Fridge brought back inside.
It happened again. Defrosting required.
The Incredible Melting Man!
EQ M4.3 @longbeach
2021-09-18 02:58:34 (UTC) / 07:58:34 (PDT)
I've uploaded the schematic and PCB PDF for End DAC Adapter Unit D2100647.
Please review the design.
The internal assembly drawing & BOM are still coming.
Over the weekend and today, the wifi was acting bad with frequent disconnections and no internet access. I tried to log into the web interface of the ASUS wifi but with no success.
I pushed the reset button for several seconds to restore factory settings. After that, I was able to log in. I did the automatic setup and defined the wifi passwords to be what they used to be.
Internet access was restored. I also unplugged and plugged back all the wifi extenders in the lab and moved the extender from the vertex inner wall to the outer wall of the lab close to the 1X3.
Now, there seems to be wifi reception both in X and Y arms (according to my android phone).
Running update of Sat Amp modification work, which involves the following procedure (x8) per unit:
TP4 @ LED1,2 on PCB S2100568 is 13V instead of 5V
TP4 @ LED4 on PCB S2100559 is 13V instead of 5V
Ug, factory resets... Caltech IMSS announced that there was an intermittent network service due to maintenance between Sept 19 and 20. And there seemed some aftermath of it. Check out "Caltech IMSS"
Decided to do a quick check of the remaining Sat Amp units before component replacement to identify any unit with defective LED circuits. Managed to examine 5 out of 10 units, so still have 5 units remaining. Also installed the photodiode bias voltage jumper (JP1) on all the units processed so far.
TP4 @ LED3 on chan 1-4 PCB was ~0.7 V instead of 5V
Koji checked the solder connections of the various components, then swapped out the IC OPAMP. Removed DB9 connections to the front panel to get access to the bottom of the board. Upon close inspection, it looked like an issue of a short connection between the Emitter & Base legs of the Q1 transistor.
Solution - Remove the short connection between the Emitter & Base legs of the Q1 transistor legs.
This issue was caused by a short connection between the Emitter & Base legs of the Q1 transistor.
Solution - Remove the short connection between the Emitter & Base legs of the Q1 transistor legs.
Defective unit with updated resistors and capacitors in the previous elog
This issue was caused by a short between the Collector & Base legs of the Q1 transistor.
Solution - Remove the short connection between the Collector & Base legs of the Q1 transistor legs
Complications - During the process of flipping the board to get access to the bottom of the board, a connector holding the two middle black wires, on P1, came loose. I resecured the wires to the connector and checked all TP4s on the board afterwards to make sure things are as expected.
All units now have the correct TP4 voltage reading needed to drive a nominal current of 35 mA through to OSEM LED. The next step is to go ahead and replace the components and test afterward that everything is OK.
This issue was caused by a short between the Emitter & Base legs of the Q1 transistor.
Solution - Remove the short connection between the Emitter & Base legs of the Q1 transistor legs
Complications - I was extra careful this time because of the problem of loose cable from the last flip-over of the right PCB containing chan 5-8. Anyways, after I was done I noticed one of the pink wires (it carries the +14V to the left PCB) had come off on P1. At least this time I could also see that the corresponding front panel green LED turn off as a result. So I resecured the wire to the connector (using solder as my last attempt yesterday to reattach the via crimping didn't work after a long time trying. I hope this is not a problem.) and checked the front panel LED turns on when the unit is powered before closing the unit. These connectors are quite flimsy.
I have noticed that the dumbells coming back from C&B had glue residues on them. An example is shown in attachment 1: it can be seen that half of the dumbell's surface is covered with glue.
Jordan gave me a P800 sandpaper to remove the glue. I picked the dumbells with the dirty face down and slid them over the sandpaper in 8 figures several times to try and keep the surface untilted. Attachment 2 shows the surface from attachment 1 after this process.
Next, the dumbells will be sent to another C&B.
The remaining machined parts for the SOS adapter ring have arrived. I will inspect these today and get them ready for C&B.
Late elog, original date Sep 15th
We found that the power switch of HV supply that powers the PZT drivers for M1 and M2 on Xend green laser injection alignment was tripped off. We could not find any log of someone doing it, it is a physical switch. Our only explanation is that this supply might have a solenoid mechansm to shut off during power glitches and it probably did so on Aug 23 (see 40m/16287). We were able to align the green laser using PZT again, however, the maximum power at green transmission from X arm cavity is now about half of what it used to be before the glitch. Maybe the seed laser on the X end died a little.
Koji requested current state of BHD 3D model. I pushed this to Box after adding the additional SOSs and creating an EASM representation (also posted, Attachment 1). I also post the PDF used to dimension this model (Attachment 2). This process raised some points that I'll jot down here:
1) Because the 40m CAD files are not 100% confirmed to be clean of any student license efforts, we cannot post these files to the PDM Vault or transmit them this way. When working on BHD layout efforts, these assemblies which integrate new design work therefore must be checked for most current revisions of vault-managed files - this Frankenstein approach is not ideal but can be managed for this effort.
2) Because the current files reflect the 40m as built state (as far as I can tell), I shared the files in a zip directory without increasing the revisions. It is unclear whether revision control is adequate to separate [current 40m state as reflected in CAD] from [planned 40m state after BHD upgrade]. Typically a CAD user would trust that we could find the version N assembly referenced in the drawing from year Y, so we wouldn't hesitate to create future design work in a version N+1 assembly file pending a current drawing. However, this form of revision control is not implemented. Perhaps we want to use configurations to separate design states (in other words, create a parallel model of every changed component, without creating paralle files - these configurations can be selected internal to the assembly without a need to replace files)? Or more simply (and perhaps more tenuously), we could snapshot the Box revisions and create a DCC page which notes the point of departure for BHD efforts?
Anyway, the cold hard facts:
- Box location: 40m/40m_cad_models/Solidworks_40m (LINK)
- Filenames: 3002.zip and 3002 20211001 ITMY BHD for Koji presentation images.easm (healthy disregard for concerns about spaces in filenames)
What: Anchal and I measured the XARM OLTF last Thursday.
Goal: 1. measure the 2 zeros and 2 poles in the analog whitening filter, and potentially constrain the cavity pole and an overall gain.
2. Compare the parameter distribution obtained from measurements and that estimated analytically from the Fisher matrix calculation.
3. Obtain the optimized excitation spectrum for future measurements.
How: we inject at C1:SUS-ETMX_LSC_EXC so that each digital count should be directly proportional to the force applied to the suspension. We read out the signal at C1:SUS-ETMX_LSC_OUT_DQ. We use an approximately white excitation in the 50-300 Hz band, and intentionally choose the coherence to be only slightly above 0.9 so that we can get some statistical error to be compared with the Fisher matrix's prediction. For each measurement, we use a bandwidth of 0.25 Hz and 10 averages (no overlapping between adjacent segments).
The 2 zeros and 2 poles in the analog whitening filter and an overall gain are treated as free parameters to be fitted, while the rest are taken from the model by Anchal and Paco (elog:16363). The optical response of the arm cavity seems missing in that model, and thus we additionally include a real pole (for the cavity pole) in the model we fit. Thus in total, our model has 6 free parameters, 2 zeros, 3 poles, and 1 overall gain.
The analysis codes are pushed to the 40m/sysID repo.
Fig. 1 shows one measurement. The gray trace is the data and the olive one is the maximum likelihood estimation. The uncertainty for each frequency bin is shown in the shaded region. Note that the SNR is related to the coherence as
SNR^2 = [coherence / (1-coherence)] * (# of average),
and for a complex TF written as G = A * exp[1j*Phi], one can show the uncertainty is given by
\Delta A / A = 1/SNR, \Delta \Phi = 1/SNR [rad].
Fig. 2. The gray contours show the 1- and 2-sigma levels of the model parameters using the Fisher matrix calculation. We repeated the measurement shown in Fig. 1 three times, and the best-fit parameters for each measurement are indicated in the red-crosses. Although we only did a small number of experiments, the amount of scattering is consistent with the Fisher matrix's prediction, giving us some confidence in our analytical calculation.
One thing to note though is that in order to fit the measured data, we would need an additional pole at around 1,500 Hz. This seems a bit low for the cavity pole frequency. For aLIGO w/ 4km arms, the single-arm pole is about 40-50 Hz. The arm is 100 times shorter here and I would naively expect the cavity pole to be at 3k-4k Hz if the test masses are similar.
Fig. 3. We then follow the algorithm outlined in Pintelon & Schoukens, sec. 18.104.22.168, to calculate how we should change the excitation spectrum. Note that here we are fixing the rms of the force applied to the suspension constant.
Fig. 4 then shows how the expected error changes as we optimize the excitation. It seems in this case a white-ish excitation is already decent (as the TF itself is quite flat in the range of interest), and we only get some mild improvement as we iterate the excitation spectra (note we use the color gray, olive, and purple for the results after the 0th, 1st, and 2nd iteration; same color-coding as in Fig. 3).
I have finished assembling the 1U adapters from 8 to 5 DB9 conn. for the satellite amp boxes. One thing I had to "hack" was the corners of the front panel end of the PCB. Because the PCB was a bit too wide, it wasn't really flush against the front panel (see Attachment #1), so I just filed the corners by ~ 3 mm and covered with kapton tape to prevent contact between ground planes and the chassis. After this, I made DB9 cables, connected everything in place and attached to the rear panel (Attachment #2). Four units are resting near the CAD machine (next to the bench area), see Attachment #3.
Thanks. You should be able to find the chassis-related hardware on the left side of the benchtop drawers at the middle workbench.
Hardware: The special low profile 4-40 standoff screw / 1U handles / screws and washers for the chassis / flat-top screws for chassis panels and lids
Trying to finish 2 more Sat Amp units so that we have the 7 units needed for the X-arm install.
S2100736 - All good
S2100737 - This unit presented with an issue on the PD1 circuit of channel 1-4 PCB where the voltage reading on TP6, TP7 and TP8 are -15.1V, -14.2V, and +14.7V respectively, instead of ~0V. The unit also has an issue on the PD2 circuit of channel 1-4 PCB because the voltage reading on TP7 and TP8 are -14.2V, and +14.25V respectively, instead of ~0V.
Make sure the inputs for the PD amps are open. This is the current amplifier and we want to leave the input pins open for the test of this circuit.
TP6 is the first stage of the amps (TIA). So this stage has the issue. Usual check if the power is properly supplied / if the pins are properly connected/isolated / If the opamp is alive or not.
For TP8, if TP8 get railed. TP5 and TP7 are going to be railed too. Is that the case, if so, check this whitening stage in the same way as above.
If the problem is only in the TP5 and/or TP7 it is the differential driver issue. Check the final stage as above. Replacing the opamp could help.
Yesterday afternoon Paco and I measured the PRM L2P transfer function. We drove C1:SUS-PRM_LSC_EXC with a white noise in the 0-10 Hz band (effectively a white, longitudinal force applied to the suspension) and read out the pitch response in C1:SUS-PRM_OL_PIT_OUT. The local damping was left on during the measurement. Each FFT segment in our measurement is 32 sec and we used 8 non-overlapping segments for each measurement. The empirically determined results are also compared with the Fisher matrix estimation (similar to elog:16373).
Fig. 1 shows one example of the measured L2P transfer function. The gray traces are measurement data and shaded region the corresponding uncertainty. The olive trace is the best fit model.
Note that for a single-stage suspension, the ideal L2P TF should have two zeros at DC and two pairs of complex poles for the length and pitch resonances, respectively. We found the two resonances at around 1 Hz from the fitting as expected. However, the zeros were not at DC as the ideal, theoretical model suggested. Instead, we found a pair of right-half plane zeros in order to explain the measurement results. If we cast such a pair of right-half plane zeros into (f, Q) pair, it means a negative value of Q. This means the system does not have the minimum phase delay and suggests some dirty cross-coupling exists, which might not be surprising.
Fig. 2 compares the distribution of the fitting results for 4 different measurements (4 red crosses) and the analytical error estimation obtained using the Fisher matrix (the gray contours; the inner one is the 1-sigma region and the outer one the 3-sigma region). The Fisher matrix appears to underestimate the scattering from this experiment, yet it does capture the correlation between different parameters (the frequencies and quality factors of the two resonances).
One caveat though is that the fitting routine is not especially robust. We used the vectfit routine w/ human intervening to get some initial guesses of the model. We then used a standard scipy least-sq routine to find the maximal likelihood estimator of the restricted model (with fixed number of zeros and poles; here 2 complex zeros and 4 complex poles). The initial guess for the scipy routine was obtained from the vectfit model.
Fig. 3 shows how we may shape our excitation PSD to maximize the Fisher information while keeping the RMS force applied to the PRM suspension fixed. In this case the result is very intuitive. We simply concentrate our drive around the resonance at ~ 1 Hz, focusing on locations where we initially have good SNR. So at least code is not suggesting something crazy...
Fig. 4 then shows how the new uncertainty (3-sigma contours) should change as we optimize our excitation. Basically one iteration (from gray to olive) is sufficient here.
We will find a time very recently to repeat the measurement with the optimized injection spectrum.
(S2100737) - Debugging showed that the opamp, AD822ARZ, for PD2 circuit was not working as expected so we replaced with a spare and this fixed the problem. Somehow, the PD1 circuit no longer presents any issues, so everything is now fine with the unit.
(S2100741) - All good.
The 4 units of Satellite Amp Adapter were done:
- The ears were fixed with the screws
- The handles were attached (The stock of the handles is low)
- The boards are now supported by plastic stand-offs. (The chassis were drilled)
- The front and rear panels were fixed to the chassis
- The front and rear connectors were fixed with the low profile 4-40 stand-off screws (3M 3341-1S)
We did some more measurements on the PRM L2P TF.
We tried to compare the parameter estimation uncertainties of white vs. optimal excitation. We drove C1:SUS-PRM_LSC_EXC with "Normal" excitation and digital gain of 700.
For the white noise exciation, we simply put a butter("LowPass",4,10) filter to select out the <10 Hz band.
For the optimal exciation, we use butter("BandPass",6,0.3,1.6) gain(3) notch(1,20,8) to approximate the spectral shape reported in elog:16384. We tried to use awg.ArbitraryLoop yet this function seems to have some bugs and didn't run correctly; an issue has been submitted to the gitlab repo with more details. We also noticed that in elog:16384, the pitch motion should be read out from C1:SUS-PRM_OL_PIT_IN1 instead of the OUT channel, as there are some extra filters between IN1 and OUT. Consequently, the exact optimal exciation should be revisited, yet we think the main result should not be altered significantly.
While a more detail analysis will be done later offline, we post in the attached plot a comparison between the white (blue) vs optimal (red) excitation. Note in this case, we kept the total force applied to the PRM the same (as the RMS level matches).
Under this simple case, the optimal excitation appears reasonable in two folds.
First, the optimization tries to concentrate the power around the resonance. We would naturally expect that near the resonance, we would get more Fisher information, as the phase changes the fastest there (i.e., large derivatives in the TF).
Second, while we move the power in the >2 Hz band to the 0.3-2 Hz band, from the coherence plot we see that we don't lose any information in the > 2 Hz region. Indeed, even with the original white excitation, the coherence is low and the > 2 Hz region would not be informative. Therefore, it seems reasonable to give up this band so that we can gain more information from locations where we have meaningful coherence.
For the oplev, there are DQ channels you can use so that its possible to look back in the past for long measurements. They have names like PERROR
We report here the analysis results for the measurements done in elog:16388.
Figs. 1 & 2 are respectively measurements of the white noise excitation and the optimized excitation. The shaded region corresponds to the 1-sigma uncertainty at each frequency bin. By eyes, one can already see that the constraints on the phase in the 0.6-1 Hz band are much tighter in the optimized case than in the white noise case.
We found the transfer function was best described by two real poles + one pair of complex poles (i.e., resonance) + one pair of complex zeros in the right-half plane (non-minimum phase delay). The measurement in fact suggested a right-hand pole somewhere between 0.05-0.1 Hz which cannot be right. For now, I just manually flipped the sign of this lowest frequency pole to the left-hand side. However, this introduced some systematic deviation in the phase in the 0.3-0.5 Hz band where our coherence was still good. Therefore, a caveat is that our model with 7 free parameters (4 poles + 2 zeros + 1 gain as one would expect for an ideal signal-stage L2P TF) might not sufficiently capture the entire physics.
In Fig. 3 we showed the comparison of the two sets of measurements together with the predictions based on the Fisher matrix. Here the color gray is for the white-noise excitation and olive is for the optimized excitation. The solid and dotted contours are respectively the 1-sigma and 3-sigma regions from the Fisher calculation, and crosses are maximum likelihood estimations of each measurement (though the scipy optimizer might not find the true maximum).
Note that the mean values don't match in the two sets of measurements, suggesting potential bias or other systematics exists in the current measurement. Moreover, there could be multiple local maxima in the likelihood in this high-D parameter space (not surprising). For example, one could reduce the resonant Q but enhance the overall gain to keep the shoulder of a resonance having the same amplitude. However, this correlation is not explicit in the Fisher matrix (first-order derivatives of the TF, i.e., local gradients) as it does not show up in the error ellipse.
In Fig. 4 we show the further optimized excitation for the next round of measurements. Here the cyan and olive traces are obtained assuming different values of the "true" physical parameter, yet the overall shapes of the two are quite similar, and are close to the optimized excitation spectrum we already used in elog:16388.
We did a few quick XARM oltf measurements. We excited C1:LSC-ETMX_EXC with a broadband white noise upto 4 kHz. The timestamps for the measurements are: 1318199043 (start) - 1318199427 (end).
We will process the measurement to compute the cavity pole and analog filter poles & zeros later.
PMC has been unlocked since ~ 2:30 AM. Seems like the PZT got saturated. I moved the DC output adjuster and the PMC locked immidiatly although with a low transmission of 0.62V (>0.7V is the usual case) and high REFL.
IMC locked immidiately but IFO seems to be completely misaligned. The beams on the AS monitor are moving quite alot syncronously. BS watchdog tripped. I enabled the coil outputs. Waiting for the RMS motion to relax...
Its not relaxing. RMS motion is still high. I disabled the coils again and reenabled them. This seems to have worked. Arms were locked quite easily but the ETMs oplevs were way off and the ASS couldn't get the TRX and TRY more than 0.7. I align the ETMs to center the oplev. I realign everything else and lock the arms. Maximium TR is still < 0.8.
I went to get a sandwich around 10:20 AM and when I came back BS was moving like crazy. We shutdown the watchdog.
We look at the spectra of the OSEMs (attachment 1). Clearly, the UR sensing is bad.
We took the BS sattelite box out. Anchal opened the box and nothing seemed wrong visually. We returned the box and connected it to the fake OSEM box. The sensor spectra seemed normal.
We connected the box to the vacuum chamber and the spectra is still normal (attachment 2).
We turn on the coils and the motion got damped very quickly (RMS <0.5mV).
Either the problem was solved by disconnecting and connecting the cables or it will come back to haunt us.
We are going to kick the optics tonight at 2am.
The optics we will kick are the PRM BS ITMX ITMY ETMX ETMY
We will kick each one once and record for 2000 seconds and the log files will be placed in users/ian/20211015_FreeSwingTest/logs.
We aligned the IFO in the PRMI state and let it swing freely.
we ran the free swinging test last night and the results match up with in 1/10th of a Hz. We calculated the peak using the getPeakFreqs2 script to find the peaks and they are close to previous values from 2016.
In attachment 1 you will see the results of the test for each optic.
The peak values are as follows:
The results from 2016 can be found at: /cvs/cds/rtcdt/caltech/c1/scripts/SUS/PeakFit/parameters2.m
[Chub, Jordan, Anchal, Koji]
- Checked the main volume is isolated.
- TP1 and TP2 were made isolated from other volumes. Stopped TP1. Closed V4 to isolate TP1 from TP2.
- TP3 was made isolated. TP3 was stopped.
- We wanted to vent annuli, but it was not allowed as VA6 was open. We closed VA6 and vented the annuli with VAVEE.
- We wanted to vent the volume between VA6, V5, VM3, V7 together with TP1. So V7 was opened. This did not change the TP1 pressure (P2 = 1.7mmTorr) .
- We wanted to connect the TP1 volume with the main volume. But this was not allowed as TP1 was not rotating. We will vent TP1 through TP2 once the vent of the main volume is done.
- Satrted venting the main volume@Oct 18, 2021 9:45AM PDT
- We started from 10mTorr/min, and increased the vent speed to 200mTorr/min, 700mTorr/min, and now it is 1Torr/min @ 20Torr
- 280Torr @11:50AM
- 1atm @~2PM
We wanted to vent TP1. We rerun the TP2 and tried to slowly introduce the air via TP2. But the interlock prevents the action.
Right now the magenta volume in the attachment is still ~1mTorr. Do we want to open the gate valves manually? Or stop the interlock process so that we can bypass it?
[S2100738, S2100745, S2100751] Completed three more Sat Amp units modification with seven remaining.
[Chub, Jordan, Yehonathan, Anchal, Koji]
North door of the BS chamber opened
I learned that TP1 was vented through the RGA room in the past. This can be done by opening VM2 and a manual valve ("needle valve")
I checked the setup and realized that this will vent RGA. But it is OK as long as we turns of the RGA during vent and bake it once TP1 is back.
- It'd be nice to take a scan for the current background level before the work.
- Turn RGA EM and filament off, let it cool down overnight.
- Vent with clean N2 or clean air. (Normal operating temp ~80C is to minimize accumulation of H-C contaminations.)
- There is a manual switch and indicators on the top of the RGA amp. It has auto protection to turn filament off if the pressure increase over ~1e-5.
Probably the hard disk of c0rga is dead. I'll follow up in this elog later today.
Looking at the log in /opt/rtcds/caltech/c1/scripts/RGA/logs , it seemed that the last RGA scan was Sept 2, 2021, the day when we had the disk full issue of chiara.
I could not login to c0rga from control machines.
I was not aware of the presence for c0rga until today, but I could locate it in the X arm.
The machine was not responding and it was rebooted, but could not restart. It made some knocking sound. I am afraid that the HDD failed.
I think we can
- prepare a replacement linux machine for the python scripts
- integrate it with c1vac
I had 8 standoffs made at the Caltech chemistry machine shop to be used as spacers for the side magnets on the 3" Ring assembly. This is to create enough clearance between the magnet and the cap screws directly above on the wire clamp.
These are 0.075" diameter by .10" length. Putting them through clean and bake now.
Things that I need to start suspending optics:
1. Winch adapter plate (D970314). Might need to make one.
2. Quad photodetector
3. Camera and camera mount
4. Beam height target
5. Height gauge
1. We have a rack at the 40m storage. We are free to take it to the lab. If there is a tag, tell the info to Liz. Let's move it to the lab tomorrow right after the meeting.
2. We have a few racks in WB B1 (Attachment 1). Liz and I checked a rack which looks suitable for us. 46U height. Caltech transport will move it to the lab.