Today I pulled the ETM ring heater driver to investigate why its response to current was so different from the ITM ring heater driver. I found that resistor R44, which controls the gain of the input, was left void on the ETM. The circuit designs had been updated to include a 49.9k resistor, raising the gain by a factor of about 2. I added the 49.9k resistor, returned the ETM ring heater driver to the field, and recalibrated the driver. The calibration was performed by measuring the voltage over a 0.5 ohm resistor on the ring heater driver board (test points TP1 and TP2). The supplied current was increased from 0 to 425 "mA" of DC offset in steps of 25 "mA".

The driver's calibration is much closer to the ITM calibration, and is more consistent with using milliamps for the DC offset on the medm screen. Previously, it was calibrated at 0.0498 mA/ADC count. The updated calibration is 0.02396 mA/ADC count. The attached trace shows the data using the old calibration on the same axes as the data using the new calibration.

   This afternoon Andres and I checked MC2 for rubbing. We found the two left side (under BOSEM T1) Lower Blade Stops almost touching their respective blades. We backed both stops off to closer to the specified 0.75mm spacing. We also found the upper left EQ stop on the Bottom mass was lightly touching the glass, which we backed off. We checked the remaining EQ stops and adjusted as necessary. MC2 should be ready to continue testing.    

Reportedly, Jeff and Andres went in and fixed some EQ stop rubbing on MC2 inside of HAM3 today.  With this done, I will now attempt more TFs as part of the Phase 3a testing (while at LLO).

ScottL BubbaG & Hugh

No issues with this.   First locked up HEPI.  Centering Pins in, Spring Locating Fixtures in place, Springs in place.  Lift the Mass, position over Pins, lower to placement.  Pull Centering Pins, replace with Safety Pins or Leg Screws, remove Locating Fixture.  Next, repeat seven times.

Couple things.  The Viton cork Springs are considerably shorter so the Leg Screws, which prevent the Mass from flying off if the world turns upside down, are installed without the Custom Thick washer (D972716, 3/8"thick).  See the first photo with a comparison.
The Safety Pins D972715-5 into the Support Table are installed with a 0.089" thick vented washer although it really doesn't need it.

We are ready to fly the Optical Table to the South Bay for install.  Then payload up, level, check the height & horizontal alignment (IAS.)

See the attached photos to experience a few of the thrills we had today!

Second cleaning was completed early this morning. Three doors and the dome were removed from the chamber by COB today.

- Quiet time after 03:00 PM
- Kyle to crane flange assembly 09:31AM
- Christina is cleaning HAM3 
- Apollo replacing leg on the beam splitter test stand.
- Dave is going to change some code to the SUSH2a IOP watchdog, needs a restart of the front end, awaiting Betsy (at LLO) to call. 

Doors were taken off of HAM3 first thing this morning. I informed Jeff B. (SUS rubbing issues)and Kyle (conflat leaks) that the doors were off so that they could proceed with their work.

Cheryl, Rodica

On Monday we started aligning the TGG crystals inside the Faraday magnet, and found that we could not get the same rotation as at LLO. The single TGG crystal was rotating properly 22.5 deg, but the double crystal system was rotating the difference instead of sum of the individual rotations. We realized that the magnetic field orientation inside the magnet is OPPOSITE to the one in the LLO magnet, for the same mechanical orientation (end cap to right as described in E0900301 assembly document). We decided to rotate the magnet so that now the configurations/rotations at LLO and LHO are the same, even if the mechanical assembly shows now the LHO magnet reversed.

Once the magnet was rotated and we re-centered the beam through, was very easy to position the crystals  for the optimum rotation.

Next we hit another snag - we noticed that one of the threaded rods used to lock the crystal holders in place on each side of the magnet would be interfering with the heat sink, since the holes in the magnet housing were too low. We removed the crystals again, and unbuckled the omega-shaped straps and rotated the magnet about its axis to clear the bottom space for the heat sink.

At this moment we re-inspected the crystals under bright light and they still look nice and clean. A couple of tiny spots which didn't blow off, but we assesed they did not need recleaning. 

We firmly retighten the cap on the quartz crystal, which surprisingly was slightly loose, probably from twisting/untwisting the holder to insert inside the dust sleeve in the magnet. We also wiped again the inside of the dust shield with IPA.

Finally we inserted the crystals back in the magnet and optimized the positioning:

TGG+QR

TGG+QR+TGG

Attached is the calibrated spectrum with PSL (red). References are all with the old refcav setup. Apparently PSL doesn't look good, but don't take it too seriously (yet).

When I took the data I've turned off the PSL laser room HEPA, PSL ante room HEPA and PSL room A/Cs off, and turned the make up air down to 30% level with an approval of Michael Rodruck.

Power fluctuation in the cavity is ridiculously large (you can see that the beam spot is moving by the beam radius or more on the ETM), which might be due to high wind today. I'll take another shot tomorrow.

Also it might be that the Prometheus temperature is too low. It's not that I'm seeing that Prometheus is misbehaving, but in the past Bram experienced some problem operating it at too low or too high a temperature. I want to unlock the PSL refcav and raise the crystal temperature a bit but I don't think I'm qualified for PSL room.

BTW we tried turning ISS on and it didn't make any difference.

Jim & Hugh

Based on our dial indicators, we had a little more aligning to do left over from Friday.  We did that and then fine tuned the elevation, again with the dial indicators.
Next we opened up the Chamber and shot the position with the Sokkia SetIIX.  The East/West position was right there (y=0), of course the machine only reads out to the millimeter.  The North/South position was due west of monument LV25 with the west end of the Support Table 2" (<0.1mm south) and the east end 14" or <0.2mm north.
So with the position confirmed we checked the level of the Table.  It is 0.1mm low and level to +-0.1mm.  Tomorrow we'll start building the stack, if we have the forklift.

Attached are my notes from this for your perusal.

Went to EY. The power coming out of the fiber was 174 uW.

Originally the Prometheus red crystal temperature was 42.36 degree C. We ended up lowering it down to 31.39 degree C to get a beat note.

The green power dropped by about 20% judging from the QPD sums (e.g. QPDB sum used to be 7500, now it is 6000) and H2:ALS-Y_REFL_B_PWR_INMON (uset to be 12700 unlocked, now it's more like 10200). I changed the offset in REFL_B_PWR accordingly. This means that the old 8000 counts is now 6400 counts.

The waveplate for the fiber output was adjusted to maximize the beat note, which was about -39dbm. Turned on the servo, adjusted the temperature knob several times to relieve the slow temperature servo, and it worked OK.

We measured the OLTF of the PLL even though there's no reason it should change. The UGF was about 23 kHz.

See Jax's entry about the green power going to the chamber and the actual data of the PLL OLTF.

Now the arm locks.

While I am at LLO, I am running the Phase 2a chamberside testing of MC1.  I have read the log and see no reasons why I should not actualte on MC1 chamberside.  I am aware that people are on the floor and even possibly working on the same table.  I'll look at the DQ as I go.  Please email me (or call my cell) if you need to.

The Apollo crew is staging for ICC. Cleanroom sock will be put in place. Christina and Karen got first cleaning in this morning. We will try for second cleaning dome/door removal tomorrow.

Thursday, few measurements were performed with the cavity locked. This aLOG presents some results.
In order to keep the cavity locked, Isolation filters on the HEPIs were always engaged, HEPI-BSC6 was yawed by ~180micro radian, damping filters on ISIs, TMS, QUADs and the FM were always engaged. The ISC longitudinal error signal was fed back to BSC6-HEPI (UGF ~1mHz). The simplified control schemes of the BSC-ISI and the HEPI are presented in attachment (SEI_Simplified_Control_Scheme.pdf)

The isolation filters of the 2 ISIs are tuned using the following parameters:
- UGF: 15Hz on all DOFs
- Phase margin > 45deg
- Gain margin>20dB
- Gain peaking <2

The HEPIs are tuned using the following parameters:
- Blend IPS-L4C at 800mHz
- UGF: 10Hz
- Phase margin > 45deg
- Gain margin>20dB
- Gain peaking <2

The measurements were performed using DTT, and then the spectra are extracted and calibrated using Matlab. In order to extract the data from DTT and save them in a .mat file, I used the Matlab and the python scripts called respectively ddt2mlab.m and ddt2mlab.py found in userapps/trunk/cds/common/scripts/dtt2mlab. Due to a bug, I modified (a hack, not a fix) ddt2matlab.py and dtt2matlab.m but I didn’t commit the changes.

The Calibrated spectra presented in attachment were measured in the following configurations:
-          HEPI ON - ISC Y - No Sensor Correction - ISI Damping
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping + Isolation with ST1 L4C blended at 250mHz
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping + Isolation with ST1 L4C blended at 250mHz + ST2 GS13 blended at 100mHz
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping + Isolation with ST1 L4C blended at 100mHz + ST2 GS13 blended at 100mHz
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping + Isolation with ST1 T240 blended at 250mHz + ST2 GS13 blended at 250mHz
-          HEPI ON - ISC Y - Sensor Correction - ISI Damping + Isolation with ST1 T240 blended at 100mHz + ST2 GS13 blended at 250mHz

The plots show spectra of the length of the cavity (LHO_OAT_ALS-Y_ARM_LONG_IN1_DQ_2012_09_06.pdf), the motion of stage 1 (LHO_OAT_ISI-ETMY_ST1_BLND_Y_T240_CUR_IN1_DQ_2012_09_06.pdf) and stage 2 (LHO_OAT_ISI-ETMY_ST2_BLND_Y_GS13_CUR_IN1_DQ_2012_09_06.pdf) of ISI-BSC6 (ETMY). The mystery noise (fiber?) mentioned in 4128 slightly disturbed the measurements; it is visible on some spectra (on the black curve of LHO_OAT_ALS-Y_ARM_LONG_IN1_DQ_2012_09_06.pdf around 2 Hz for instance).

On the spectra of the cavity, the effect of the sensor correction on the HEPIs is noticeable (blue vs green). In both cases, the ISIs are only damped. However, there is a significant amplification below 100mHz (corner frequency of the STS-2 (on the ground) high pass filters at 40mHz). Above 100mHz, there is a reduction by a factor of 3-4 visible up to 2-3Hz.
Once the isolation filters are engaged on stage 1 only (blend at 250mHz on the L4C – in red), the attenuation is important above 250mHz and the amplification is still visible below 100mHz (should be amplified by the stage 1 CPS low blend filters).
Next, stage 2 isolation filters were also engaged and blend frequencies were lowered down to 100mHz and finally the T240s were introduced in the stage 1 super sensor (CPS + T240 + L4C). The extra isolation (low blend + T240s + 2 stages controlled) provided by the ISIs is not visible on the cavity above 200mHz (reaching the noise floor of “something”). Only the amplification below 100mHz is visible due to the use of aggressive blend filters (100mHz) and the 2 stages of isolation. The largest amplification is obtained when the 2 stages are controlled and the position sensors are blended with the seismometers at 100mHz.

The isolation provided by the ISIs is presented in figures (stage 1 - LHO_OAT_ISI-ETMY_ST1_BLND_Y_T240_CUR_IN1_DQ_2012_09_06.pdf) and (stage 2 - LHO_OAT_ISI-ETMY_ST2_BLND_Y_GS13_CUR_IN1_DQ_2012_09_06.pdf). The best isolation is obtained when the T240s are introduced in the stage 1 super sensor with a blend frequency of 100mHz. Actually, the CPSs are blended with the T240s at 100mHz and the T240s with L4Cs at 2Hz (cf scheme control).

Comments on the amplification at low frequency (peak at 60mHz)?
 At 60 mHz, when the ISIs are not controlled, the ISIs absolute motions are about 1 micrometer and the relative motion between the 2 ISIs is 100nm. A transfer function from the STS-2 at the end station to the STS-2 at the corner station showed that the LVEA and the end station are moving in phase around 100mHz (a 5-6 degrees phase would explain the 100nm of relative motion between the ISIs).
Once controlled, the absolute motion of the ISIs is amplified by 10 but what is the phase between the 2 ISIs? I tried to measure transfer functions from the T240s in BSC6 to the T240s in BSC8 but the coherence is close to zero.
Under control, the relative motion between the 2 ISIs is 10^4nm (x100 amplification). A phase of 60 degrees between the ISIs would explain that. But, it would be surprising to see this large phase since the filters used on both ISIs are quasi identical.

At low frequency, the platforms are locked to the ground using the position sensors. But if the so called vertical position sensors are not all “perfectly” aligned with the vertical, a translation of the platform in the horizontal plan will create some tilt. Under control, if the ISIs are moving in phase in the Y direction but one ISI is tilting in +Rx while the other one is tilting –Rx, the variation of the length between the test masses hanging points will be increased.

The tilt correction has not been implemented on the ISIs. Few weeks ago, I quickly tried but I didn’t see any significant improvements. It may be worth trying again.

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%'