Daniel suggested that the mystery noise that comes and goes might be a parasitic interference in the fiber.

This morning, before anybody started any noisy activities, I went into the optics lab and gently tapped the fiber that is hanging from the ceiling panel of the clean room, from 8:13 AM (15:13:00 07/Sep/2012 UTC) for 30 seconds.

Attached is the short time spectra taken at various times before, during and after the tapping period, and sure enough, only the trace with tapping (blue) shows a very high noise in the right frequency band while everything else looks the same.

If you're interested in the data file, find the file name in the screen shot.

Note that "everything else" is still somewhat noisier than the black reference taken on 22/Aug.

I'm turning the WFS loops off (@ 7:20:00 UTC).

Alberto recentered the beam on WFS, I tweaked the alignment of the cavity, and WFS still didn't work (this time its running off in YAW).

I remeasured the sensing matrix, which didn't change much from what Daniel measured:

 WFSAPIT = 0.047*POS -5.66*ANG

 WFSBPIT = 0.906*POS - 3.760*ANG

 WFSAYAW = 0.086*POS + 2.379*ANG

 WFSBYAW = -0.293*POS + 3.302*ANG

Note that the coherence for WFSA against POS injection was poor both for PIT and YAW, but everything else had an excellent coherence.

Inverting these, PIT input matrix is [-0.759, 1.143; -0.183, 0.009]

YAW input matrix is [3.366, -2.425; 0.299, 0.088]

But of course it still didn't work, everything was running off in YAW.

Since, unsurprisingly, POS YAW feedback was the bad guy, I enabled POS_PIT, ANG_PIT and ANG_YAW, centered the wfs using picos, lowered the gain for POS_YAW, enabled all four DOFs, disabled the input, recentered, enabled, recentered, and at some point it stopped running away. I set the gain of POS_YAW to the same value as ANG_YAW and it still worked.

UGF of all DOFs are supposedly 50mHz with the filter gain of -5. I think we can go higher, but sadly the cavity power is hashier with WFS enabled, even with this low gain. But at low frequency it is certainly doing its job (I can push TMs and WFS automatically brings them back).

I leave it with WFS on for tonight.

Note:  At some point I started isolating ISIs and tripped HEPI and ISI, and put ISI back to damped without isolation.

Note2: To make it easier for people to look at angle data later, WFS sensing matrix data also contains the TFs from POS and ANG excitation to ETM and ITM oplev.  See the snapshot to find the location of the file in the title bar.

Note3: The reason why I seem to have done this at 0.04736b4 Hz is because of DTT quirk. I told dtt to make a sweep from 0.1Hz to 0.09Hz with one data point, and somehow dtt decided to do it at 0.047something, or maybe it did measure at 0.1Hz but displayed as if everything was done at that frequency.

Joe G, Cheryl, Rodica

On Tuesday, Joe G and I assembled a temporary half waveplate to align the polarization of the forward transmitted beam parallel to the table (p-pol). We used a pick-off mirror (borrowed ALS_M3) to direct the low power s-pol beam away from the main beam to be monitored properly. We started measuring the power ratios between the two transmitted beams to check the rotation of the polarization after the FI.

Continued the alignment work with Cheryl on Wednesday when we noticed contamination of the crystals due to metal particles and glove marks. We removed the first calcite polarizer and the TGG and TGG+QR holders and transfered them to the Optics Lab to be cleaned under the flow bench. 

We applied First Contact on the calcite wedge while still in its mount, and also on the quartz rotator which was successfully removed from its holder. However, the two TGG crystals could not be removed, the single piece being held too tight in place by the clamps of the holder, while in the other holder the metal parts were stuck together, possibly the threads of the assembly got crossed. 

We have been engaging the clean and bake crew (Jodi and Joe) into finding a solution to clean these crystals in their holders and we have some new ideas to try tomorrow. 

Most of the day, Vincent was taking data including the calibrated spectra of the cavity length.

Attached are plots of dust counts > .5 microns in particles per cubic foot. Also attached is a plot of the mode of the dust monitor at end X (H0:PEM-EX_DST1_MODE) to shown approximately when it was reconnected.

OAT:  Quiet requirement all day!

• Fiber guys continued work around H1 Input.
• Continue dressing ISC cables
• Rodruck and crew continue Reference Cavity work
• Contractor on-site to work with Roll-up doors (did not address EY/LVEA doors)
• Lock & Key contractor on-site.
• Thomas went to EY Receiving area to do work on TCS Ring Heater driver
• Patrick addressing EX Dust Monitor
• Bubba making measurements around HAM3&4
• Doug D. checking viewports around HAM1&3

The dust monitor at end X had been turned off. The dust monitor and the weather station at end X were restarted. This involved power cycling the weather station and the Comtrol box. The Comtrol box was moved to the upper shelf in the rack.

Scott, Mark L. and I spent time preparing for ICC at BSC9. Scott and Mark dealt with cleanroom location, assembly, and repair issues. They also moved the flam cabinet from the emergency exit air-lock into the VEA. I cleaned up from the iLIGO optics de-install, organized garbing and staging materials, packed up unneeded items, etc. Two large staging tables were returned to the corner station so they could be used for work at HAM1 and HAM4.

Bubba took measurements and confirmed that the cleanroom from HAM4 can be put into the space remaining around HAM3. John, Bubba, and Mark H. have agreed on a method for the pick and placement. We will attempt this dance tomorrow AM unless otherwise directed.

[Michael R, Richard M, Alberto]

Richard and his contractor brough a PC/PC fiber into the PSL enclosure. Since Richard's fiber has a PC connector and the collimator's pigtail has an APC connector, we had to use an adapter made of a fiber with APC and PC ends.

Mark B and Jeff B.

We stumbled across a nasty bug in the Matlab script plotHSTS_dtttfs.m. We were trying to generate plots for PRM data from 9/5/12 at 1900, but the script was failing to write the expected files. Eventually we realized it was writing files with "1300" for the time. This was because there was a line

fileInfo = dir([dataDir '*' meas.yyyymmdd '*tf.txt']); 

which was intended to look for all files in the Data directory matching the date/time pattern specified in the settings at the top of the script. Unfortunately it omitted any reference to the time, which meant the subsequent search would always find the first dataset for the day. We changed it to match the equivalent HLTS script which has

fileInfo = dir([dataDir '*' meas.yyyymmdd '_' meas.hhmm '*tf.txt']); 

and committed it as r3308.

As far as past data goes, no raw data will have been corrupted. We _think_ all PDFs and any diagnoses and approvals based on them should be valid - even if data for some particular excitation DOF was read from a file with the wrong time, the resulting PDFs should have same time in their names, so the names would match the contents. However what was displayed in Matlab figure windows would sometimes have been old data if there was more than data set for the requested day. Also, a corrupt .mat file could conceivably have been generated if a partial data set was taken in the morning (e.g., only 3 excitation DOFs) and a full one in the afternoon.

[Michael R., Alberto]

We temporarily borrowed the 1064 Farady that was purchased by Bram for the ISCT1 table (ALS vertex) to install it before the fiber collimator on the PSL table.

After this addition, the power coupled into the fiber went down to 2.1 mW (was 3 mW) due to the induced beam shift. Unfortunately the current setup of the steering mirrors doesn't let us displace the beam by much: one fo the steering mirrors is out of hand reach and it's close to a high power beam.

We're still coupling more power from the PSL than ifrom the ALS refcav. So it should be okay, unless we're going to lose more  than .5 mW downstream when we'll connect the new fiber going to the optics lab..

35W beam

From initial alignment data, we know the following:

Positive offset in PIT (H2:SUS-ETMY_M0_OFFSET_P and H2:SUS-ITMY_M0_OFFSET_P) will tilt the mirros such that the reflected beam off of the mirrors will go down.

Positive offset in YAW will tilt the mirrors such that the reflected beam off of the mirrors will go toward the inside of L.

That is, the upper stage of ITM looks like the mirror image of the ETM. Why is this the case? I thought that they are identical.

Also, I think oplev sign is somehow wrong. It's not consistent with initial alignment data.

FYI, the sign of the things in initial alignment was figured out by:

First using baffle diodes to figure out the sign of the TMS to figure out the TMS sign, and make the first beam hit the center of the ITM.

Then using ETMY cage and CCD camera, make the reflected beam from the ITM hit the cage bars to figure out the sign of ITM.

Then move offset of ETMY so that the beam comes back to the table, then move TMS and repeat, to see if ETMY sign is the same as TMS (it is).

As you can see, there is not much ambiguity there.

M. Barton, J. Kissel, J. Shapiro, S. Stepleskwi

Mark has spent a good bit of time,
(a) creating a new parameter set of the QUAD model to represent the current, odd-ball main-chain of H2 SUS ITMY configuration (a wire hang of the a glass mass) called 'wirerehang' (originally reported in LHO aLOG 3017), and
(b) while creating the awesome new QUAD model mode shape wikipages, discovered a few bugs in the reaction chain model parameter sets ('erm' and 'thincp'), and has fixed them.

Here, I document these changes by
(1) Comparing the updated model against the previous version (in the case of the reaction chain parameters), and comparing against what we would have used otherwise (in the case of the wire rehang models),
(2) Comparing both models to representative measurements we have of each, and
(3) Explaining / justifying the details of the parameters that have changed. 

For (1) and (2), see attached plots for each of the three updated models, and for (3) see the tables below. Note, only parameters that have changed are shown, and of those, only the changes in hard-coded (as opposed to derived/calculated from hard-coded) parameters are shown.

As of this entry, the updates to

${SusSVN}/sus/trunk/QUAD/Common/MatlabTools/QuadModel_Production/quadopt_wirerehang.m
${SusSVN}/sus/trunk/QUAD/Common/MatlabTools/QuadModel_Production/quadopt_thincp.m
${SusSVN}/sus/trunk/QUAD/Common/MatlabTools/QuadModel_Production/quadopt_erm.m

which are options for the buildType argument of the function

${SusSVN}/sus/trunk/QUAD/Common/MatlabTools/QuadModel_Production/generate_Quad_Model_Production.m

which produces models all production analysis software suites have been committed to the svn, under rev 3304. Please svn up!

Executive summary of changes:
-----------------------------
 Wire Re-hang 
Major Changes:
- Changed sign of TOP ('n' stage) off-diagonal moments of inertia due to misinterpretation of coordinate system used in Final Design Document (though this has little affect on the predicted dynamics because the magnitude is small)

Small Changes:
- TOP ('n' stage)  and UIM ('1' stage) mass weights ('m' s) and moments of inertia ('I' s) adjusted to reflect QUAD retrofits
- Radius, mass and moments of inertia of TST ('3' stage) changed to reflect the (glass mass and prisms) vs. (metal mass and prisms)
- Change of d's to better reflect measured pitch frequencies of (glass mass and prisms) vs. (metal mass and prisms)
- PUM to TST horizontal separations ('n3', 'n4','n5') changed to match glass mass and prisms vs. metal mass and prisms
- Spring stiffness ('k') updated to match Brett's 2010 fit to vertical TFs (vs. a prior, 2008 fit).

From the plots:
- Most features remain identical, and match up well with either the wire measurements or the one wire-rehang H2 SUS ITMY measurement.
- As usual, Pitch, the most sensitive degree of freedom, is now better matched to the data, but have changed no more than 10%.
- The changed parameters only affect Pitch dynamics, so the model hasn't changed, and still matches the data exquisitely.

 Thin CP 
Major Changes:
- Changed sign of TOP ('n' stage) off-diagonal moments of inertia due to misinterpretation of coordinate system used in Final Design Document (though this has little affect on the predicted dynamics because the magnitude is small)

Minor Changes:
- UIM ('1' stage) mass weights ('m' s) and moments of inertia ('I' s) adjusted to reflect QUAD retrofits (specifically the pitch adjuster).

From the plots:
- Without lacing cables, the model continues to match the data extremely well.
- With lacing cables, in L, T, V, R, and Y, there's still a bit of difference between the model and measurements, though only in stiffness as expected. The resonant frequencies still match just about as good without lacing cables.
- Pitch, the DOF most affected by the lacing cables (who's surprised?) is the worst, but still, only the lowest two modes in frequency are increased (i.e. modeP1 and modeP2 which involve the TOP and UIM masses, which have the most lacing cables running through them).
- Any and all remaining discrepancies between model and measurement are not of much concern, since this is a reaction chain which has no where near the control-noise performance requirements as the main chain, so we'll most likely rely on a simple set of damping filters that are robust against the differences.

 ERM 
Major Changes:
- Corrected TST stage thickness, it had the Thin CP value (copy'n'paste oversight).
- Changed sign of TOP ('n' stage) and PUM ('2' stage) off-diagonal moments of inertia due to misinterpretation of coordinate system used in Final Design Document (though this has little affect on the predicted dynamics because the magnitude is small)

Minor Changes:
- Updated TST stage moments of inertia for an ERM, as opposed to a Thin CP.

From the plots:
- For L,T,V,R, and Y, either model doesn't perfectly capture the changes brought on by lacing cables, or from switching from metal to glass -- specifically the increase in stiffness (from cables), and the bifurcation of the second trans mode -- but, as with the Thin CP, it's expected and not a big deal.
- For Pitch, neither model gets the stiffness right, cables or no cables, though we should triple check this against other no-lacing cable, ERM chain measurements. Unclear why this is. Naturally, when you add lacing cables, the lowest resonant modes increase in frequency, but this is exactly the same as on a Thin CP, so it's understandable since they have the same cables, the same configuration of routing, and the mode shapes are the same (see modeP1 and modeP2 of the last version of the production models).
- Any and all remaining discrepancies between model and measurement are not of much concern, since this is a reaction chain which has no where near the control-noise performance requirements as the main chain, so we'll most likely rely on a simple set of damping filters that are robust against the differences.

Full details of parameter changes
---------------------------------
Table 1: Wire Rehang

    'Param'                          'Former Production Value'    'Updated Value'        'Differnce'      'Difference'
    ''                               'Model: wire'                'Model: wirerehang'    '(Absolute)'     '(Percent)' 
    'mn'                             '21.9'                       '22'                   '0.0696'         '0.317%'    
    'Inyz'                           '4.65e-05'                   '-4.65e-05'            '-9.3093e-05'    '-200%'     
    'Inzx'                           '0.00172'                    '-0.00172'             '-0.0034368'     '-200%'     
    'm1'                             '22.3'                       '21.5'                 '-0.81226'       '-3.64%'    
    'I1x'                            '0.509'                      '0.505'                '-0.0040466'     '-0.795%'   
    'I1y'                            '0.0711'                     '0.0724'               '0.0013481'      '1.9%'      
    'I1z'                            '0.518'                      '0.518'                '0.00013532'     '0.0261%'   
    'I1xy'                           '-0.0132'                    '-0.0132'              '5.271e-06'      '-0.0399%'  
    'I1yz'                           '0'                          '1.37e-05'             '1.3742e-05'     'Inf%'      
    'I1zx'                           '0'                          '-8.08e-06'            '-8.084e-06'     '-Inf%'     
    'm3'                             '39.6'                       '39.6'                 '0.031'          '0.0783%'   
    'I3x'                            '0.598'                      '0.568'                '-0.029963'      '-5.01%'    
    'I3y'                            '0.418'                      '0.42'                 '0.0011272'      '0.269%'    
    'I3z'                            '0.4'                        '0.411'                '0.010141'       '2.53%'     
    'dm'                             '-0.00351'                   '-0.00353'             '-2.2308e-05'    '0.636%'    
    'dn'                             '0.00328'                    '0.00423'              '0.00095167'     '29%'       
    'd0'                             '-0.00174'                   '-0.00175'             '-1.0004e-05'    '0.575%'    
    'd1'                             '0.00299'                    '0.00399'              '0.00099789'     '33.3%'     
    'd2'                             '0.00709'                    '0.00708'              '-4.0147e-06'    '-0.0566%'  
    'd3'                             '0.001'                      '-0.00116'             '-0.0021609'     '-216%'     
    'd4'                             '0.001'                      '-0.00116'             '-0.0021609'     '-216%'     
    'n3'                             '0.176'                      '0.172'                '-0.00425'       '-2.41%'    
    'n4'                             '0.171'                      '0.172'                '0.00075'        '0.438%'    
    'n5'                             '0.171'                      '0.177'                '0.00555'        '3.24%'     
    'ln'                             '0.445'                      '0.449'                '0.004192'       '0.942%'    
    'l1'                             '0.311'                      '0.309'                '-0.002415'      '-0.777%'   
    'l2'                             '0.339'                      '0.331'                '-0.008213'      '-2.42%'    
    'l3'                             '0.604'                      '0.604'                '0.00029403'     '0.0487%'   
    'r1'                             '0.000355'                   '0.000356'             '5e-07'          '0.141%'    
    'kcn'                            '1.41e+03'                   '1.43e+03'             '17.9919'        '1.27%'     
    'kc1'                            '1.65e+03'                   '1.65e+03'             '-1.8307'        '-0.111%'   
    'kc2'                            '2.42e+03'                   '2.38e+03'             '-40.5505'       '-1.67%'    
    'kw3'                            '1.15e+05'                   '1.15e+05'             '-56.022'        '-0.0487%' 


Table 2: Thin CP

    'Param'    'Former Production Value'    'Updated Value'             'Differnce'      'Difference'
    ''         'Model: thincp'              'Model: thincp_20120831'    '(Absolute)'     '(Percent)' 
    'I1y'      '0.073'                      '0.0734'                    '0.00040601'     '0.556%'    
    'I1z'      '0.519'                      '0.518'                     '-0.00077135'    '-0.149%'   
    'den3'     '3.98e+03'                   '2.2e+03'                   '-1780'          '-44.7%'    
    'Inyz'     '4.36e-05'                   '-4.36e-05'                 '-8.7197e-05'    '-200%'     
    'Inzx'     '-0.00171'                   '0.00171'                   '0.0034279'      '-200%' 


Table 3: ERM

    'Param'                          'Former Production Value'    'Updated Value'          'Differnce'      'Difference'
    ''                               'Model: erm'                 'Model: erm_20120831'    '(Absolute)'     '(Percent)' 
    'I1y'                            '0.073'                      '0.0734'                 '0.00040601'     '0.556%'    
    'I1z'                            '0.519'                      '0.518'                  '-0.00077135'    '-0.149%'   
    'tx'                             '0.1'                        '0.13'                   '0.02996'        '29.9%'     
    'tr'                             '0.17'                       '0.17'                   '-1.5e-05'       '-0.00882%' 
    'den3'                           '3.98e+03'                   '2.2e+03'                '-1780'          '-44.7%'    
    'I3x'                            '0.376'                      '0.376'                  '-6.6301e-05'    '-0.0176%'  
    'I3y'                            '0.21'                       '0.225'                  '0.014932'       '7.12%'     
    'I3z'                            '0.21'                       '0.225'                  '0.014932'       '7.12%'     
    'Inyz'                           '4.36e-05'                   '-4.36e-05'              '-8.7197e-05'    '-200%'     
    'Inzx'                           '-0.00171'                   '0.00171'                '0.0034279'      '-200%'     
    'I2yz'                           '-2.38e-05'                  '2.38e-05'               '4.751e-05'      '-200%'     
    'I2zx'                           '-4.41e-05'                  '4.41e-05'               '8.8146e-05'     '-200%'     

Vincent finally made the HEPI and ISI behave, but I had a hard time realigning. TMS has a rather large offset in PIT which seems to be caused by HEPI incident.

Anyway, in the end I started over from scratch, centering on ITM using TMS and baffle diodes.

PD1 max (28500 counts) : TMSP=-92313, TMSY=26574

PD2 max (29300 counts): TMSP=-922420, TMSY=11355

PD4 max (29200 counts): TMSP=-54958, TMSY = 11817

I took the mid point of PD1 and PD4 and set TMS offset to (p,Y) = (-73636, 19196).

I used manual alignment followed by tdsdither to obtain this:

ETM: (P,Y)=(-3028.634, 5409.607)

ITM: (P,Y) = (5771.803, 761.433)

REFL_B_PWR went up to about 8100 counts, which is really good (remember, we inserted 10% pick off for WFS, which means that 8100 counts is equivalent of 9000 counts before the change).

However, WFS refuses to work. PIT just goes away even if I reduce the gain considerably. In an attempt to center WFS, one of the picos on the table might have dropped. I haven't looked at the table yet.

I'll leave it WFS-less for now.

Attached is the calibrated spectrum as of now (references are from Aug/25 (blue) and Aug/22 (green), respectively). Somehow 1/f-ish noise between 1 and 20Hz increased, though low frequency noise is good.

The file is here:  /ligo/home/controls/keita.kawabe/OAT_2012/length_example_20120905.xml

The differences between now and then are:

1. Sensor correction is on now.

2. VCO to HEPI relief is off now because Vincent wanted to leave it that way.

3. Alignment is different (HEPI didn't go back exactly to the original position and relatively large realignment of cavity and TMS was necessary).

4. WFS path is different now though WFS is off.

I haven't checked the refcav status except that it is locked.

Foton GUI quietly discarded (some of?) notch filter definitions and replaced them with a flat gain of 1.

This is easily reproduced by first opening e.g. /opt/rtcds/lho/h2/chans/filter_archive/h2iscey/H2ISCEY_120828_143926.txt and saving it to some other file, e.g. test.txt, and take a diff (attached).

Probably because of this bug, all WFS notches are gone from current H2ISCEY filter file.

This is extremely worrisome.