model restarts logged for Wed 12/Mar/2014
2014_03_12 16:09 h1ioppemmy
2014_03_12 16:28 h1ioppemmy
2014_03_12 16:28 h1pemmy
2014_03_12 21:02 h1fw1

All expected except for the h1fw1 restart.

Yesterday, we found that the reaction chain of ETMY quad was rubbing, so Betsy and Travis made some adjustements and a round of TF was ran overnight. The results are now clean, meaning the suspension is free of rubbing for both chains. This will be our official phase 3a set of transfer functions.

The first attachement shows the transfer functions for the 6 DOF of the main chain and the second attachement for the reaction chain. TF have their peaks matching very well with the model, except T DOF of the reaction that has an extra resonance at 0.86Hz which is a roll mode. (and as usual the reaction chain pitch which differs because of added stiffnes from cables which couples into the L DOF).

I added to the plots the phase as well as the ratio between model and measurement.

I attach here three plots showing the Local and Cartesian positions for the ETMY HEPI for the last 72 hours.  I conclude that, at least in this instance, the high frequency excitations (100-1000Hz) which ran this morning, destresses the platform and exhibits strains of significant magnitude.

The first plot is the four vertical Inductive Position Sensors showing the zeroing of the IPS after Alignment approval Tuesday afternoon. When Mitchell pulls ACB elements Wednesday Morning, there is vertical shift of 100s of nm; as we expected, not too much to worry about.  Toward the end of the plot, the start of TFs beginning at 500 to 1000Hz and then continuing with 100to 500Hz as well shows small steps.

The second plot however shows the four horizontal IPS and much larger steps in the IPS readouts at the start of the TFs.  The third plot are the trends of the Cartesian channels.  The Wednesday AM Matrix changes I made are very insignificant but not so the horizontal shifts from the TFs.  The 0.3mm translations of X & Y are ignorable but the Rz of -15urads may not be. With Jason's alignment of ETMY indicating a 20urad CCW error, and if we've all got our signs correct, the -15urads should actually put us closer to zero error.

Notice that the H2 IPS had the largest shift.  I attempt to push it back and was successful with a 1000ct local offset but it went back as soon as I removed the offset.  In the last plot attached you can see all the position senors responding to the stopping of the excitations this morning and then to  the offset and all pretty much returning to their previous values when the offset is removed.

So I would suggest that a destressing exercize of the HEPI may be a valuable step in the alignment process and of course an explicit zeroing (or at least a logging) of the IPS value are in order right after alignment, something we haven't always done.  This also stresses the importance of getting the posirtion loops turned on.

• Y Axis Position (longitudinal): 3,999,455.7 mm
  • Target: 3,999,455.4 mm
  • Error: +0.3 mm
  • Tolerance: ±3.0 mm
• X Axis Position (lateral): -199.97 mm
  • Target: -200.0 mm
  • Error: +0.03 mm
  • Tolerance: ±1.0 mm
• Z Axis Position (vertical): -79.6 mm
  • Target: -80.0 mm
  • Error: +0.4 mm
  • Tolerance: ±1.0 mm
• Pitch: 665 µrad down
  • Target: 639 µrad down
  • Error: 26 µrad
  • Tolerance: ±50 µrad
• Yaw: 20 µrad CCW
  • Target: 0 µrad
  • Error: 20 µrad
  • Tolerance: ±50 µrad

ERMy (set parallel with respect to the ETMy AR surface.  Error numbers are reported from this desired parallelism)

• Pitch Error: 860 µrad down
  • Tolerance: ±1.47 mrad
  • Actual Pitch: 2.86 mrad down [ETMy pitch (665 µrad) + ETMy wedge (1.33 mrad) + ERMy pitch error (860 µrad)]
• Yaw Error: 340 µrad CW
  • Tolerance: ±1.47 mrad
  • Actual Yaw: 320 µrad CW

ACB

• Lateral Error: -0.6 mm
  • Tolerance: ±2.0 mm
• Vertical Error: -0.9 mm
  • Tolerance: ±2.0 mm

All IAS equipment has been removed from the spool area and the spool is being installed this morning.

Cranework is beginning at EY for Spool Work (involves moving IAS table out of way, inserting spool, etc.).  Bubba noted the Dust Monitor was inoperative & Jeff B. will be heading out there to get their Dust Monitor back online.

We found that the BS ISI had been tripped. We untripped it with stage 1 isolated at level with the Tcrappy blend filter.

I tap tested ISCT1 while the arm was locked. The broad peak at about 71 Hz was associated with the red/green periscope, but the sharp peak at 67.9 Hz did not appear to originate on ISCT1. The tall supports used to dress some cables had similar Qs but slightly different frequencies. The tight ones should probably be unscrewed slightly to damp the flag pole resonance and lower their Qs, but they were not the source.

I am summarizing here recent progress on BSC-ISI units

Blend Filters for the BSC-ISI

We have standardized the blend configurations. All the BSC-ISIs are equipped with 3 different blends filters: 'Start', 'T750mHz', 'Tcrappy'

BSC-ISI Controllers

All the BSC-ISIs are equipped with a working lvl3 controller for all the DOFs, Stage 1 and Stage 2

BSC-ISI config

The most robust configuration providing good performance on all BSCs is the following:

- control lvl3 on ST1 & ST2

- Tcrappy blend filters on ST1 & ST2

To properly turn this config on, see here.

Sensor correction Stage 1 to Stage 2 has been installed on all the BSCs but ITMY.

Tilt decoupling ST1 has been installed on all the units

Tilt decoupling ST2 has been installed on BS and ITMY. I started to do X tilt decoupling on ITMX but didn't have the time to do Y.

Matrices

After the reboot of the system on February 25th, old input and output matrices have been restored on BS and ETMX. This is not a big deal, we just have to find a quiet time to restore the new ones. This process might disturn the currnt alignment though.

Performance

Find attached BS performance plot. The behavior of the beamsplitter is very representative of the behavior on the other chambers. I took BS as an example because it was available at the time, but I expect to have the same kind of results on all the chambers.

Thre configuration are tested here:

- the robust Tcrappy on ST1 and ST2

- Tcrappy on ST1, Start on ST2 with sensor correction #1 (filter 'BandPass2')

- Tcrappy on ST1, Start on ST2 with sensor correction #2 (filter 'BandPass4') > more aggressive sens corr

It is interesting to notice the different compromise between Tcrappy and sensor correction. Also, we want to be careful with sensor correction and not reinjecting very low frequency noise.

This shows that there is still some room to tweek our blends/feedforward.

I haven't had the time to try your blend Rich (next time!), and the windy configuration.

Dave O and Stefan B

We measured the round trip gouy phase of the PRC using the same phase-locked sub-carrier that we used to measure the PRC length.

We scanned the sub-carrier offset frequency over a full spectral range of the PRC (2.6 MHz) from 68.4 MHz - 72.4 MHz. We then monitored the amplitude and phase of the beat- note as measured by Refl-Air-B diode. Two plots are shown. 

The first shows the full sweep. Three tracs are shown. The blue trace is the transfer function for the full beat-note signal scanned over a full PRC FSR. The other two show the traces, when half the photo-diode is blocked and the sub-carrier is locked on either side of the main carrier. Unfortunately the interferometer lost lock half-way through both of these scans. The broader bumps show the resonance of the TEM01 modes.

The second plot is the same trace zoomed in around this area. From this plot we can determnine that TEM01 modes resonate at 375kHz +/- 10 kHz off the main resonance and hence the round trip guoy phase for the PRC is 52 +/- 3 degrees.

Delaying until 1am.  Since SUS will not be done until midnightish and ISI is locked.  These matlabs are running on opsws0.

Stefan, Yuta, Kiwamu

We have measured the length sensing matrix in the sideband locked PRMI. The data is now under analysis and will be posted later.

Also since we now know that the in-vac REFL is functional (see alog 10661), we switched the PRMI sensors from the in-air one to the in-vac one. This is a permanent change and in fact, it is already reflected in the guardian.

Preparations (adjustment of PD gains and demod phases):

After we locked the PRMI with the sidebands resonant, we re-adjusted the demod phases such that the PRCL signal is maximized in all the in-phase paths. This was done by inserting a new notch at 100 Hz both in MICH and PRCL filters and exciting PRM with an amplitude of 30000 cnts at the output side of the LSC. We used dtt to check the demod phases. The new settings are now:

• REFL_A_RF9 = 84.9 deg
• REFL_A_RF45 = 19.2 deg
• REFLAIR_A_RF9 = 90 deg
• REFLAIR_A_RF45 = 144.6 deg
• REFLAIR_B_RF27 = 91.8 deg
• REFLAIR_B_RF135 = 76.3 deg

We didn't phase the POP detectors this time as we were focusing on the REFL detectors. Also, we changed the PD gain in the digital system to make all of them identical to REFLAIR_45. This was meant to make the calibration easier. The new gain settings are now:

• REFL_A_RF9_I(Q)_GAIN = 0.252
• REFL_A_RF45_I(Q)_GAIN = 0.275
• REFLAIR_A_RF9_I(Q)_GAIN = 1.040
• REFLAIR_A_RF45_I(Q)_GAIN = 1 (because this was chosen to be the reference for everyone else)
• REFLAIR_B_RF27_I(Q)_GAIN = 0.210
• REFLAIR_B_RF135_I(Q)_GAIN = 1 (we didn't do it on this guy for some reason)

At this point, we could see all the I-phase signals beautifully overlaid on each other in the spectrum.

The measurement:

We then moved on to the measurement of the LSC sensing matrix. We continued shaking PRM with the same amplitude of 30000 cnts. We left the notches in at 100Hz to avoid surpression from the LSC control loops. Since we wanted to quickly get a result, we decided to use dtt instead of the online lockins. Monitoring the DAC of BS, PRM and PR2 suspensions we didn't observe a saturation during the measurement. Good. All the 1f detectors had a whitening gain of 0 dB while REFL_RF27 and REFL_RF135 had a whitening gain of 27 dB and 21 dB respectively. We set the bandwidth of the FFT to be 0.1 Hz and averaged it by 10 times. Note that the PRCL loops should have a UGF of about 35-ish Hz and the MICH loop should have a UGF of about 10-ish Hz. So the excitation is above the UGFs.

As for the MICH sensing matrix measurement, we tried three different excitations -- (1) excitation on the diagonalized combination of PRM and BS at 100 Hz, (2) excitation on only BS at 100 Hz, and (3) excitation on ITMs at 18 Hz. The third configuration was not really successful in a sense that we didn't see a big excitation. Also we didn't spend a long time to study the optimum excitation on ITMs this time.

In the first and second excitation configurations, we injected an excitation with an amplitude of 300 cnts above of which the BS saturated at its DAC. Since the excitation was puny, we narrowed dtt's bandwidth down to 0.01 Hz this made the coherence somewhat better.

A permanent change -- in-vac locking:

We did nothing special to switch the sensor from the in-air to in-vac. We simply set the LSC gains right. Currently REFL_A_RF45_I is for PRCL and REFL_A_RF45_Q. for MICH. We then confirmed that the in-vac detector grabbed the PRMI fringe without a problem. Also we noticed that the in-vac Q-signal contained less noise by a factor of 5-ish (actually I forgot the exact number, sorry) above 30 Hz and therefore the BS DAC should be happier now.

Additionally, we confirmed that we could still transition to the 3f diodes smoothly by the guardian.

Mitchell,
CPS racks were put together. Class A probes sorted. CPS sub assemblies started and nearly completed. Probes will be attached to their sub assemblies and staged on the ISI to be attached at a later date.

The IOC had apparently stopped running. I telneted into the procServ for it on h0epics and it automatically restarted. I burtrestored it.

After TMSY work on monday I took some overnight measurements yesterday night to check for rubbing, and compared the results with model and TMSX data.

TF looks suspiciously different in the vertical degrees of freedom (VERT and ROLL) than TMSX and model, which indicates that there is probably still something blocking the table to move freely.

After lunch we went back to EY to find the mechanical grounding in the ETMy reaction chain.  After a while we spotted a top mass MRB block (hanging part) brushing the tablecloth (structure part).  Our pitch alignment earlier in the day caused the top mass to pitch into the structure.  We could not adjust the structure out of the way* so we adjusted pitch to alleviate the brushing.  The reaction chain pitch has a  ~1.47mRad tolerance and we are still within this at ~860uRad.  Quick low-coherence TFs looked promising so we are restarting the night run full suite Matlab TFs.

*We could not adjust the table cloth easily since 1) everything is suspended - ISI and HEPI included so it all bounces to the lightest touch, 2) the ACB is now mounted and difficult to maneuver around, and 3) the table cloth serves purpose for both chains simultaneously so adjusting it for one chain somewhat anti-adjusts it for the other chain - too risky at this point.

-Betsy, Travis

I re-measured BS and PRM actuation transfer functions in PRY configuration after plant inversion done on Mar 5 (see alog #10559).
It seems like we succeeded in BS and PRM balancing within ~8 % and MICH to PRCL coupling is expected to be supressed by factor of ~4, compared with using only BS as an actuator.
For the sensing matrix measurment, the effect of residual MICH to PRCL coupling gives ~6 % error for MICH to REFL45Q element and ~16000 % error for MICH to REFL45I element.

[Motivation]
Before measuring the PRMI sensing matrix, we wanted to estimate how good output matrix diagonalization is.


[Method]
1. Lock PRY and measure open loop transfer function. Compare it with the model to derive optical gain.

2. Measure actuator transfer function of BS and PRM from ISCINF to REFLAIR_RF45_I_ERR in PRY (using the same template used in alog #10450). Calibrate these TFs into m/counts with the optical gain derived in step 1.

3. Closed loop correct TFs measured in step 2. TFs should look like 1/f^2 at 1-300 Hz (see comments on alog #10450). Since output matrix for MICH in PRMI are set to (BS,PRM)=(1,-0.5), these TFs should be equal (see alog #10559 and table below).

-table of actuation efficiency (optic motion to interferometer length change in m/m)-
      PRY      PRCL      MICH
BS    sqrt(2)  1/sqrt(2) sqrt(2)
PRM   1        1         0

4. Calculate expected actuator TFs for MICH to PRCL coupling using the measured TFs. BS ISCINF to PRC length change will be half as that of PRY. BS-0.5*PRM gives the residual MICH to PRCL coupling.


[Result]
1. OLTF_PRCL_1078572000.png: Openloop transfer function of PRY lock. By comparing with the model, this gives PRY optical gain of 1.8 W/m. So, the calibration factor for REFLAIR_RF45_I_ERR in PRY is 4.7e11 counts/m. Note that this calibration factor includes losses in the PD signal chain (e.g. loss from long cable). Also, note that PRM suspension model was 30 % off from the measurement (see #10482; measurement = 0.77 * SUS model). This correction factor is included in the model to derive the optical gain.

2. BSandPRMact_PRY.png: Measured actuator transfer functions for BS and PRM in PRY. x marks show raw measured TFs and dots show closed loop corrected ones. After closed loop correction, actuator TFs look like they follow 1/f^2. From the fit, BS actuator TF is 1.79e12 Hz^2/f^2 m/counts and PRM actuator TF is 1.93e12 Hz^2/f^2 m/counts for PRY. Considering the error bar from coherence and cavity build up fluctuation during the measurement, this 8% difference between BS and PRM is significant (error bars in TF magnitude are derived using the formula in alog #10506). We have done the balancing with the precision of ~10%, so this difference is reasonable.

3. BSandPRMact_MICH2PRCL.png: Estimated MICH to PRCL coupling from actuator diagonalization. Blue dots show BS ISCINF to PRC length change and red dots show BS and PRM combined actuator to PRC length change. Fitted lines show that MICH to PRCL coupling is expected to be supressed by factor of ~4 by actuator balancing. We can improve this supression ratio a little bit by changing the gain balancing between BS and PRM by 8%, but it's not easy to improve more and prove we did more.


[Is this enough?]
This means that our MICH actuator (BS - 0.5*PRM) changes MICH length by 1.79e12 Hz^2/f^2 m/counts and PRC length by 2.06e11 Hz^2/f^2 m/counts. According to Optickle simulation in LIGO-T1300328, sensing matrix for PRMI sideband is

            PRCL    MICH
REFL 45I    3.4e6   2.5e3
REFL 45Q    6.4e4   1.3e5  W/m

So, the estimated effect of residual MICH to PRCL coupling to the sensing matrix measurement is;

MICH to REFL45Q element:   6 % error (= 6.4e4/1.3e5/(1.79e12/2.06e11) )
MICH to REFL45I element: 16000 % error (= 3.4e6/2.5e3/(1.79e12/2.06e11) )

If we ignore MICH to REFL45I element, which is hard to measure anyway, I think this is acceptable.


[Next]
 - Update gain balancing factor between PRM and BS from 1/16 to 1/14.7 (FM5 in H1:SUS-BS_M3_LOCK_L)
 - Update IQ demod phase in H1:LSC-REFLAIR_A_RF45_PHASE_R to minimize PRCL to MICH coupling
 - Measure sensing matrix in PRMI