There was no clear reason for this trip, no one was in the lvea at the time.
Sheila, logged in as Alexa
No touching.
I started this last week, finished it today. Not going to give a lot of details of the measurement, but we drive the ISI hard at low frequency in one direction and adjust some cps align elements until a hooked line becomes mostly straight. This will give us some gains in the low frequency region. St2 still needs to be done, but should go relatively quickly. Also need to add sensor correction, which I'm starting to look at right now. Posting a screen of the St1 cpsalign values here for posterity.
Day's Activities:
Alarms in the morning:
I went back to the end station today to look into the beam quality. At Keita's suggestion I put a retro reflector in to look at the beam without having to worry about what happens in the chamber. With the retroreflector after the last steering mirror on the table, I set up the nanoscan in the path to WFS B and the thorlabs beam scan in the path to the HWS, whic doesn't double pass the Faraday. Using the two profiles, I tried to move the Faraday around to find a position where both the beam in the HWS path (the first pass beam) and the beam in the WFS B path (double passed) were good. Although there were many positions that gave a good beam after the single pass, I didn't find anything that gave a nice gaussian profile in the rejected path. I swapped the Faraday with a simliar one, and the beam quality was immediately better. With a small adjustment I found beams that look guassian in both the WFS path (measured at 3 different positions) and the HWS path, using the retroreflector. Reflecting off the ETM the beam is a little bit worse, but still bassically a guassian beam.
(Keita, Sheila, Alexa)
After Sheila swapped out the Faraday we noticed that the incident light on each of the green QPDs was not the same and one of them was almost saturating. It turned out that the two Faraday output angles were not the same. We adjusted that HWP after the Faraday so that we maximized the s-pol. In addition, we manually recentered the beam onto the QPDs with the servo off.
(Alexa, Daniel)
We added an FDD in the IMC VCO path (currently borrowed the ALS DIFF FDD). In doing so, we have reduced the signal by a factor of 10. We adjusted the MC common mode board fast gain to 14dB from the original -6dB. The MCL-MCF Crossover is still the same (UGF: 14.7Hz w/ 39 deg phase margin). I have attached a DTT plot with the current crossover and a reference taken on 03-17-2014. We have also adjusted the gain in the IMC_F filter to be 0.1 to account for the reduced VCO DC gain. We remeasured the IMC_F noise as done in alog 5311; the results are suffeciently consistent (see second DTT image; DTT is saved uner my public directory). Finally, we measured the IMC OLTF; the UGF is 31kHz with a phase margin of 38deg (close enough to the nominal UGF: 53kHz, 45 deg phase margin). The data and plot are attached.
I have placed an IFR below the 79Mhz RF source on the ISC C4 Rack. The IFR is set to 78.95MHz with an RF level of 10dBm and is now used instead of the RF source.
We are waiting for the x-arm to test if the 1/f noise has actually decreased with these changes...TBD.
(Alexa, Sheila)
This alog is refering to work done yesterday...
We have reverted to the nominal configuration, i.e. no FDD for the IMC VCO and we are using the RF source at 79.2MHz again.
Cyrus, Jim, Jonathan and Dave
Cyrus got the right hand projector operational by setting up a Mac Mini to drive it via the VGA port. The computer's name is projector0 and is accessible via the screen sharing application.
Jim and Dave worked on room lighting to make this screen visible without having to turn both banks of flourescent tubes off. By removing tubes in the front right corner of the room we were able to acheive this.
Dave worked on rearranging the control room figures of merit (FOMs) to make optimal use of the projector. The screens most important to the operator were positioned to be as close to the operator's sight line as possible.
The FOM wiki page was updated accordingly:
https://lhocds.ligo-wa.caltech.edu/wiki/Operations/FiguresOfMerit
to do: we need to convert frequently used StripTools into DMT monitors to make them more accessible if they show a long trend (12 hours) and update every minute.
The Instrument Air for MX has been alarming (about every 15min) since early Fri morning [see attached]. (should vacuum crew take care of this, or do we change alarm level settings? Sending email to Vacuum Team).
UGF=5Hz now, the separation between different DOFs is more than 20db. You can increase the BW more but watch for gain peaking.
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I decided to diagonalize based on PZTs (don't remember how it was done at EY). If you want to do it based on QPDs, just swap input and output matrix.
Sensing matrix was measured by turning on the servo with 3-8Hz band stop filter, then stop it holding the output, then injecing at 3.1, 4..1, 5 and 6.5Hz for PZT1_PIT, PZT2_PIT, PZT1_YAW and PZT2_YAW. Inverted the matrix to make a new input matrix such that POS=PZT1 and ANG=PZT2, and that the filter TF becomes equal to OLTF at low frequency where PZT response is flat.
I removed "calibration" filter bank as it's not useful. Now the filter comprises a simple integrator (FM1 and 2 together), "boost" (FM3) which I disabled as our UGF is much higher, and LF100 (FM10).
Integrator is scaled such that the absolute value is 1 at 1Hz. With just the integrator and LF100, filter gain is equal to the UGF.
The first plot shows the OLTF of all four DOFs when the filter gain was set to 10. Since the phase margin at 10Hz is already getting thin, I changed the gain to 5 after this measurement (UGF=5Hz).
The second plot (right bottom) shows that the loops are separated from each other by more than 20dB (look at red and blue for PIT modulations at 3.1Hz and 4.1Hz, green and brown for YAW at 5 and 6.5Hz).
When you need more BW for some reason, disabling LF100 will allow you to push to the gain of 50 or so. Since PZT starts to fall off from 20Hz or so, gain of 50 doesn't give you of about 30Hz UGF instead of 50.
If you need to have even higher BW for whatever reason, Stefan says that the MadCityLabs control box lets you switch to high BW mode which he disabled at some stage because the 2" PZT was oscillating with that setting.
I made EY QPD servo similar to EX (PZT based diagonalization, UGF5Hz without boost).
Black trace shows the OLTF when gain is set to 50 without LF100.
On Friday Jason shot us in on the WHAM5 ISI Optical Table position. We started needing to go South 2.4mm, East 3.6mm and CCW 880urads. Vertically it was 1.1mm low (see log 11061.) Couple adjustments with the DSCW Springs and Jason gave us the close-enough sign at 1mm West, CW <400urads and good N-S. After that work, I checked the DIs and it looked like we had disturbed the vertical.
This morning we checked and sure enough we were out of level across the Optical Table by almost a mm. We corrected this easily bringing up the three low corners. I thought this would correct the low elevation but the average elevation is still low 1.1mm, just outside of tolerance. The disturbance friday must have dropped rather than raised anything. I should have looked closer earliar. Today's vertical move disturbed the horizontal position slightly, improving the yaw by ~50urads, shifting west and south 0.1mm. I'll check with the PTB if this is close enough to move on.
Gate valves GV5 and GV7 were soft closed this morning to allow Apollo do some craning. Gate valves were soft closed at 9:00 am.
After Apollo was done craning GV7 was opened at 10:52 am. GV5 will remain soft closed.
At request of A. Pele and J. Warner so as to confirm noise source at Y-end. Also, shut down leak detector at BSC6 (left off)
I am out at the end station working on the table (on the side closer to the chamber sometimes), and the ISI tripped. Stage 1 said CPSs were the first trigger, GS13s were the first trigger on stage2.
I don't think the plotting scripts work on the CDS Imacs, but these trips were probably due to me walking around.
No, sorry, that was me... too many of the same screens open.
On the Guardian Screen, I noticed a RED HAM4 ISI. Looking at the LOG, it said it had an ERROR from last Wed (4/9) after a WD Trip. Here are the last few lines from Guardian's Log regarding the issue:
20140409_18:58:49.069 ISI_HAM4 W: EzcaError: Could not connect to channel (timeout=2s): H1:ISI-HAM4_WD_MON_STATE_INMON
20140409_18:58:49.090 ISI_HAM4 ERROR in state WATCHDOG_TRIPPED_FULL_SHUTDOWN. See log for more info. MODE=>LOAD to reset
I went to MODE, hit LOAD (HAM4 Guardian went white for 10s of seconds & then came back YELLOW), and then hit EXEC (now it's GREEN).
Started morning with several systems tripped. Arnaud posted about an EQ around 1pm on Sat. So trips I'm posting about here are for trips on Sat around 5pm and on Sun around 5pm
So by about 9am, I got everybody back to untripped (GREEN). This was pretty easy:
NOTE: For the ISIs, I wasn't aware Guardian DOES NOT take care of the Blend Filters for us. So Operators (as long as it's OK with commissioners) should make sure to ensure the Blend Filters are enabled. Jim tells me there has been alogs stating what type of Blend Filters we are to engage per ISI.
