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ID Date Author Typeup Category Subject
  1141   Mon Nov 17 16:59:22 2008 JenneUpdatePEMSeismometer hooked up, reading channels on DataViewer
Alberto, Jenne

The Guralp Seismometer is (finally) hooked up to the PEM ADCU. Alberto helped me make channels in the c1pem1 .ini file, which correspond to:

Guralp1 VERT = channel 9 on PEM ADCU = C1:PEM-SEIS_MC1_VERT
Guralp1 NS = channel 10 on PEM ADCU = C1:PEM-SEIS_MC1_NS
Guralp1 EW = channel 11 on PEM ADCU = C1:PEM-SEIS_MC1_EW

We also renamed the Ranger seismometer's channel to C1:PEM-SEIS_MC2_Y from C1:PEM-SEIS_MC1_Y, since tomorrow I'll move the Ranger Seismometer to be underneath MC2's chamber (it's currently sitting somewhere in the middle of the Mode Cleaner).

I can see the VERT and NS channels with dataviewer, but EW looks dead. I need to figure out if this is a bad cable thing, or if the ADC channel is no good, or if something in the box on that channel is no good. All 3 channels were tested and working after all the soldering was completed by Caryn, but something may have come undone while putting the box into its new place in the top of 1Y1. (In dataviewer, it looks like the EW channel is just floating, and not connected to anything.)

Plan of Attack:
* figure out why EW looks dead on Dataviewer
* redo Rana's static Wiener filter analysis, now that we have 2 seismometers (1 Ranger and 1 Guralp)
* work on adaptive Wiener filtering with the Guralp
  1144   Tue Nov 18 19:37:23 2008 YoichiUpdateIOOMC1 OSEM signals sign flipped and c1susvme1 restart problem
Around 2PM, MC1 started to swing crazily.
The damping feedback was not working and it was actually exciting the mirror wildly.
It turned out that the sign of the UR and UL OSEM signals flipped at that time.
Restarting c1sosvme fixed the problem.

While I was looking for the cause of the problem, c1susvme1 and c1susvme2 failed several times.
I don't know if it is related to this problem.
Now it is not trivial to restart c1susvme1. It fails to restart if you just power cycle it.
Alberto and I had to connect an LCD and a keyboard to it to see what was going on. After pushing the reset button on the front panel,
I had to press Ctrl+x. Otherwise, the state LED of c1susvme1 stays red and nothing happens.
After Ctrl+x, the boot screen came up but the boot sequence failed and an error message something the following was shown:
"PXE Boot failed, check the cable"
So I swapped the network cable with c1susvme2, which was already up and running.
This time, c1susvme1 started fine and surprisingly, c1susvme2 stayed alive.
Currently, both c1susvme1 and c1susvme2 are up and running with the LAN cables swapped.
We have to check the LAN cables.
  1145   Tue Nov 18 19:44:53 2008 AlbertoUpdateGeneralX Arm Cavity "Negative" FSRs Measured
Previous measurements on the X arm cavity revealed a shift of the frequencies of the cavity resonances from where one would expect these to be by just looking at integer multiples of the cavity FSR. In particular, plotting the resonant frequencies versus the order of their occurrences while sweeping the laser frequency (in our case that of the beat between the two lasers), the linear fit of the data contained an unwanted offset:

resonant_frequency = n x FSR + offset

In part, we attributed this offset to the local oscillator of the PLL, the Marconi, which was not referred to an absolute frequency clock.
For that reason, I connected the Marconi to the RS FS275 which uses the 1PPS from the GPS to generate a 10 MHZ reference signal, and then scanned the cavity again. This time I started from negative beat frequencies, that happen when the frequency of the secondary laser is smaller than the main laser's, to positive frequencies. The way I made sure of the sign of the frequency was looking at the effect of changing the temperature of the NPRO. I decided that negative frequencies where those for which an increase in temperature lowered the beat frequency and positive frequencies those for which increasing the temperature made the beat frequency go up.
I then plotted the data and obtained the attached plot.

The offset was reduced to about 80 Hz (from more than 200 in the previous measurements). I think the residual offset has to do with something that happens in the cavity, something, as Koji found out, related to the alignment of the mirrors.

Thanks to the more data points, the measurement of the FSR improved to (3897627 +/- 5) Hz, which would let us know the measure of the cavity length with an error of 50um, if it weren't for the offset. I have to understand whether and how to take this into account to determine the precision in the cavity length. I guess it depends on whether it is real or it is still a systematic error due to the measurements.
Attachment 1: 2008-11-17_Linear_Fit.pdf
  1149   Thu Nov 20 09:37:39 2008 steveUpdatePSLMZ vs temp
This 12 days plot shows that it can hold lock if the daily temp variation is not more than 3/4 of a degree C
The MZ is happy if it's HV is above 100V
Attachment 1: mztemp.jpg
  1151   Fri Nov 21 16:11:26 2008 rana, alberto, robUpdatePSLMach Zender alignment
The Mach Zender's dark port DC voltage had gone up too high (~0.5 V)and was turning yellow
on the screen. I re-aligned by touching the knobs on the 166 MHz path. Doing alignment after the
166 EOM had very little effect. The main improvement came from doing yaw on the turning mirror
just ahead of the 166 MHz EOM; this is the one which as no adjustment knobs (duh).

During this procedure, I had the MC off, the ISS off, and the MC autolocker off. After finishing
the alignment, the power on the ISS PDs had railed and the dark port power was ~0.29 V. So we
put in a ND0.2 on the ISS path and now the voltages are OK (~2 V on each PD). We have to remove the
ND filters and change the first ISS turning mirror into a ~10-20% reflector.

So now the MZ alignment seems good; Alberto is on the MC periscope alignment like a cheap suit.
Attachment 1: PB210051-1.JPG
  1152   Fri Nov 21 16:52:48 2008 JenneUpdatePEMGuralp seismometer's Channel Problems are solved
PROBLEM noticed earlier this week: It looked like one of the seismometer channels (VERT-1) wasn't working, no matter how I put which channel into which input of the PEM ADCU. Watching the channel on Dataviewer, it looked like the ADC was measuring VERT-1 to be zero (actually measuring zero, not digital noise-type zero). I had checked the ADC by putting in a sine wave with a function generator, and saw on Dataviewer the wave I expected, so I knew that I had the correct channel, and that the channel was good.

SOLUTION: This afternoon I took the box out of the rack and opened it up. As soon as I opened it, I saw that I had left something inside the box which was causing the problem. Back when we were measuring the noise of the box, to ensure that it is lower than the ADC's noise, Rana and I had shorted the test points on the input of the VERT-1 channel with a little piece of wire. It turns out that I had closed up the box without remembering to remove the wire.

CONCLUSION of the story: I took out the piece of wire, and now all three seismometer channels (VERT-1, N/S-1, E/W-1) all work, and all detect me jumping around near the BSC. Since the seismometer breakout box reads a differential measurement, and since the input test points were connected, it was indeed measuring zero. Zero equals zero is all well and good, but it's even better now that it's measuring actual seismic motion.
  1153   Fri Nov 21 17:27:47 2008 JenneUpdatePEMGuralp noise measurement
Here is the data from the Guralp Seismometer for the past day or so, before I fixed the VERT-1 channel. The NS and EW show what's going on in the world, and VERT is measuring essentially the noise of the box, through the ADC, in counts.
Attachment 1: guralp_vert_shorted.jpg
  1154   Fri Nov 21 19:47:26 2008 ranaUpdatePEMGuralp noise measurement
and here's the spectra with them connected - from the coherences, it looks like it needs to be rotated by 90 deg.

I'll next rename the channels to fix this so that we get good seismic data over the weekend with the MC.
Attachment 1: a.png
  1155   Fri Nov 21 20:29:43 2008 rana, alberto, robUpdatePSLMach Zender alignment

So now the MZ alignment seems good; Alberto is on the MC periscope alignment like a cheap suit.

And alignment is now mostly done - MC locks on the TEM00.

Unlocked           4.50  V
Locked noWFS       1.30  V
Locked + WFS       0.42  V
and the 29.5 MHz modulation depth is really small.

We should be able to rerun the Wiener analysis on this weekends MC data.

I don't know what our nominal StochMon numbers now are, but after Alberto tweaks up the alignment he can tell us if the RFAM has gotten any better.
  1156   Fri Nov 21 21:20:24 2008 ranaUpdatePEMGuralp noise measurement
This is the spectra and time series of the Guralp channels along with the Ranger (MC2). Looks like we could reduce the gain
on the ranger. The Guralp channels run into ADC noise around 40 Hz (which is OK). We'll have to look at the weekday trends
to see if they saturate.
Attachment 1: a.png
  1160   Mon Nov 24 17:14:44 2008 ranaUpdatePSLMach Zender trends
It looks like the MZ has gotten less drifty after the alignment on Friday.
Attachment 1: Untitled.png
  1162   Tue Nov 25 18:38:03 2008 Alberto, RobUpdatePSLMC Periscope Alignment
This morning when I came in I found the MC cleaner unlocked and the autolocker script could not lock it. The reflected beam was quite off and showed in the bottom left corner of the IMCR camera. After turning off the WFS locking, I started slightly changing the alignment of the steering mirrors on the MC periscope, waiting for the LSC servo to lock the cavity. It didn't work. At some point I lost the beam from the IMCR camera and that is how someone might have found it when I left it for about one hour.

When I came back and tried again adjusting the steering mirrors, I noticed that the autolocker was working and was trying to lock the cavity. After just a bit of adjustment, the MC got easily locked.

After that, I spent a couple of hours trying to improve the alignment of the periscope to minimize the reflection and maximize the transmission. I started with a transmission of 0.4 V but, despite all the tweaking (I used the technique of turning both yaw knobs at the same time), I couldn't get more than 1.2 V (and 2.4 V at the reflection) if only the LSC servo was on. Looking at the camera, I moved the beam around to look for a more favorable spot but the MC wouldn't lock with the beam in other places. Maybe I could do better or maybe not because the cavity is not aligned. I'm going to try again tomorrow.
  1165   Mon Dec 1 15:09:27 2008 robUpdatePEMhalf-micron particle count is alarming
  1168   Tue Dec 2 19:51:32 2008 ranaUpdatePEMhalf-micron particle count is alarming
The 0.5 micron dust monitor count is now pretty high (36000). I wandered around the lab to see if there was anything
nasty going on but I didn't see or smell anything in particular. Since today Alberto was sitting around where the
dust monitor is while aligning the PSL beam, we should blame him. Its either garlic, cologne, or time to bathe.

The 400 day hour trend shows that while the counts are not so unusual, the 40m is dirtier than it was last year.
Attachment 1: Untitled.png
Attachment 2: dust.png
  1169   Wed Dec 3 11:58:10 2008 AlbertoUpdatePSLMC Alignment
Rana, Alberto,

more details on the MC alignment we did yesterday.

Last week Rana re-aligned the Mach Zender (MZ) on the PSL table to reduce the power at the dark port (see elog entry #1151). After that, the beam was aligned to the MZ but not properly aligned to the Mode Cleaner (MC) anymore. As a result the MC could not lock or did it on unwanted transverse modes. To fix that we decided to change the alignment of the MC input periscope on the PSL table.

The ultimate goal of the operation was to align the MC transmitted beam to the IFO and to maximize the power.
Such a condition depends on:
a) a good cavity alignment and
b) input beam matching to the cavity TEM00 mode.

Since the MZ alignment had only affected the input beam, we assumed the cavity alignment was still good, or at least it had not changed, and we focused on the input beam.

The IOO computer, by the MC autolocker script, is able to change the cavity alignment and the length to match the input beam and lock the cavity. Although both the length servo (LSC) and the alignment servo (WFS) have a limited effective operating range. So for the script to work properly and at best, input beam and cavity matching have to be not far from that range.

The MC periscope has two mirrors which control the pitch and yaw input angles. By changing either yaw or pitch of both mirrors together (“two-knob" technique) one can change the input angle without moving the injection point on the cavity input mirror (MC1). So this is the procedure that we followed:

  • 1) turned of the autolocker running the MC-down script
    2) brought the reflected beam spot back on the MC-reflection camera and on the reflection photodiode (REFL-PD)
    3) turned on the LSC servo
    4) tweaked the periscope's mirrors until the cavity got locked on a TEM00 mode
    5) tweaked the periscope aiming at ~0.3V from the REFL-PD and ~3V on the transmission photodiode (TRANS-PD).

Following the steps above we got ~0.5 V on the REFL-PD and ~2V on the TRANS-PD but no better than that.

Looking at the Drift Monitor MEDM screen, we found that the cavity was not in the reference optimal position, as we initially assumed, thus limiting the matching of the beam to the MC.

We restored the optics reference position and repeated the alignment procedure as above. This time we got ~3V on the TRANS-PD and ~0.5 on the REFL-PD. We thought that the reason for still such a relatively high reflection was that the beam was not well centered on the REFL-PD (high order modes pick-up?).

On the AS table we centered the REFL-PD by aligning a beam splitter in the optical path followed by the light to reach the photodiode.

We also centered the beam on the reflection Wave Front Sensors (WFS). To do that we halved the power on the MZ to reduce the sidebands power and prevent the WFS QPD from saturating. We then aligned the beam splitters on the QPD by balancing the power among the quadrants. Finally we restored the power on the MZ.

As a last thing, we also centered the transmitted beam on the TRANS-QPD.

The MC is now aligned and happily locked with 3V at the TRANS-PD and 0.3V at REFL-PD.
  1170   Wed Dec 3 12:49:11 2008 jenneUpdateComputerssomething sketchy with NDS ... or something
Never mind...I had forgotten that you have to run mdv_config every time you open matlab, not just every time you boot a computer.

I am not able to get channels using get_data from the mDV toolbox on Allegra, Megatron or Rosalba.

The error I get while running the "hello_world" test program is:
setting up configuration...
added paths for nds
added paths for qscan
couldn't add path for matapps_SDE
couldn't add path for matapps_path
couldn't add path for framecache
couldn't add path for ligotools_matlab
added paths for home_pwd
fetching channels for C...
Warning: get_channel_list() failed.
??? Error using ==> NDS_GetChannels
Failed to get channel list.

Error in ==> fetch_nds at 47
eval(['CONFIG.chl.' server ' = NDS_GetChannels(ab);']);

Error in ==> get_data at 100
out = fetch_nds(channels,dtype,start_time,duration);

Error in ==> hello_world at 6
aa = get_data('C1:LSC-DARM_ERR', 'raw', gps('now - 1 hour'), 32);
  1172   Wed Dec 3 20:10:09 2008 Jenne, RanaUpdatePEMComparing Wiener subtraction with different seismometers
Attached is a plot of MC_L, and then the residual MC_L after static Wiener filtering, using different combinations of our accelerometers and seismometers.

This is the same type of plot that Rana has included in the past few weeks, using Wiener filters calculated with c1wino.m

This data is from GPS 912312914, duration = 7200 sec, sometime during the night last night.

Unfortunately, it doesn't look like adding the Guralp seismometer to the Accelerometers and the Ranger did much, especially at low frequencies (all sensors = black curve). We'll have to investigate why this is true, and what we can do to get some low-frequency subtraction going on.

In the legend, "Residuals Accels, Guralp, Ranger" implies that the residual has been calculated using all of the sensors listed.
Attachment 1: Dec032008_c1wino_seisCombos.png
  1173   Wed Dec 3 20:36:07 2008 Jenne, RanaUpdatePEMComparing Wiener subtraction with different seismometers
The Ranger has now been moved over to sit underneath the MC2 tank (it was previously close to the PSL rack). It
is still pointed in the +Y direction (towards ETMY, aka south).

New spectra attached - looks like the coherence is still there between the Guralp and the Ranger which are now
seperated by the MC length (~12 m). At LLO, I have witnessed a coherence of less than 0.3 above 1 Hz for these
distances. Curious.

L960019-00-F describes measurements done at SLAC on seismic coherence. The iLIGO LSC PDD
(http://www.ligo.caltech.edu/docs/T/T970122-00.pdf) discusses in sec 4.2 how this was incorporated into the LSC design.

When we get our next Guralp, it will be interesting to move them around and determine what the cross-spectrum
is between different points in the lab during typical times.

In the second attachment, I have plotted the square of the quantity used in the LSC PDD (S_xy) which I think is
what we now plot in DTT as 'Coherence'.

The third attachment shows the coherences among the TM SUSPOS_INs. I've turned off the oplev servos for this but
the OSEM damping is still on. Its not quite the same as the theory, but we could probably measure/tweak the
seismic velocity and then get better agreement.
Attachment 1: d.pdf
Attachment 2: sco.png
Attachment 3: fly.pdf
  1174   Thu Dec 4 13:49:39 2008 JenneUpdatePEMMore of: Comparing Wiener subtraction using different sensors
Here is another version of the same type plot I put in the elog yesterday. This plot is looking at the 7200 seconds after 04Dec2008 08:45:00 UTC. This time was last night, when there was no crazy seismic activity, and well after the Ranger seismometer was moved to its new place under MC2.

This plot includes all possible combinations of the accelerometers, Guralp seismometer and Ranger seismometer (taking all 6 accelerometers as a set, and all 3 Guralp channels as a set). It is good to see that for the set of traces which do not include the accelerometers - brown, dark green and light blue - the subtraction at higher frequencies isn't all that great. Thus, the accelerometers are doing their job, and work well with the Wiener subtraction.

Still under investigation is why we don't see a whole lot of improvement at low frequency.
Attachment 1: Dec042008_c1wino_seisCombos.png
  1176   Thu Dec 4 17:42:23 2008 carynUpdateIOOdrum modes observable without excitation
So, the mode cleaner was evidently aligned better and now the drum modes are observable using DTT.
The Lock-In was set to 27.8kHz and the drum mode frequencies were previously observed to be 28.039kHz(MC2), 28.222kHz(MC3) and 28.221kHz(MC1). So, we might expect peaks at ~239Hz,421Hz,422Hz.
Peaks have been observed around the expected frequencies in channel IOO-MC-DRUM1.
Note that it is possible to resolve the separate MC1 and MC3 peaks which are so close together.
(sorry these are pdf's and not png's)
Attachment 1: drum_modes.pdf
Attachment 2: drum_modes2.pdf
  1179   Fri Dec 5 09:29:59 2008 ranaUpdateIOOdrum modes observable without excitation
Not sure what the y-scale is since there aren't any y axis labels in the plot, but it seems like we
now get an SNR of a ~few with a BW of 0.1 Hz. IN principle, the frequency noise out of the PSL ought
to be limited by the VCO phase noise at these frequencies (sort of) so the broadband MC_F level
is very roughly equal to 20-100 mHz/rHz.

Since dnu = dL*(c/lambda)/L_MC, the thermal peaks have a height of ~10^-15 m_RMS. We (Caryn) should check
that these numbers are true and then see if this is the correct amount of energy for thermally excited
mirror modes.
  1182   Fri Dec 5 21:31:11 2008 YoichiUpdateIOOdrum modes observable without excitation
The calibration of the MC_F feedback is posted in elog:1032.
I'm not sure where Caryn took MC signal, but if you take the signal from the servo out BNC on the MC board, it
directly corresponds to the voltage sent to the FSS VCO.
The DC calibration of the VCO is 1.75MHz/V. Since the AOM is the double-pass, the PSL frequency
change is 3.5MHz/V. At frequencies above 40Hz, the VCO calibration drops by a factor of 39/1000,
because of the pole/zero at 1.6Hz/40Hz in the VCO box.
So at the frequencies of interest (around 30kHz), the servo out voltage can be converted to the PSL frequency
change by 0.137MHz/V.
Since 30kHz is still within the bandwidth of the MC servo, the feedback signal should correspond to the actual
length change of the MC. So the above calibration factor can be used to calibrate Caryn's measurement and check
what Rana suggested.
  1183   Sun Dec 7 16:02:46 2008 ranaUpdateGeneralMag 5.1 EQ halfway to Vegas
There was a Mag 5.1 EQ Friday night at 8:18 PM.

It tripped most of our optics. They all damped down passively except for MC2. Further more, ITMY seems to have come back to a different place.

Don't know why MC2 was so upset but I think maybe its watchdog didn't work correctly and the side loop is unstable when there are
large motions. After I lowered the side gain by 10x and waited a few minutes it came back OK and the MC locked fine.

I have just now put all the WDs into the Shutdown state so that we can collect some hours of free swinging data to see if there's been
any damage. Feel free to redamp the optics whenever you need them. Someone should do the eigenfrequency check in the morning and compare
with our table of frequencies in the wiki.

I excited the optics using the standard SUS/freeswing-all.csh script. Here's the output:
Excited all optics
Sun Dec  7 16:07:32 PST 2008
Attachment 1: g.png
Attachment 2: Untitled.png
  1184   Sun Dec 7 16:12:53 2008 ranaUpdateDAQbooted awg
because it was red
  1187   Mon Dec 8 11:54:27 2008 YoichiUpdateGeneralIFO mirrors aligned
This morning, I re-aligned the IFO mirrors to see if they were badly moved by the earthquake.
The both arms locked just by the restoring scripts, but the transmission was about 0.7. So I aligned them
with the dithering scripts.
To lock the PRMI, I had to manually tweak the PRM alignment. After running the dithering script, the SPOB
went up to 1200.
I also had to tweak the SRM to get the DRMI locked. After the dithering script, the SPOB was 4200 and REFL166Q
was 3000.
  1188   Mon Dec 8 17:50:21 2008 YoichiUpdateSUSITMY drift
The suspension drift monitor shows that the ITMY alignment was shifted after the earthquake.
Looks like only the UL sensor had a step at the earthquake (see the attachment 1).
So it is probably an electronics problem.
I pushed in the cable between the rack and the ITMY satellite amplifier, but no change observed.
Actually, the ITMY-UL sensor looks like it has been dead before the earthquake.
The second attachment shows a long-term trend of the UL sensor.
The sensor output had been around zero since Nov. 17th.
When I disabled the output of the UL sensor, the sus-drift-mon fields turned green.
So I think the drift-mon's reference values are wrong, and currently the ITMY is in a good alignment.

I also attached the free-swing measurements of the ITMY taken on Aug. 18th and today.
There is no notable change in the resonant frequencies.
Attachment 1: ITMY-OSEMs.png
Attachment 2: ITMY-UL.png
Attachment 3: ITMY-08-18.pdf
Attachment 4: ITMY-12-08.pdf
  1190   Fri Dec 12 22:51:23 2008 YoichiUpdatePSLReference cavity ring down measurement again
Bob made new HV-cables with HV compatible coaxes. The coax cable is rated for 2kV, which was as high as Bob
could found. I used it with 3kV hoping it was ok.
I also put a series resistor to the pockels cell to tame down the ripples I saw in elog:1136.

Despite those efforts, I still observed large ringings.
I tried several resistor values (2.5k, 1k, 330ohm), and found that 330ohm gives a slightly better result.
(When the resistance is larger, the edge of the PBS Refl. becomes dull).
Since the shape of the ringing does not change at all even when the pulse voltage is lowered to less than 1kV,
I'm now suspicious of the DEI pulser.

Anyway, I estimated the cavity pole using the MATLAB's system identification toolbox again.
This time, I locked the reference cavity using only the PZT feedback, which makes the UGF about a few kHz.
So, within the time scale shown in the plot below, the servo does not have enough time to respond, thus the laser
frequency stays tuned with the cavity. This was necessary to avoid non-linear behavior of the transmitted power
caused by the servo disturbing the laser frequency. With this treatment, I was able to approximate the response of
the cavity with a simple linear model (one pole low-pass filter).

MATLAB estimated the cavity pole to be 47.5kHz.
The blue curve in the plot is the measured RC transmitted power.
The incident power to the cavity can be inferred from the inverse of the red curve (the PBS reflection power).
The brown curve is the response of the first order low-pass filter with fc=47.5kHz to the input power variation.
The blue and brown curves match well for the first 10usec. Even after that the phases match well.
So the estimated 47.5kHz is probably a reasonable number. I don't know yet how to estimate the error of this measurement.

According to http://www.ligo.caltech.edu/~ajw/PSLFRC.png the designed transmission of the reference cavity mirrors is 300ppm (i.e.
the round trip loss (RTL) is 600ppm).
This number yields fc=35kHz. In the same picture, it was stated that fc=38.74kHz (I guess this is a measured number at some point).
The current fc=47.5kHz means, the RTL has increased by 200ppm from the design and 150ppm from the time fc=38.74kHz was measured.
Attachment 1: RC-Ringdown.png
  1191   Tue Dec 16 19:06:01 2008 YoichiUpdatePSLReference cavity ring down repeated many times
Today, I repeated the reference cavity ring down measurement many times to see how much the results vary.

I repeated the ring down for 20 times and the first attachment shows the comparison of the measured and estimated cavity transmission power.
The blue curve is the measured one, and the red curve is the estimated one. There are only 10 plots because I made a mistake when transferring data
from the oscilloscope to the PC, and one measurement data was lost.

The second attachment shows the histogram of the histogram of the estimated cavity pole frequencies.
I admit that there are not enough samples to treat it statistically.
Anyway, the mean and the standard deviation of the estimated frequencies are 47.6kHz and 2.4kHz.
Assuming a Gaussian distribution and zero systematic error, both of which are bold assumptions though, the result is 47.6(+/-0.6)kHz.

Now I removed the Pockels Cell from the RC input beam path.
I maximized the transmission by tweaking the steering mirrors and rotating the HWP.
Since the transmission PD was saturated without an ND filter on it, I reduced the VCO RF power slider to 2.85.
Accordingly, I changed the nominal common gain of the FSS servo to 10.5dB.
Attachment 1: RC_Ringdown_Estimates.png
Attachment 2: Cavity_Pole_Histogram.png
  1196   Fri Dec 19 14:35:58 2008 Yoichi AlbertoUpdateIOOMC WFS and IOO-POS QPD re-centering
For the past two days, the MC alignment has kept drifting.
This morning, the MC alignment was so bad that it wouldn't lock to the TEM00 mode.
We aligned the MC mirrors manually until the reflection looks like a nice bull's-eye (the WFSs were off at this moment).
Then we un-locked the MC and centered the beams on the WFS QPDs.
Since the QPDs were saturated with the full laser power falling on them, I reduced the PSL power by turning the HWP after the MOPA.
After this, we turned on the WFSs and everything looks normal now.
We will see the trend of the MC related channels to monitor the drift.

Although unlikely, it might be caused by the drift of the input beam to the MC.
We found that the IOO-POS QPD was mis-centered and saturating.
We replaced the BS picking up the beam for the QPD from 33% reflection to 10% one. The QPD was still saturated.
So we put the 33% BS in the beam path to the QPD to further reduce the power. The beam kicked by the 33% BS
is dumped to a black aluminum plate. We should use a better beam dump later.
Now the IOO-POS QPD should tell us some information about the beam pointing of the PSL, though it has no sensitivity
to the relative motion of the PSL table to the vacuum chambers.
  1197   Fri Dec 19 16:38:09 2008 steveUpdateLSCall optlevs centered
All optlevs were centered after full alignment.

Qpd sums are:
ETMX 12,229 counts
ITMX 9,932
ETMY 12,043
ITMY 4,362
BS 1,880
PRM 1,423
SRM 11,641
  1199   Sun Dec 21 13:00:06 2008 steveUpdateall down cond.vac and laser back on
There was a power outage sometimes early Saturday.

All things are down.

The Maglev was started and reached normal operating condition.
V1 was opened at P1 3.8 mTorr and cc1 is back to 3e-6 Torr now

The MOPA was turned on.
Ion pump HV on to FSS cavity.
  1200   Sun Dec 21 14:18:04 2008 YoichiUpdateComputersRFM network bypass box's power supply is dead
I restarted the front-end computers by power cycling them one-by-one.
After issuing startup commands, most of them started normally at least by looking
at the output from telnet/ssh.
However, the status monitors of the FE computers on the EPICS screen are still red.
I noticed that all the LEDs on the VMIC 5594 RFM network bypass box are off.
According to the labels, fb40m, c0daqctrl, c0dcu are connected to the box.
This means (I believe) c1dcuepics cannot access the RFM network. So we have no control over
the FE computers through EPICS.

I pushed the reset button on the box, power cycled it, but nothing changed.
I checked the fuse and it was OK. Then I found that the power supply was dead.
It is a small AC adapter supplying +5VDC with a 5-pin DIN like connector.
We have to find a replacement.
  1201   Mon Dec 22 13:48:22 2008 YoichiUpdateComputersRFM network bypass box's power supply is dead
As a temporary fix, I cut the cable of the power supply and connected it to the Sorensen power supply +5V on the rack.
Now, the RFM bypass box is powered up, but some LEDs are red, which looks like a bad sign.
I restarted all the FE computers, but this time I got errors during the execution of the startup commands in the VxWorks machines.
The errors are "General Protection Fault" or "Invalid Opcode".
The linux machines do not show errors but still the status lights in EPICS are red.
We need Alex's help. He did not answer the phone, so Alberto left a voice mail.
  1202   Tue Dec 23 10:35:40 2008 YoichiUpdateComputersRFM network breakdown mostly fixed
Rana, Rolf, Alberto, Yoichi

The source of the problem was the RFM bypass box, as expected.
Rana pointed out that the long cable I used to bring the 5V from the Sorensen to the box
may cause a large voltage drop considering that the box is sucking ~3A.
So we connected the cable to another power supply (5V/5A linear power supply).
Then the LEDs on the bypass box turned green from red, and everything started to work.

A weired thing is that when I connected the cable to the wrong terminals of the power supply which
have lower current supply capabilities, the supply voltage dropped to 3V, but still the LEDs on the bypass box
turned green. This means the bypass box can live with 3V.
I noticed that there is a long cable from the Sorensen to the cross connect on the side of the rack, where I
connected my cable to the bypass box. This long cable had somewhat large resistance (1 or 2 Ohms) and dropped
the supply voltage to less than 3V ?
Anyway, the bypass box is now on a temporary power supply. Alberto was assigned a task to find a replacement power

There are two remaining problems.
c1susvme1 fails to start often claiming a DMA error on a Pentek. After several attempts, you can start the machine,
but after a while (1 hour ?) it fails again.
op340m is not responding to ssh login. It responds to ping.
We hooked up a monitor and keyboard (USB because the machine does not have a PS/2 port) to it and rebooted.
At the boot, it briefly displays a message "No keyboard, try TTYa", but after that no display signal.
Steve found me a serial cable. I will try to login to the machine using the serial port.

  1203   Wed Dec 24 10:33:24 2008 YoichiUpdateComputersSeveral fixes. Test point problem remains.
Yesterday, I fixed several remaining problems from the power failure.

I found a LEMO cable connecting the timing board to the Penteks was lose on the c1susvme1 crate.
After I pushed it in, the DMA error has not occured on c1susvme1.

I logged into op340m using a Null Modem Cable.
The computer was failing to boot because there were un-recoverable disk errors by the automatic fsck.
I run fsck manually and corrected some errors. After that, op340m booted normally and now it is working fine.
Here is the serial communication parameters I used to communicate with op340m:
>kermit      (I used kermit command for serial communication.)
>set modem type none
>set line /dev/ttyS0     (ttyS0 should be the device name of your serial port)
>set speed 9600
>set parity none
>set stop-bits 1
>set flow-control none

After fixing op340m, the MC locked.
Then I reset the HV amps. for the steering PZTs.
Somehow, the PZT1 PIT did not work. But after moving the slider back and forth several times, it started to work.

I reset the mechanical shutters around the lab.

I went ahead to align the mirrors. The X-arm locked but the alignment script did not improve
the arm power.
I found that test points are not available. (diag said test point management not available).
Looks like test point manager is not running. Called Rolf, but could not reach him.
I'm not even sure on which machine, the tp manager is supposed to be run.
Is it c0daqawg ?
  1204   Wed Dec 24 12:46:54 2008 YoichiUpdateComputersTest points are back
Rob told me how to restart the test point manager.
It runs on fb40m and actually there is an instruction on how to do that in the Wiki.

I couldn't find the page because when I put a keyword in the search box on the upper right
corner of the Wiki page and hit "enter", it only searches for titles. To do a full text
search, you have to click on the "Text" button.

Anyway, now the test points are back.
  1205   Mon Dec 29 18:01:07 2008 AidanUpdateAuxiliary lockingUpdated 40m Upgrade Document T080074-00-R

Added a paragraph to the 40m Upgrade document describing the fiber stabilization and frequency doubling proposed for auxiliary locking.

Also added a complete diagram of the fiber stabilization and a draft sketch of the frequency doubling.

Uploaded to https://nodus.ligo.caltech.edu:30889/svn/trunk/docs/upgrade08/ via svn.
  1206   Mon Dec 29 21:38:57 2008 YoichiUpdateComputersSnapshots of MEDM screens
I wrote scripts to take snapshots of MEDM screens in the background.
These scripts work even on a computer without a physical display attached.
You don't need to have X running.
So now the scripts run on nodus every 5 minutes from cron.
The screen shots are saved in /cvs/cds/caltech/statScreen/images/

There is a wiki page for the scripts.

Someone has to make a nice web page summarizing the captured images.
  1210   Thu Jan 1 00:55:39 2009 YoichiUpdateASCAlignment scripts for Linux
A Happy New Year.

The dither alignment scripts did not run on linux machines because tdscntr and ezcademod do not run
on linux. Tobin wrote a perl version of tdscntr and I modified it for 40m some time ago.
Today, I wrote a perl version of ezcademod. The script is called ditherServo.pl and resides in /cvs/cds/caltech/scripts/general/.
It is not meant to be a drop-in replacement, so the command line syntax is different. Usage is explained in the comment of the script.

Using those two scripts, I wrote linux versions of the alignment scripts.
Now when you call, for example, alignX script, it calls alignX.linux or alignX.solaris depending on the OS of
your machine. alignX.solaris is the original script using the compiled ezcademod.
In principle, ezcademod is faster than my ditherServo.pl because my script suffers from the overhead of
calling tdsdmd on each iteration of the servo. But in practice ditherServo.pl is not that bad. At least, as far as
the alignment is concerned, the performances of the both commands are comparable in terms of the final arm power and the convergence.

Now the alignXXX commands from the IFO Configure MEDM screen work for X-arm, Y-arm, PRM and DRM. I did not write a script for Michelson, since
it is optional.
I confirmed that "Align Full IFO" works correctly.
  1214   Fri Jan 2 18:49:54 2009 YoichiUpdateLSCLSC modulation frequencies adjusted
I noticed that the IFO did not lock in the MICH configuration.
This was because AS166Q signal was too small.
The demodulation phase seemed not right, i.e. the I-phase signal was larger than Q.
I suspected that the 166MHz modulation frequency was not exactly on the MC FSR, since I just
recovered the number written on the Marconi after the power failure.
I measured the optimal frequency by the method explained in elog:752.
It was 165981500Hz, which is pretty close to the number Rob measured in elog:952, but significantly different from
the label on the Marconi.
I set the frequencies of all the MARCONIs accordingly and updated the labels.

After this, the AS166 demodulation phase was still not good enough (the Q and I signals were about the same).
So I rotated the phase by 45deg. In principle, this should set the demod-phase right for DARM too. Is it correct, Rob ?
I also adjusted the PD offsets. After those adjustments, MICH locks stably with a slightly increased gain (20 as compared to 10 before).
  1219   Fri Jan 9 09:14:17 2009 steveUpdatePEMifo is recovered after eq
There is no obvious damage from last night earth quake.
All sus dampings were turned on, MC locked and the arms locked right on
Attachment 1: eq4.5sb.jpg
  1220   Fri Jan 9 16:52:18 2009 steveUpdateVACtp3 forline pump replaced
Alberto took 40m vacuum 101 class as we replaced the drypump at the annulus pump line.

He is still not authorized to use the monster 2 3/8" open end wrench that is 36" long.

The fore line pressure dropped to 20 mTorr from 1 Torr as the pumps were swapped.
Bob needs to be given credit for replacing the tip seal on this Varian SH-100 drypump
The ss-hose felt dry at the tp3 exhaust end but it was some what "teflon coated-placticky-
-almost oily" at intake end of the dry pump.
We'll have to replace this metal hose next time.

This is a reminder that the 40m vacuum operation is fully manual.
It requires two people to switch a vacuum valve and one of them has to be experienced.
  1221   Fri Jan 9 17:30:10 2009 KakeruUpdateComputersSnapshots of MEDM screens
I wrote a web page which shows snapshots of MEDM screens generated by Yoich's script (e-log #1206).
This page refreshes itself every 5 minutes automatically.

The .html file is generated by /cvs/cds/caltech/statScreen/bin/genHtml.pl
This script generates the .html file contains snapshots listed on /cvs/cds/caltech/statScreen/etc/medmScreens.txt every 5 minutes with cron.
When you wont to display other screens, please edit this .txt file and wait 5 minutes!

To make thumbnails, I wrote /cvs/cds/caltech/statScreen/bin/genThumbnail.pl
This script reads /cvs/cds/caltech/statScreen/etc/medmScreens.txt, too.
(Sometimes, it makes thumbnails with larger storage...)

I wrote scripts to take snapshots of MEDM screens in the background.
These scripts work even on a computer without a physical display attached.
You don't need to have X running.
So now the scripts run on nodus every 5 minutes from cron.
The screen shots are saved in /cvs/cds/caltech/statScreen/images/

There is a wiki page for the scripts.

Someone has to make a nice web page summarizing the captured images.
  1222   Mon Jan 12 10:57:38 2009 robUpdateGeneralsome stuff

The AS beam was not hitting the AS166 diode, so I aligned the last little steering mirror and adjusted the phase for MICH locking.

I turned on the HV supplies for the OMC.

Then I realigned the beam onto the AS166 diode, since the steering mirrors came on when I turned on the HV supplies.

It took awhile to find the alignment of the beam into the OMC. Once that was done, the output beam alignment was set, so I aligned onto the AS166 diode a third time.

The bottom two Sorensens in the OMC voltage supply don't look right. They have stickers that say +-24V, but each is sitting at 17.5V and showing no current draw. What's going on here?
  1223   Mon Jan 12 18:53:03 2009 YoichiUpdateLSCAS CCD centering and ASDD demod phase
After Rob's AS beam work, I centered the beam on the AS CCD.
I also optimized the ASDD demod-phase for the MICH signal.
Rob suggested to me that whenever we restart or change the frequency of the DD Marconis, we have to re-optimize the demod-phase
because the initial phase of the Marconi is random. We had the power failure, so it was time to do so.
I confirmed that MICH hand-off from REFL33Q to AS133DDQ is ok.
I will do the same thing for the PRCL, SRCL hand-offs.
  1225   Tue Jan 13 18:59:09 2009 KakeruUpdateLSCAS CCD centering and ASDD demod phase
I tuned the demod-phase for PRCL and SRCL hand-off, but it have not been optimized enoughly.
I continue this work tomorrow.

After Rob's AS beam work, I centered the beam on the AS CCD.
I also optimized the ASDD demod-phase for the MICH signal.
Rob suggested to me that whenever we restart or change the frequency of the DD Marconis, we have to re-optimize the demod-phase
because the initial phase of the Marconi is random. We had the power failure, so it was time to do so.
I confirmed that MICH hand-off from REFL33Q to AS133DDQ is ok.
I will do the same thing for the PRCL, SRCL hand-offs.
  1229   Thu Jan 15 09:19:32 2009 steveUpdateIOOMC locking
MC2 sus damping was found tripped at the morning the second time this week.

Damping was restored, ISS gain lowered to avoid saturation, MZ manually locked
and MC locking was back.
  1231   Fri Jan 16 11:28:54 2009 YoichiUpdateComputersLab. laptop needs wireless lan driver update
One of the lab. laptops (belladonna) cannot connect to the network now.
I guess this was caused by someone clicked the update icon and unknowingly updated the kernel, which resulted in the wireless lan driver malfunctioning.
It was using a Windows driver through ndiswrapper.
Someone has to fix it.
  1233   Fri Jan 16 18:25:32 2009 Yoichi, Kakeru, RanaUpdateLSCArms were unstable
The single arm lock had been unstable for both arms in the past few days.

When an arm was locked by itself, the transmitted power showed a lot of fluctuations (sharp drops).
The first attachment shows the arm power fluctuations in power spectrum and time series.
References are when the boost filters are off for the arm feedback.
You can see that when the boosts are off, the power fluctuates a lot.
Also it is obvious that X-arm is a lot worse than Y.

The second attachment is the comparison of the error signal spectra between boosts on and off.
(PD3_I is the error signal of X-arm, PD4_I is Y arm). References are boost on.
Since the arm power fluctuation was suppressed by the gain increase, it was suspected that the main
reason for the power fluctuation is not alignment fluctuation. Rather, it is length or frequency fluctuation.

Then I took spectra and coherences of PD3_I, PD4_I and MC_F with both arms locked independently.
You can see broadband coherence between PD3_I (Xarm) and MC_F (frequency noise). In contrast the coherence
between PD4_I and MC_F is smaller. This means X-arm is more susceptible to the frequency noise than Y.
What can make a simple Fabry-Perot cavity more susceptible to frequency noise ? An offset ?
So I canceled the X-arm offset at the X-arm filter bank. Bingo ! The arm power fluctuation of X-arm became as small as Y-arm
in the dataviewer.
But what is making this offset ?
After watching the dataviewer screen for a while, the arm power fluctuation became larger again. I had to re-adjust the artificial offset
to minimize the fluctuation. This made me think that the source of the offset must be something to do with alignment.
In this case, clipping of the beam at the PD was very suspicious.
So I checked the centering of the POX and POY PDs. As expected, POX was terribly off-centered.
POY was also not exactly at the center of the plateau of DC output.
After centering those PDs, the large offset in the arm loops went away.
Now the arm powers are stable without artificial offset in the loop filters.
The last attachment shows the comparison of arm power fluctuation before and after the PD centering.
(references are the measurements before the centering).
Attachment 1: TRXY.pdf
Attachment 2: ErrorSignals.pdf
Attachment 3: coherenceBetweenArms.pdf
Attachment 4: ArmPowersAfterPDwasCentered.pdf
  1234   Fri Jan 16 18:29:08 2009 YoichiUpdateSUSOplevs QPDs centered
Kakeru centered ITMX and BS optical levers with the help of Jenne on the walkie-talkie.
ELOG V3.1.3-