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ID Date Author Typeup Category Subject
  59   Sat Nov 3 16:20:43 2007 waldmanSummaryOMCA good day's work

I followed up yesterday's test of the PZT with a whole mess of characterizations of the PZT control and finished the day by locking the OMC with a PZT dither lock and a 600 Hz loop. I haven't analyzed any of the data yet, so its not calibrated in physical units and etc. etc. etc. Since a lot of the sweeps below are of a "drive the PZT, look at the PDH signal" nature, a proper analysis will require taking out the loop and calibrating the signals, which alas, I haven't done. Nonetheless, I include all the plots because they are pretty. The files included below are:

  • DitherLock_sweep: Sweep of the IN2/IN1 for the dither lock error point showing 600 Hz UGF
  • HiResPZTDither_sweep: Sweep of the PZT dither input compared to the PDH error signal. I restarted the front end before the sweep was finished accounting for the blip.
  • HiResPZTDither_sweep2: Finish of the PZT dither sweep


More will be posted later.
  65   Tue Nov 6 09:14:37 2007 steveSummaryVACpump down 65
8 hr plot,
precondition: 5 days at atm,
vent objective: drag wiping mc1, mc2 & mc3 accomplished,
hardware changes: IOO access connector, mc2 chamber door south & west
were removed and reinstalled
pump down mode: slow to avoid steering up dust
One roughing pump was used with closed down valve position in the first 4 hrs

Andrey was very helpful
  66   Tue Nov 6 09:45:22 2007 steveSummarySUSvent sus trend
The mc optics dragwippings were done by locking optics by eq stops and rotating-moving
cages so access were good. This technic worked well with mc1 & mc2
MC3 osems were reoriented only.
  104   Thu Nov 15 04:18:11 2007 JohnSummaryPSLPMC cavity pole measurements
In connection with our work on the ISS I attempted to measure the PMC cavity pole.

I swept the PMC PZT and looked at the transmission through the cavity on the ISS Monitor diode (which is now back on the table, feel free to remove it again tomorrow).

To avoid thermal effects I reduced the laser power using the half wave plate at the laser ouput (rotated from 6 deg to 340deg).

I swept the PZT using the triangle wave command "trianglewave C1: PSL-PMC_RAMP -3.5 3.3 20 200". I noticed that the functional form of the resonances deteriorated over the duration of the excitation. Each sweep was able to capture just over one FSR. The resonances were a little close to the 'points' of the triangle wave for my liking although I don't think PZT hysteresis was a big factor.

Looking at the data the peaks are not of uniform width across a sweep or between consecutive sweeps. Hence any results from this mesurement are not particularly useful. I can't be sure if this was due to misalignments, thermal effects, higher order mode content or some other affect.

Rob suggests sweeping the laser frequency using the NPRO PZT instead.
  108   Thu Nov 15 18:36:48 2007 JohnSummary PSL table work
I've rotated the lambda/2 plate to 340deg (from 6 deg) and blocked one arm of the Mach-Zender. Undo both if you need to.
  116   Tue Nov 20 10:11:33 2007 JohnSummaryPSLPMC pole measurements
We measured the PMC pole in the following way.

1. Reduced laser power by rotating lambda/2 plate at laser output. Thermal effects in the PZT distort resonance peaks. Reducing power too much leads to problems with digitisation error.

2. Sweep NPRO PZT (C1: PSL-FSS_INOFFSET) using trianglewave. Record ramp, PMC transmission and reference cavity transmission ('C1: PSL-FSS_FAST','C1: PSL-ISS_INMONPD_F','C1: PSL-FSS_RCTRANSPD_F).

3. Since the PZT cannot sweep a full FSR in the PMC we looked at the sideband resonances within the reference cavity to calibrate the actuator.
Result: 7.35 +/- 0.22 MHz/V

4. Use #3 to calibrate the x axis of the PMC transmission.

5. Fit PMC resoances to an Airy function to get finesse. Take an average, weighted according to the resnorm. Calculate cavity pole frequency.
Result: 380kHz +/- 59kHz. This corresponds to a finesse of ~936. According to this plot the nominal pole is at 488kHz and the finesse is 732.

This is by no means a definitive measurement due to the misshapen resonance peaks recorded.
  119   Tue Nov 20 18:02:54 2007 JohnSummaryComputersPSL_Main screen
I've updated the PSL_MAIN screen. The old version may be found in cvs/cds/caltech/medm/old/medm/psl.
  144   Fri Nov 30 11:22:22 2007 ajwSummaryCDSGEO DV => LIGO DV

Quote:
Martin Hewitson of GEO600 fame has modified the cool GEO DV
to work with the LIGO NDS system with some NDS advice from Rolf (who's over in Germany this week).

I've moved it onto the 40m CDS system and installed it on the AdhikariLab computer named 'django'. It worked immediately.

I modified the main .m file to include the 40m's NDS server. When you run it you have to include the path to the NDS
client written by Ben Johnson.

The attached is a screenshot of it working on a Mac; it looks as cool on Linux.

Its installed in /cvs/cds/caltech/apps/ligoDV/. In matlab you navigate to that directory and then
type addpath('/cvs/cds/caltech/apps/linux/UNIX_NDS_Client_beta2/') to add the NDS client.
On the Solaris machines, type type addpath('/cvs/cds/caltech/apps/solaris9/UNIX_NDS_Client_beta2/') instead.

Then type ligoDV to start it up. Then click away and have fun.

In the example I've selected
C1:PEM-BS_ACC_EAST_Z
and plotted its specgram.

Big grin


Download and installation instructions, as well as a few examples for use
can be found here (typical lsc username and password):

https://www.gravity.phy.syr.edu/dokuwiki/doku.php?id=ligodv:home
https://www.gravity.phy.syr.edu/dokuwiki/doku.php?id=ligodv:downloading_the_ligodv_software
  150   Fri Nov 30 20:13:57 2007 dmassSummaryGeneralHeNe UniPhase Laser
Data for the Uniphase 1.9 mW HeNe laser (labeled: "051507 From ISCT-BS") SN: 1284131 Model: 1103P

I used the Photon Beamscanner to obtain all data, then fit w(z) as shown on the plot with parameters w_0, z_R, and hidden parameter delta,
where z = delta + x, z is waist distance, x is distance from the laser.

Copies of the matlab code used to fit (/plot) are attached in .zip below.
  174   Thu Dec 6 15:22:42 2007 AndreySummaryElectronicsPictures of the inside of He-Ne laser

Steve gave me an old "dead" He-Ne laser that long time ago was used for ETMX optical lever.

I dismantled it (cutting the metallic enclosure with a metallic saw), and these are two pictures of what is inside.
  178   Fri Dec 7 00:02:26 2007 ranaSummaryIOOMC/FSS Frequency Noise
The FSS frequency noise is not very bad.

I compared the MC_F spectra between Hanford and the 40m using DTT and its 'User NDS' option.
After Sam, Jenne, and DavidM installed the new MC Servo some time ago, the MC_F spectrum here
has had some whitening before it goes into the DAQ (on board; same as LLO & LHO). The tuning
coefficient of the VCO is also basically the same between all PSLs since everyone has the same
chip in the VCO driver.

Therefore, at the frequencies where the MC gain is more than ~4, the MC_F signal calibration is
the same here as anywhere. Since its the servo control signal, its basically a measure of the
frequency noise incident on the MC -- its just what comes out of the FSS with the table noise on
top. At low frequencies (< 100 Hz) its a measure of the motion of the MC mirrors.

Above 200 Hz ours is the same as theirs; except for the enormous power line spikes. I think that's
either all on the light. But our acoustics are better and the noise above 1 kHz levels off at the
same flat floor (the phase noise of the VCO) as H1. The huge lump around 100 Hz is the MC2 DAC noise and
it goes down to the H1 levels when we flip on the dewhites. The giant excess from 5-50 Hz is just the fact
that our stacks don't do much until 20-30 Hz.

So we can stop blaming the FSS and move on with life as soon as Tobin gets the ISS back in shape.
  199   Tue Dec 18 23:41:00 2007 AndreySummaryComputer Scripts / ProgramsResults of Mon/Tue overnight measurements (entry #194)

Here I inform our community about the results of the measurements of RMS values in XARM during the previous night from Monday to Tuesday (I announced those measurements in ELOG entry #194).

All the plots in today's report seem to agree well with the analogous plots from the night from Saturday to Sunday (those results are given in ELOG entry # 195).

All the intervals in which RMS have been calculated are the same as in yesterday's ELOG entry #195.

I plotted three results for RMS in the abovementioned three intervals in three different ways:

1) view from the top in the axes (Q_{ITMX}+Q_{ETMX})/2 and (Q_{ITMX}-Q_{ETMX}) -> first three graphs (attachments 1 -3);

2) view from the side in the same sum- and difference-axes -> next three graphs (attachments 4-6);

3) view from the side in Q_{ITMX} and Q_{ETMX} axes -> next three graphs (attachments 7-9, also attch. 12), above accelerometer spectra (attachments 10-11).

Also, I compared the ground noise level by comparing spectra of accelerometer signals at different times during that night. As a reminder, before my disease I installed one accelerometer near ITMX and another accelerometer near ETMX (see entries 161 and 172 in ELOG). The plots of ratios of accelerometer signals at different times (pairs of times that were used: 11PM and 2AM, 11PM and 5AM, 11PM and 8AM) are given below, see attachments 10-11. The program was running from 11PM on Monday till 9AM on Tuesday.

As I explained in the previous ELOG entry # 198, tonight I am taking experimental data in the narrowere interval from 1.00 to 4.50 with a smaller step 0.25.
  202   Wed Dec 19 16:07:37 2007 AndreySummaryComputer Scripts / ProgramsResults of overnight measurements Tue/Wed night (entry #198)

As indicated in ELOG entry 198, I was making overnight measurements during last night from Tuesday to Wednesday.

I was changing the suspension damping gain in ETMX and ITMX in "position" degree of freedom between values of 1.00 and 4.50 with the step 0.25.

Results for RMS of peaks (A) at 0.8Hz, (B) at about 3.0Hz and (C) in the range from 0.6Hz to 3.7Hz ("RMS in a broad interval") are given below:

I plotted three results for RMS in the abovementioned three intervals in three different ways:

1) view from the top in the axes (Q_{ITMX}+Q_{ETMX})/2 and (Q_{ITMX}-Q_{ETMX}) -> first three graphs (attachments 1 -3);

2) view from the side in the same sum- and difference-axes -> next three graphs (attachments 4-6);

3) view from the side in Q_{ITMX} and Q_{ETMX} axes -> next three graphs (attachments 7-9)

Attachments 10 and 11 show ratios of accelerometer signals at different times of the night/morning.


A little discussion about these graphs:

1) The areas of minima and of rapid growth are the same for all the measurements during all three nights.

2) Tonight there was a strange spike for the values of Q_{ETMX}=2.5 and Q_{ITMX}=4.0. I interpret that as an error of experiment.

3) On all the plots from all three nights there is a wide area of minimum on the plots for RMS at 0.8Hz and for "RMS in the broad interval",
and the graph for "RMS at 3Hz" indicates a clearer minimum in a localized area for Q_{ITMX}=2+-1, Q_{ETMX}=2+-1. Note that this area 2+-1
is included into the wide region of minimum for "RMS at 0.8Hz" and "RMS in a broad range".

Therefore, my guess at this stage is that we can choose the optimized value of suspension damping gains for both Q_{ITMX} and Q_{ETMX} somewhere
around 2+-1. I would like to make another overnight measurement (tonight) in that narrowed region with a small step to have more certainty.

By the way, I realized that I was a little bit careless and at some plots Q_I stands for {Q_ITMX}, and Q_E stands for Q_{ETMX}.
  209   Thu Dec 20 21:58:28 2007 AndreySummaryComputer Scripts / ProgramsResults for 2 previous XARM measurements have been added

I attached results (plots) of yesterday's daytime and overnight measurements to the initial reports about those measurements.

These are ELOG entries # 201 and # 205.
  219   Wed Jan 2 11:38:56 2008 tobinSummaryWIKI-40M Updatewiki spam
Our wiki keeps getting spammed. It turns out that you can upload attachments without a password, which is a bug. I'll ask David Barker whether there's a fix for this.
  231   Thu Jan 10 00:12:01 2008 tobinSummaryLockingDR
[John, Tobin, Rana]

1. We found SUS_BS_SENSOR_UL to have a ratty signal and low DC value. Twiddling the cables at the BS satellite amplifier and vacuum feedthrough brought the signal back (to 0.667V), but it is still spiky, spiking up to a couple times per second. Rana suggested that these spikes might be scattered YAG laser light (as hypothesized in August). The spikes go away when we misalign the PRM or either ITM, and when we unlock the mode cleaner, lending credance to this theory. SUS_BS_SENSOR_UR also spikes, but much less frequently. We turned off C1:SUS-BS_ULSEN_SW2 and continued.

2. After dither alignment the oplev beams were centred and we were able to lock DRM plus either arm reliably (however locking in this state broke ./drstep_bang at the first ``Going DD''). We ran scripts/DRFPMI/bang/nospring/drdown_bang and were subsequently able to lock DRFPMI (i.e., full IFO) a couple times.

3. To do: Debug ./drstep_bang with just the DRM (no arms).
  256   Wed Jan 23 12:31:36 2008 AndreySummarySUSDissapointing Results of XARM optimization (PDF-file)

I attach a PDF-file which summarizes briefly the results of measurements/calculations of Q-factors for ITMX mass as a function of suspension damping gain,

and this file contains the results of measurements of RMS peaks on the values of suspension gains of ITMX and ETMX (see ELOG entries from December 2007, specifically #202, #199, #194)),
but now those dependences are plotted in Q-ITMX and Q_ETMX axes.

Unfortunately, there are no clear narrow areas of minimum in those dependences (that explains the sad title of this ELOG entry).

The attached pdf-file can be shown as a short presentation for a wall during our Wednesday meeting.
  257   Wed Jan 23 20:52:40 2008 ranaSummaryEnvironmentFlooding from construction area
We noticed tonight around 7 PM that there was a lot of brown water in the control room and also in the interferometer area mostly concentrated around the north wall between the LSC rack and the AP table.

The leak was mainly in the NW corner of the interferometer area.

The construction crew had set up sandbags, plastic sheet, and gravel to block the drains outside of the 40m along the north wall. The rain had produced ponds and lakes outside in the construction area. Once the level got high enough this leaked through holes in the 40m building walls (these are crappy walls).

We called the on-call facilities team (1 guy). He showed up, cut through the construction fence lock, and then unblocked the drains. This guy was pretty good (although inscrutable); he adjusted the sandbags to control the flow of the lake into the drains. He went along the wall and unblocked all 3 drains; there were mini-lakes forming there which he felt would eventually start leaks all along our north wall.

In the morning we'll need volunteers to move equipment around under Steve's direction while the floor gets mopped up. There's dirt and mud all over, underneath the chambers and racks.

Luckily Alberto spotted this early and he, Jon, Andrey and Steve kept the water from spreading and then scooped it all up with a wet-vac that the facilities guy brought over.
Extra Napoleon to them for late evening mud clearing work.

Many pictures were taken: Update and pictures will appear later.
  259   Thu Jan 24 12:50:50 2008 JohnSummaryTreasureSugar Napoleons
Some pictures from the group meeting yesterday.
  271   Sat Jan 26 02:02:43 2008 JohnSummaryGeneralNew Channels
I added the following channels.

# C1ASC_QPDs
[C1:SUS-ETMY_QPDSUM_MON]
[C1:SUS-ETMY_QPDYAW_MON]
[C1:SUS-ETMY_QPDPIT_MON]

[C1:SUS-ETMX_QPDSUM_MON]
[C1:SUS-ETMX_QPDYAW_MON]
[C1:SUS-ETMX_QPDPIT_MON]

The old .ini file is /cvs/cds/caltech/chans/daq/C0EDCU_26_1_2008.ini
  275   Sat Jan 26 18:48:43 2008 JohnSummaryComputersRestart iscepics
iscepics died this afternoon. We restarted it and restored settings from yesterday. I've written up instructions in the wiki.
  283   Mon Jan 28 19:35:55 2008 ranaSummaryPEMAccelerometer and Seismometer Coherences
The attached PDF shows that there is some strange behavior at low frequencies.

From the plot it looks like to me that the Wilcoxon accelerometers (which are supposed to have good response down to 0.05 Hz) are not displaying real seismic motion below 0.3 Hz. Because the coherence length for seismic waves at those frequencies should be 100's of meters we should expect that the accelerometers would have good coherence (>0.8) down there. Instead, my guess is that its all air currents, temperature, or electronics noise. These sensors are not reliable indicators for the microseism.

The Ranger seismometer, however, seems to work fine down to just below the microseism. The Ranger is mounted down around the X end and pointing in the z-direction. The coherence I plotted between it and EX_Z is larger than any other acc/seis pair (as expected).

JM and I discussed what could be done; if we get a SURF student who's into building stuff we can ask them to make a styrofoam hut for the Wilcoxons to see if that helps anything. JM also asked what the point of all this is.

IF we want to do good Adaptive Noise subtraction then we need sensors which can sense the motion which disturbs the mirrors and they need to sense it with a good SNR to get a good subtraction ratio. If the styrofoam thing doesn't work, we should probably look into getting a Guralp 3-axis seismometer for the corner area and just move the accelerometers down to the ends. The sites have Guralp CMG-40T units (~ 8k$). I think we should check out the CMG-3T or the CMG-3ESP.

Does anyone know someone in the Geo depts that we can borrow one from?
  285   Wed Jan 30 11:49:30 2008 AlbertoSummaryElectronicsRF monitor's filters final schematics and transfer functions
These are the final schematics for the 6th order Chebyshev filters of the RF monitor board. I'm also attaching the TF as I measured. The tuning is probably not optimal, less insertion noise could be achieved.
  293   Fri Feb 1 17:17:05 2008 JohnSummaryPSLMach-Zender tweaking
I helped Rob adjust the alignment of the Mach-Zender to try and reduce any AM on the laser light. Our goal was to reduce the large offsets in the DD signals.

We reduced the MZ refl from 0.54 to 0.39. We were able to re-lock the mode cleaner without problems. We then centred the WFS heads.

No change in the DD signal offsets.
  294   Sat Feb 2 14:11:27 2008 JohnSummaryComputersOPTLEVmaster screen
I changed the layout of the optlev master screen. The old version is /cvs/cds/caltech/medm/old/C1ASC_OPTLEVmaster080202.adl
  296   Mon Feb 4 22:01:57 2008 JohnSummaryLSCFibres auxiliary locking - Fibers
I managed to couple ~75% of the light transmitted from the y arm, through the fibre, back to the SP table. I hoped that this would be a good way to match the beam from the fibre into the arm. Still no flashes. It looks like the cameras just aren't sensitive enough.
  304   Sat Feb 9 13:05:48 2008 JohnSummaryIOOPMC camera/ HEPA
I replaced the Gig-E camera on the PMC trans beam. The PZT was close to railing and I wanted to adjust it. I just did a quick job, there is a little scattered light on the image. If Joe is finished with the Gig-E I'll take another look at it.

The HEPA in the PSL table was turned off for some reason. I turned it back on.
  305   Sat Feb 9 13:32:07 2008 JohnSummarySUSAll watchdogs tripped
When I arrived this afternoon the watchdogs had tripped on all optics. I reset them and enabled the coil currents.

I had to adjust the alignment of the mode cleaner to get it to lock.
  306   Sun Feb 10 20:47:01 2008 AlanSummarySUSAll watchdogs tripped
A moderate earthquake occurred at 11:12:06 PM (PST) on Friday, February 8, 2008.
The magnitude 5.1 event occurred 21 km (13 miles) NW of Guadalupe Victoria, Baja California, Mexico.
http://quake.wr.usgs.gov/recenteqs/Quakes/ci14346868.html
  328   Thu Feb 21 18:29:28 2008 JohnSummaryGeneralHP Network Analyser Analyzer
The HP 4195A network analyser may be broken, measurements below 150MHz are not reliable. Above 150MHz everything looks normal. This may be caused by a problem with its output (the one you'd use as an excitation) which is varying in amplitude in a strange way.

Analyzer
  338   Fri Feb 22 20:42:44 2008 AndreySummaryComputer Scripts / ProgramsIt seems I succeeded in theoretical simulations

I am pretty happy at this moment.

I definitely feel that it took me too much time to understand how to do the Matlab program and how to overcome difficulties,

but eventually at last my Matlab program seems to start working.

Briefly: What the program does?
--> take time-domain signal from two accelerometers near ITMX and ETMX (use 'get_data');
--> calculate the time-evolution of those two signals through the system "stack + pendulum" to the test-masses ITMX and ETMS (use 'lsim' in Matlab),
which gives us the time-domain evolution of the deviation of the position of individual test-mass from its average position.
--> Subtract the two results from each other in time-domain, this gives us the deviation of the length of the XARM-cavity from its average value
(roughly speaking, deviation of the length of the cavity from exactly 40 meters, although I am aware that the exact average length of XARM is less than 40 meters).
--> Take the amplitude spectrum of the result, using Sqrt(pwelch) and calibrate it from "counts" to "meters".
--> Calculate root-mean-square of peaks at different frequency intervals, for example near 0.8Hz,
and plot the three-dimensional surface showing the dependence of RMS on Q-factors Q_{ETMX} and Q_{ITMX}.

Eventually I am able to create these dependences of RMS.

I see that the minimum of the dependence is close to the diagonal corresponding to exact equality of Q_ETMX} and Q_{ITMX}, but not exactly along the diagonal. The plot allows to say
which of two conditions "Q_I > Q_E" or "Q_E < Q_I" should be fullfilled for optimization reasons. My plot is raw, I might have made a mistake in axis-label, I do not garantee now that the axis label "Q_ITMX - Q_ETMX" is correct,
maybe I need to change it for "Q_ETMX - Q_ITMX". I need some more time to determine this on Monday, but clearly there is asymmetry between Q_I and Q_E.

The peak at 0.8 Hz is pretty stable, while the peak at around 3Hz is not very repeatable, therefore in both experimental measurements and these simulations the amplitude of RMS of peak at 3Hz) is several orders of magnitude smaller than for RMS of peak at 0.8Hz, and I do not see minimum somewhere in the RMS-dependence, I see now only steady growth of RMS as Q_factors increase.

I will need to spend some time on Monday trying to understand how the sampling frequency and number of fft-points influence my results when I take amplitude spectrum using pwelch-command, as well I will need to double-check the correctness of normalization from counts to meters (I am not confident right now that amplitude of order of 10^(-12) meters is correct).

So, I need some time after the weekend to analyze my results and maybe make some slight changes, but I am glad that my Matlab model started to work in principle. I wanted to let others know about the status of the progress in my work. The fact that Matlab program works now is a good ending of a week.

Andrey.
  341   Tue Feb 26 20:24:04 2008 AndreySummaryTMISorrow
As for that plot of three-dimensional surface, I indeed was wrong with the axis "Q_ETMX-Q_ITMX" (I put there wrong string "Q_ITMX-Q_ETMX"). On Friday plot there were values 10^(-12) on the z-axis, and that should be really meters, but the point that as I realized on Monday, I have never calibrated experimental measurement results from counts to meters , that's why it is this difference between 10^(-6) and 10^(-12). I still did not find the way to compare experim. and theoretical plots, because even if I leave "counts" on both plots, so that I have scale 10^(-6) on both plots, then the change in theoretical plot is just 0.02*10^(-6) for the range of Q-factors change, while the change in experimental measurements is an order of magnitude more 0.4*10^(-6), so the surface for theretical plot would be almost flat in the same axes as experimental results.
  348   Fri Feb 29 13:51:17 2008 JohnSummaryLSCPD6 response
I checked the response of PD6 using the AM laser. It looks happy enough.

16 averages
-10dBm source power
77.3mV dc on the diode
  359   Wed Mar 5 12:35:09 2008 JohnSummaryComputer Scripts / ProgramsPlot photodiode responses in MatLab
A matlab function to plot the responses of photodiodes. There's still plenty of room for improvement but it should work for all our diodes without any changes. You may want to adjust which points are used in the fit to remove time delay.




% Plot data from diode response measurements
function out = diodeplot(f_Hz,mag_dB,phase_deg,f_beat_MHz)

% $$$ clear all
% $$$ close all
% $$$ clc
% $$$
% $$$
% $$$ mag = dlmread('D:\40m\PD6\M7.txt','\t', 15, 0);
% $$$ phase = dlmread('D:\40m\PD6\P7.txt','\t', 15, 0);
% $$$
% $$$ % Frequency i.e. x-axis
% $$$ f = mag(:,1);
% $$$
% $$$ % Magnitude in dB
% $$$ mag_dB = mag(:,2);
% $$$
% $$$ % Phase in degrees
% $$$ phase_deg = phase(:,2);
% $$$
% $$$ % Frequencies of interest
% $$$ f_beat_MHz = [33 133 166 199]*1e6;
% $$$
% $$$ diodeplot(f, mag_dB, phase_deg, f_beat_MHz)

% x axis limits
xmin = 10e6;
xmax = 500e6;

% Unwrap phase
phase_deg = (180/pi)*unwrap((pi/180)*phase_deg);

%Find values at our freqeuncies of interest
Mag_f_beat = interp1(f_Hz,mag_dB,f_beat_MHz);

% Remove the time delay from the phase data
% (May want to adjust which points are selected here)

straight = @(a, x) a(1) * x + a(2);

xdata = f_Hz;
ydata = phase_deg;

aguess = [10 0.1];
a = lsqcurvefit(straight,aguess,xdata,ydata);
fit = straight(a,xdata);

phase_deg = phase_deg-fit;

figure(1)
ha = axes('units','normalized','position',[0 0 1 1]);
uistack(ha,'bottom');
I=imread('PDbw.jpg');
hi = imagesc(I);
colormap gray
set(ha,'handlevisibility','off', ...
'visible','off')
plot(xdata,ydata,'r')
hold on
plot(xdata,fit,'k')
plot(xdata,phase_deg,'b')
hold off
ylabel('Phase/ degrees', 'FontSize',12)
xlabel('Frequency/ Hz', 'FontSize',12)
title('Removing the time delay','FontSize',16)
legend('data','fit','data-fit',0)
set(hi,'alphadata',.35)
set(gca,'Color','None')
box off




figure(2)
set(gcf,'Color', [1 1 1])
subplot(4,1,[1 3])

semilogx(f_Hz,mag_dB,'k','LineWidth',2.5)
title('Response of PD6','FontSize',16)
ylabel('Magnitude/ dB', 'FontSize',12)
xlim([xmin xmax])
grid

MagLayout = get(gca, 'Position');
YLimits = get(gca, 'YLim') ;
LabelExt = [];

for ivar = 1:length(f_beat_MHz);

a = text(f_beat_MHz(ivar),1.05 * min(Mag_f_beat),...
sprintf('%2.1fdB @ %dMHz', Mag_f_beat(ivar),f_beat_MHz(ivar)/1e6),...
'FontSize',10,'FontWeight','Bold','HorizontalAlignment','right',...
'VerticalAlignment','top','BackgroundColor',[.7 .9 .7],...
'Margin',0.5, 'Rotation',90);
LabelExt = [LabelExt; get(a,'Extent')];
LabelPos = get(a,'Position');

end

% Change YLim so that it is around the bottom of the labels
% There must be a better way
set(gca, 'YLim', [min(LabelExt(:,2)) YLimits(2)])

% Remove the last tick mark so that it doesn't overlap with the
% +180 of the phase plot
YTickLabelNew = str2num(get(gca, 'YTickLabel'));
YTickNew =[[] YTickLabelNew(2:end) ];
set(gca,'XTickLabel', [], 'YTick', YTickNew)

% Add lines now we know what the YLims are
for ivar = 1:length(f_beat_MHz);
line([f_beat_MHz(ivar) f_beat_MHz(ivar)], get(gca, 'YLim'))
end

subplot(4,1,4)
semilogx(f_Hz,phase_deg,'r','LineWidth',2.5)
xlim([xmin xmax])
ylabel('Phase/ degrees', 'FontSize',12)
xlabel('Frequency/ Hz', 'FontSize',16)
grid
PhaseLayout = get(gca, 'Position');
PhaseLayout(4) = MagLayout(2)-PhaseLayout(2);

% Make the top of the phase plot align to the bottom of the
% magnitude plot
set(gca, 'Color', 'None', 'Position',PhaseLayout, 'YTick',[-180:45: ...
180])
set(gcf,'units','normalized','outerposition',[0 0 1 1]);
  360   Wed Mar 5 12:51:48 2008 JohnSummaryLSCInitial Ligo Arm finesse versus lambda
I've taken the coating recipes for the initial ligo arm cavity from Rana's web page (ligo.caltech/edu/~rana/mat/)
and plotted the finesse as a function of wavelength. There is some uncertainty over the indices of refraction but
the main conclusion remains unchanged - i.e. it appears that using other wavelengths will be difficult.
Stefan is looking at how to tune the layers of any new mirrors to make dichroic optics.
  387   Thu Mar 20 17:45:36 2008 ranaSummaryASSAdaptive Filtering in the ASS system
Over the past couple weeks we (Matt, Alex, Rob, me) have worked on getting an adaptive filter
system working. We wanted to load this system into c1ass to use this processor. The dither alignment
system hasn't been employed here for awhile and so we have just used this box.

The signals are acquired in the PEM ADCU. Alex modified the code there to send the signals over to
the new system. We also get the SUS-LSC_OUT signals from each of the suspensions so that we can
try to minimize them.

The outputs of the adaptive filter go into the unused SUS-MCL inputs of all the suspensions (except
for MC2). In the current setup, we have 6 accelerometers and 1 seismometer around the MC to be used
to demonstrate the principle of the whole thing.

Much more documentation and description of everything is necessary. We'll try to get Matt, Rob, and Alex
to use the elog.
  394   Sat Mar 22 22:39:02 2008 mevansSummaryCDSDirect Form 2 filters are bad
Here I show a comparison between the filter algorithm currently used in LIGO (Direct Form II), and an alternative algorithm designed to reduce numerical noise. The input signal is

x = sin(2 * pi * t) + 1e-9 * sin(2 * pi * (fs / 4) * t);

where fs = 16384 is the sample rate. The filter is a 4th order notch at 1Hz (f_poles = f_zeros = 1Hz, Q_poles = 1, Q_zeros = 1e6). It is clear that the DF2 algorithm produces a noise floor that is, for this simple filter, 1e-11 / rtHz smaller than the input drive amplitude (see plots). That should probably be scary given how many second-order-sections we run our signals through. The low-noise form does a somewhat better job. The low-noise algorithm has the same memory and computational requirements as DF2, and our CDS guys have the code in hand. I suggest we start testing soon.

(The code is included below. You will need my Matlab library to run the top level test script.)
  397   Sun Mar 23 10:42:54 2008 ValeraSummaryElectronicsRFAM of the RF stabilization box is measured
I reconstructed Tobin's setup to measure the RFAM after the RF stabilization box in the 166 MHz modulation path.
The setup consisted of the splitter and the mixer followed by the RF low pass filter and the SR560 (gain x100).
The RF level into splitter was 20 dBm. The Mini-Circuits ZLW-3H (17 dBm LO) mixer was used. The LO was taken
straight out of the splitter and the RF path was attenuated by 11 dBm, The DC out of the mixer was 700 mV.
The noise floor was measured with the RF input of the mixer terminated on 50 Ohm. The 45 MHz measurement
in broad band setting looks better than the noise floor at high frequencies. I am not sure what was wrong with
one or both of those measurements. The 9 MHz measurements are above the noise floor.

The RFAM meets the AdvLIGO requirements in the detection band (f > 10 Hz).

The attached zipped files are:
SRS003 9 MHz DC-200 Hz
SRS004 9 MHz DC-26 kHz
SRS006 45 MHz DC-200 Hz
SRS005 45 MHz DC-26 kHz
SRS007 Noise floor DC-200 Hz
SRS008 Noise floor DC-26 kHz
  399   Mon Mar 24 20:15:03 2008 JohnSummaryComputersc1susvme2
c1susvme2 isn't behaving itself. It keeps getting out of sync and/or giving a red status light.

After going through the usual restart procedures a few times (unsuccessfully) we power cycled the c1susvme & c1sosvme crates. We think everything came back okay.

We still can't get the status and CRC (cyclic redundancy check) to return to normal on c1susvme2. If Alex is around tomorrow please ask him to take a look.
  407   Mon Mar 31 14:01:40 2008 jamieSummaryLSCSummary of DC readout PD non-linearity measurements
From March 21-26, I conducted some measurements of the response non-linearity of some mock-up DC readout photodetectors. The detectors are simple:
Vbias ---
        |
       PD
        |-------- output
     resistor
        |
       ---
        -
This is a description of the final measurement.

The laser current modulation input was given a 47Hz sine wave at 20mV. A constant small fraction of the beam was shown onto the reference detector, and a beam that was varied in DC power level was incident on the test detector. Spectra were taken from both detectors at the same time, 0.25Hz bandwidth, over 100 averages.

At each incident power level on the test detector, the Vpk in all multiples of the modulation frequency were measured (ie. V[i*w]). The difference between the 2f/1f ratio in the test and reference was then calculated, ie:
V_test[2*w]/V_test[1*w] - V_ref[2*w]/V_ref[1*w]
This is the solid black line in the plot ("t21-r21_v_power.png").

The response of a simulated non-linear detector was also calculated based on the Vpk measured at each harmonic in the reference detector, assuming that the reference detector had a purely linear response, ie:
V_nl[beta,2*w]/V_nl[beta,1*w] - V_l[2*w]/V_l[1*w]
these are the dashed colored lines in the plot ("t21-r21_v_power.png").

The result of the measurement seems to indicate that the non-linearity in the test detector is less than beta=-1.

The setup that was on the big optics table south of the laser, adjacent to the mode cleaner, is no longer needed.
  410   Thu Apr 3 18:33:17 2008 AndreySummaryEnvironmentStatus of Weather Station

During the last two days some things related to weather station have been improved.

1) Startup file for the computer (processor) 'c1pem1' was changed so that now 'c1pem1' can be rebooted from "Linux1". Computer 'c1pem1' is responsible for communicating data between 'Weather Monitor' and control UNIX machines. Before April 1st it was impossible to reboot the computer 'c1pem1'. Now 'c1pem1' runs without difficulties.

2) It was determined that some ethernet cables of category "cat 5" were bad. I replaced one short cat 5 cable between 'c1pem1' and 'network-switch board' in the neighboring computer rack, and I still need to replace the internet ending of another long (~20 meters) cat 5 cable after Alex Ivanov will bring the tool for that.

3) 'Weather monitor' and 'WeatherLink' are temporarily moved away from their "nested" positions on the north wall, and they are now in the proximity of processor 'c1pem1'. Thus the signal about "Inside Temperature" goes into 'c1pem1' computer without any additional ethernet cables, and "inside temperature" is correctly displayed on the "Checklist" adl. MEDM screen on the control UNIX machines. The cable with a signal from the roof sensors (which might be dead due their 7-year age) is temporarily disconnected from the 'Weather Monitor'.

Result: 'Weather Monitor' and computer (processsor) 'c1pem1' are alive, they communicate reasonable "Inside Temperature" to the control UNIX-machines.

The fate of the outside sensors is currently unknown, I plan to go to the roof together with Mr. Steve Vass tomorrow and try to determine what should be done with them.

I am also writing (right now) a wiki-40 page which explains what is the "Weather Station" and what is its status.
  413   Thu Apr 3 19:27:50 2008 AndreySummaryPhotosTour for prospective grad students
Last Friday (March 28), there was a tour of 40-meter lab for prospective graduate students.

Rana showed to the prospective students the interferometer. See pdf-attachment with pictures (two pictures of Rana with undergraduates (I took them) and two old pictures which I discovered on the memory card of Nikon d-40, it was not me who took those two last pictures).
  414   Fri Apr 4 16:54:06 2008 AndreySummaryEnvironmentWeather station is fully alive

After today's trip to the roof of our building the weather station seems to be completely resurrected!

We went to the roof together with Steve Vass, and we discovered that:

(1) Sensors of wind speed, wind direction and the bowl that measures the amount of precipitation do not have any visible defects, so there is no problem with all those sensors even after being outside for seven years.

(2) We discovered that there are cable junctions located on the roof, and those junctions were located close to the rim (edge) of the roof, before the cables go inside of 40-meter lab room. The taping in the place of the junction was not good due to the age, and the connections between the cables were disrupted (cable endings were out of the connectors). Therefore, no signal from the roof sensors could be transferred to the 'Weather Monitor'. It was not wise from the person who installed the weather station to leave the fragile cable connections outside, on the roof, because the length of the cables allowed to locate those three connectors inside of the building.

See the attached PDF-file with pictures.

(3) After the cables were plugged into the connectors, these cable junctions were gently pulled into the inside of the 40-meter interferometer room. These cable junctions should not be located outside of the building!

Immediately after all the above-mentioned steps, the reasonable indications of outside temperature, humidity, pressure, wind speed and direction appeared on the 'Weather Monitor'.

In order to see if there is any problem of communication between the 'Weather Monitor' and UNIX control computers through 'c1pem1', I rolled out two brand new black cat-5 ethernet cables on the floor of the interferometer room (they are on the floor temporarily, the ethernet cable will go from the floor into the ceiling cable tray eventually), connected the two cables together through freshly purchased from Caltech bookstore cable connectors, and thus connected the 'Weather Monitor' to the processor 'c1pem1'.

Result: Now we can see reasonable indications of outside temperature, pressure, amount of precipitation, wind speed and direction on the EPICS screen! Moreover, these indications are changing with time.

As a reminder for everyone: standard atmospheric pressure is about 101kPa, so the indications of pressure as 99900Pa is quite reasonable.

One thing is not clear for me yet: wind speed on the 'Weather Monitor' is fluctuating between 2 and 4 mph, while MEDM EPICS-screen values are fluctuation in the range between 0 and 3mph.

Many thanks to Steve Vass and Alexander Ivanov for their help.
  420   Wed Apr 16 09:47:35 2008 AndreySummaryPEMWeather Station
The weather station is functional again.

The long ethernet Cat5 cable connecting 'WeatherLink' and processor 'c1pem1' was repaired yesterday, namely the RJ45 connector was replaced,
and information about weather conditions is now again continuously being transferred from the 'Weather Monitor' to the control UNIX computers. We can see this information in 'c0Checklist.adl' screen and in Dataviewer.

Below are the two sets of trends for the temperature, wind speed and direction, pressure and the amount of precipitation.

The upper set of trends ("Attachment 1") is "Full Data" in Dataviewer for the 3 hours from 6.30AM till 9.30AM this morning,
and the lower set of trends ("Attachment 2") is "Minute Trend" in Dataviewer for 15 hours from 6.30PM yesterday till 9.30AM this morning.

I also updated the wiki-40 page describing the Weather Station and added to there a description of the process of attaching the RJ45 connector to the end of ethernet Cat5 cable. To access the wiki-40 page about the "weather station" you should go from the main page to "PEM" section and click on "Weather Station".
  422   Wed Apr 16 21:11:12 2008 ranaSummaryDAQAA/AI Filters for the DAQ & FE systems
I used Foton to make up some new filters which will be used all over the project in order to downsample/upsample.

There will be 2 flavors:

  • The first one will be a downsampling filter for use in the DAQ system.
    Whenever you specify a sampling rate in the .ini files below the natural rate of the ADC,
    the data will be downsampled using this filter (called ULYAW_0 in the plot). This one was
    designed for flat bandpass and a 'good' bandstop but no care given to the phase shift.

  • The second one will be used in the FE systems to downsample the ADC signal which is often
    sampled at 64 kHz down to something manageable like 2k or 16k. This one was tweaked for
    getting less phase lag in the 'control' band (usually 3x or so below Nyquist).

Here is the associated filter file:
# SAMPLING ULYAW 16384
# DESIGN   ULYAW 0 zpk([0.512+i*1024;0.512-i*1024;2.048+i*2048;2.048-i*2048], \
#                      [515.838+i*403.653;515.838-i*403.653;318.182+i*623.506;318.182-i*623.506;59.2857+i*827.88; \
#                      59.2857-i*827.88],0.988553,"n")
# DESIGN   ULYAW 1 zpk([0.512513+i*1024;0.512513-i*1024;1.53754+i*2048;1.53754-i*2048], \
#                      [200+i*346.41;200-i*346.41;45+i*718.592;45-i*718.592],1,"n")
# DESIGN   ULYAW 2 zpk([0.768769+i*1024;0.768769-i*1024;1.53754+i*2048;1.53754-i*2048], \
#                      [194.913-i*331.349;194.913+i*331.349;53.1611+i*682.119;53.1611-i*682.119],1,"n")
###                                                                          ###
ULYAW    0 21 3      0      0 DAQAA         0.00091455950698073    -1.62010355523604     0.67259370084279    -1.84740554170818     0.99961738977942
                                                                   -1.72089534598832     0.78482029284220    -1.41321371411946     0.99858678588255
                                                                   -1.85800352005967     0.95626992044093     2.00000000000000     1.00000000000000
ULYAW    1 21 2      0      0 FEAA            0.018236566955641    -1.83622978049494     0.85804776530302    -1.84740518752455     0.99961700649533
                                                                   -1.89200532023258     0.96649324616546    -1.41346289594856     0.99893883979950
ULYAW    2 21 2      0      0 ELP             0.015203943102927    -1.84117829296043     0.86136943504058    -1.84722827171918     0.99942556512240
                                                                   -1.89339022414279     0.96048849609619    -1.41346289594856     0.99893883979950
  429   Sun Apr 20 18:23:27 2008 ranaSummaryLSClocking attempts
I noticed that the adaptive FF for the MC had stopped doing anything; this turned out
to be that the MC lost lock and the mcdown script turned off the FF path to MC1.

Although there's no elog, it looks like there was ~60 attempts at locking the IFO
between 12:38 and 4:27 on Saturday afternoon. I'm attaching here a plot showing
lock attempt durations and a histogram of lock times.
  431   Sun Apr 20 23:39:57 2008 ranaSummarySUSMC1 electronics busted
I spent some time trying to fix the utter programming fiasco which was our MCWFS diagonalization script.

However, it still didn't work. Loops unstable. Using the matrix in the screen snapshot is OK, however.

Finally, I realized from looking at the imaginary part of the output matrix that there was something
wrong with the MC1 drive. The attached JPG shows TFs from pit-drives of the MC mirrors to WFS1.

MC1 & MC3 are supposed to have 28 elliptic low pass filters in hardware for dewhitening. The MC2
hardware is different and so we have given it a software 28 Hz ELP to compensate. But it looks like
MC1 doesn't have the low pass (no phase lag). I tried switching its COIL FM10 filters to make it
switch but no luck.

We'll have to engage the filters to make the McWFS work right and to get the MC noise down. This
needs someone to go check out the hardware I think.

I have turned the gain way down and this has stabilized the MC REFL signal as you can see from the StripTool screen.
  441   Thu Apr 24 11:50:10 2008 josephbSummaryComputer Scripts / ProgramsUseful tidbits learned while tracking the network setup
In process of understanding the network setup I've learned several things:

1) The status lights on C0DAQ_RFMNETWORK.adl are controlled by the fiber network, as opposed to the ethernet network. However, even if everything is working properly on the VME end, you may still need to reboot it in order to be able to contact it via the ethernet (ssh or telnet).

2) After disconnecting the hub out by 1Y9, I was able to telnet into c1vac1, but not c1vac2. I was told that the Turbo pump and Ion pump readbacks on C0VACMONITOR.adl had not been working for awhile (years?). So I went out and rebooted the c1vac2 card. This seemed to restore the epic channels and we now have correct readbacks on the turbo pumps. The ion pumps all are reading no voltage, which is good because they're turned off. However C1:Vac-IPSE_mon is reading "On", although Steve assures me the actual unit is currently off, so there may be a minor channel issue there.
  444   Thu Apr 24 22:06:47 2008 AndreySummaryComputersEthernet Cables and Hubs
Today in the morning (between 8.30AM and noon) Joe and I were working on understanding which ethernet cables connect "processors controlling the work of equipment in the interferometer room" and "Internet hub in the computer room".

Firstly, we took off several times the blue ethernet cables from the router located near ETMX in the morning. We were trying to understand which port in the hub is responsible for the interaction with that processor.

Secondly, we were working on reviving the connection with the computer controlling vacuum in the interferometer.

Later in the middle of the day (around 2PM) Joe continued some work with ethernet cables without me. We plan on continuing the cable work on Friday morning. A better and more detailed elog will appear then.
  449   Fri Apr 25 13:53:11 2008 josephbSummaryComputersNetwork setup
This is the promised more in detail summary from Andrey's log ID 444.

What we did was go around to each hub, one at a time, unplug the network connection, and figure out which light on which hub went out. We then, went back to the control room, confirmed that we were still able to talk to the devices connected to the hub, and if not, rebooted them. This process was repeated for each hub.

As it stands, the hubs located at the ends of arms (in racks 1X4 and 1Y9) are connected to the really old 24 port 10 Base T hub located in 1Y7. In addition, the 5 port SMC hub is plugged into the 8 port SMC switch in 1Y5 (which actually has enough ports to simply move all the connections over to it, so I'm not sure why there are two...).

All other hubs/switches are connected back to the control room 24 port switch.

Attached is a simple diagram of the network connections for the 40m lab.
ELOG V3.1.3-