During my visit to FNAL, we have been working toward the goal of prepping the Dewar for final shipment to Caltech.
When I arrived the Dewar was assembled and pumped down (without greasing any O-rings) to a leak rate of 10^-4 or 5. 

We then performed leak tests using helium and a helium detector to pinpoint a few locations for possible leaks.
Upon dismantling the entire device, I could locate a few particles of dust, debris, and fibers that may have caused these leaks and warked areas of concern with possible micro scratches or abrasions to the sealing surface of one of the inner cubes. We expect that on the second test, bringing the Dewar to vacuum to leak check for Thursday and sealing with vacuum grease, we will see a majority of these leaks disappear. Great care and meticulous cleaning were done in preparation for this cycle, so we will post the results on our leak rate tomorrow. 

Some other notes to take into consideration when I am to get back to Caltech:
- The copper cube for the "free space" optics has 2 notes.

     1. When manufacturing the plate for it, they were unable to meet the spec we initially required for the optics, thus each of the tapped holes is set to a tolerance of +-1 thousandth true position rather than 0.5 thousandths, this may or may not affect our alignments, but we will have to see when testing the dewar fully.

     2. These holes were made blind, they are through holes and will need to be blocked underneath with plugs or taped over with copper tape to block the light out. If this is a huge issue and the tape is not cutting it, we can also send it to the manufacturer for them to weld seal the holes. 

- All copper plates and components have been designed without helicoils as they would greatly affect the conduction inside the copper cubes. Thus we must take great caution when bolting anything together with the copper boxes to not strip any of the components!

- That being said, all thermal specs were done for bolts to have been tightened to 25 foot-lbs of force, we should buy some torque wrenches for the reassembly. 

- The copper is being passivated such that it is less likely to rust and is more durable over time, but this may need to be done again in the future (5-8 minute citric acid bath and 250-300 degree bakeout and cool down for 18 hours) 

- A few of the boxes being shipped will have not been opened before, so we will need to do a full inspection of the components inside them to alert the manufacturers if anything is wrong or damaged from shipment. 

- When the dewar is fully assembled it must not ever be tipped on its side as the G10 legs for the copper could be broken or damaged!

- Anytime we bring the dewar back to normal pressure (1 atm) we will want to infill with nitrogen, thus we will be adding a pressure relief valve to add a layer of safety when doing so and not overpressurizing the vessel. 
Things to check up on with Boris and the SNSPD group regarding components for the Dewar:

- Did we order the XYZ stage? We will also need to do a bit of testing with its internal fine-threaded bolts and their susceptibility to expanding in low-temperature environments (may need to have them made out of aluminum or steel instead of brass)

- Have we ordered the feed-throughs for the XYZ stage aligning?

- Suggested we order an extra set of the G10 feet (erik@precisioncryo.com) - they will have our order info for a bit and could replicate our parts (Fermi PO# PO711633)

[Jeff, Daniel]
 

I moved parts out of the mobile clean room and wipes down the tables in side them. I also cleaned the outside of the end cubes to remove any anti sieze.
 

I then swiffered and vacuumed the floors of the entirety of B111 and B110. 
 

Jeff and I cleaned all of the B111A and B111B tables.
 

Jeff has cleaned all of the electronics racks.

I loaned a bag of Silver Plated 12 Point Bolts (1/4-28 x 7/8") with 1/4" washers, 25/pk to Paco. Duniway Part Number SBX-28-087. Paco said he would return the bag on Thursday, 9/26.

I have installed Debian 11 on the server which is currently the only machine in the mobile server rack in B111D. Here is a guide to the steps I took.

1) create a bootable usb drive. This tutorial is very detailed. Here is the downloads page for Debian 11 (bullseye). Use the netinst CD image.

2) Plug into the machine: keyboard, monitor, ethernet connection to network, and bootable usb drive (also called installation media)

3) boot up the machine and press F11 when the option appears to enter a boot menu

4) select your usb drive from the list and then follow the installation wizard

5) when asked to select a network I was given the options 'eno1' and 'eno2', only eno2 worked (I do not know what these two options refer to)

6) I selected the hostname 'babbage' and username 'cymac'. The root and user passwords are on the labsecrets wiki page.

7) When asked about disk partitioning, I did a 'guided' partition of the entire disk, and did not modify any of the defaults.

8) When asked what software you'd like, unselect "Debian Desktop Environment" and "GNOME" and select "MATE". Leave "Standard tools" selected. Installing GNOME led to graphics related crashes down the line.

That's all! There will be a future post about configuring Bios settings and installing CyMAC software.

I took some particle counter measurments in B102, B111, B111A, and B111B. In all the clean rooms, the particle count was 0. These clean rooms were the B102 cleanroom with the optical cavities, the B111B mobile cleanrooms, the Southern most B111A long table, and the Northern most B111B short table.

I also took some 10 second particle counts outside the clean rooms. Data is 0.3 um count/0.5 um count/1.0 um count)

B102: 1268/72/28 (there were lots of people and activity during this measurment)

B111 (entryway): 495/46/28

B111B: 177/51/39

B111A: 95/17/13

These seem like very good measurments.

The particle counter is on the optics tables in B111B.

[Jeff, Ian, Torrey, Alex, Daniel]

We turned off the lasers in B102 for safety purposes (we'd be opening and closing the curtains frequently) and moved both Holometer End Cubes designated for the LFC into B111B onto a 2' tall table.

The next steps are cleaning B111B (with special attention to the mobile clean rooms) and replacing the bottom flange with one with a breadboard pattern.

The 1550 seed laser and amplifier in B102 are now off. The sign on the outside of the room is also off.

The particle counter calibration certificate expires October 15th. The company reached out for a recalibration service. We've declined it at this time. 
Point of contact: Sophia Correia (srcorreia@beckman.com)

[Jeff, Sander, Alex, Daniel]

We raised the screws holding the breadboard connecting the two optics tables and raised the optics tables up onto thier wheels. We then moved the tables 1' North so that the pump out station would not conflict with the wall. We moved the tables as West as possible so that the vacuum beam tubes won't hit the door frame but not so far West that the mobile clean rooms can't fit around them in their final configuration. We ensured the optics table was parallel with the West wall.

We then lowered the tables. The joint between the two tables is not level, so we will need to shim the legs (or replace the bottom of the legs). Ideally, the tables are in the same plane and all the legs make contact with the tables to prevent any rocking modes. Rigidly connecting the tables seems to remove most of these rocking modes. The gap between the table and legs is smaller than in the previous configuration.

[Jeff, Ian, Torrey, Sander, JC, Lee, Daniel]

We moved a central vessel and 2 bend cubes from B150 into B111B. The central vessel is on a borrowed furniture dolly and the bend cubes are on a lowered "side table" (not an optical table).

We also lowered and moved a 2nd side table into the mobile clean room to hold and "operate on" the end cubes that are designated for the LFC.

Lastly, we raised the screws on the sled connecting the optical tables and engaged the caster wheels.

Jeff and I propose the future steps are as follows with a rough timeline for the rest of the week

Move the optical tables into place 1' North so that the transmitted arm pumpout stations don't hit the wall (Wednesday at 10 AM)

Maybe we move the mobile clean rooms 6" North

Place the central vessel into place (Thursday morning)

Move LFC Cubes onto side table (Thursday afternoon)

Clean B111B, with special attention to the mobile clean rooms

Open the bend cube insides to evaluate whether we need to replace the bottom flange with another flange that can hold optical posts

Replace the end cube bottom flanges with flanges with a 1/4-20 hole pattern and add my custom base plate

Place the end cubes into their LFC final position (or ~0.5" further apart than their final position and we push them together when making the vacuum system)

(Maybe replace the bend cube bottom flanges with flanges with a 1/4-20 hole pattern and) add my custom base plate

Place the bend cubes into position

Move shelf into place

Move equipment supporting optics in B102 like Mokus

Move optics sleds

[Jeff, Sander, Torrey, Daniel]

We assembled the PTA281 Optical Table Shelf in B111B. We plan on putting this East by the end of the optics table. We decided on the shelf heights so that the IFO arms can fit under them. The table is not in its final location in the photo.

[Daniel, Jeff]
 

We performed a rough cleaning (dusted with compressed air, wiped with isopropanol wetted Kimwipes) of the two end cubes in B150 as well as one of the service vessels. They are ready to be moved into to main lab space (B111B).

I have created a labutils repo on github to be used when the McCuller Gitlab is down.

The filter cavities have very bad audio pick up, most likely coupled through sound moving the flexture mounts/mirrors. In an attempt to mitigate this we've floated the idea of cavity earmuffs. This is the first iteration of it. The design fits well enough. A few issues on this first iteration:

-We should have it contacting the metallic section of the cavity to form a seal.

-A major oversight, this was designed with only the location pictured in the above photo. This is uncharacteristic to the other 3 locations where we would need one in terms of space. For example, its never fitting here without a major redesign, or spacing out some optics.

-It would be good to glue some metal to the outside and some kind of damping plastic/foam to the inside. Will worry about this when I have a more concrete design.

I observed a spectrum of the error signal while the cavity was locked with and without the earmuff while making a similar amount of noise, and the earmuff had little to no effect. This is expected still as I only had it on one side of the cavity. Attached is the stl for this design (the print ready .3mf file for the new bambu labs printers won't upload, if you want it just reach out). Will update when I come up with a new version.

The NAS is running a docker instance of pi-hole That software blocks ads, but it also allows one to set up local DNS. The router should now be exposing the NAS/pihole DNS and itself as a DNS server. You can check if it is working by name resolving mokupro1 or checking that your DNS is set to 192.168.50.94 (the NAS) and 192.168.50.1 (the router).

See how to log in to add DNS entries and the password at:

https://wiki.mccullerlab.com/Main/LabSecrets

The VPN isn't yet set up to forward the DNS entries, but I'll do that soon and post a comment.

[Jeff, Torrey]

We had some plans for filter cavity diagnostics to be done, first step in accomplishing this is locking a filter cavity with an AOM. This has been done. This post will describe the process in case anyone wants to replicate this in the future.

Attached is a screenshot showing the multi instrument mode used to accomplish this. Inputs and outputs are as follows:

Input 1 - Cavity REFL PD

Input 2 - Cavity TRANS PD

Out 1 - To the DC modulation port of the laser

Out 2 - RF in of AOM

Out 3 - RF to EOM to create sidebands

The idea is very similar as in previous posts. Create sidebands on EOM, demod in laser lock box to give an error signal, fast controller output goes to Waveform Generator which acts as a VCO (accomplished by choosing frequency modulation and input A as the reference voltage). And thats it! Relatively easy once we had the proper loop in mind. The output on the slow controller is to the laser (UGF ~10 Hz) to control any low frequency laser drifting which is known to occur. One other note that is worth mentioning is the value for the frequency modulation depth needs to be manually set. Since the FSR of the cavity is 125 MHz we initially set this range to be +/- 50 MHz to have enough range. You could also set this lower, to say 5 MHz, and then scan around on the laser to find the resonance in this range.

[Jeff, Torrey, Daniel]

LIGO (Maty Lesovsky was my point of contact) has loaned a 24" long, 8" diameter (with 10" CF Flange) cylindrical vacuum chamber (LIGO DCC D2300310) for use in testing the output filter cavities in vacuum. Jeff and I placed it in B111A by the South optics table. I have a design for placing the OFC in the vacuum chamber. I believe I need to get a custom parts (assembly is LIGO DCC D2300308) that LIGO has designed but not procured. I will share my designs no later than next week.

I connected the laser DC modulation port to the Moku input of a spectrum analyzer. The spectrum analyzer always sees the 875Hz if it is connected to the laser, but the amount that the 875Hz shows up in the pdh error spectrum changes a bit on changing the spectrum analyzer input properties. Could the problem have something to do with impedance matching? the input impedance to the laser modulation port is 1kOhm.

We should plug the laser modulation port into a non-Moku spectrum analyzer and see if the problem persists.

[Sander, Jeff, Torrey, Daniel]

We moved the optics tables together and joined them with a 2' x 4' breadboard. The tables are unfortunately not level, likely due to the floor not being level. We think this can mostly be fixed by placing shim stock under some of the table legs.

The tables should be in their final location.

See attached photo.