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ID Date Author Type Category Subject
2617   Sun Jul 25 21:45:46 2021 KojiSummaryCryo vacuum chamberAbout the radiation heat transfer model

The following radiation cooling model well explained the cooling curve of the test mass (until ~150K)

$\dot{Q}=0.15 A\,\sigma (T_{\rm SH}^4-T_{\rm TM}^4)$

where dQ/dt is the heat removed from the test mass, A is the surface area of the test mass, $\sigma$ is the Stefan-Boltzmann constant, T_SH and T_TM are the temperatures of the surrounding shield and the test mass.

Can we extract any information from this "0.15"?

I borrowed "Cryogenic Heat Transfer (2nd Ed)" by Randall F. Barron and Gregory F. Nellis (2016) from the library.
P.442 Section 8.5 Radiant Exchange between Two Gray Surfaces can be expressed by Eq 8.44

$\dot{Q} = F_e F_{1,2} \sigma A_1 (T_2^4-T_1^4)$

where T_i is the temperature of objects 1 and 2. For us, OBJ1 is the test mass and OBJ2 is the shield. A1 is the surface area of A1. F_1,2 is the view factor and is unity if all the heat from the OBJ1 hits OBJ2. (It is the case for us.)

$F_e$ is an emissivity factor.

The book explains some simple cases in P 443:

Case (a): If OBJ2 is much larger than OBJ1, $F_e = e_1$ where the e_i is the emissivity of OBJi. This means that the radiated heat from OBJ1 is absorbed or reflected by OBJ2. But this reflected heat does not come back to OBJ1. Therefore the radiative heat transfer does not depend on the emissivity of OBJ2.

Case (b): If OBJ1 and OBJ2 has the same area, $\frac{1}{F_e} = \frac{1}{e_1} + \frac{1}{e_2} -1$. The situation is symmetric and the emissivity factor is influenced by the worse emissivity between e1 and e2. (Understandable)

Case (c): For general surface are ratio,  $\frac{1}{F_e} = \frac{1}{e_1} + \left(\frac{A_1}{A_2}\right)\left(\frac{1}{e_2} -1 \right )$. OBJ2 receives the heat from OBJ1 and reradiates it. But only a part of the heat comes back to OBJ1. So the effect of e2 is diluted.

For our case, OBJ1 is the Si mass with DxH = 4in x 4in, while the shield is DxH = 444mm x 192mm. A1/A2 = 0.12.
We can solve this formula to be Fe=0.15. e1 = (0.147 e1)/(e2-0.0178).

Our inner shield has a matte aluminum surface and is expected to have an emissivity of ~0.07. This yields the emissivity of the Si test mass to be e1~0.2

How about the sensitivity of e1 on e2? d(e1)/ d(e2) = -0.95 (@e2=0.07).

Depending on the source, the emissivity of Aquadag varies from 0.5 to 1.
e.g. https://www.infrared-thermography.com/material-1.htm / https://www.mdpi.com/1996-1944/12/5/696/htm

• Assuming Aquadag's emissivity is ~1
• If only the test mass is painted, F_e increases from 0.15 to 0.39 (x2.6)
• If the inner shield is also painted, F_e increases to 1, of course. (pure black body heat transfer)
• If shield panels are placed near the test mass with the inner surface painted, again F_e is 1.
• Assuming Aquadag's emissivity is ~0.5
• If only the test mass is painted, F_e increases from 0.15 to 0.278
• If the inner shield is also painted, F_e increases to 0.47.
• If shield panels are placed near the test mass with the inner surface painted, F_e is 0.33 assuming the area ratio between the test mass and the shield panels to be unity.

It seems that painting Aquadag to the test mass is a fast, cheap, and good try.

2618   Mon Jul 26 01:30:42 2021 KojiSummaryCryo vacuum chamberPrep for the 2nd cooling of the suspension

Updated Jul 26, 2022 - 22:00

1. Reconstruct the cryostat
1. [Done] Reinstall the cryo shields and the table (Better conductivity between the inner shield and the table)
2. [Done] Reattach the RTDs (Inner Shield, Outer Shield)
-> It'd be nice to have intermediate connectors (how about MIllMax spring loaded connectors? https://www.mill-max.com/)
3. Reattach the RTD for the test mass
2. Test mass & Suspension
1. [Done] Test mass Aquadag painting (How messy is it? Is removal easy? All the surface? [QIL ELOG 2619]
2. [Done] Suspension geometry change (Higher clamping point / narrower loop distance / narrower top wire clamp distance -> Lower Pend/Yaw/Pitch resonant freq)
3. [Done] Setting up the suspension wires [QIL ELOG 2620]
4. [Done] Suspend the mass
3. Electronics (KA)
1. [Done] Coil Driver / Sat Amp (Power Cable / Signal Cables)
2. Circuit TF / Current Mon
3. [Done] DAC wiring
4. [Done] Damping loop
4. Sensors & Calibration (KA)
1. [Done] Check OSEM function
2. [Done] Check Oplev again
3. Check Oplev calibration
4. [Done] Check Coil calibration
5. Use of lens to increase the oplev range
6. Recalibrate the oplev
5. DAQ setup (KA)
1. [Done] For continuous monitoring of OSEM/OPLEV
2619   Mon Jul 26 22:49:00 2021 KojiSummaryCryo vacuum chamberAquadag painting

[Stephen Koji]

We decided to paint the silicon test mass with Aquadag to increase the emissivity of the test mass.

Stephen brought the Aquadag kit from Downs (ref. C2100169) (Attachment 1)

It's a black emulsion with viscosity like peanut butter. It is messy and smells like squid (Ammonium I think) (Attachment 2)

We first tried a scoop of Aquadag + 10 scoops of water. But this was too thin and was repelled easily by a Si wafer.
So we tried a thicker solution: a scoop of Aquadag + 4 scoops of water. (Attachment 3)

The thicker solution nicely stayed on the Si wafer (Attachment 4)

We want to leave the central area of the barrel unpainted so that we can put the suspension wire there without producing carbon powder. (Attachment 5)
1.5" from the edge were going to be painted. The central1" were masked.

The picture shows how the Si test mass was painted. The test mass was on a V-shaped part brought from the OMC lab. The faces were also painted leaving the mirror, while the place for RTD, and the magnet were not painted. (Attachment 6)

It looked messy while the painting was going, but once it started to dry, the coating looks smooth. It's not completely black, but graphite gray. (Attachment 7)

After the test mass got dry, another layer was added. (Attachment 8)

Then made it completely dry. Now the mask was removed. Nice! (Attachments 9/10)

Attachment 1: 20210726164254_IMG_0768.jpeg
Attachment 2: 20210726164530_IMG_0769.jpeg
Attachment 3: 20210726164225_IMG_0766.jpeg
Attachment 4: 20210726164957_IMG_0772.jpeg
Attachment 5: 20210726173608_IMG_0774.jpeg
Attachment 6: 20210726174523_IMG_0775.jpeg
Attachment 7: 20210726182715_IMG_0783.jpeg
Attachment 8: 20210726192042_IMG_0784.jpeg
Attachment 9: 20210726192837_IMG_0790.jpeg
Attachment 10: 20210726192853_IMG_0791.jpeg
2620   Wed Jul 28 00:59:47 2021 KojiSummaryCryo vacuum chamberThe test mass successfully suspended

[Stephen Koji]

While Stephen worked on the RTD reattachment, I worked on the suspension part.

- First of all, we found that the magnet was delaminated from the silicon mass (Attachment 1). It was bonded on the test mass again.

- The suspension frame was tweaked so that we have ~max suspension length allowed.

- The first attempt of suspending the mass with steel wires (0.0017" = 43um dia.) failed. Stephen and I went to downs and brought some reels.

- I chose the wire with a diameter of 0.0047" (= 119um) (Attachment 2). ~8x stronger! The suspension was successfully built and the mass is nicely sitting on the 4 strain releasing bars (improvised effort). (Attachments 3/4)

We can install the suspension in the chamber tomorrow (today, Wed)!

Attachment 1: P_20210727_154143.jpeg
Attachment 2: P_20210727_190356.jpeg
Attachment 3: P_20210727_190426.jpeg
Attachment 4: P_20210727_190543.jpeg
2621   Thu Jul 29 00:42:38 2021 KojiSummaryCryo vacuum chamberThe test mass successfully suspended

[Stephen Koji]

• The suspension with the test mass was installed in the chamber again
• Looking at the oplev beam, we jiggled the wire loop position to adjust the alignment approximately.
• The oplev beam was aligned more precisely.

• We intentionally kept the OSEM at the "fully-open" position, while it is still close to the magnet so that we can have some actuation.
• The coil driver was tested before closing the chamber, but it did not work.
The coil itself was still intact, and the mirror was responding to the coil current if the coil current of ~100mA was applied from a bench power supply with the current ~100mA).
So the problem was determined to be external.

• Once we were satisfied with the oplev/OSEM conditions, the inner and outer lids were closed. Then the chamber was closed.

•  Started pump down.
• Started cooling down @18:30 / started temp logging too. Log filename: temp_log_cool_down_20210728_1830.txt

The coil driver issue was resolved:

• It was necessary to take care of the enable switch. Made a DB9 short plug for this purpose.
• The output R was 1.2K (i.e. 2.4K across the + and - outputs). We needed ~10x more to see visible motion of the mass
• e.g. The internal gain of the driver is x1.1. If we connect 5VDC input across the diff input of the driver yields, +11V shows up across the outputs of the final stage.
If the R across the coil is ~100Ohm, we get ~100mA.
• Soldered 6 x  330Ohm (1/8W) in parallel to 1.2K R_out. -> This ended up 51.5Ohm x2 across the coil. Each R=330 consumes ~1/10W. ->OK

Checking the DAQ setup / damping loop

• DAQ setup
• ADC: QPD X->FM16 / Y->FM17 / S->FM18 / OSEM-> FM19
• DAC: CH11 -> Coil Driver In
• Connected FM16 and FM17 to the coil drive by setting C4:TST-cdsMuxMatrix_12_17 and C4:TST-cdsMuxMatrix_12_18 to be 1.0
• It was not obvious if the coil could damp the rigid body modes.
• Actating the magnet caused Yaw motion most. Some Pitch motion too.
• Configured FM16 and FM17 for the damping loop.
• Filter Bank #1: [Diff0.1-10]  Zero 0.1Hz / Pole 10Hz
• Filter Bank #10: [Anti Dewht]  Zero 1&200Hz / Pole 10&20Hz
• Tried various damping gain. The mass was moving too much and the proper gain for the damping was not obvious.
• So, the initial damping was obtained by shorting the coil at the coil in of the sat amp unit. (Induced current damping)
• Once the test mas got quieter, it was found that -0.01 for FM16 could damp the yaw mode. Also it was found that +0.1 for FM17 could damp the pitch mode. (But not at once as the filters were not set properly)

• TF measurement for calibration
• The beam was aligned to the QPD
• The test mass was damped by using the damping loops alternately
• Taken a swept sine measurement Filename: OSEM_TF_210729_0243.xml
Recorded the time, saved the data, and took a screenshot
• This measurement was taken @T_IS=252K / T_TM=268K @t=8hr (2:30AM), Rcoil=15.6Ohm
• Second measurement Filename: OSEM_TF_210729_2147.xml
• @T_IS=172K / T_TM = 201K @t=27.5hr (10PM), Rcoil=10Ohm
• 3rd measurement Filename: OSEM_TF_210730_1733.xml
• @T_IS=116K / T_TM = 161K @t=47hr (5:30PM), Rcoil=?
• 4th measurement Filename: OSEM_TF_210731_2052.xml
• @T_IS=72K / T_TM = 134K @t=75hr (9:30PM), Rcoil=6.0Ohm

OSEM LED/PD

• The Satellite amp brought from the 40m is used as-is.
• The initial OSEM reading was 8.8V, this corresponds to ~30000cnt.
• As the OSEM was cooled, this number was increasing. To avoid the saturation, a voltage divider made of 4x 15kOhm was attached. I didn't expect to have the input impedance of the AA filter (10K each for the diff inputs), this voltage divider actually made 18.24V across POS and NEG output to be 5.212V to the AA fiter. So the voltage division gain is not 0.5 but 0.2859.
• This made the ADC range saved, but we still have a risk of saturating the PD out. If this happens. The PD TIA gain will be reduced before warming up.
-> The TIA and whitening stages use AD822, and the diff output stage uses AD8672. AD822 can drive almost close to rail-to-rail. AD8672 can drive upto ~+/-14V.

There was not enough time for the QPD calib -> Tomorrow

2622   Thu Jul 29 13:11:17 2021 KojiSummaryCryo vacuum chamberCooling progress: Update

The current cooling curve suggests that the radiative cooling factor Fe (black body =1) increased from 0.15 to 0.5.

Update: The test mass temp is reaching 200K at ~27hrs. cf previously it took 50hrs
Update: The test mass temp is 170K at ~41.5hrs.

OSEM illumination & photodetector efficiency has been kept increasing @41.5hrs

Attachment 1: temp_log_cool_down_20210728_1830.pdf
Attachment 2: cooling_model1.pdf
Attachment 3: cooling_model2.pdf
Attachment 4: OSEM_cooling.pdf
2625   Fri Jul 30 12:22:56 2021 KojiSummaryCryo vacuum chamberCooling curve comparisons

In all aspects, the latest cooling shows the best performance thanks to better thermal connection, thermal isolation, and the black paint.

- The cold head cooling is faster and cooler

- The inner shield cooling is faster

- The test mass cooling is faster

Attachment 2: comparison_inner_shield.pdf
Attachment 3: comparison_test_mass.pdf
2628   Fri Jul 30 18:18:21 2021 KojiDailyProgressCDSConnecting CTC100 to EPICS/rtcds system

During the process, we corrected the channel labeling for RTD #3/#4. So  for a few first data points, the numbers for the workpiece and the outer shield were swapped.

2629   Sun Aug 1 22:22:00 2021 KojiSummaryCryo vacuum chamberCooling update

The test mass temperature indicates 121K@100hr but there seemed a few sensor glitches for the test mass (𝛥=-4.2K) and the inner shield (𝛥=-0.43K).
So the actual test mass temperature could be 125K.

The temp was read to be 119K@114hr (Attachment 1)

There was very little cooling capability left for the test mass (Attachment 2)

The OSEM reading is now stable @12.3V (Attachment 3)

The raw temp data and the minimal plotting code are attached (Attachment 4)

Attachment 1: temp_log_cool_down_20210728_1830.pdf
Attachment 2: cooling_meas.pdf
Attachment 3: OSEM_cooling.pdf
Attachment 4: cooldown_210728.zip
2632   Mon Aug 2 21:51:37 2021 KojiDailyProgressCDSConnecting CTC100 to EPICS/rtcds system

The legit way to restart st.cmd is

systemctl restart CTC100
2633   Tue Aug 3 23:56:00 2021 KojiDailyProgressCryo vacuum chamberWarmup started 02 August

- Confirmed the heating stopped in the evening -> The heater was deactivated @~23:00

- Made some measurements and checks - the oplev spot was approximately on the center of the QPD before warming up. Now it is ~4mm above the center (note that the QPD size is 0.5" in dia) (Attachment 2). This corresponds to ~2mrad misalignment.

- Dismantled the OSEM electronics and power supply from the table. The electronics were salvaged into the OMC lab -> to be returned to the 40m.

- A 2" Al mirror package was brought to the OPLEV periscope so that the gold mirror (too thin) can be replaced. (Attachment 1)

Attachment 1: P_20210804_000247.jpg
Attachment 2: P_20210803_235421.jpg
2642   Wed Aug 11 18:00:19 2021 KojiDailyProgressCryo vacuum chamberCooldown model fitting for MS

How about incorporating radiative and conductive terms from the object at 300K?

2645   Sun Aug 15 00:33:15 2021 KojiSummaryCryo vacuum chamberAquadag painting on the inner shield

[Stephen Koji]

We applied Aquadag painting on the inner side of the inner shield.

• Upon the painting work, we discussed which surfaces to be painted. Basically, the surface treatment needs to be determined not by the objects but by the thermal link between the objects.
• We want to maximize the heat extraction from the test mass. This means that we want to maximize the emissivity factor between the test mass and the inner shield.
• Therefore the inner barrel surface of the inner shield was decided to be painted. The test mass was painted in the previous test.
• For the same reason, the lid of the inner shield was painted.
• It is better to paint the cold plate (table) too. But we were afraid of making it too messy. We decided to place the painted Al foil pieces on the table.

• The outer surface of the inner shield and the inner surface of the outer shield: Our outer shield is sort of isolated from the cold head and the steady-state temp is ~240K. Therefore we believe that what we want is isolation between the inner and outer shields. Therefore we didn't paint these surfaces. (note that in Mariner and beyond, the outer shield will be cooled, not isolated, and the radiative link to the outer shield would be strong by design)
• I believe that this is not the ideal condition for the inner shield. We need to model the cryo stat heat load and take a balance between the isolation and the conduction between the outer shield and the cold head so that we gain the benefit of the outer shield as a "not so hot" enclosure.

• OK, so we painted the inner barrel of the inner shield, the lid of the inner shield, and some Al foils (shiny side).
• Stephen made the Aquadag solution. The solution was 2 scoops of Aquadag concentrate + 6 scoops of water, and the adhesion/runniness test was done on a piece of aluminum foil.
• The barrel and the lid were painted twice. Attachment 1 shows the painting of the inner shield cylinder. Attachment 2 shows a typical blemish which necessitates the second coat.
• To accelerate the drying process, we brought the heat gun from the EE shop --> (update - returned to EE shop, see Attachment 3)

• We took some photos of the process. They are all dumped in the QIL Cryo Vacuum Chamber Photo Dump album in the ligo.wbridge account.
Attachment 1: IMG_9636.JPG
Attachment 2: IMG_9632.JPG
Attachment 3: IMG_9646.JPG
2740   Mon Mar 28 18:00:43 2022 KojiSafetyCleanlinessLab flooding

2743   Wed Mar 30 16:25:06 2022 KojiSafetyCleanlinessLab flooding

Muddy Waters is not new, but if the facility can fix it we'd take it.

1910   Mon Mar 9 18:57:21 2015 Kate, StephanieMiscSeismometerUpdated tilt-free seismometer design concept

Rana and I visited Fabrice and Matt at MIT last week to discuss our line of thinking for a tilt-free seismometer design. They've spent about 3 years working on the design, construction, and testing of their own concept, a T240 seismometer placed on a suspended platform. Tilt is filtered simply by virtue of the suspension point. They successfully measured their tilt-to-displacement transfer functions through the use of a tilt-shaker, showing measurement matches theoretical predictions. They got stuck at the point of doing a huddle test of 2 such tilt-free seismometers due to extra noise from magnetic fields in the local environment. Thus, as of yet, they haven't been able to demonstrate the displacement sensitivity.

Warnings from Fabrice had to do with keeping the initial experimental set up simple and remotely controllable. He recommended, for instance, using two wires to hang the mass, so as to restrict one of the two longitudinal degrees of freedom. Eddy current damping is also good. He also showed us how he attached a picomotor onto the side of his mass. Driving the picomotor is his method for adjusting the location of the center of mass. The picomotor is on the right in the first photo; the second photo focuses on the wire clamping.

In discussion including Matt, Fabrice, and Rich M. about designs, we discussed what is needed to make a pendulum with a resonance as low as around 10 mHz. This can be done with inverted pendula and Matt pointed us to a mechanical design from Virgo involving 4 legs under tension that we could look into further. Rather than having two pendula of different lengths / moments of inertia hanging side by side and measuring the relative tilt / displacement between them, we could place an inverted pendulum on top of the mass of a ~1 Hz pendulum. The suspension point of the inverted pendulum should be at the rotational axis of the main pendulum (its center of mass) and the main pendulum could be designed to have a very large moment of inertia to help in improving the bandwidth in which tilt can be measured. Furthermore, the main pendulum could have its mass distributed such that some of it is in the same plane with the inverted pendulum mass, creating a natural location to set up an interferometer for readout.

Stephanie took our sketches and made a drawing to aid with visualization of the newest scheme.

1911   Wed Mar 11 15:12:51 2015 Kate, StephanieMiscSeismometerUpdated tilt-free seismometer design concept

I color coded the drawing of the newest scheme so that it's easier to identify the different parts (eDrawing file attached).

Attachment 1: Seismometer2.EASM
1913   Thu Apr 2 23:24:19 2015 Kate, StephanieMiscSeismometerDesign of low rotational freq. mass

Stephanie and I spent some time today working out a practical design for the first of two suspended masses that will make up the seismometer.

Restrictions we set included the following requirements:

• the mass must have a large moment of inertia
• the top of the mass must be in the same plane as the top of the suspension cage
• it should fit within the existing (arbitrary) size of the cage
• the center of mass should be at (slightly below) the suspension point

We will use Bosch parts to create the frame of the mass and try to concetrate weight at the top and bottom. To do this, we'll use an optical breadboard at the bottom (it appears Zach might have an extra we could use). We can't use a breadboard at the top because the second mass will need to fit in its interior. The second mass itself can serve to add weight to the top of the first. Optics + mounts used for the readout will also add weight to the top.

Some sketches we came up with are below. We'll need to slightly modify the existing cage to accomodate a need to move the crossbar from which the first mass will be suspended. The crossbar will sit below the top of the cage. In the bottom two right drawings, some cage parts are partially transparent to see the mass behind them. We also made a list of some hardware we will need in order to construct the mass. This includes more brackets (32 total) like the ones in the picture and some hardware (32+ pieces) that slides into the frame slots which allows 1/4-20 screws to secure pieces like optical mounts and brackets to the frame.

Stephanie took note of some dimensions and will determine how tall the mass can be and therefore what size Bosch parts we should buy. She'll also make a model in SolidWorks to compute the total mass and moment of inertia.

Attachment 2: drawing.svg
1964   Thu Jul 9 00:37:35 2015 Kate, AlessandraElectronicsSeismometerPCB

I have attached some pictures of the PCB required to make digital measurement for the seismometer.

Attachment 1: IMG_1128.JPG
Attachment 2: IMG_1130.JPG
Attachment 3: IMG_1131.JPG
1951   Fri Jun 26 18:02:17 2015 Kate, Alastair, MeganMiscSeismometerSuspension attempt

We spent the afternoon preparing the rhomboid to be suspended once more. This was done once already with two wires, but we had found the wire lengths were not equal enough to work out. This time we set up a device to carefully adjust the wire lengths. This required cutting new wires and re-clamping them in the pin vises. Unfortunately, one of the upper pin vises broke (see photo). This is one of the two that we had died so that we could screw bolts onto it. It broke at a location such that the mechanism for closing the collet around the wire no longer functions. In a spirit of pushing through to try to get the rhomboid suspended anyway, we mixed up some expoxy and glued the wire into the collet and the collet into the pin vise head. We decided we would adjust the other wire to match this particular wire's length. We prepared the other wire and slowly lowered the rhomboid. Upon letting the 2 wires fully take the weight, the second wire pulled out of its bottom pin vise. The wire didn't break, but the pin vise was simply not clamping it well enough. Upon inspection, it turns out this was the pin vise that had previously been damaged. The collet teeth don't fit together perfectly anymore, and there is indeed a gap between two of them which is most likely the cause of the malfunction. We taped the free end of the wire so it's not a hazard and are leaving the setup as is for now until we get a replacement pin vise.

Attachment 1: IMG_0823.JPG
1961   Mon Jul 6 19:52:28 2015 Kate, Alastair, MeganMiscSeismometerIdeas for new pin vise clamp

Last week Alastair, Megan, and I had a brainstorming session about how to design a better pin vise clamp. Alastair's suggestion was to take the route of eliminating all of the pin vise parts except for the collet. Our approach so far was to do a lot of machinig on the pin vise handle, but the result is something that's weak, easily breaks, and not very well secured. I'm attaching a picture of the white board with some of our sketches. Alastair's taking the better ideas and making a real drawing that we can review in detail and send to the machine shop. He also suggested we can try using some guitar tuning pegs to take the weight and use the collet only for the purpose of defining the bending point.

Attachment 1: IMG_0834.JPG
1896   Fri Jan 23 15:33:46 2015 Kate, AlastairMiscSeismometerPin vise holder, version 1

Here is the first version of a design for a mounting block for the pin vise. The concept is that the pin vise will be screwed into this aluminum block and the block will be screwed into the optical breadboard (i.e. inertial mass). We want to have the flexure point of the wire be located (ideally) at the center of mass of the system, so I computed where the center of mass would be using the estimation that both the breadboard and mounting block are solid Aluminum (density = 2.7 g/cm^3).

For the dimensions as follows:

optical breadboard = 12" x 10" x 0.5" (2655 grams)

mounting block = 2" x 2" x 1.75" (310 grams)

the center of mass would be:

$R = \frac{m_1 r_1 + m_2 r_2}{m_1 + m_2} = \frac{0 + (310)*(1.125)}{2655 + 310} \approx 0.12\,\mbox{inches} \approx 3\,\mbox{mm}$

below the center of mass (also geometric center) of the breadboard. I haven't yet calculated the flexure length for the wire, but the consensus between Alastair and Koji is that it won't be more than a couple mm. This means the tip of the pin vise which grasps the wire should be yet another few mm lower, or approximately co-located with the bottom surface of the breadboard. However, since the flexure point will need to be slightly above the center of mass for stability and because we will load the breadboard with some weights (i.e. mirrors for optical readout of the mass's motion and balancing weights) which will raise the center of mass, I decided to make the tip of the pin vise somewhere in the middle of the lower half of the breadboard.

I  brought this design to the machine shop in the sub-basement of Lauritsen, but the guy I talked with there said the 1 mm thick wall of the pin vise handle is too thin to die (add threads to) with any of the machines they have. We discussed an alternate solution of tapping two holes into the side of the block and just grasping the pin vise with the force of screws. He also suggested filling the pin vise handle with aluminum to make it stronger.

Attachment 1: SCAN7247_000.pdf
1897   Fri Jan 23 15:46:13 2015 Kate, AlastairMiscSeismometerSteel wire for seismometer

Norna and Calum provided me with two different rolls of wire from storage that I could use for the seismometer. They're 252 um and 410 um in diameter.

Alastair provided me with the data from a stress test they've done on the wire. He says, "Here's a typical breaking strength measurement on that music wire.  It looks to go plastic around 2.5GPa, so lets a assume that you don't want to load it more than 1GPa.  For the thinner (252um) wire that comes out to a maximum force of 50N, so approximately 5kg of weight."

1915   Thu Apr 16 15:21:11 2015 Kate, AlastairMiscSeismometerFiber pulling lesson (belated entry)

Feb. 26, 2015

Alastair got the glass fiber pulling setup back in working order and gave me a first lesson. This is in preparation for later making fused silica fibers for suspending the main mass of the tilt-free seismometer. For the initial prototypes, we will be using steel wires instead.

This method of pulling fibers does not make use of a machine and is done by hand. We create a flame by mixing Oxygen and Hydrogen, and keep it in a stable resting place on a tabletop. Then, upon holding the two ends of a glass rod, we place the center of the rod in the hottest part of the flame and rotate the rod around its long axis to heat the entire circumference evenly. Once the center of the rod is bright white and feels fluid, we lift the rod up out of the flame and pull quickly in one even motion to the desired length. Welding glasses must be worn to protect the eyes. In my one attempt to pull a fiber, I found the dark glasses made it very difficult to be able to see whether or not I was holding the glass rod in the flame. I also found it challenging to rotate the rod without also moving it up and down. Alastair's ease of pulling a fiber demonstrates how practice makes a difference. A video is attached.

A few notes about the gas tanks and their valves:

• Oxygen is in the green tank
• Hydrogen is in the red tank
• To close the regulator valve, turn knob anti-clockwise (the spring will be loose)
• To close the cylinder valve, turn knob clockwise

The standard procedure for initiating gas flow from a tank is as follows:

• Check that the regulator is closed
• Open the cylinder
• Take a reading of the pressure
• Close the cylinder (pressure reading should not change)
• Wait 1 min. and watch to see if pressure drops (would indicate a leak)
• Open cylinder
• Open regulator until gas flow sounds right

The procedure for creating the flame is as follows:

• Turn on Hydrogen
• Light it (Hydrogen self burns)
• Add Oxygen until flame looks right (hottest part should be a few mm long)

And for extinguishing the flame:

• Turn Oxygen off
• Turn Hydrogen off
Attachment 1: IMG_0457.MOV
1889   Wed Dec 3 18:31:15 2014 KateLab Infrastructure First tilt-free seismometer entry

Stephanie Moon, Kate Dooley

We've started getting the lab in order and some parts assembled for putting together an early prototype of a tilt-free seismometer concept. We're using the optics table furthest from the door (i.e. not Zach's) and have cleaned up a good portion of it, putting things away in cabinets. Because we need a fair amount of height for the suspension cage, we disassembled half of the upper shelf that had been used for storing electronics. Last week we ordered Bosch-Rexroth struts for building the cage (invoice is attached). They arrived today and we now have them assembled per design with the exception of one additional bar that will go across the top:

Calum and Norna are letting us borrow 2 spools of phosphate-coated steel wire (and a pair of safety glasses). These are on the optics table.

We also ordered a 10"x10"x1" piece of Aluminum from the machine shop on campus next to the 40m to be used as our first test mass. It is unfortunately so poorly machined!

Photo of Aluminum test mass

1891   Tue Dec 16 21:36:07 2014 KateLaser Fiber coupler work

We started working on getting some stable light from the CTN experiment fiber-coupled into the ATF lab. It's not set up and working yet, but the fiber + coupler is fixed to the seismometer table and the output immediately dumped. Please take note that the laser hazard sign is more likely now to be on at times compared to the last couple months.

1895   Wed Jan 21 15:27:08 2015 KateMiscSeismometer1 dof seismometer noise budget

Here is the first version of a noise budget for a seismometer based on a pendulum principle. The only noise sources I include so far are thermal noise and sensor noise. I've used Chris' noise budget software, which does the loop math (using Simulink) and automatically produces nice plots. A sketch of the system which I'm modelling is shown below. The basic concept is that from a measurement of relative displacement (delta) between an inertial mass and the ground, we want to extract the motion of the ground (X). For this to work, we need to know the transfer function of ground displacement to the inertial mass motion and we need to know what the displacement-equivalent sensor noise is. From a practical standpoint, we assume that the sensors (i.e. mirrors forming an interferometer) are rigidly attached to the inertial mass and ground, respectively.

The transfer function from ground to inertial mass motion is:

$\frac{x}{X} = \frac{k+i \gamma \omega}{k+i \gamma \omega - m\omega^2}$

where $\gamma$ is the force coefficient for viscous damping of the mass.

The displacement noise of the mass due to thermal noise from viscous damping has the following power spectral density:

$x_{thermal}^2(f) = \frac{k_B T \gamma}{\pi^2 f^2 (\gamma^2 + (2 \pi f m - k/2 \pi f)^2)}$

For now, I have assumed that sensor noise is flat in frequency at a level of 1e-13 m/rtHz.

The simulink model is shown below. The NoiseSink block is located where we make our measurement: the relative motion between ground and the inertial mass ($\delta = X -x$). The Cal block is at the location of the quantity we wish to know: ground motion $X$. This snapshot also includes the beginnings of adding in tilt-to-displacement coupling to the model.

The noise budget for a mass m=5 kg at room temperature with a resonant frequency of 5 Hz is shown below. Low frequencies are limited by thermal noise and high frequencies by sensor noise. The sensor noise has a dip at the resonant frequency because here the mass' motion is amplified, resulting in a higher SNR. I've added in the dashed black curve, which is a sketch of the Ringler & Hutt measurement of the STS2 noise floor. This serves as a figure of merit for our design to surpass.

Attachment 1: Screen_Shot_2015-01-21_at_2.16.12_PM.png
Attachment 2: Screen_Shot_2015-01-21_at_2.10.05_PM.png
Attachment 3: IMG_0432.JPG
1898   Mon Jan 26 15:58:18 2015 KateMiscSeismometerDetermining tilt/translation couplings

We want to compute the tilt/translation coupling matrices for a few potential 'tilt-free' seismometer designs to evaluate how good the designs are. We'll make a collection of calculations here for minor variations of a simple pendulum and then expand from there. Some of the basic elements that will need to be included are as follows:

• the suspension point of the mass is *not* located at the center of mass
• the effect of a translation of the top suspension point on the motion of the mass
• the coupling between a tilt of the ground and displacement of the top suspension point
• the effect of the reference point being fixed to the moving ground
• finite wire stiffness

The first attachment shows the calculation of the equations of motion using a Lagrangian for the simplest scenario of a block suspended as a pendulum at its center of mass. In this case, there is no coupling between the angle of the pendulum and that of the mass. The second attachment shows the start of the calculation for the scenario where the mass is suspended a distance d away from its center of mass. This will result in a set of equations of motion showing the relationship between the angle of the pendulum wire and the position of the mass.

What we will eventually be interested in is the transfer function from suspension point translation and tilt to coordinates describing the motion of the mass. We'll probably want to later represent the location of the mass as a function of x and theta rather than the currently used phi and theta.

Attachment 1: SCAN7248_000.pdf
Attachment 2: SCAN7250_000.pdf
1899   Thu Jan 29 15:54:26 2015 KateMiscSeismometerSeismometer work update

I've worked some more on computing equations of motion for modifications to a simple pendulum. The first attachment shows two different scenarios, on p. 1 and p. 2, respectively:

• top suspension point can be translated; point mass
• top suspension point fixed; mass suspended away from center of mass

The second attachment shows the computation of the Langrangian for the first example.

The equations of motion for both examples reduce properly to that of a simple harmonic oscillator in the limits of the suspension point not moving and the mass being suspended at its center of mass. I'm not sure yet whether the decoupled forms of the equations of motion make sense. Also, I think I need to choose to use different coordinates before I go on to combine the two scenarios. I also need to think about how to have the right variables for compting a transfer function from top point motion to mass motion.

In addition, Alastair and I have started playing with SimMechanics. We've each modeled a simple pendulum, but have more to do to figure out if we can turn it into a realistic model.

Attachment 1: SCAN7252_000.pdf
Attachment 2: SCAN7253_000.pdf
1901   Wed Feb 4 17:53:58 2015 KateMiscSeismometerSeismometer work update

I'm attaching 2 pages of math which finish the problems started from the main entry.

The first attachment solves the second equation of motion for the example of the block suspended away from its center of mass, and shows that it reduces properly to the SHO when the distance from suspension point to center of mass is set to 0. The second attachment continues the driven oscillator problem, which correctly uses just one equation of motion (the attempt to find an equation of motion by varying "x" in the main entry was wrong). For this example, I also take the Fourier transform and show that the transfer function from ground excitation to mass position reduces to the familiar form.

 Quote: I've worked some more on computing equations of motion for modifications to a simple pendulum. The first attachment shows two different scenarios, on p. 1 and p. 2, respectively:  top suspension point can be translated; point mass top suspension point fixed; mass suspended away from center of mass The second attachment shows the computation of the Langrangian for the first example.  The equations of motion for both examples reduce properly to that of a simple harmonic oscillator in the limits of the suspension point not moving and the mass being suspended at its center of mass. I'm not sure yet whether the decoupled forms of the equations of motion make sense. Also, I think I need to choose to use different coordinates before I go on to combine the two scenarios. I also need to think about how to have the right variables for compting a transfer function from top point motion to mass motion. In addition, Alastair and I have started playing with SimMechanics. We've each modeled a simple pendulum, but have more to do to figure out if we can turn it into a realistic model.

Attachment 1: SCAN7270_000.pdf
Attachment 2: SCAN7271_000.pdf
1902   Wed Feb 4 18:09:22 2015 KateMiscSeismometerSome Mathematica modeling for a driven, suspended block

I've worked through the calculation of the equations of motion for a driven pendulum with a mass suspended away from its center of mass. Both the pen and paper and Mathematica versions are attached and confirm each other. A main point of this excercise is to make sure I have a Mathematica model I trust and understand. I will next use it to add in more realistic features of the pendulum and try finding an optimal configuration to realize a tilt-free seismometer.

The result so far is a set of two coupled equations of motion:

$(\omega_0^2-\omega^2)\~x_M = \omega_0^2(\~x+h \tilde{\theta}) \\ g \tilde{\theta} - \omega^2 \~x_M - \frac{I}{mh} \omega^2 = 0$

where the tilde means the variable is a function of frequency, I is the moment of inertia, m is the mass, h (or d in the hand-written attachment) is the distance from suspension point to center of mass, theta is the angle of the mass with respect to gravity, and $\omega_0^2 = g/l$, with l the length of the pendulum. A picture defining the variables is in the first attachment.

What remains to be done with this excercise is to compute the $\~x_M/\~x \mbox{ and } \tilde{\theta}/\~x$ transfer functions.

Attachment 1: SCAN7272_000.pdf
Attachment 2: SCAN7274_000.pdf
Attachment 3: kate_pendulum.nb
(* Content-type: application/vnd.wolfram.mathematica *)

(*** Wolfram Notebook File ***)
(* http://www.wolfram.com/nb *)

(* CreatedBy='Mathematica 10.0' *)

(*CacheID: 234*)
(* Internal cache information:
NotebookFileLineBreakTest

... 832 more lines ...
1903   Fri Feb 6 13:10:22 2015 KateMiscSeismometerSome Mathematica modeling for a driven, suspended block

The attached Mathematica model is now the complete version of code for computing the translation to translation and translation to tilt transfer functions of a suspended block. Transfer functions are shown for the example case of a 0.25 m long pendulum and 3 kg cubic mass suspended 1 mm above its center of mass. The mass dimensions are 5 cm on each side.

$\frac{x_M}{x_G} = \frac{(ghm-I\omega^2) \omega_0^2}{ghm(\omega^2-\omega_0^2)+\omega^2(h^2m\omega_0^2-I(\omega^2-\omega_0^2))}$

$\frac{\theta}{x_G} = \frac{hm\omega^2 \omega_0^2}{ghm(\omega^2-\omega_0^2)+\omega^2(h^2m\omega_0^2-I(\omega^2-\omega_0^2))}$

 Quote: I've worked through the calculation of the equations of motion for a driven pendulum with a mass suspended away from its center of mass. Both the pen and paper and Mathematica versions are attached and confirm each other. A main point of this excercise is to make sure I have a Mathematica model I trust and understand. I will next use it to add in more realistic features of the pendulum and try finding an optimal configuration to realize a tilt-free seismometer. The result so far is a set of two coupled equations of motion: $(\omega_0^2-\omega^2)\~x_M = \omega_0^2(\~x+h \tilde{\theta}) \\ g \tilde{\theta} - \omega^2 \~x_M - \frac{I}{mh} \omega^2 = 0$ where the tilde means the variable is a function of frequency, I is the moment of inertia, m is the mass, h (or d in the hand-written attachment) is the distance from suspension point to center of mass, theta is the angle of the mass with respect to gravity, and $\omega_0^2 = g/l$, with l the length of the pendulum. A picture defining the variables is in the first attachment.  What remains to be done with this excercise is to compute the $\~x_M/\~x \mbox{ and } \tilde{\theta}/\~x$ transfer functions.

Attachment 4: pendulum_basic.zip
1904   Tue Feb 10 22:15:42 2015 KateMiscSeismometerSeismometer mass and pin vise clamp

I have a few more pieces of hardware in hand now for the seismometer prototype. The mass as well as the mount for the pin vise are complete. The pictures show the two pieces screwed together. The close-up photo (below) shows the top of the mass. The wire will be clamped in the pin vise. The other photo (attachment 2) shows the bottom of the mass. The bending point of the wire is designed to be within mm of the center of mass of the system (http://nodus.ligo.caltech.edu:8080/AdhikariLab/1896).

I had the machine shop in Lauritsen/Downs cut the hole in the middle of the optical breadboard and make the pin vise mount per the drawing in the first attachment. Eddie made a technical version of the drawing, which is in the DCC: LIGO-D1500018.

Attachment 1: SCAN7283_000.pdf
Attachment 2: IMG_0441.JPG
1918   Wed Apr 29 17:57:38 2015 KateMiscSeismometerPreliminary Michelson design to prompt discussion

We want to order parts by the end of the week for building a table-top Michelson that will later be mounted on top of the seismometer masses.

This is a first sketch of what the layout might look like. We'll most likely fiber couple light from the NPRO on the gyro table over to the table we're working on. The plan is to first test the amplitude and frequency noise of such a setupt by using the approximate fiber length and path, but instead mounting the output on the gyro table so we can beat it with a pick-off of the original light. In the actual setup, the output coupler will be mounted on top of the 45mm diameter Bosch suspension frame. The sketch below shows a potential arrangement of optics. The most important part is that one arm of the Michelson will be fixed in length and the other will be along the same axis as the pitch mode of the two intertial masses. A PZT will be mounted on one of the end mirrors (the one on the main mass, not the inverted pendulum) in order to dither lock the Michelson. Both the dither (10s of kHz?) and the feedback can be applied to the same PZT. The PD output will need to be demodulated. We'll need both a frequency generator and demodulation electronics.

The input to the Michelson should be along the pitch axis so that there is no translation of the beam entering the Michelson as the rhomboid pitches back and forth. We will want to also expand the beam so it's relatively large in the Michelson and then put a lens just in front of the PD.

There will need to be counterweights added to the rhomboid to compensate for the weight of optics on one the side.

Parts list:

• high reflectors: 2x Y1-1025-0
• beam splitter: 1x BS1-1064-50-1012-45P
• PBS: 1x PBSH-450-1300-050
• steering mirror: 1x Y1-1025-45
• lenses
• fiber coupler hardware
• beam dumps
• mounts
• PZT actuator
• DC photodiode
Attachment 1: MichelsonTopView.pdf
1919   Thu Apr 30 21:41:38 2015 KateMiscSeismometerAnalytic estimate of primary mass moments of inertia and frequencies

I made a crude model of the primary mass to compute an order of magnitude check of its moment of inertia compared to the Solid Works model results.

I treated the system as a set of 4 infinitely thin rods and 2 cuboids. The rods each have mass 0.5 kg and the cuboids 5 kg and the system is 0.82 m tall. My script is attached, which calculates the moments of each object about its own center of mass and then uses the parallel axis theorem to find the moments about the system's pitch axis. I get a pitch moment of 2.02 kg m^2 and roll of 1.98 kg m^2 (the difference is due to the cuboid being deeper than it is wide). This is reasonable in comparison to Stephanie's results of 1.43 kg m^2 and 1.40 kg m^2. The SolidWorks yaw result is 1.19 kg m^2; I still need to compute my estimate.

From Malik's single loop suspension document (T000134), the pitch and yaw resonant frequencies are, respectively:

$\omega_\theta ^2 = \frac{m_{tot} g}{I_\theta L} b (L+b) \newline \omega_\phi ^2 = \frac{m_{tot} g}{I_\phi L} R_1 R_2$

and quantities are defined as in the script below. L is the wire length; b the separation from the wire suspension point and the system's center of mass; R1 and R2 are the separations between the wires at the top and bottom suspension points, respectively.

Using the SolidWorks moments of inertia with my estimates of the other parameters (defined in script and with R1 and R2 of 5 cm and 20 cm), the resonant frequencies are:

• pitch = 46 mHz
• yaw = 210 mHz
Attachment 1: MOI.m
%% tilt-free seismometer primary mass
% estimate of pitch moment of inertia
% KLD Apr. 30, 2015

%  ===========       <-- cuboid mass
%  |         |
%  |         |
%  |         |
%  |         |
%  |         |       <--> pitch axis about which system rotates

... 61 more lines ...
1923   Fri May 15 22:34:32 2015 KateMiscSeismometerRhomboid de-suspended for now

I de-suspended the rhomboid tonight, so work can continue next week under safe conditions. One end of the wire is still in a pin vise and I taped the other end with bright yellow electrical tape to the middle breadboard.

Both the aluminum upper pin vise clamp and the pin vise are dented. We certainly need a different clamping solution.

Attachment 1: IMG_0643.JPG
Attachment 2: IMG_0645.JPG
1925   Wed May 27 22:51:11 2015 KateMiscSeismometerInverted pendulum design

I talked with Steve Penn at GWADW, and he made a suggestion for an inverted pendulum design based on something he built some time ago to measure the thermal noise of fused silica fibers. His sketch is attached and I've labeled key parts. The sketch on the left provides a side view and the sketch on the right is a top-down view. The thick rod-like ends of a pulled fiber are welded to glass disks which can be easily clamped to a metal structure. The clamps are not depicted below, but would take the form of an 'L', sandwiching the glass disk against the metal plate. The clamps themselves would be screwed to the plate. The top plate is attached to support arms which are fixed rigidly to a table (or, in our case, to the rhomboid). The structure beneath the glass fiber has three legs that extend up and beyond the support arms. At the top of these legs is a disk and on top of the disk is a vertical rod with a mass that can slide up and down. The height of the mass is adjusted to set the resonance frequency.

This seems like a design that is quite compatible with what we need. The moveable mass would need to be designed such that we can fix a mirror for the Michelson on top of it. Steve also suggested that if we want to limit the number of degrees of freedom, we could pull a glass ribbon instead of using multiple fibers.

Attachment 1: SCAN7432_000.pdf
1929   Mon Jun 8 16:30:24 2015 KateLab InfrastructureHVAChot spots in lab - hot air coming from Gyro table HEPA

The HEPA filters at either end of the far optics table are now blowing hot air. The air near the Gyro table seems to be fixed--it's cool.

 Quote: Kate noticed that two spots were hot in the lab. The east and west ends of the Gyro optical table. Just to check that she wasn't crazy, I checked that it was so. The HEPA filters are blowing hot air. The ones near the other table are not. I will contact someone. Also, Kate has gotten the wall lights replaced as well as the laser safety sign light bulbs.

Zach gave me the controls password for ws1 and I just tried logging in. The following error message (see attachment) shows up. Suggestions?

Attachment 1: IMG_0803.JPG

Nicolas took a look at this with me. We turned the computer off and attempted to reboot it, but it did not boot. Looking in the BIOS menu, no hard drive is found. I've ordered a new one (Samsung SSD 250MB) and will install the latest version of Ubuntu on it next week when it arrives.

 Quote: Zach gave me the controls password for ws1 and I just tried logging in. The following error message (see attachment) shows up. Suggestions?

1939   Fri Jun 19 16:54:39 2015 KateMiscSeismometerThermal Enclosure concept

I've ordered some 0.08" (~2mm) thick Aluminum sheets for the inner layer of the thermal enclosure. McMaster offers many different types of Aluminum alloys, but only 3003 Al was available in the size we need, so that's what I ordered. We'll have to do some machining to cut the sheets down to the exact size once they arrive. This is a medium strength alloy with a relatively high thermal conductivity of 190 W/mK. Pure aluminum, in contrast, has a thermal conductivity of 244 W/mK.

 Quote: Some Foam Notes: I've ordered some different kinds of foams and sealing tape from McMaster.

1943   Tue Jun 23 11:34:28 2015 KateMiscSeismometerUpper pin vise clamp (drawing)

I'm attaching the drawing for the upper pin vise clamps. This had somehow not previously made it into the elog. Two of these were made by the machine shop in Lauritsen. Stephanie has since modified them so the pin vises fit into the end holes and by adding a counterbore in order to accommodate screwing a nut onto the pin vise handle.

Attachment 1: SCAN7472_000.pdf
1945   Thu Jun 25 15:22:19 2015 KateMiscSeismometerMore thermal enclosure parts purchased

I ordered the remaining foam we'll need to surround the frame, as well as the screws and fasteners we'll use to secure the foam + aluminum panels in place.

1950   Fri Jun 26 17:32:16 2015 KateMiscSeismometerMore on the seismometer frame

Could you elaborate on the plan for how the aluminum fits around the top? We'll need the entire frame, including the top bar, enclosed.

 Quote: Yesterday afternoon I finished building the seismometer frame by adding the cross bar across the top face. Picture below is the frame as of yesterday afternoon (25 June): This morning Ignacio and I went with Steve to the machine shop and cut the aluminum siding panels to the correct size. Sheets were cut for the top and bottom faces as well; the sheet for the top will be modified to fit around the cross bar. Picture below is one of the aluminum sheets next to the frame: The next steps will be measuring where thru holes can be drilled for the M8 attachment screws, and testing the die cuts (to punch holes for electronics wires) on scrap aluminum.

2182   Wed Sep 27 12:41:57 2017 Jon RichardsonLab InfrastructureComputingTCS Subnet Back Up

The TCS lab did not get Internet back after the the ATF lab pipe work was done. I traced the problem back to the fiber connecting the TCS switch to the main switch in the ATF lab next door. It was plugged into the wrong slot. If anyone has network problems in other labs, check the fibers in the main switch because many of them are unlabelled.

2194   Thu Feb 22 12:09:20 2018 Jon RichardsonComputingGeneralReset Gateway Router

The gateway router went down sometime since yesterday. I reset it, and it is accessible again.

2197   Mon Apr 23 12:44:07 2018 Jon RichardsonComputingGeneralAdded TCS/AWC Lab Port Forwards back to Linksys Router

Here they are for future reference.

Attachment 1: TCS-AWC_port_fwd.jpg
2175   Wed Sep 6 11:50:12 2017 JonLab InfrastructureComputingGateway PC set up

Jon's Edits to Andrew's Setup of the Linksys Router

Andrew is right that the Linksys router (10.0.1.1) can be configured to do everything we want from a gateway, namely providing password-protected ssh access into the LAN machines from the outside while blocking all other ports. I made some minor changes to Andrew's initial setup to balance security with ease of accessibility.

First, I made the Caltech-assigned IP address (131.215.115.216) discoverable on the ligo.caltech.edu network. This makes the gateway pingable, which is useful for determining whether the LAN is down. Note that this gateway is still only discoverable from inside the ligo.caltech.edu network, not from the outer Internet.

Second, I enabled the default port for SSH communications, port 22. I think this is fine security-wise because, again, the machine is only discoverable from within the ligo.caltech network and access is password-protected.

To connect to one of the LAN machines from another machine on the ligo.caltech.edu network with X11 graphics forwarding, you can add this script to your .bashrc file:

connect_onsite()
{
     ssh -Xt controls@<IP> \
     ssh -X controls@10.0.1.XX
}

where 10.0.1.XX is the address of the machine on the local network. You'll be prompted twice for a password, first for the gateway and second for the inside machine.

To connect from outside the ligo.caltech.edu network, forward the connection through a network machine (e.g., I use my office desktop) by adding the line:

connect_offsite()
{
     ssh -Xt USERNAME@MACHINE.ligo.caltech.edu \
     ssh -Xt controls@<IP> \
     ssh -X controls@10.0.1.XX
}
2176   Wed Sep 6 11:51:40 2017 JonLab InfrastructureComputingGateway PC set up

Jon's Edits to Andrew's Setup of the Linksys Router

Andrew is right that the Linksys router (10.0.1.1) can be configured to do everything we want from a gateway, namely providing password-protected ssh access into the LAN machines from the outside while blocking all other ports. I made some minor changes to Andrew's initial setup to balance security with ease of accessibility.

First, I made the Caltech-assigned IP address (131.215.115.216) discoverable on the ligo.caltech.edu network. This makes the gateway pingable, which is useful for determining whether the LAN is down. Note that this gateway is still only discoverable from inside the ligo.caltech.edu network, not from the outer Internet.

Second, I enabled the default port for SSH communications, port 22. I think this is fine security-wise because, again, the machine is only discoverable from within the ligo.caltech network and access is password-protected.

To connect to one of the LAN machines from another machine on the ligo.caltech.edu network with X11 graphics forwarding, you can add this script to your .bashrc file:

connect_onsite()
{
     ssh -Xt controls@<IP> \
     ssh -X controls@10.0.1.XX
}

where 10.0.1.XX is the address of the machine on the local network. You'll be prompted twice for a password, first for the gateway and second for the inside machine.

To connect from outside the ligo.caltech.edu network, forward the connection through a network machine (e.g., I use my office desktop) by adding the line:

connect_offsite()
{
     ssh -Xt USERNAME@MACHINE.ligo.caltech.edu \
     ssh -Xt controls@<IP> \
     ssh -X controls@10.0.1.XX
}
2317   Thu Mar 28 18:16:59 2019 JonUpdateComputingCymac assembly started

This afternoon Chris and I installed the ADC and DAC cards in fb4.

• We connected them to the timing card adapters (left external to the computer chassis for now).
• We found fb4 to be running Debian 8 so first attempted to upgrade to 9, as that is the version supported by Jamie's cymac binaries.
• However, we encountered problems during the upgrade, apparently with gdm (the linux GUI).
• By switching to consol mode and killing gdm, were able to proceed to the point of updating all the packages.
• It completed successfully, but then the system failed to reboot, even in recovery mode.
• During boot, the advligo-rts kernel fails to start, and then boot hangs completely at the point the graphical interface is started.

We may want to start with a fresh install of Debian 9 and just reinstall the LIGO binaries.

ELOG V3.1.3-