Investigating alternative to craning Genie over XBM and YBM -> Am considering scaffolding+plank catwalk etc.  (TCS table on south side of BSC1 is impeding access)

Kyle, Gerardo 

Moved pump cart from X-end and added to HAM1 -> Pumped HAM1/HAM2 annulus from HAM1 pump port and HAM2 pump port -> Pumped BSC3 annulus 

1530 hrs. local -> Shut down annulus pumping (continue during Tuesday maintenance)

Scott L. Ed P. Chris S.

Cleaning is complete from single door between X-1-4/5 to X-1-4 double doors. Cleaning report to follow tomorrow and relocation of equipment to begin cleaning from single door to X-1-5 double doors.
Continuous monitoring of the beam tube pressures by control room. 

Summary--No answers yet but, Guardian still kicks RZ when Z ISO loop is started, command scripts don't; Guardian ST2 gain/whitening scheme still not right(believe we have corrected this now;) Isolation Loop Spectra amplified with MICH engaged.

1) See first attachment of 8 minutes of second trend.    T=1 is when the guardian turns on the Z Isolation loop as evidenced by the start of non-zero _Z_OUT16.  Notice above this channel, the _RZ_OUT16 is not on.  Notice though on the upper left plot how the RZ_INMON is influenced by the Z loop turn on at T=1.  About 30 seconds after T=1, the RZ loop turns on with a large spike.    At T=2, the Z loop is started with the command script and while the INMONs before the start times are different, the Z turn on does not do near the abuse to RZ as does the Guardian.  See the attachment of aLOG 17402 17042 for several more comparisons where the turn on is not possibly contaminated by watchdog trips and MICH influence.

Still, my conclusion, Guardian does something abusive when clearly it isn't necessary.

2) I need to have more time to understand exactly what guardian is doing during the steps but when Mich is locked and Guardian moves the ISI toward HIGH_ISOLATED, the gain/whitening of the Stage2 GS13 are switched to an analog whitened high gain state and trips immediately.  Again, I need to study this exactly as it isn't verbose in the Guardian Graph but this is my observation recollection.  With the MICH locked and the Stage2 tripped (which it did many times,) the ISI could not be untripped as the MICH was pushing the ST2 too much.  Maybe it would do it in low gain but I'm not sure I even tried that with Guardian doing its own thing.  I finally did get the guardian to leave the GS13 gains alone, obvious now to me, by using the command scripts where I could leave the GS13 in analog whitened low gain.

Conculsion: More test time needed but for now it seems the GS13 must be kept in whitened low gain when MICH comes on.  ADD ON--We found a spot in the Guardian and corrected this-see aLOG 17092.

3) By using the command scripts, I was able to turn on the Z and RZ ISO loops with Boost of ST2.  I then turned on the Y dof without boost and it managed to stay Isolated long enough to get reasonable looking spectra.

See second attachment: The lighter colored thicker reference traces were collected yesterday morning when I engaged all 4 loops without the MICH locked.  I can't recall now if I did this with the guardian or not.  This morning, finally with MICH locked, I got the loops on while running a 3 average exponential ASD.  The thin dark current traces are the Z RZ and Y Isolation OUTs.  I managed to pause the measurement before the trip contaminated these spectra.  Maybe the traces were settling down still at the time this spectra was frozen but, the Z RZ & Y loops were on for 180 135 & 45 seconds respectively before the measurement stopped.  Still, clearly, there is much elevation in the drive spectra from several 100hz down to 1 to 20 hz depeneding on the DOF.  Around 70-80hz, the increase is 2+ orders of magnitude.

Further conclusions w/JeffK--We will try to do similar with the Actuator Outputs (no  DQ channels.)  Otherwise, with this isolation output elevation and the shapes of the Actuator output filters, it isn't surprising that we could be near DAC saturation.

While looking for my Guardian -vs- Command Script Isolation turn on problem, we (JeffkK & JimW) spotted the GS-13 gain switch error.  So we changed guardian code to reflect the correct GS13 gain switching.

changed

/opt/rtcds/userapps/release/isi/common/guardian/isiguardianlib/isolation/util.py

WHAT IT WAS

######################## HP 12/04/14 ########################
# Added to allow T240 gain switch on BS
def switch_gs13_inf(command):
    #command is 'HighGain' or 'LowGain'
    ez_ca = myEzca()
    chamber_type = top_const.CHAMBER_TYPE
    chamber = top_const.CHAMBER
    for ddd in iso_const.ISOLATION_CONSTANTS_ALL['BSC_ST1']['LOC_DOF']:
        if command == 'HighGain':
            ez_ca.switch( 'ISI-' + chamber + '_ST2_GS13INF_' + ddd, 'FM5', 'ON', 'FM4', 'OFF')
        if command == 'LowGain':
            ez_ca.switch( 'ISI-' + chamber + '_ST2_GS13INF_' + ddd, 'FM4', 'ON', 'FM5', 'OFF')
    wait(3) # To account for the 2s zero-crossing timeout
#############################################################

WHAT IT IS NOW

######################## HP 12/04/14 ########################
# Added to allow T240 gain switch on BS
def switch_gs13_inf(command):
    #command is 'HighGain' or 'LowGain'
    ez_ca = myEzca()
    chamber_type = top_const.CHAMBER_TYPE
    chamber = top_const.CHAMBER
    for ddd in iso_const.ISOLATION_CONSTANTS_ALL['BSC_ST1']['LOC_DOF']:
        if command == 'HighGain':
            ez_ca.switch( 'ISI-' + chamber + '_ST2_GS13INF_' + ddd, 'FM4', 'OFF', 'FM5', 'OFF')
        if command == 'LowGain':
            ez_ca.switch( 'ISI-' + chamber + '_ST2_GS13INF_' + ddd, 'FM4', 'ON', 'FM5', 'ON')
    wait(3) # To account for the 2s zero-crossing timeout
#############################################################

So this sets the "HighGain" state to FM4 & 5 off which gives us non-whitened high analog gain, and,

the "LowGain" had FM4 and 5 on giving us analog whitened low gain.

Attached are the current PSL DBB scans. We will review in the PSL meeting. 

Gabriele, Elli, Dan, Sheila

Today we worked on ASC for DRMI + arms off resonance.  

• Changes to input matrix-
  • Gabriele made a nice script that measures the sensing matrix.  (alog 17085 )
  • Previously we had simply copied the input matrix that livingston used, which was close enough to let us close several loops, but clearly was not the best choice of signals for us.
  • Based on the measured sensing matrix we changed our input matrix so that we are using REFL A 9I for PR2 and POP A for PRM.   Both of these choices seem like clear improvements over what we did in alog 17028, with about 20 times more signal in POP A than POP B for PRM.

• Higher bandwidth PRC loops
  • both PRC1+PRC2 loops were ridiculusly slow in our first attempt at these loops.  We have added pairs of poles at 0.3 Hz to each of these loops, which allow us to increase the gain to have UGFs of around 100 mHz.  PRC1 is still slower that PRC2.  This helped make the AS_C signal seem more sensible, before it seemed to be contaminated by PRC fluctuations.  
  • We also moved gains into filter modules, screen shot of all of these changes attached.   
  • After these changes we were able to close the PRC1, PRC2, MICH, and INP1 loops several times and at first things seemed to be better. We were engaging BS first, then IM4, then PR2, and PRM last.  

• demod phase of AS 36 WFS is very sensitive to SR2 alingment
  • we then ran into trouble, and found that we weren't able to engage the BS WFS (they would come on and reduce the sideband build ups.) We redid the initial alingment, but this was still true.  The BS WFS had seemed reliable since the rephasing described in 17005,
  • Gabriele rephased AS36 B carefully, quadrant by quadrant, to minimize the SRM signal seen in the Q phase.  After this we saw that there is still an offset between the WFS signal zero and a good buildup in DRMI.  
  • We moved SR2 by ~4 urad, and saw that the carefull phasing we had just done was wrong by 70-90 degrees.  We also see that we can mode hop by moving SR2 by a couple of microradians, even though based on the DRMI build ups we seem to be in a good alignment tonight.  
  • It could be that servoing to AS_C could help this problem, but we need to think about how to set the centering onto AS_C to accomplish this, since the method Elli and I used was not precise to the level of a micro radian (17085. )

I wrote a script to measure a genereric sensing matrix, and today we tested it for the pitch degree of freedom in the DRMI configuration.

The script (attached) configuration is at the beginning of the python file. One has to set

• the list of excitation channels to be used, the corresponding line frequencies and amplitudes, the duration of each measurement
• the list of error signals (the one you want to include in the sensing matrix, at the "numerator" of the transfer function)
• the list of monitoring channels that are used to measure the motion of the optics (those will be used as the "denominator" in the transfer functions)

When lauched, the script switches on the excitation one at a time (GPS times are saved to a log file for future reference).

When all line injections are done, the script reads the data and compute the sensing matrix. Basically, it's the value of the transfer function (error signals) / (monitoring channels).

The output is saved to an HTML file that contains three tables:

• the absolute values of the sensing matrix, with the dominant degree of freedom emphasized for each error signal, and not coherent elements grayed out
• the table of coherences
• the sensing matrix with the full complex elements

For reference, the attached script shows the configuration we used to measure the ASC pitch sensing matrix in DRMI. Beware that the excitation amplitudes are no more correct, since we changed some of the loop filters. We were injecting the lines at the error point of the ASC loops, monitor the mirror motions using local sensors (optical levers and OSEMs) and considering all the corner  WFS and QPD.

The result, copied directly from the output of the script, follows:

Sensing matrix (abs)

Coherence matrix

Sensing matrix (complex)

In response to Evan's alog (alog 17065), I took a look at the DARM spectra. Here are conclusions at the moment:

• In the 2.8 W configuration, the optical gain seems to have decreased by approximately 9% compared with the noise curve from Feb. 26th (alog 16982) with the assumption that the high frequency band is limited by shot noise. This resulted in a too-good noise curve last night.

• The origins of this discrepancy is not clear.
  • Note that the arm build up (e.g. ASC_TR_X(Y)_B_QPD_SUM) were lower than that of Feb. 26 th only by 1-2% which is not big enough to explain the discrepancy. See the attached trends for more details.
  • One possible factor can be different sensing gain in the digital system such as OMC-READOUT_SCALE and LSC input matrix which the midnight lockers change every time they are transitioning to DC readout. I did not get chance to carefully go through these values yet.

• In the 8 W configuration, the 9% discrepancy was inherited and hence too good noise again by 9% above 1 kHz. On the other hand the power scaling from 2.8 to 8 W seems to have been done precisely.

• A strange thing is that the noise curve at around 2.8 kHz became further too low for some reason in the 8 W configuration. This can not be explained by the 9% overall discrepancy factor. The noise in this region seems lower by 10-ish% than the GWINC curve.

(Noise spectra)

The data sets that I used are from:

• 2015-02-26 10:2:50 (at 2.8 W)
• 2015-03-04 10:08:55 (at 2.8 W)
• 2015-03-04 14:03:55 (at 8 W)

Here is a comparison of all three curves with the GWINC theoretical curves above 400 Hz up to 7600 Hz.

As Evan reported, indeed the measured curves from last night are lower than the GWINC curve in 1 - 4 kHz band while the one from Feb-26 looks fine.

(Discrepancies between the curves)

Now, I want to answer how much the Mar-4 data differed from the one from Feb-26th by taking the ratio between them. I divided the Feb-26th by Mar-4th spectra in 400-7600 Hz band. Then I convert it into a histogram to see how they differ on average. Since there were many peaks whose amplitude varied as a function to time, I excluded them by limiting the histogram range from 0 to 2. The ratio is shown as red bars in the below plot.

Note that I could have done a fancy Gaussian fit for it, but for now I picked the highest bar in the histogram in order to coarsely estimate the ratio. As shown in the plot, the Feb-26 data had a higher noise level by a factor of 1.09 on average.

Then I did the same ratio analysis for the 2.8 W and 8 W data of Mar-4th. It is shown as blue bars in the same histogram plot. Picking the highest bar, I measured the ratio to be 0.58 which agrees with what we expected i.e. sqrt( 2.8W / 8W) = 0.59. So the power scaling from 2.8 W to 8 W seems to have been done correctly last night.

(Unexplainable dip at around 2.8 kHz in the 8 W data)

However, it is not the end of the story yet. The noise curve of the Mar-4 at 8 W had a funny feature at around 2.8 kHz where the noise go down below the GWINC curve even if i apply the 9 % correction.

The below plot shows "normalized" spectra of all the three data sets. In order to line up all the spectra at the same level, I "normalized" the Mar-4th-2.8W data by multiplying a factor of 1.09. In a similar manner, I "normalized" the Mar-4th-8W data by a factor of 1.09/0.59. In this way I checked the shape of all the spectra.

The Mar-4th-8W data was lower by the rest of the two curves by 10-ish %. I did not do a serious histogram analysis.

Finally , if I apply only the 1.09 correction factor to the data from last night, they look like this:

Apparently the Mar-4-8W data is lower at around 2.8 kHz than the GWINC curve.

The usual BruCo report can be found here:

https://ldas-jobs.ligo.caltech.edu/~gabriele.vajente/bruco_1109509816/

Here is my summary:

• Around 10-20 Hz there is coherence with PEM-CS_ACC_LVEAFLOOR_HAM1_Z_DQ and ISI-HAM2_BLND_GS13Z_IN1_DQ, and a bit less with PEM-CS_ACC_PSL_PERISCOPE_X_DQ. Maybe some seismic noise entering as beam jitter?
• In the 10-100 Hz region we start seeing some coherence with MICH and SRCL. Almost time to install MICH and SRCL subtraction
• The accelerometer on the PSL periscope shows good coherence at the peaks around 200-400 Hz
• There is coherence with intensity noise above 100 Hz, even though not too large yet. The coherence is comparable with the one we see wit PRCL and SRCL at high frequency.
• We see the (likely) ring heater line at 75 Hz

These are the OpLev trends for the past 24 hours. Will review with the OpLev group.

Scott L. Ed P. Chris S.

Frozen water in the D. I. tank made for a slow start this morning. Cleaned 50 meters moving south towards X-1-4 double doors. Tube pressures continually  monitored by control room and frequently by the vacuum crew.
Safety meeting this afternoon. 

Early H1 DARM spectra showed strong coherence with the IMC WFS dc readouts, particularly in yaw. In DARM this showed up as a fairly smooth noise bump between 100 and 200Hz. It was thought this was input beam jitter caused by the input beam PZT mount (on the PSL/IO periscope). Since then, low pass filters have been added to the PZT driver outputs to reduce the PZT mount pointing noise. The attached plot shows the coherence between DARM and the IMC WFS dc channels for last night's lock. We no longer see the broadband coherence betwen 100 and 200Hz (though there is some in a narrower band around 175 Hz). But there is significant coherence in other frequency bands -- in particular around 250-270 Hz, and around 350 Hz. The only place that the coherence manifests as a real peak in DARM is at 285 Hz. At least some of this coherence should go away when the input PZT mount is moved from the periscope down to the table surface.

The attached plot shows the frequency of the IMC VCO, when the common tidal feedback path to the ETMs is running. At the beginning of the plot the offset in the IMC_F filter module was set to zero. This then puts the IMC VCO in average ~150 kHz below the fixed frequency oscillator which drives the fiber EOM. In the second half of the plot the offset was changed to -3500 counts and the IMC VCO shifted to ~200 kHz above the AOM frequency. Under nominal conditions the offset is at –1750 counts, which corresponds to roughly zero offset at the output of the filter module.

The important thing is to avoid a frequency crossings of these two RF sources, since this is one of the reasons for RF crosstalk into the laser frequency noise. We should probably try to move the IMC VCO frequency up by another 100 kHz to make sure we stay away from zero.

The COMM and DIFF VCOs are running at nominal 78.92 MHz. Since they implement two stages of the frequency-difference-divider, their range is no larger than ±150 kHz. Hence, they cannot reach the AOM frequency—or the IMC VCO frequency when it is above the AOM one. Once we are in full lock and the green beams are turned off, we need to make sure that these two VCOs are at least 10 kHz apart from each other. This should then prevent RF crosstalk by the VCOs from reaching the detection band.