ELOG 40m

MC WFS

MC WFS are on. They seem to do some good during the day.

600

Mon Jun 30 08:59:23 2008

steve

IOO-MC_DEMOD_LO is low

The alarm handler is beeping relentlessly: asking for help in high partical count and low demod signal

599

Mon Jun 30 05:33:38 2008

Abs. Len. Meas. ~ Optical setup (II)

o The position of the iris was adjusted so as not to disturub the beam for OMCR CCD.

o The RF spectrum analyzer was returned to the place of the network analyzer.

Quote:

In the process of making this report, I noticed that one of the iris apertures is about disturbing the beam for OMCR CCD. I will check this before I go to Hanford. Also an RF spectrum analyzer is at the AP table. I try to return this near the PSL on Monday morning.

598

Mon Jun 30 01:49:06 2008

I'm in the process of aligning the mode cleaner/ input beam.

I turned off the WFS and cleared their histories, adjusted the input periscope and re-aligned the mode-cleaner accordingly.
I then unlocked the cavity and centred the beams on the WFS.

MC transmission is ~3.3 and the REFL beam looks a little better.

However, turning the WFS on now lowers the transmission. More thought tomorrow.

I'm leaving the MC locked with WFS off.

597

Sun Jun 29 20:29:48 2008

Correlation of PSL SLOW control v. Room temperature

PSL

596

Sun Jun 29 20:09:40 2008

mcup and mcdown indicators

I edited the mcup and mcdown scripts so that C1IFO_STATE shows when these scripts are running.

I also added indicators to the LockMC screen.

595

Sun Jun 29 19:53:26 2008

Quote:

I reduced the gain of the ISS (C1: PSL-ISS_VGAGAIN) from 5dB to 2dB. Any higher and it constantly saturates.

Seemed to go back to normal after the frame builder came back.

594

Sun Jun 29 19:19:47 2008

Trends of the PSL/IOO Quads over 1000 days

Only IOO POS has been working for the past 2 years. I guess we should recommission the IOO ANG and REFL QPDs

593

Sun Jun 29 18:58:43 2008

1e20 is too big for AWG and/or IOVME

Computers

While testing out my matlab/awgstream based McWFS diagnostic script I accidentally put a
huge excitation into

C1:IOO-WFS1_PIT_EXC

. This went to 1e20 and then caused
some SUS to trip and c1susvme2 to go red. I tried booting it via the normal procedures
but it wouldn't come back, even after 2 crate power cycles. I also tried booting AWG
via the vmeBusReset, but that didn't do it. Then I booted c1iovme from the telnet prompt
and then I could restart c1susvme2 successfully.

The reason the excitation was so large is that the following filter command is unstable:
[b,a] = butter(4,[0.02 30]/1024);

The low pass part is OK, but it looks like making such a low frequency digital filter
is not. Que lastima. On the bright side, the code now has some excitation amplitude
checking.

592

Sun Jun 29 14:53:02 2008

Quote:

All of the computers are now showing green lights.

Remaining problems:

Alignment scripts are failing with "ERROR: LDS - NDS server error #13"
I think this is a server transmission error.

Dataviwer shows all channels as zero.

Fixed. Just started the testpoint manager on fb40m.

su
/usr/controls/tpman &

591

Sun Jun 29 11:31:52 2008

I reduced the gain of the ISS (C1: PSL-ISS_VGAGAIN) from 5dB to 2dB. Any higher and it constantly saturates.

590

Sun Jun 29 02:33:28 2008

Abs. Len. Meas. ~ Optical setup (I)

I have constructed the beam injection optics for the abs length measurement.

The injection beam was coarsely aligned to the interferometer. The reflected beam from SRM was already seen at AS CCD.
I have attached the optical configration for this measurement and the optics layout at the AP table.

I am going to go to LHO for three weeks. During the absence Alberto tunes the mode matching and the alignment of the interferometer.

In the process of making this report, I noticed that one of the iris apertures is about disturbing the beam for OMCR CCD. I will check this before I go to Hanford. Also an RF spectrum analyzer is at the AP table. I try to return this near the PSL on Monday morning.

Attachment 1: Optical configuration for the abs length measurement.
1) One of the arms is locked to the PSL beam by the main control system (red).
2) A laser beam is injected from the AS port (blue). This laser essentially has different frequency from that of PSL.
3) The injected beam and the outgoing PSL beam appear at the output of the faraday in the injection system.
4) They beat each other at the frequency difference of those two lasers.
5) A PLL is used to lock the frequency difference to a local oscillator (LO).
6) The LO frequency is swept at around 3.87MHz, that is the approximate FSR frequency of the arm cavity.
7) If the LO frequency hits the FSR within the resonant width, the beating also appears at the transmitted light as the injected beam also becomes resonant to the arm cavity.
8) Amplitude of the beating at the transmitted light is measured by a RF spectrum analyzer as a function of the LO frequency. We get the FSR frequency (= the arm cavity length) from the top of the resonance.

Attachment 2: Optics at the AP table for the laser injection
700mW NPRO, laser source. vertically polarized.
Periscope, to raise the beam 1 inch to make the beam at the 4 inch elevation.
INJ_SM1/INJ_SM2, steering mirrors to align the injection beam to the IFO beam.
HWP1, half wave plate to make the beam to the farady horiz-polarized. nominal 42deg on the readout.
FI, Faraday isolator for protection of the NPRO from the returning light, for obtaining the returning light.
HWP2, to make the beam from the Faraday horiz-polarized. nominal 357deg on the readout.
MM_Lens, f=125mm to match the laser mode to the IFO beam.
SM1/SM2, steering mirrors to align the IFO beam to the Farady Isolator.
IRIS1/IRIS2, for the coarse alignment of the injection beam.
FLIP, flipper mount to turn on/off the injection optics.

Alignment procedure of the injection system
0) Ignite NPRO several hours before the experiment so that the laser frequency can be stable.
1) Turn up FLIP. Close the shutter of NPRO.
2) Adjust SM1/SM2 so that the ifo beam can appear at the output of FI.
3) Adjust height and position of IRIS1/IRIS2 with regard to the ifo beam so that the ifo beam goes through IRIS1/IRIS2 even when they are closed.
4) Turn down FLIP. Open the shutter of NPRO.
5) Adjust INJ_SM1/INJ_SM2 so that the injection beam can go through IRIS1/IRIS2 even when they are closed.
6) At this time, it is expected that the reflection of the injection beam from SRM appears at AS CCD, if SRM is aligned.
7) Adjust INJ_SM1/INJ_SM2 so that the injection beam at AS CCD can overlap to the IFO beam.
8) Confirm the beam at the output of the FI also overlaps.
---- We are here ----
9) Change the ifo configuration to the X or Y arm only.
10) Scan the crystal temperature of the 700mW NPRO in order to try to have the beating of the two beams at the PD. AS OSA may be useful to obtain the beating.
11) Once the beating is obtained, adjust INJ_SM1/INJ_SM2 such that the beating amplitude is maximized.

589

Sat Jun 28 23:23:50 2008

Sat Jun 28 14:56:44 2008

In short, I was editing the ini files yesterday evening, I didn't e-log it and after some investigation this afternoon it apears
that I am to blame for all the computer problems which followed.

I wanted to edit C0EDCU.ini and C1IOOF.ini to change C1: PSL-FSS_FAST to a fast channel as C1: PSL-FSS_FAST_F
was dead.

I opened these files and made backups. It appears this is where it all went awry. My backup for C1IOOF
is called C1IOO.ini.090627 i.e. missing the F.

Later c1susvme2 and c1iovme crashed. After failing to bring c1iovme back I wondered if my edits had
caused the problems so I restored the back up files. It appears that here I wrote over C1IOO with my backup of
C1IOOF (presumably because I had made a typo in the name).

To remedy the situation we could restore C1IOO from e.g. chans/archive/C1IOO_080618_160028.ini

No excuses for not e-logging this activity.

587

Sat Jun 28 03:10:25 2008

Quote:

C1susvme2 and C1iovme crashed which sent the optics swinging and tripped the watchdogs.

Koji and I were able to restore c1susvme2 without any trouble.

We have been unable to revive c1iovme. We have tried telneting in and running startup.cmd,
the process runs for a while then hangs with "DAQ init failed -- exiting".

Resetting the board doesn't help. I didn't try keying the whole crate.

All optics are back to normal with damping restored.

I tried keying the crate, then keying the DAQ controller & AWG, then powering down & restarting the framebuilder.
On coming up, the framebuild doesn't start a daqd process, and I can't get one to start by hand (it just prints "652", and then stops).
No error messages and daqd doesn't appear in the prstat.

I then tried keying the DAQ controller again (after the fb0 reboot), which blew the watchdogs on all the suspensions. So then I went around and keyed all the crates.

Now, the suspension controllers are back online. Still no c1iovme, and now the framebuilder/DAQ/AWG are also hosed. We can try keying all the crates again, in the order that Yoichi did last week.

After some more poking around, I found the daqd log file. It's now complaining about

Jun 28 03:00:39 fb daqd[546]: [ID 355684 user.info] Fatal error: channel `C1: PSL-FSS_MIXERM_F' is duplicated 126

This is the second error message like this. It first complained about C1: PSL-FSS_FAST_F, so I commented that out of C1IOOF.ini and rebooted the framebuilder (note this is an actual reboot of the full solaris machine). Eventually I discovered that C1IOOF.ini and C1IOO.ini are essentially identical. They presumably will keep getting these duplicate channel errors until one of them is completely removed.

C1IOO.ini has a modification time of seven PM on Friday night. Who did this and didn't elog it? I've now modified C1IOOF.ini, and I don't remember when it was last modified.

586

Fri Jun 27 19:59:44 2008

Fri Jun 27 18:21:01 2008

Response of the LO input on the MC demod board

Electronics

The alarm handler has been flipping out saying that the LO input of the MC's demod board is too low, so at Rana's suggestion, Eric and I measured the response of the LO input. We used an SR345 function generator at 29.485MHz and several different amplitudes to make a table. The demod board should see an input from the LO between 0-2dBm. When I measured what was going into the LO input from the 29.5MHz delay line phase shifter, the LO input was seeing 4dBm. I'm going to put a 3dB attenuator between the phase shifter and the demod board.

Also, now that we have this table of response values, I'm going to change the settings of the alarm handler to something more reasonable.

Amplitude of 29.485MHz input sine wave [dBm]    |        Value of channel C1:IOO-MC_DEMOD_LO
--------------------------------------------    |        -----------------------------------
-10                                             |        -0.000449867
-8                                              |        -0.000449867
-6                                              |        -0.000449867
-4                                              |        0.000384331
-2                                              |        0.00526733
0                                               |        0.0199163
2                                               |        0.0492143
4                                               |        0.0931613
6                                               |        0.161523
8                                               |        0.229885
10                                              |        0.293364

584

Fri Jun 27 18:03:46 2008

Another bad cable in the MC servo

Electronics

Eric was helping me to measure the response of the LO input on the MC's Demod board, and when we disconnected the end of the cable between the demod board and the delay line phase shifter for the 29.5MHz oscillator, we noticed that the phase shifter's end of the cable was loose, like the connector wasn't fully connected. When we checked it by wiggling the connector, the SMA end fell off. I made a new SMA end for the cable, and reinstalled the cable. The MC locked as soon as I plugged the cable in, so everything seems good again. I tried to not change the cable length when I remade the connector, but the cable is shorter than it was by a small amount, due to the way the end fell off.

583

Fri Jun 27 15:20:52 2008

I removed C1:LSC-XARM_CTRL from the frames and added C1:LSC-CARM_ERR

582

Fri Jun 27 14:36:39 2008

dust particle count is up & alarm handler is on

Locking

Rob, Yoichi, John

Some progress last night:

Switched back to SPOB_DC for CARM.

Shaped the MC LSC loop to reduce excess noise in the 20-30Hz band. Likely the most significant change.
Could this be due to fan noise from the laptop on the SPOB table?

Brought in the AO path earlier (at low gain).

Reduced offset to 6 and increased MC gain before handing off to SPOB. Ramped up AO and MC gain then switched off the
moving zero.

Looks like PD11 is the most promising candidate for RF CARM although the demod phase needs attention.

581

Fri Jun 27 09:20:15 2008

steve

Frogs

PEM

This 3 years plot show the trend of seasons.
When outside air quality goes bad ( 0.5 micron > 1 million ) the lab follows.
I will demonstrate this effect with a 4th of July fire works calibration.
Let's do not forget the construction activity next door either.

The alarm handler is busy:
It's sound level were reset to a modest level yesterday.
It would be nice to change the alarm sound so it can play Wagner:Der Ring des Nibelungen:
Das Rheingold, Die Walkure & Siegfried and Gotterdammerung
or something more appropriate than the present frog call

1, half micron count is climbing ( it's close to 16k now )
2, MZ refl signal is too high
3, MC lenght servo LO is too

580

Thu Jun 26 22:08:33 2008

3.7MHz bandstop filter in MC Servo

Electronics

The 3.7MHz elliptical bandstop filter that I made during my SURF summer is now installed in the MC servo loop to reduce the noise at 3.7MHz.

I have taken transfer functions with and without the filter between TP1A and TP2A, with EXCA at -20dBm, using the HP4195A Network Analyzer. I have also taken power spectra of TP1A with and without the filter, and time domain data with the filter of OUT2 on the MC Servo Board and Qmon on the Demod board just before the MC servo board. The filter is between Qmon and OUT2 in the loop.

The UGF and phase margin don't change noticeably with and without the filter, and the MC still locks nicely (after the minor fiasco this afternoon), so I think it's okay. The UGF is around 57kHz, with about 38 degrees phase margin.

1 July 2008: I redid the plots. Same info, but the traces with and without the filters are now on the same graph for easier readability.

579

Thu Jun 26 21:07:11 2008

I realized today, that yesterday while we were trying to debug the adaptive noise canceler, I turned
off the analog dewhitening on MC1. I did this by changing settings on the Xycom screen but I
forgot to elog this -- this may have caused problems with locking via increased frequency noise.
I have now returned it to its nominal, dewhitening on, configuration.

I also used mDV to look at the last year of dust trend. I have plotted here the cumulative
histogram in percentile units of the 0.5 micron dust level. The x-axis is in units of particles per cu. ft.
and the y-axis is percentage. For example, the plot tells us that over the last year, the counts were
below 6000, 90% of the time. I have set the yellow and red alarm levels to alarm at the 95-th and 99-th
percentile levels, respectively.

578

Thu Jun 26 20:59:22 2008

Computer Scripts / Programs

Alarm Handler

Please do not turn off the Alarm Handler on op540m.

577

Thu Jun 26 18:29:44 2008

MC Back online

Jenne, Rob, Yoichi

I was playing with the Mode Cleaner earlier today, working on measuring the effect of the new filter (see next post for loop gain measurements etc.), and bumped something which made it so the Mode Cleaner would not lock.

After much poking around by Rob and Yoichi, we found that the TNC-to-2 pin LEMO from Out1 of the MC Servo Board to Ch1 of the Pentek Generic board to the right of the MC Servo Board was bad. If we touched the cable, the MC would lock, but as soon as we let go, the MC would fall out of lock. The LEMO end of the cable was not heat shrink wrapped, so the 2 wires could have been touching. I replaced the cable, and the MC locked immediately after plugging it in, so I think that has fixed the problem.

576

Thu Jun 26 18:27:04 2008

Computer Scripts / Programs

No Dataviewer No Cry

Dataviewer was hanging. It would open the Grace window but then not plot anything. Since DTT was working
fine we diagnosed this as a DV only problem. It turned out that there was a boatload of messages in the
dataviewer queue. You can check for extra messaages using the command 'ipcs -q' and then use 'rmq' to remove them.

Dataviewer is working now.

Here's the screen dump from op440m:

op440m:~>ipcs -q
IPC status from <running system> as of Thu Jun 26 18:19:32 PDT 2008
T         ID      KEY        MODE        OWNER    GROUP
Message Queues:
q        400   0x1a51     -Rrw-rw-rw- controls    staff
q          1   0x501      -Rrw-rw-rw- controls    staff
q          2   0x512      -Rrw-rw-rw- controls    staff
q        103   0x553      -Rrw-rw-rw- controls    staff
q          4   0x574      -Rrw-rw-rw- controls    staff
q          5   0x18be     --rw-rw-rw- controls    staff
q         56   0x1d9f     -Rrw-rw-rw- controls    staff
q          7   0x1e56     -Rrw-rw-rw- controls    staff
q          8   0x1efd     -Rrw-rw-rw- controls    staff
q        109   0x2044     -Rrw-rw-rw- controls    staff
q         10   0x207a     -Rrw-rw-rw- controls    staff
q         11   0x24c4     -Rrw-rw-rw- controls    staff
q         12   0x24d7     -Rrw-rw-rw- controls    staff
q         13   0x251b     -Rrw-rw-rw- controls    staff
q         14   0x2fe8     -Rrw-rw-rw- controls    staff
q        115   0x3a65     -Rrw-rw-rw- controls    staff
q        116   0x967      -Rrw-rw-rw- controls    staff
q         17   0x98e      -Rrw-rw-rw- controls    staff
q        118   0x456c     -Rrw-rw-rw- controls    staff
q        669   0x194      -Rrw-rw-rw- controls    staff
q        620   0xe70      -Rrw-rw-rw- controls    staff
q         71   0x15d0     -Rrw-rw-rw- controls    staff
q        222   0x3586     -Rrw-rw-rw- controls    staff
q        173   0x5e37     -Rrw-rw-rw- controls    staff
q        624   0x5e4d     -Rrw-rw-rw- controls    staff
q        475   0x10d7     -Rrw-rw-rw- controls    staff
q        176   0x5ee3     -Rrw-rw-rw- controls    staff
q        277   0x4e22     -Rrw-rw-rw- controls    staff
q        428   0x25f3     -Rrw-rw-rw- controls    staff
q         29   0x3354     -Rrw-rw-rw- controls    staff
q        180   0x368f     -Rrw-rw-rw- controls    staff
q        131   0xb0f      -Rrw-rw-rw- controls    staff
q         82   0x47a5     --rw-rw-rw- controls    staff
q         83   0x4b83     -Rrw-rw-rw- controls    staff
q         34   0x4f6d     -Rrw-rw-rw- controls    staff
q         85   0x4539     -Rrw-rw-rw- controls    staff
q         86   0x67a1     --rw-rw-rw- controls    staff
q         37   0x4b7      -Rrw-rw-rw- controls    staff
q         38   0xd37      -Rrw-rw-rw- controls    staff
q         39   0x156c     -Rrw-rw-rw- controls    staff
q         40   0x2b62     -Rrw-rw-rw- controls    staff
op440m:~>rmq
---------------------------------------------------------------
Deleting message queues which are owned by user: controls ....
---------------------------------------------------------------
      Deleted message queue: 400
      Deleted message queue: 1
      Deleted message queue: 2
      Deleted message queue: 103
      Deleted message queue: 4
      Deleted message queue: 5
      Deleted message queue: 56
      Deleted message queue: 7
      Deleted message queue: 8
      Deleted message queue: 109
      Deleted message queue: 10
      Deleted message queue: 11
      Deleted message queue: 12
      Deleted message queue: 13
      Deleted message queue: 14
      Deleted message queue: 115
      Deleted message queue: 116
      Deleted message queue: 17
      Deleted message queue: 118
      Deleted message queue: 669
      Deleted message queue: 620
      Deleted message queue: 71
      Deleted message queue: 222
      Deleted message queue: 173
      Deleted message queue: 624
      Deleted message queue: 475
      Deleted message queue: 176
      Deleted message queue: 277
      Deleted message queue: 428
      Deleted message queue: 29
      Deleted message queue: 180
      Deleted message queue: 131
      Deleted message queue: 82
      Deleted message queue: 83
      Deleted message queue: 34
      Deleted message queue: 85
      Deleted message queue: 86
      Deleted message queue: 37
      Deleted message queue: 38
      Deleted message queue: 39
      Deleted message queue: 40
---------------------------------------------------------------
op440m:~>

575

Thu Jun 26 18:24:28 2008

Yoichi

FSS input ofset slider problem - fixed

PSL

I checked the FSS servo interface board and found that a LT1125CSW used to differentialize offset channel was broken (no virtual short).
So I replaced it. Now the slider is working.
The op-amp was hitting the rail. So it seems like we had been applying the maximum offset to the FSS input all the time.
The reason why the FSS loop still worked with the large offset is that the applied offset (~14V) is attenuated by a factor of 500 at the summing point.

574

Thu Jun 26 14:06:00 2008

Masha

500mW INNOLIGHT NPRO info

Below is the placement of 500mW INNOLIGHT NPRO mephisto laser. It is set up on the Symmetric Port table.

573

Thu Jun 26 12:30:40 2008

Idea:

Try REFL_DC as the error signal for CARM rather than PO_DC.

Reasoning:

The PO signal is dominated by sideband light when the arms are detuned so that any misalignment in the recycling cavity introduces spurious signals. Also, the transfer function from coupled cavity excitation to REFL signal is not so steep and hence REFL should give a little more phase. Finally, the slope of the REFL signal should make it easier to hand over to RF CARM.

Conclusion:

The REFL signal showed no clear improvement over PO signals. We've gone back to PO.

During the night we also discovered that the LO for the MC loop is low.

572

Thu Jun 26 10:56:15 2008

I removed the Bartington Magnetometer on the x arm to one of the outside benches. I'll be trying to determine if and how it works today. It makes a horrible high pitched sound which is due to the fact that the battery is probably 16 yrs old. It still works with ac power though and I want to see if it is still operating correctly before I ask to buy a new battery. Sorry for the bother.

571

Thu Jun 26 01:10:18 2008

Alarm Handler indicates that dust level is high

PEM

In its first useful act, the Alarm Handler started beeping indicating that the dust particle
counts for particles of diameter less than 0.5 micron had exceeded 5000 /cu. ft. Here's the
80 day trend of particles, temperature and humidity:

570

Thu Jun 26 01:08:22 2008

Configuration

FSS Input Offset slider problem

Alarm Handler Revived

I have revived the Alarm Handler by turning it on on op540m and adjusting the levels of
several of the alarming channels to not alarm (like laser power). The alarm levels are now
set to something reasonable and people should start actually paying attention to them.

I also removed the EO Shutter and Stacis alarm stuff since we don't use them.

To really get in and edit it, you have to close the Alarm Handler and edit the file
in /cvs/cds/caltech/alh/. It allows you to add/subtract useful channels and put in
guidance information.

If the alarm handler beeps about something, don't just close it or silence it, Steve. Just
fix it somehow (either set the threshold better or find the real cause).

569

Wed Jun 25 18:03:21 2008

Yoichi

Configuration

PSL

While working on the PMC scanning, I noticed that the FSS input offset slider is doing nothing.
I traced the signal flow and checked the cables/boards.
The slider changes the output voltage from a VMIVME4116 DAC in the PSL rack. This output voltage is confirmed to be correct at the FLKM64 connector. The signal is connected to the FSS servo interface box (D040423) trough a ribbon cable. However, the output from the interface box is always -27V regardless of the slider position.
Therefore, either the interface box (D040423) or the ribbon cable has a problem.
I will debug the interface box using an extension card when no one is working on the interferometer.

568

Wed Jun 25 13:56:56 2008

Locking

Tuesday night locking

Rob, John

Worked to try and reduce the CARM offset using the dc arm transmissions before changing to SPOB DC. This proved somewhat unsuccessful, the offset couldn't be reduced to more than five (arms storing 5x more power than single arm cavity lock).

567

Wed Jun 25 13:38:22 2008

Abs. Len. Meas. ~ Placement of the 700mW NPRO on the AP table

This morning I have put the 700mW NPRO on the AP table for the abs length measurement.

The RF amplifier was moved (the cables were not changed). I cleaned up some cable arrangements. I was keen not to disturb any of the other optical path. Even so, please let me know if any suspicious behaviour is found on the AP table.

566

Wed Jun 25 12:25:28 2008

Eric

Cameras

2D Gaussian Fitting Code

I initially wrote a script in MATLAB that takes pictures of the laser beam's profile and fits them to a two dimensional gaussian in order to determine the position and width of the beam. This code is now (mostly) ported to C so that it can be imbedded in the camera software package that Joe is writing. The fitting works fairly well for pictures with the beam directly incident on the camera, and less well for pictures of scatter off the end mirrors of the arms, since scatter from defects in the mirror have intensities much greater than the intensity of the beam's gaussian profile.

The next steps are to finish up porting the fitting code to C, and then modify it so it can better handle the images off the end mirror. Some thoughts on how to do this are to use a fourier transform and a low pass filter, or to simply use a center-of-mass calculation (with the defect peaks reduced in intensity), since position is more important than beam width in this calculation. The eventual goal is to include the edge of the optic in the picture and use the fit of the beam position in comparison to the optic's position to find the beam's location on the mirror.

565

Wed Jun 25 11:36:14 2008

Max Jones

Computer Scripts / Programs

First Week Update

For the first week I have been modifying the noise budget script in caltech/NB to run with 40 m parameters and data. As per Rana's instructions, I have tried to run the script with only seismic and Darm sources. This involves identifying and changing channel names and altering paramter files (such as NB/ReferenceData/C1IFOparams.m). To supply the parameter files, I have copied the H1 files with (as yet only) slight modification. The channel name changes have been made to mirror the sites for the most part. Two figures are attached which show the current noise budget. The Day plot was taken 6/23/08 at ~10:30 am. The night plot was taken 6/22/08 at ~11:00 pm . Note that the SRD curve is for the sites and not for the 40 m (I hope to change that soon). Also in one of the plots the DARM noise signal is visible. Obviously this needs work. A list of current concerns is

1) I am using a seismic transfer function made by previous SURF student Ryan Kinney to operate with channels of the form C1:PEM_ACC-ETMY_Y (should I be using C1:DMF-IX_ACCY?) and the channels I am currently using are the acceleraometers for the mode cleaner with names of the form C1:PEM_ACC-MC1_X. Rana said that he thinks these may be the same but I need to be sure.

2) We don't have a DARM_CTRL channel but the code requires it, currently I am using DARM_ERR as a substitute which is probably partly responsible for the obvious error in DARM noise.

Any suggestions are appreciated. Max.

564

Wed Jun 25 11:01:45 2008

For the first week, I have been learning about fiber noise cancellation, auxiliary locking techniques, and other relevant helpful topics in more detail. I am now working on a setup (more detail in previous entry) to measure phase noise introduced by 25m(?) fiber, and then will proceed to try to cancel the noise.

563

Wed Jun 25 09:46:45 2008

Sharon

Adaptive Filters

I have been learning about different methods for applying adaptive filters to improve the Mode Cleaner lock in specific, and other LIGO systems in general.
Finding the exact number of coeffs we would like to apply for our FIR adaptive filter is very important to the efficiency of the filter. Getting this number higher might improve the accuracy of the filter, but costs time we do not have. Another important number to find is the step size. The step size is the variable that controls how far back we want to look into our data for finding the new coeffs. To understand more about the step size it is necessary to learn about the standard deviation of our input and output signals. By getting the step size too big, we are considering long term behavior, but might be missing out on a short term one.
In the near future I will be learning about the meanings of these variables and their contribution to the over all accuracy of our filters.
Results will be posted.

562

Wed Jun 25 01:30:19 2008

Frequency noise after the MC

I made some (very) rough estimates of the contribution made to the noise after the mode cleaner by three sources.

Seismic noise - how much of the signal is due to the mode cleaner compenstaing for seismic disturbance of CARM.
Actuator noise - coil drivers and DAC noise.
MC_F - estimate of MC_F suppressed by the loop gain.

561

Wed Jun 25 00:35:40 2008

Optical Layout on the AP table

I have visited the AP table in order to investigate where we are going to put the optical setup for the abs. length meas.
I have attached the PNG and PDF files to share the optical layout. It is not complete. Any comments or corrections are welcome.

560

Tue Jun 24 22:43:23 2008

Tue Jun 24 22:31:10 2008

Masha

my first step in fiber stabilization

Auxiliary locking

There is a new 1W INNOLIGHT NPRO laser at the Symmetric Port.

Set up an interferometer to measure difference in phase noise introduced by a fiber. Works as expected without the fiber! (balanced intensity, out of phase noise in the two outputs).

558

Tue Jun 24 17:12:10 2008

josephb, Eric

Configuration

Cameras

GC750 setup, 1X4 Hub connected, ETMX images

The GC750 camera has been setup to look at ETMX. In addition, the new 1X4 rack mounted switch (131.215.113.200) has been connected via new cat6 cable to the control room hub (131.215.113.1?), thanks to Eric. The camera is now plugged into 1X4 rack switch and now has a gigabit connection to the control room computers as well as Mafalda (131.215.113.23).

By using ssh -X mafalda or ssh -X 131.215.113.23, then typing:

target
cd Prosilica/bin-pc/x86/
./Sampleviewer

A viewer will be brought up. By clicking on the 3rd icon from the left (looks like an eye) will bring up a live view.

Closing the view, and then cd ../../40mCode, and then running ./Snap --help will tell you how to use a simple code for taking .tiff images as well as setting things such as exposure length and size of image (in pixels) to send.

When the interferometer was set to an X-arm only configuration, we took two series of 200 images each, with two different exposure lengths.

Attached are three pdf images. The first is just a black and white single image, the second is an average of 100 images, and the third is the standard deviation of the 100 images.

557

Tue Jun 24 15:15:09 2008

Rob, Rana, John

In the past week or so we've been working on reducing the CARM offset using a DC signal (SPOB DC).
We were able to get up to arm powers of around 30 (where a single arm cavity lock is a power of 1)
before instability set in and we would lose lock for, as yet, unknown reasons.

In recent nights locking efforts have taken a few backward steps.

Since last Thursday engaging the AO path has proved troublesome, i.e. engaging it would instantly
cause loss of lock. This seems to be related to problems with the mode cleaner servo. For the past
few nights it has been behaving strangely and could not be operated with the usual super boost stages.
Last night the situation was improved. MC boost stages could be used and the AO path engaged. The
cause of this problem and its spontaneous resolution are not understood.

Last night we were unable to switch CARM to SPOB DC. I've attached a spectrum of the MC2 length signal.
This path is being used for CARM and so gives an indication of the frequency noise after the mode
cleaner. At the moment the plot is calibrated in units of Rana's gut feeling. We already tested to see if
any of the excess noise was introduced by the WFS. No evidence was found. We'll try to make a useful
calibration soon and see if our problems are related to excess frequency noise.

Another realisation from last night was the effect of arm detuning on the analogue CARM path. When CARM is detuned
the coupled cavity pole removes an extra 90 degrees of phase. The digital path has the `moving zero' to compensate
for this. The analogue path has no such compensation and can therefore become unstable at moderate detunings.
We propose trying to reduce the CARM offset further before engaging the analogue path. This will give higher
gain and move the UGF to a region of increased phase margin.

556

Tue Jun 24 10:24:43 2008

Abs. Len. Meas. ~ Cavity Swing Measurement (2)

At the entry 555, Alberto reported the results of the cavity length measurement using cavity sweeping.
As expected, each result inevitably has an ambiguity depending on which resonance do we take as an upper sideband.

In order to exclude this ambiguity Steve and Koji performed a primitive non-optical measurement using a tape and photos:
This morning Steve and Koji did tape measurements to know the lengths between the ITM/ETM chambers.
Yesterday, Koji took photos of the optical tables in vacuum to know the actual positions of the suspensions.

The results are shown in the figures attached. From those non-optical measurements the lengths of the X/Y arm are known to be 38.48+-0.03 / 38.67+-/0.03 [m].

Then, we could exclude the shorter lengths of the values in the entry 555. i.e. The Y arm is longer than the X arm about 0.2 m.

These approximate lengths will be used in the further precise measurements which use precise scans of the FSR frequencies.

555

Mon Jun 23 21:51:19 2008

Alberto

Arm Cavity Length Measurement

We measured the arm cavity lengths sweeping the ETM mirror position and looking at the reflected demodulated output. We excited the mirror by a sine wave of 0.2 Hz and amplitude of 30000 counts. From the time series of the occurrences of the resonances of the sidebands and of the carrier we evaluated the free spectral range of the cavities and thus the lengths. The details of the procedure are explained in the attached document. As discussed in it, for each cavity we obtain two possible values of the length depending on which of the sideband resonances is that corresponding to the upper sideband and which corresponds to the lower one instead. The numbers are:
Lx=(38.30 +/- 0.08)m / (38.45 +/- 0.08)m
Ly=(38.16 +/- 0.08)m / (38.70 +/- 0.08)m

Since the difference between the two possibilities is quite large, we should be able to decide which one is correct by somehow measuring directly the cavity length. We want to try it tomorrow by a tape meter.

Alberto and Koji

554

Mon Jun 23 19:48:28 2008

rana,alberto