Here's a noise spectrum of the RSE interferometer, in anti-spring mode, with RF readout. I'd say the calibration is "loose."
I used the Buonanno & Chen modification of the KLMTV IFO transfer functions to model the DARM opto-mechanical response. I just guessed at the quadrature, and normalized the optical gain at the frequency of the calibration line used (927Hz, not visible on the plot).
I checked out a copy of matapps into /cvs/cds/caltech/apps/lscsoft so that I could find the matlab function strassign.m, which is necessary for some old mDV commands to run. I don't know why it became necessary or why it disappeared if it did.
For the 40m Upgrade, we plan to eliminate the Mach-Zehnder and replace it with a single EOM driven by all three modulation frequencies that we'll need: f1=11MHz, f2=5*f1=55MHz, fmc=29.5MHz.
A frequency generator will produce the three frequencies and with some other electronics we'll properly combine and feed them to the EOM.
The frequency generator will have two crystals to produce the f1 and fmc signals. The f2 modulation will be obtained by a frequency multiplier (5x) from the f1.
The frequency multiplier, for the way it works, will inevitably introduce some unwanted harmonics into the signals. These will show up as extra modulation frequencies in the EOM.
In order to quantify the effects of such unwanted harmonics on the interferometer and thus to let us set some limits on their amplitude, I ran some simulations with Optickle. The way the EOM is represented is by three RF modulators in series. In order to introduce the unwanted harmonics, I just added an RF modulator in series for each of them. I also made sure not to leave any space in between the modulators, so not to introduce phase shifts.
To check the effect at DC I looked at the sensing matrix and at the error signals. I considered the 3f error signals that we plan to use for the short DOFs and looked at how they depend on the CARM offset. I repeated the simulations for several possible amplitude of the unwanted harmonics. Some results are shown in the plots attached to this entry. 'ga' is the amplitude ratio of the unwanted harmonics relative to the amplitude of the 11 & 55 MHz modulations.
Comparing to the case where there are no unwanted harmonics (ga = 0), one can see that not considerable effect on the error signals for amplitudes 40dB smaller than that of the main sidebands. Above that value, the REFL31I signals, that we're going to use to control PRCL, will start to be distorted: gain and linearity range change.
So 40 dB of attenuation in the unwanted harmonics is probably the minimum requirement on the frequency multiplier, although 60dB would provide a safer margin.
I'm still thinking how to evaluate any AC effect on the IFO.
** TODO: Plot DC sweeps with a wider range (+/- 20 pm). Also plot swept sines to look for changes in TFs out to ~10 kHz.
With the common mode servo bandwidth above 30kHz and the BOOST on (1), I was able to switch on the test mass dewhitening. Finally.
Last night Rob ran senseDRM and loadDRMImatrixData and came up with the following for the input matrix:
tdswrite C1:LSC-ITMTRX_b2 0.065778 \
C1:LSC-ITMTRX_d2 2.2709 \
C1:LSC-ITMTRX_f2 2.9361 \
C1:LSC-ITMTRX_122 0.42826 \
C1:LSC-ITMTRX_b3 -0.064839 \
C1:LSC-ITMTRX_d3 -0.016913 \
C1:LSC-ITMTRX_f3 -0.021576 \
C1:LSC-ITMTRX_123 -0.0025243 \
C1:LSC-ITMTRX_b5 0.3719 \
C1:LSC-ITMTRX_d5 1.3109 \
C1:LSC-ITMTRX_f5 -0.16412 \
C1:LSC-ITMTRX_125 0.39574 \
C1:LSC-ITMTRX_33 0 \
C1:LSC-ITMTRX_42 0 \
Today, I reran these and got the following, and DD_handoff remained happy:
tdswrite C1:LSC-ITMTRX_b2 -0.10329 \
C1:LSC-ITMTRX_d2 2.0344 \
C1:LSC-ITMTRX_f2 3.2804 \
C1:LSC-ITMTRX_122 0.22516 \
C1:LSC-ITMTRX_b3 -0.076292 \
C1:LSC-ITMTRX_d3 -0.014603 \
C1:LSC-ITMTRX_f3 -0.12101 \
C1:LSC-ITMTRX_123 0.0054128 \
C1:LSC-ITMTRX_b5 0.33521 \
C1:LSC-ITMTRX_d5 1.1425 \
C1:LSC-ITMTRX_f5 -0.32759 \
C1:LSC-ITMTRX_125 0.25877 \
C1:LSC-ITMTRX_33 0 \
C1:LSC-ITMTRX_42 0 \
I wanted to remeasure with the canonical output matrix (-0.7 from MICH to PRM and 0.7 from MICH to SRM), but the DRM freaked out when MICH to PRM went below -0.3.
The IFO is locked, at the operating point (zero CARM offset). The problem with reducing the residual CARM offset in the last stage appears to have been because the common mode gain was getting too high, and so the loop was going unstable at high frequencies.
The cm_step script is currently a confusing mess, with all the debugging statements. I'll clean it up this afternoon and check that it still works.
The maglev fore line pressure is 3e-6 torr at CC2 after 4 days of pumping. Varian turbo V-70 is pumping on it through V4 and VM2
Actual pumping speed ~10 l/s for N2. There was no baking. The maglev performance looks good : 3e-9 torr on CC4 with RGA -region only.
Lock is still being lost, right at the end of the process when trying to reduce the CARM offset to zero.
I had trouble getting the SRC handoff from SD to DD to work. I tried different gains, flipping the PD7 & 8 demod phases by 180 degrees, and messing with the output matrix to reduce cross-couplings in the state with MICH & PRC on DD and SRC on SD. Eventually I decided to try to make the DRM matrix diagonalization work.
It does, mostly. The handoff is now stable, and the loops all have UGFs around 100Hz. So, tonight anyways, it's possible to run senseDRM and then loadDRMImatrixData.m and run the resulting tdswrite command, and have a working handoff. I had to eliminate a few PDs (PD5 & PD10) to get it to work properly.
It would be nice if this script would measure all the PDs and allow individual setting of loop UGFs and measurement frequencies.
Joe and Steve
The retrofitted Osaka 390 was installed on the pumpspool yesterday.
V1 gate valve is disabled for safety by disconnected pneumatic power plug.
The foreline of this maglev now have a KF25 size viton o-ring directly on the turbo.
This is bad for leak hunting.
Joe is ready with new interface cable. Power supply and cables are in place.
The maglev was pumped down this morning.
All new gas kits and metal hose were leak checked by sprayed methanol.
There is no obvious sign of leak. I was expecting the pressure to drop below 1e-5 Torr in one hour.
TP2 is drying out the levitating coils of the turbo at ~7 l/s for N2
We'll start the pump as soon as Joe is in.
Joe and Steve
The Maglev is running at 680 Hz, 40,800 RPM with V1 gate valve closed and valve disabled to change position. C1vac2 was rebooted before starting.
Interlocks are not tested yet, but the medm COVAC_MONITOR.adl screen is reading correctly. RGA scan will determine the need for baking on Monday
The foreline pressure is still ~2e-5 Torr
Acceleration takes 3 minutes 30sesconds without load. There is no observabale temp effect on the body of the turbo during braking and acceleration.
The IFO is still pumped by the CRYO only
The new Maglev fore line pressure is at 4e-6 torr at day 3
Valve VM1 was closed to isolate IFO from RGA and valve VM2 was opened so the RGA can scan the Maglev only.
We updated the vacuum control and monitor screens (C0VAC_MONITOR.adl and C0VAC_CONTROL.adl). We also updated the /cvs/cds/caltech/target/c1vac1/Vac.db file.
1) We changed the C1:Vac-TP1_lev channel to C1:Vac-TP1_ala channel, since it now is an alarm readback on the new turbo pump rather than an indication of levitation. The logic on printing the "X" was changed from X is printed on a 1 = ok status) to X is printed on a 0 = problem status. All references within the Vac.db file to C1:Vac-TP1_lev were changed. The medm screens also now are labeled Alarm, instead of Levitating.
2) We changed the text displayed by the CP1 channel (C1:Vac-CP1_mon in Vac.db) from "On" and "Off" to "Cold - On" and "Warm - OFF".
3) We restarted the c1vac1 front end as well as the framebuilder after these changes.
I started two scripts, senseDRM and loadDRMImatrixData.m, which Peter will bang on until they're correct. They're in the $SCRIPTS/LSC directory. The first is a perl script which uses TDS tools to drive the DRM optics and measure the response at the double demod photo-detectors, and write these results to a series of files loadable by matlab. The second loads the output from the first script, inverts the resulting sensing matrix to get an input matrix, and spits out a tdswrite command which can be copied and pasted into a terminal to load the new input matrix values.
What's left is mainly in figuring out how to do the matrix inversion properly. Right now the script does not account for the output matrix, the gains in the feedback filters at the measurement frequency, or the fact that we'll likely want the UGF of our loops to be less than the measurement frequency. Peter's going to hash out these details.
This afternoon I tuned the handoff script for the SRC, after that Rob eralier during the day had already adjusted that for PRC. To do that, I followed the procedure in the Wiki.
After that the SRC could get locked with the double demod signals. the open loop transfer function emasurement on the PRC loop showed that it was nearly unstable. Rob reduced a little its gain to improve the stability.
The DD handoff is now working and we can get back to locking the interferometer.
After poking around for a few minutes several facts became clear:
1) At least one GPIB interface has a hard ethernet connection (and does not currently go through the wireless).
2) The wireless on the laptop works fine, since it can connect to the router.
3) The rest of the martian network cannot talk to the router.
This led to me replugging the ethernet cord back into the wireless router, which at some point in the past had been unplugged. The computers now seem to be happy and can talk to each other.
tonight we worked on the tuning of the double demod phases for the handoff of the short DOFs control signals.
Only MICH can now undergo the handoff. PRC can't make it.
Basically, we tuned the PD6 demod phase and reduced the offset in PD6_I. Then we tuned the relative gain of PD6_I and PD2_I so that the two open loop transfer function of the control loops would match. We tried that in several ways and several times but without success.
I guess we're missing to do/check something.
The PMC alarm was on this morning. It was relocked at lower HV
The FSS_RMTEMP jumped 0.5 C so The PZT was compensating for it.
I moved the mobile HEPA filter from ITMX's north door to ITMX-ISCT and covered it up with a merostate tent to accommodate the aluminum foil particle measurement on June 5
It lowered the 40m baseline counts by about a factor of 3 of 0.5 micron and a factor of 2 of 1.0 micron.
The HEPA filter is sweeping the floor and blowing the particles upwards. The MET ONE counter is on the top of the IOOC looking south at ~75 degrees upward.
Pete, Rob, Alberto,
yesterday we thought that some of the problems we were having in locking the IFO might be related to a change of the length of the mode cleaner. So today we decided to measure it again.
We followed the Sigg-Frolov technique (see 40m Wiki, Waldman, Fricke). For the record, the MC_AO input corresponds to IN2 on the MC Servo board.
We obtained: L = 27.092 +/- 0.001 m
From the new measurement we reset the frequencies of the Marconis to the following values:
Lock acquisition is proceeding smoothly for the most part, but there is a very consistent failure point near the end of the cm_step script.
Near the end of the procedure, while in RF common mode, the sensing for the MCL path of the common mode servo is transitioned from a REFL 166I signal which comes into the LSC whitening board from the demodulator, to another copy of the signal which has passed through the common mode board, and is coming out of the Length output of the common mode board. We do this because the signal which comes through the CM board sees the switchable low-frequency boost filter, and so both paths of the CM servo (AO and MCL) can get that filter switched on at the same time.
The problem is occurring after this transition, which works reliably. However, when the script tries to remove the final CARM offset, and bring the offset to zero, lock is abruptly lost. DARM, CM, and the crossover all look stable, and no excess noise appears while looking at the DARM, CARM, MCF spectra. But lock is always lost right about the same offset.
I've seen this before. At that time, the problem was gone spontaneously the next day.
You could stop just before the offset reaches zero and then try to slowly reduce the offset manually to see where is the threshold.
Well, it hasn't gone away yet. It happened Sat, Mon, and Tues afternoon, as well as Friday. The threshold varies slightly, but is always around ~200-300 cnts. I've tried reducing the offset with the signal coming from the CM board and the signal not going through the CM board, I've also tried jumping the signal to zero (rather than a gradual reduction).
Tonight we'll measure the MC length and set the modulation frequencies, and maybe try some MZ tweaking to do RFAMMon minimization.
I measured the ETMY oplev beam size at a couple different distances away from the HeNe by taking out the steering mirror and letting the light propagate a ways. I put the steering mirror back, aligned the oplev, and was able to relock the Yarm, so I think it's all back as it has been the last couple of weeks.
Now I need t o do some geometry and ray-tracing matrices to decide what focal length lens to buy, then we'll have a shiny new ETMY oplev.
I just added two slow channels to C0EDCUEPICS to monitor the input of PD11. The names are:
After fixing the tp problem, I tried locking again. Grabbing and DD handoff, no problem. Died earlier than last night, handing off CARM to REFL_DC, around arm power of 4 or so. Seems to happen after turning off the moving zero, Rob says it might be touchy in daytime.
tdsavg 5 C1:LSC-PD4_DC_IN1
was causing grievous woe in the cm_step script. It turned out to fail intermittently at the command line, as did other LSC channels. (But non-LSC channels seem to be OK.) So we power cycled c1lsc (we couldn't ssh).
Then we noticed that computers were out of sync again (several timing fields said 16383 in the C0DAQ_RFMNETWORK screen). We restarted c1iscey, c1iscex, c1lsc, c1susvme1, and c1susvme2. The timing fields went back to 0. But the tdsavg command still intermittently said "ERROR: LDAQ - SendRequest - bad NDS status: 13".
The channel C1:LSC-SRM_OUT16 seems to work with tdsavg every time.
Let us know if you know how to fix this.
Did you try restarting the framebuilder?
What you type is in bold:
op440m> telnet fb40m 8087
Restarting the framebuilder didn't work, but the problem now appears to be fixed.
Upon reflection, we also decided to try killing all open DTT and Dataviewer windows. This also involved liberal use of ps -ef to seek out and destroy all diag's, dc3's, framer4's, etc.
That may have worked, but it happened simultaneously to killing the tpman process on fb40m, so we can't be sure which is the actual solution.
To restart the testpoint manager:
what you type is in bold:
rosalba> ssh fb40m
fb40m~> pkill tpman
The tpman is actually immortal, like Voldemort or the Kurgan or the Cylons in the new BG. Truly slaying it requires special magic, so the pkill tpman command has the effect of restarting it.
In the future, we should make it a matter of policy to close DTTs and Dataviewers when we're done using them, and killing any unattended ones that we encounter.
We were stymied early in the evening by a surreptitiously placed, verbo-visually obfuscated command in the drstep script.
Looks like yesterday was particularly noisy. It's unclear to me why diurnal variation much more visible in MC1_Y, and why the floor wanders.
The first plot shows 5 days. The second plot shows 20 days.
I played with the DD handoff during the day. The DRM dark port was flickering like a candle flame in Dracula's castle. The demod offsets for the handoff signals looked fine. After MICH handoff, the MICH_CTRL started to get unstable at some low frequency, maybe 3 Hz (I didn't measure). So I increased the MICH gain from 0.1 to 0.17 and it settled down. PRC and SRC went fine. Then the DD_handoff script raised the MICH gain to 0.7, and an instability started to grow in MICH_CTRL (at some higher frequency). I decreased the MICH gain from 0.7 to 0.5, and it settled down and stayed stable.
The Neslab chiller is working well. It's temp display shows 20.0 C rock solid. Flow meter rotating at 13.5Hz at the out put of the chiller.
The MOPA temp was measured with a hand held thermocouple . The PA was 34 C and 29 C at NPRO heat sink.
The NPRO flow meter was not rotating at this time. There was just trickeling water flow though the meter.
I closed the needle valve this point. It needed 8 turns clockwise. This drives head temp to 19.9 C
Than I opened the needle valve 9 turns and the flow meter wheel was rotaing at ~ 1 Hz
We gained a little power. Can you explain this?
Here is a set of mode scans of the AS port, using the OMC as a mode scanner. The plot overlays various configurations of the IFO.
To remove PZT nonlinearity, each scan was individually flattened in fsr-space by polynomial (3rd order) fitting to some known peak locations (the carrier and RF sidebands).
Rana, Alberto, Pete
We have the DD handoff nominally working. Sometimes, increasing the SRC gain at the end makes MICH get unstable. This could be due to a non-diagonal term in the matrix, or possibly because the DRM locks in a funky mode sometimes.
To get the DD handoff working, first we tuned demod phases in order to zero the offsets in the PD signals handed-off-to. Based on transer function measurements, I set the PRC PD6_I element to 0.1, and set the PD8_I signal to 0, since it didn't seem to be contributing much. We also commented out the MICH gain increase at the end of the DD_handoff script.
It could still be more stable, but it seems to work most of the time.
Tonight I centered the oplevs for ITMX/Y, SRM, PRM, BS.
After doing that I noticed that the BS drifted a little from where I had set it.
rob, alberto, rana, pete
we reset this computer, which was out of sync (16384 in the FE_SYNC field instead of 0)
I restarted ntpd on op440m to solve a "synchronization error" that we were having in DTT. I also edited the config file (/etc/inet/ntp.conf) to remove the lines referring to rana as an ntp server; now only nodus is listed.
To do this:
log in as root
/usr/local/bin/ntpd -c /etc/inet/ntp.conf
We worked on tuning the DD handoff tonight. We checked the DD PD alignments and they looked fine. First I tuned the 3 demod phases to minimize offsets. Then I noticed that the post-handoff MICH xfer function needed an increase in gain to look like the pre-handoff xfer function (which has a UGF of about 25 Hz). I increased the MICH PD9_Q gain from 2 to 7 in the input matrix. But, the handoff to PRC still failed, so tomorrow we will try to find out why.
In the plot, ref0 is before MICH handoff, and ref1 is after MICH handoff. There is also a PRC trace (before PRC handooff).
Some thoughts on what happened with the MOPA cooling.
Some unknown thing happened to precipitate the initial needle valve jiggle, which unleashed a torrent of flow through the NPRO. This flow was made possible by the fact that the cooling lines are labeled confusingly, and so flow was going backwards through the needle valve, which was thus powerless to restrict it. The NPRO got extremely cold, and most of the chiller's cooling power was being used to unnecessarily cool the NPRO. So, the PA was not getting cooled enough. At this, point, reversing the flow probably would have solved everything. Instead, we turned off the chiller and thus discovered the flaky start-motor capacitor.
Now we have much more information, flow meters in the NPRO and main cooling lines, a brand-new, functioning needle valve, a better understanding of the chiller/MOPA settings necessary for operation, and the knowledge of what happens when you install a needle valve backwards.
I added op540m's display 0 (the northern-most monitor in the control room) to the MEDM screens webpage: https://nodus.ligo.caltech.edu:30889/medm/screenshot.html
Now we can see the StripTool displays that are usually parked on that screen.
The laser power seems to have become more stable after fixing the laser chiller. The power is lower than it used to be (MOPA amplitude 2.5 versus 2.7) but, as shown in the attchement, it became more steady.
c1susvme2 has been running just a bit late for about a week. I rebooted it.
The plot shows SRM_FE_SYNC, which is the number of times in the last second that c1susvme2 was late for the 16k cycle. Similarly for ETMX.
The reboot appears to have worked.