligned, because I changed a bit the angle of the periscope mirror inside the cryo (pressed 4 copper strips between the periscope mount and the bottom of the heat shield).
I identified the following modes at room temperature:
When the pressure reached 2e-4 torr (Tue May 14 22:30:43 2019) I began cooldown.
All RTDs are dysfunctional, so we only have the eigenfrequency temperature probe.
I refill the dewar (Tue May 14 23:38:43 2019), but somewhat before it was full the large dewar ran empty. This is surprising, the gauge on the dewar reads just under half full. Won't be cold tomorrow; I've ordered a new dewar.
Several of the SURFs this summer will want to model the experiment in COMSOL, or look at the solidworks drawings of the cryostat to get a sense for what's going on.
Once you have access to Pleione and ligo.org credentials, you should be able to access all our files.
These are on Pleione. To access:
We have several working COMSOL models you can get started with.
Is there anything stopping us from using these printed circuits for the entire RTD leads?
So we would have two holes for the RTD leads to solder into, and 4 traces along a ~10cm piece of Kapton tape. As long as we can choose something like phosphor-bronze for the traces (lower conductivity), I don't think the extra Kapton should affect our temperature measurement, and it would help the wire management.
[shubha, anna, aaron]
We gathered this morning to clean up the cryo lab a bit. We spend some time moving optics from the NW cabinet (which will contain optoelectronics and Si fab materials) to the SW optics cabinet.
The FE were down, so I ran killAll. Cymac1 became unresponsive to ssh and commands from the existing session, and I did a hard reboot, then startAll.
The lab should be ready for Shubha to start measuring the laser noise of the green pointer, and I showed him what disk to use to measure temperature as a function of laser power (in air first). The SiQ experiment should be ready for Anna to measure Qs.
Mon Jul 1 17:19:57 2019
Anna and Shubha reported that cymac1 never woke up. I did an Advanced Reboot (unplugged the machine, in addition to rebooting), and monitored the startup directly via VGA.
As had happened once before, cymac1 was getting stuck in emergency boot mode. This had happened once before, I entered the root password, plugged in the external hard drive (this was the backup drive, which cymac1 was searching for during boot), and am now able to finish booting cymac1. Please do not unplug the external hard drive behind cymac1. We will make the backup drive internal when we reorganize the rack.
I pulled the second laser driver circuit box from the cryo cavs table, and we took it to the EE shop. We tested it in stages:
Shubha will post about what's still undiagnosed (including the real circuit diagram) and what is to come.
Anna wasn't able to get modes exciting on the disk, so I'm taking a look. Shubha and I had disconnected the cable carrying the ESD excitation signal to the HV driver, so we could temporarily use that channel for the laser driver circuit. When we went to replace the cable, I noticed that the janky DB9-to-BNC I'd made had finally broken, so we replaced it with a PCB DB-BNC breakout.
The ESD excitation still wasn't reaching the HV drive, and though the DAC TP channels were reading the correct values, we weren't seeing any voltages out of the DAC chassis. I ran killAll/startAll, but am getting the characteristic increasing checksum errors (code 0x1000 on the DC status part of the GDS_TP screens). There were no bad frames, and in the past we've narrowed this down to a timing issue. At some point while digging through old elogs to find what we did last time, cymac1 crashed (all white boxes, no ping).
We pressed (not held down) the power button once, waited 5 minutes, then did it once more. With no response, we held down the power button for a hard reboot.
When the system came back online, I ran startAll and burtwb the 'measureReady' snapshot. All (usual) indicators green (attachment 1), but we still aren't getting any signal out of the DAC.
Thu Jul 11 10:39:36 2019 we filled the nitrogen.
Anna mentioned today that she is getting errors when running diaggui in the past. I don't find any problems, and cymac1 has been running with no problems for an unusually long time. Note that only the _DQ channels are saved to frames, so only those channels can be viewed in the past.
I did find that the pressure channel is reading 0. Not sure if it's just not plugged in, we can check later today.
What crimp pins go with that kind of connector?
Shubha - CONTACT SOCKET 20-24 AWG CRIMP connectors
Anchal and I started the process of building the new cryo stand. The result is attached, and that we determined I need to order (or modify from the cryo graveyard) a plate to clamp the bottom of the cryostat.
I also mostly finished up the reorganization of the cryo lab, up to some electronics parts to be sorted into the EE shop, a couple boxes in the vacuum cabinet, and projects in progress. Please try to follow the new organization scheme (see the labels; if you don't know where something goes don't just put it anywhere but find the appropriate place or talk to the other lab members about where it should go).
Following the discussion with Anchal on Friday about the new cryostat mount, I found the calibrated leak and associated buffer gas piping in the vacuum cabinet. We need some more careful planning to set up buffer gas cooling, and since it may change the space requirements in the cryostat I've returned to the new GeNS design with a buffer gas in mind. Loosely, I think we need to design/decide on the following (working list)
To tackle any of those, I'd like to review a bit more the cryostat design literature. I've picked up these from the library:
I've attached a screenshot of the design so far, please come discuss how it should go.
Today I've been reading up on light-tight seals for cryostat design. I'll compile some resources here:
Here's a working copy of the eDrawing.
The ESD should look like a capacitor from the outside, so I would expect a very large (~infinite) resistance. On the curernt pins--are there three RTD installed? Recall that the RTD are wired in series, so removing a single RTD will leave the current leads with an open circuit.
The ESD can be stuck near 0 for a few reasons
Cool! Models! Data! Here are some thoughts/suggestions:
I unplugged the BNC from the HV driver input, and observed the driver output drop from 0.52V to 0V (according to the digital display). Probing the BNC with the multimeter, indeed the DAC is giving only 2mV instead of the expected 5V.
Attachment #1 is the state of the testpoint screens before I restarted the FE. After taknig that screenshot, I did the following:
Screenshot #2 is the state after startAll finishes running. I'm still seeing the FE lights red on the SIQ_GDS_TP screen, but looking back at some previous instances of this problem I think everything is nominal now. I probed the BNC again and get the expected 5V output. I ran
to restore the settings from before this FE restart, and the system should be ready to go!
Yesterday Anna measured some disk eigenfrequencies at room temperature, then we cooled down.
I topped off the nitrogen at Fri Aug 16 13:20:15 2019 . Temperatures were still above 200K at the RTDs (nitrogen had boiled off this morning), so it's going to take some time to cool still.
I disconnected the SS-8BS leak valve from the shutoff valve so I could bake it, but found an unpleasant surprise. The photos probably tell it best. The labelled parts in attachment 1 are:
There was a glass sleeve of some kind inside the valve, shattered; I can't find mention of it on the elog, but maybe I don't know what it was used for in the past?
Tue Oct 8 11:20:52 2019. We restarted the FE after seeing the same failure mode as before.
We were able to excite two modes, optimized the phase on MR0, and calibrated the temperature of MR0; mode was at ~973 Hz. At the last minute we excited MR1 as well, but didn't do much playing around.
Looks pretty good. I suspect you're getting the diverging solution because the Q term in the denominator of your resonator TF is not imaginary. This means that the resonator has no damping, and any drive would indeed lead to diverging amplitude.
You might need to define the TF from the command line function, rather than in the simulink block; I think the block throws an error when you give it complex coefficients. This is surprising to me, so maybe I'm missing something.
Edit: That's not it, I just wasn't thinking in s-domain.
Here are a few other things I notice about this model that might be important:
Following discussion last week with Rana and Shruti, we would like to set up the early version on PSOMA in the Cryo lab. Working in cryo offers the following benefits:
I'm reviewing the existing COVID-19 guidelines from PMA and LIGO, and would like to develop a set of procedures for the people using the cryo lab to follow as we return to West Bridge. This includes:
Here are some of the resources available for answering these questions:
According to the plan for reconstituting lab activities in PMA, labs should plan with the following in mind. Open questions for cryo are in bold.
This section is an unpacking of attachment 2, with the specifics of the cryo lab in mind.
Here's my first attempt at a template / checklist for logging cryo lab entry / exit. In practice, perhaps the full checklist can be stored on a wiki page and also posted in the lab, rather than repeated many times on the elog. In that case, we can just include user name, time in and out, and purpose for lab use. Please provide changes, additions, comments, etc.
By posting this elog, I confirm that I am eligible for returning to campus work by meeting the following:
By posting this elog, I confirm that on entering the cryo lab, I did all of the following, in order
By posting this elog, I confirm that on exiting the cryo lab I did all of the following, in order:
By posting this elog, I confirm that on briefly leaving the cryo lab to use the restroom (or another room with users not from our lab), I did all of the following, in order
The cleaning and sanitizing protocol is defined in attachment 2. Note that these apply to preventative measures to remove visible debris and reduce the number and growth of bacteria, virus, and fungi. Measures for disinfecting, or killing pathogens on a known contaminated surface, are defined elsewhere (see Caltech EHS).
That's probably all that's necessary for a typical lab entry, though more details always good. Here's what I'll be doing and a couple checklists for COVID procedures.
Some of the above plans or guidance are now out of date. Here are some updates:
TLDR: I sealed the leaks around the HEPA filter. I did an inventory of PPE and cleaning supplies in cryo, and separated two sets of personal PPE for Shruti and myself from the common supply. I did not receive PPE or cleaning supplies from Downs or 40m, but have inquired after both. Any anticipated work not explicitly mentioned here was not done; I tried to take care, but still strongly suggest that Shruti wipe down anything I placed in your personal supplies, just in case.
Next steps: See prior elog
After clearing the temperature check at home, still showing no symptoms, and starting the daily log in the reporting app, I head to West Bridge.
I entered the lab at 13:10 PT, using the N (olive walk) entrance to W Bridge. I am wearing a disposable mask, applied hand sanitizer on entering the lab, and don nitrile gloves. I locate the ISO and Kim wipes and wipe down
I located the following in the cryo lab, and am storing all PPE in the staging area at the entrance.
Any tool I used that we have multiple copies of, I labeled "[aaron/shruti]" and set aside one copy for me and one for Shruti. My tools are on the blue cart holding Spirou. Shruti's are on the tan cart formerly holding screws and power supples (which I moved onto the remaining cart, the work bench, and the middle optics bench). Personal toolkit currently includes:
Personal PPE are in clear bins labeled "Shruti" or "Aaron" and with the box contents. Currently each set includes
The remaining PPE are in clear boxes near the entrance labeled "common" and with the box contents. Extra AccuTech gloves and a few more coveralls are on the shelf below the HEPA filter.
Any tool with only one copy, I am noting here for a future order. I sanitized these tools before and after use. Common tools will remain in the tall blue Crafsman tool box.
The model of the HEPA filter is not visible from the exterior, and I will have to look up its cleaning schedule. The tape sealing the edges of the filter does not adhere to the textured paint surrounding part of the filter [attachment 1] . The smooth paint on the far wall appears to support adequate adhesion. To create a seal on the textured surface, I first cleared the supplies from the shelf under the filter and pealed back the non-adhering tape. I applied rubber cement to the sticky side of the tape, and held the tape in position for drying using the small boxes of Kim wipes from before. I applied rubber cement along the entire edge wherever there was textured paint, but not on the region with smooth paint. Air flow through the filter was noticeably increased following this procedure and seal was intact after a few hours, though I did not make a quantitative measurement.
at 1500 I exited the lab to use the restroom, eat, and pick up PPE from Downs 318. I swapped gloves on exit, and resanitized my hands after using the restroom in W Bridge basement, which is designated for our lab's use. After eating, I entered Downs and took the elevator to the 3rd floor, but was not able to access room 318 for PPE. I emailed Chub and Calum (listed contacts for Thomas lab) to coordinate a pickup at a later date. Specifically, I am requesting:
At 17:15, I begin wiping down the common tools and surfaces I used and exit at 17:25, upon which I disinfect hands again.
Purpose: finish up the steps outlined above (2533)
[note: date is correct, I needed to remake the entries for July 23 but the content of 2541 is nearly identical. I had a backup.]
I stopped by my office (W Bridge 364E) to pick up the new workstation computer and a mini monitor that might be handy. Stayed < 15 min and wore fresh gloves, mask, etc; also recorded entry by door.
I entered the lab around 3:15pm and wiped down the common surfaces. I sanitized and sorted my set of PPE from the box Liz dropped off -- thank you!
We should try not to bring cardboard Into the lab, and remove any cardboard we find. I got rid of a couple boxes.
The thermostat is doing its usual thing. It is set to 'cool,' but despite the temperature reading 71.2 F at the thermostat, the temperature at the particle counter is 80F and it feels warm. When I try to lower the set point, the thermostat requests a password. I found online that the default password for is 9995. The thermostat seems to accept the password but won't let me change the setpoint.
The rubber cement at one corner of the HEPA filter delaminated, but the edge held by the kim wipes set in place. I reapplied glue and fixed the tape more securely, and noticed improved air flow through the filter again. The lab temperature also improved a bit -- the leak seems directs cold air down to the floor, while the filter sends cool air across the top of the room.
These cover most of the recommended reopening steps. I'll do some general cleaning and organization, and make some new signage, then will call it 'reopen.'
exit lab Thu Jul 23 18:09:38 2020
Purpose: PSOMA hardware inventory, find out what we can turn on
I located the materials for stage 1 PSOMA on the West optics table. I recorded what we have in the hardware inventory, and what we don't have is flagged for purchase. I start by cleaning up the electronics rack, removing anything I think is not in use.
Liz dropped off an air scrubber (Medify Airx MA-40) and an anemometer (Digi-sense 20250-15) today. I'm using the instructions on the DCC to measure the air flow and assess the occupancy limits of the cryo lab. I calculate an acceptable amount of time between lab uses, and for two people to occupy the cryo lab simultaneously. For these calculations, I use a conservative threshold of P<1% for the acceptable probability that a second person becomes infected, given one infected lab occupant who sheds virus at 10 nL/min. I measured the dimensions of the lab at about 30x20x10' (l, w, h), for a 6000 ft^3 volume. I expect that's a high estimate, as it doesn't account for things like the awkward geometry of the staircase, volume of lab equipment, or stagnant air inside cabinets.
These results are consistent with what I see for similar types of rooms in the LIGO spreadsheet.
Under an air flow model assuming perfect distribution of air from HVAC and HEPA scrubber throughout the lab, and very conservative requirements for probability of spreading COVID assuming a single lab user is infected,
Furthermore, the air in the lab Is not perfectly distributed. The air intake is several feet from the outflow, both near the door. The primary heat sources are the electronics racks along the N and NW sides of the room. The gradient from 71.1 F at the thermostat to 78 F at the cryocavs rack is uncomfortable to work in and bad for the electronics and optics. It's also too stagnant for the viral load conditions assumed in Evans P2000189 to apply.
We are not currently cleared for 2+ people to use the lab. This analysis suggests to me that before doing so, we should improve the air flow conditions in the lab. And, even under optimal conditions we may minimize the total time with multiple people in the lab simultaneously.
I disconnected the oscillator, PDH boxes, and laser drivers from the power strip, and powered the strip with the Tenma supply. I had the ground and negative pins switched at first, careful of this -- ground is black, negative is green on this cable.
I plugged in the electronics, but only turned on DC power to the laser driver. I just left them on long enough to confirm a bright green (on viewcard) beam spot for both lasers -- we're in business!
Turned off the lasers, disinfected the common surfaces and objects.
PS, the anti-fog wipes work wonders. My goggles went from fogging in seconds to no fog at all.
Purpose: Measure optical table dimensions, start to assess what we need for an enclosure. Set up EOM/EOAM to take some transfer functions. Set up realtime model. Figure out why particle counter isn't logging to frames. Turn on the HEPA for cryo cavs table.
Entered the lab at 11:00 am. The lab is far too hot (78F) and humid (45%)!
Inventoried available photodiodes in the cryo lab, on the PSOMA wiki.
Pretty tired honestly, I submitted an order for a few things we want in the lab, such as:
The PSOMA optics table is from TMC vibration control (TMC 784-29701-01). I sent them an inquiry for the datasheet, and also asked whether they sell clean enclosures or have application notes that might help us put one together. Also talked with Arian Jadbabaie a bit about the Hutzler lab enclosures, and got some photos.
Exit ~430 pm
Measurements around table
Could probably move the table a few inches from the wall and make use of the space between the lights for the enclosure. There also isn't much room in the back corner in the NS direction, and we may want to shift in either direction. Orientation seems as good as it could be. The ceiling above PSOMA is lower than above cryo cavs.
Will mark up photos and post.
Purpose: Inventory lens supply, identify some combination of optics that will let us mode match to our ring cavity. Picked up some books on silicon from the library.
The inventory is in Clickup, which is a new organizational tool I'm trying out. There' an easy csv export, so I can get it elsewhere if/when we want. We have a wide variety of lenses:
I found fewer curved mirrors, but there were a couple.
Steps I took for the temperature sensor:
1. Tried to see what's the temperature by reading the current temperature in ndscope or dataviewer. In dataviewer, go to 'Signal' tab, and enter the channel name or find it on the list of slow channels. For ndscope...
No data appears on either. I restart cymac1, which seemed frozen, but still nothing.
2. What's going on with these channels?
Looks like the channel is reading zero.
3. I traced the cable from the particle counter and found that it sends data to cominaux, the common auxiliary machine for the lab.
This is the database file that defines the channels on cominaux. I search for 'LAB_TEMP_F' and find the epics record for the temperature channels. The epics records are all "calc" records, and the temperature in Kelvin is taken from X1:AUX-ACROXT_AI_15. This corresponds to channel 15 of the acromag slow ADC.
That's starting to make sense, the cable from the particle counter didn't go to the acromag ADC. Starting from the ADC channel 15, I traced the cable back to what used to be the AD590 temperature transducer.
4. Where did the IC temperature sensor go? Searching the elog and my dusty memory... neither readily recalls where it went. Let's get another one, they are cheap and easy to use.
Date of entry: 18 Aug 2020
The cameras were unfortunately lost in the mail, but we can use my laptop or other camera. Ended up leaving to do a couple comsol things that needed completing today.
Date of entry: 24 Aug 2020
Did some mode matching, see the git.
I started a cryo lab inventory that is separate from the PSOMA hardware inventory, and intended for stock items in the lab (optics, electronics, clamps, general safety and cleaning supplies, etc). It will be a work in progress. Both are accessible to anyone logged in to google drive with their ligo.org credentials.
Both are also linked on the PSOMA project wiki.
I took some photos of the existing layout. I'll just take apart the E beam path, and leave the W path unchanged for now as reference.
I moved the E fiber output coupler closer to the edge of the table, to make this path easier to reach.
Hopped around on the laser hysterisis curve for a minute. To optimize the temperature,
Can anyone tell me the specs / history of some of the custom optics in cryo? I'm mounting the 1m Coastline mirror and will start with that in the PSOMA cavity.
Not sure how, but none of the drawers of the blue optomechanics cabinet are opening. I don't have a key. Here's what happened
Found someone who's had this problem before, might give it a try...
This worked, I used the metal meter stick to unlock the drawer.
--> note that link formatting breaks link for me, so here it is - https://www.practicalmachinist.com/vb/general/help-my-lista-locked-me-out-how-do-i-open-201606/
--> wrote up a similar experience with additional detail ENG_Labs/260
I measured the transmission of the Coastline 1m mirror at 180. ppm (S122C).
Alignment procedure while setting location of optics:
Alignment procedure subsequently:
Here's the layout.
Some easy things that should be changed:
I updated the stage 1/2 optical layout to be more detailed after getting a sense of the sizes of things again last week. Even though this isn't how the table is currently set up, it might be good to accommodate future vacuum chambers in our earlier designs to minimize how much we need to move and realign optics.
I will update the PSOMA hardware inventory tomorrow to reflect the additional details in the new drawing. The updated diagram is available on git LFS, and the hardware inventory now reflects the diagram up through stage 1.
Yesterday into today, I've been shopping for laminar flow HEPA fan filter modules for the PSOMA optical enclosure. I didn't find a lot of LIGO documentation listing specific filters, but here's what I've found online with some downselection on 'low vibration / high filter quality'. Please let me know If there's a company we often use, or if you can help direct this search at all.
Another consideration is flow rate relative to our volume. I can do this calculation, but what is the particle density (eg at 0.3 um) we want to achieve inside the enclosure? I realize that I never got the particle counter recording despite it being on my list, so I'll try to do that remotely today. We need to know the ambient particle count and the clean volume in the enclosure.
*all prices listed here are from publicly available pages
Tue Sep 22 21:33:30 2020
I'm cleaning a bit, and gathering items not in use or in need of repair. They would make less mess in my office.
took an inventory of optics cleaning supplies, first aid kit, general cleaning supplies, wipes, etc. I found most were included in the first round inventory, but I took photos this time to convince my future self of object permanence. Will add to the wiki and update in a bit.
gloved up, shoe covers, went to QIL to check out the sprinklers and CTN to grab a GHz spectrum analyzer (HP8560E).
out: Wed Sep 23 00:20:03 2020