Borja

It has taken me quite a long time to process all the data I had on the several experiments that were run at ETMX as suggested on my previous Log. It is late already and I still have to think about how to plot all the data in a more friendly way (probably tomorrow). But here goes a quick update.

As a reminder, ETMX charge measurements showed relatively small effective BIAS voltages which translates into relatively low charge. This charge probably were left overs from the process of removal of the "first contact" 1 month ago when End X was vented. Several charge measurements taken over a period of 4.5 days showed consistent charge values (within 25Volts or so) in all quadrants in pitch and yaw as shown in the next table:

ETMX was an ideal test bed because I saw no issues with the wiring (all quadrants could be driven) and there were no illuminators On, the ion pump had the gate valve closed and the only known charger that was active (for a long time) was the cold cathode at the top of the ETMX chamber. Although the consistency of values above may discard it as an effective charger for the test masses. Two main charge experiments took place with mass in the last few days:

1) Green light charge effect: Between UTC 2014-08-20 23:00:00 and UTC 2014-08-22 20:45:00 the green laser was turned on at ETMX at a maximum power of 57.5mW going into the periscope which translated to 46mW actually hitting the test mass. This is a factor of 4.5 below the expected resonant power during future normal operation of aLog (about 35mW from laser into ETM and with a finesse of 12 it means a power build up of 6) but it is the maximum I could get from the laser. Here is the summary of the measurments that took place for an interval of 46 hours. It is clear that no charging trend is observed and the change in effective voltage of less than 20V is within the normal deviations of the measurement method accuracy. The fact that green light does not seem to charge the mass is certainly good news.

2) Ion pump charging effect: After the green light was turned off in End-X, we opened the gate valve of the ion pump to see its charging effect, the gate valve was opened at about UTC 2014-08-22 20:40:00 and again we measured three times for an interval of 37 hours. The summary table is given next:

In this case also the effective voltage variation is within the 20Volt resolution with the exception of two quadrants (LL and LR) we observed in the middle measurement (in blue) a considerable votage difference with the measurements that took place before and after although only obvious for one of the deflection orientations (Pitch for LR and Yaw for LL). The fact that the increase in effective voltage took place in the middle measuremnt and then went back down may indicate that the charge change is not real or that a complex mechanism of charge dissipation or cancellation took place after the charge. I will run another charge measurement tomorrow to see if there is actually a charging trend but why would only be isolated to those quadrants?

Dan, Koji

This afternoon we completed the final remaining jobs before the doors go on HAM6:

• We checked the OMC SUS cables for ground loops at the satellite boxes, they were OK.
• We locked the ISI and moved the earthquake stops on the OMC SUS to the proper clearance.  This was a hard job that required climbing around on the table, some of the EQ stops are very hard to see.
• We unlocked the ISI and ran some quick transfer functions to check that the OMC SUS and TTs were still free-swinging. 
• We took closeout photos of the table to record the as-built positions of the optics.
• We took spectra for the tip-tilts, damped and undamped.  Files are attached.  Data has been saved in /ligo/svncomon/SusSVN/sus/trunk/HTTS/H1/OM1/SAGM1/Results and equivalent.  The scripts in /ligo/svncommon/SusSVN/sus/trunk/HTTS/Common/MatlabTools have been updated to include the filenames of the latest measurements, but nothing has been committed to the SUS SVN.  Will do this tomorrow.

Since we locked and unlocked the ISI, the seismic team may want to make a quick check in the morning that the table is floating freely.  (It's ok to turn up the purge air to keep the door covers from contacting the table.)

In the attached 'H1HTTS_ALL_Spectra' files, note that the difference between the July 18th measurements and today is the floating of the ISI.  Not sure if this accounts for the change in the spectrum (more noise below 2-3Hz, less noise above).

Borja pointed out that I had the polarity wrong in the last entry I made on charging measurements.
In plots of displacement vs bias voltage for a fixed frequency and amplitude drive, the offset of the displacement zero crossing
is positive when the charge on the mass is positive. I had it as positive when the charge was negative.

no restarts reported

model restarts logged for Fri 22/Aug/2014
2014_08_22 15:36 h1asc
2014_08_22 15:36 h1broadcast0
2014_08_22 15:36 h1dc0
2014_08_22 15:36 h1fw0
2014_08_22 15:36 h1fw1
2014_08_22 15:36 h1nds0
2014_08_22 15:36 h1nds1

no unexpected restarts, new asc model with associated DAQ restart.

Dan+Kiwamu+Koji

Today we finished the in-vacuum punchlist for HAM6.  Once the SEI and SUS teams signed off on the chamber, we started to work on some alignment servos to stabilize the beam into the OMC.  Our earlier attempts to engage a simple OMCQPD-to-TT feedback had seen a lot of angle-to-angle coupling.  I tried to perform some coil balancing on OM1 using the OMC QPDs as a readback.  The coils are clearly unbalanced, if the tip-tilt is driven in a pringle mode you can see motion in pitch and yaw on the QPD, and driving in pitch will generate some signal in yaw.  But I wasn't able to reduce the coupling using the perturbcoilbalance_fourosem.py script.  Will try again later this weekend.

Kiwamu helped us to commission a temporary servo to stabilize the beam at HAM6.  The beam coming from the IFO into the chamber has a lot of pitch motion at 0.5-0.75Hz, it's not clear where this is coming from, it has to be the ITMs, SR3, or SR2.  Once ASC-AS_C (most awkward name ever!) was in the ASC model we tried using SR2 to damp the motion, but the M3 stage has really weak actuation, and the M2 stage is complicated.  We tried using the M2 stage of the BS, but again we didn't have enough gain.  We wound up feeding the AS_C signal back to IM4, using the DC3 ASC filter modules.  This turned out to be solid as a rock, Kiwamu engaged a RG filter in pitch and an integrator in yaw and the spot on AS_C is now completely motionless.  But we've essentially taken output-port noise and impressed it on the input beam, so once we start locking the PRC we're going to have to use something else.

I tried to tweak up the OMC-QPD alignment servo, there was some improvement but the pitch-to-yaw coupling is still not good.  What we need to do is measure a proper sensing matrix.

In the attached PDF I show spectra with and without the ASC loops engaged.  The references are before the servos are engaged (top: AS_C, bottom: OMC-QPD).  The AS_C motion at 0.5Hz is totally crushed.

After the beam was more or less stabilized, Koji and I went to the chamber to find OMC TRANS.  We were able to see the OMC flashes on a card with an IR viewer, with the IMC input at 10W.  We steered the beam out the viewport emulator and clamped down the mirror.  This was an awkward job with the ISI unlocked.  We used an analog camera to see the mode structure of the flashes, these were pretty high order and many were fairly symmetric, which might indicate trouble with the mode-matching.

While we were on the table we exercised the beam diverters.  These were a little sticky, sometimes it took a few tries to open them, especially going from the closed -> open state.  We were careful to leave them in the open position.

HAM6 is ready to have the doors installed.  The only thing on our punch list we haven't accomplished is an in-air lock of the OMC.  With the motion of the beam in the chamber this might not be something we can do before pump-down.

J. Kissel, D. Hoak

Completed a set of Phase 3a transfer functions and spectra to confirm the health of H1SUSOM1, OM2, and OM3 before we close doors on Monday. Results look good, and in fact, OM1 looks better -- more like the other SUS -- than before.

Raw .xmls
H1/OM1/SAGM1/Data/2014-08-22_1800_H1SUSOM1_M1_WhiteNoise_L_tf.xml
H1/OM1/SAGM1/Data/2014-08-22_1800_H1SUSOM1_M1_WhiteNoise_P_tf.xml
H1/OM1/SAGM1/Data/2014-08-22_1800_H1SUSOM1_M1_WhiteNoise_Y_tf.xml

H1/OM2/SAGM1/Data/2014-08-22_1800_H1SUSOM2_M1_WhiteNoise_L_tf.xml
H1/OM2/SAGM1/Data/2014-08-22_1800_H1SUSOM2_M1_WhiteNoise_P_tf.xml
H1/OM2/SAGM1/Data/2014-08-22_1800_H1SUSOM2_M1_WhiteNoise_Y_tf.xml

H1/OM3/SAGM1/Data/2014-08-22_2229_H1SUSOM3_M1_WhiteNoise_L_tf.xml
H1/OM3/SAGM1/Data/2014-08-22_2229_H1SUSOM3_M1_WhiteNoise_P_tf.xml
H1/OM3/SAGM1/Data/2014-08-22_2229_H1SUSOM3_M1_WhiteNoise_Y_tf.xml

Data processed by
/ligo/svncommon/SusSVN/sus/trunk/HTTS/Common/MatlabTools/plotOMCS_dtttfs.m

And saved to
/ligo/svncommon/SusSVN/sus/trunk/HTTS/H1/OM1/SAGM1/Results/2014-08-22_1800_H1SUSOM1_M1.mat
/ligo/svncommon/SusSVN/sus/trunk/HTTS/H1/OM2/SAGM1/Results/2014-08-22_1800_H1SUSOM2_M1.mat
/ligo/svncommon/SusSVN/sus/trunk/HTTS/H1/OM3/SAGM1/Results/2014-08-22_2229_H1SUSOM3_M1.mat

TFs compared with others using
/ligo/svncommon/SusSVN/sus/trunk/HTTS/Common/MatlabTools/plotallomcs_tfs.m

All data and scripts have been committed to the repo.

J. Kissel

Completed a set of Phase 3a transfer functions and spectra to confirm the health of the OMCS before we close doors on Monday. Results look good, and comparable to previous measurements and LLO's OMC, sensors show noise comparable to what is expected. This SUS is clear for chamber close up.

TF DTT Templates:
/ligo/svncommon/SusSVN/sus/trunk/OMCS/H1/OMC/SAGM1/Data/
2014-08-22_1739_H1SUSOMC_WhiteNoise_L.xml
2014-08-22_1739_H1SUSOMC_WhiteNoise_P.xml
2014-08-22_1739_H1SUSOMC_WhiteNoise_R.xml
2014-08-22_1739_H1SUSOMC_WhiteNoise_T.xml
2014-08-22_1739_H1SUSOMC_WhiteNoise_V.xml
2014-08-22_1739_H1SUSOMC_WhiteNoise_Y.xml

TFs processed by 
/ligo/svncommon/SusSVN/sus/trunk/OMCS/Common/MatlabTools/plotOMCS_dtttfs.m

TFs .mat file 
/ligo/svncommon/SusSVN/sus/trunk/OMCS/H1/OMC/SAGM1/Results/2014-08-22_1739_H1SUSOMC_M1.mat

TFs compared with other previous results using
/ligo/svncommon/SusSVN/sus/trunk/OMCS/Common/MatlabTools/plotallomcs_tfs.m

Spectra taken by
/ligo/svncommon/SusSVN/sus/trunk/OMCS/Common/MatlabTools/plotomcs_spectra.m

ASD saved to
/ligo/svncommon/SusSVN/sus/trunk/OMCS/Common/Data/2014-08-22_1739_H1SUSOMC_M1_Spectra.mat

Spectra compared against others using
/ligo/svncommon/SusSVN/sus/trunk/OMCS/Common/MatlabTools/plotallomcs_spectra.m

All data and scripts committed to to SusSVN.

- 9:20 am, Jim W. to CS VEA, HAM6 work unlock ISI.
- 9:40 am, Anaud and Filiberto to CS VEA, HAM5 work.
- 11:00 am, Krishna to X-End VEA, retrive equipment.
- 11:13 am, Filiberto to X-End VEA, power LHO's tiltmeter.
- 12:00 pm, Fred and visitor to CS VEA, tour.
- 12:25 pm, Kyle and Gerardo to X-End VEA, to power ion pump 12.
- 1:00 pm, Karen to Y-End station, clean.
- 1:47 pm, Sheila and Borja, to X-End VEA, station is now laser safe.
- 3:30 pm, Sudarshan to visit both Y-End and X-End station for PEM work.
- 3:51 pm, Filiberto, Manuel and Borja to Y-End VEA, ESD power measurements.

Sheila, Dave, JeffK, Kiwamu

We have modified the ASC_MASTER model so that the AS_C QPD signals are routed to the input matrix. Note that these signals had been disconnected and going nowhere. This is a part of the OMC locking effort which is our recent short-term goal. I edited common/ASC_MASTER.mdl and checked it into SVN. Since I have appended these signals to the existing input matrix elements, this should not impact on the LLO commissioning.

Also, I was asked by Jeff to add two new IPC senders to the ASC model so as to broadcast the AS_C signals for evaluating the suspension coil balance performance. However this let us run into an issue where we got funny error messages [1] when compiling it. Looks like it fails compiling once two new outputs are added to the ASC_MASTER model. It is nothing to do with the IPC blocks. We gave up for the time being.

We restarted the ASC model and did subsequent DAQ restart.

[1]

Parsing the model h1asc...
first pass done 127 1
Counted 2277 parts out of total 2279
Fatal error - not all parts are in processing list!
List of parts not counted:
ADC0 Adc
ADC1 Adc
ADC2 Adc
ADC3 Adc
ADC4 Adc
Please check the model for missing links around these parts.
make[1]: *** [h1asc] Error 1
make: *** [h1asc] Error 1
make failed
log file is /opt/rtcds/lho/h1/data/buildlog/h1asc_2014_08_22_14:49:30
 

X-end pumped by both turbo and ion pump over the weekend -> Y-end pumped by turbo only over the weekend

Kyle, John, Gerardo, Borja

The ion pump gate valve in ETMX is now (about UTC 2014-08-22 20:40:00) open in order to see its charging effect on the ETMX mass.

J. Kissel, K. Venkateswara

While trying to figure out the gain mismatch between the BRS and GND T240 at EX, we discovered that the calibration filter, "T240Cal" in FM2 of the GNDSTSINF A and B (but not C!) banks had been changed from the 254.3 [(nm/s)/ct] I'd installed in March (see LHO aLOG 10635), to 4.46 [(nm/s)/ct]. This gain calibration is different (reduced) by a factor of 57 -- which is the difference between high gain and low gain mode of the T240 interface chassis. This would therefore compensate for the gain in the chassis being switched from low (as it was in March) to high.

After a lot of aLOG trolling (thankfully there are only about three people on the planet who would have the knowledge to change the analog gain, and compensate for it in foton), I found that this is a result of Rich Mittleman (see LHO aLOG 11203). The filter file had not been committed to the userapps repo until I'd committed the file for other reasons (see LHO aLOG 13483), the aLOG did not mention the calibration factor, or the filter name, the filter bank name, or that he only changed 2 out of the three filter banks, rendering the aLOG quite difficult to find.

This does not explain the factor of 0.62 that we're missing, but it certainly threw us for a loop for a half-day. Please let this be a lesson to visiting commissioners and electronics engineers who make changes to hardware /software / electronics: add as much information as you can to your aLOGs to make them as search-able as possible, take the time to commit your work to repositories, and make sure you've done a complete job. Everything you do will eventually matter and confuse someone in the future. 

For all this, we still don't understand the factor of 0.62 between the T240 and the Rotation Sensor (see LHO aLOG 13544).

After fixing cabling and rebalancing the table yesterday, I took DTT tf's this afternoon. I used a white noise excitation with 2 poles at 5hz and tuned the amplitude to just avoid saturating the seismometers. See attached screenshots. Template is saved in the HAM6 data/transfer function/undamped folder

J. Kissel, K. Venkateswara

We were able to take overnight measurement with everything working smoothly. I have analysed 35000 seconds of data starting from ~7 PM to ~5 AM this morning. The first file shows a similar plot as I had posted yesterday. The subtraction is done a bit differently:
Yesterdays subtraction -
Residual = BRSout  +  T240X * (w/g)

This simply accounts for the inertial angular acceleration measured by the bar and assumes d = 0.

Todays subtraction - 
Residual = BRSout  +  T240X * (w/g) + T240X * ( 1/w * M * d * g/I)

where BRSout is the BRS output (in rad), T240X is the velocity output, w is angular frequency (2 pi f), M is the total mass of the balance (4.2 kg), d is the distance between CoM and the suspension point ( (39 +/- 5) microns), g is 9.8 m/s^2, and I is the moment of inertia of the beam (0.59 kg m^2).
This subtraction accounts for inertial angular acceleration and horizontal acceleration coupling based on an estimate of d, which is explained below.

The second file shows the raw T240X displacement output and the tilt-subtracted output.

The third file shows the angular acceleration measured by the bar. This is similar to the first plot, but rotated by f^2. This makes the effect of various terms a bit clearer. The first plot shows the influence of inertial angular acceleration and the horizontal acceleration coupling. This allowed me to estimate d by varying it until the green curve lined up with the blue at low frequencies. In the next plot I added the residual and the autocollimator noise. Note that the residual is worse below ~8 mHz due to the influence of the low-frequency high-pass filters which mess up the phase.

To make a long story short, the Beam Rotation Sensor works as expected. The subtraction scheme we showed above is easily implementable and presently gives a factor of ~5 improvement in displacement noise below 0.1 Hz down to ~10 mHz. The d offset is larger than I expected which was due to the inaccuracies in the transfer function measurement scheme. Still, it does not present any difficulties in doing the subtraction. If we have to open up the vacuum can for whatever reason in the future, we can correct it easily.

We have learnt many lessons and if we get the opportunity to do this again, we will do better. We have some ideas for implementing a simple damping scheme to remotely damp the balance, which we will try out at UW. 

I have had a great time installing/commissioning the tiltmeter and would like to thank everybody at LHO for all the asistance. The atmosphere and energy here is terrific and I hope to be back here soon :)



edit: The matlab file I used for the above analysis is : /ligo/home/controls/tmp/BRSanalyze.m
It is very badly written and I will add comments, polish it and upload it soon.

J. Kissel, J. Warner

Jim unlocked the ISI and we installed damping loops on the H1 HAM6 ISI (such that we could run SUS close-out TFs). The damping loop install went poorly, but eventually we got it to work in an odd configuration. Below is the chronology.

- I installed a copy of HAM4 damping filters using straight copy and paste from foton.
- Tried turning loops on, got immediate trip. Repeated just to be sure, with the same result.
- Checked HAM6 ISI DAMP filters against HAM4 filters in foton, confirmed they're identical
- Checked Basis Transformation matrices, confirmed they're identical to HAM4, and they match T1000388.
- Confirmed with foton that the actuator compensation filters were installed and correct (i.e. they match HAM4).
- Confirmed with foton that the GS13 calibration filters were installed and correct (i.e. they match HAM4).
- Confirmed that all signs along the chain, in the GS13INF, DAMP, and OUTF filters were the same as in HAM4.
- Checked that gain switching on GS13s was functional, and that were were in low gain.
- Tried closing loops again, still unstable.
- Jim installed HAM6 damping filters using the "normal" Matlab quack method from commission scripts that were designed from an old set of plant data.
- Confirmed with foton they installed correctly and showed very little difference between HAM4's filters.
- Tried them, still unstable.
- Noticed that all corner station ISIs had ADC saturations on CDS overview screen. Found it to be STSA (i.e. the one by HAM2) which was railed, and being piped to every ISI and HPI front end.
- Went out to racks, re-zeroed STSA, saturations disappeared, still no change in behavior. Damping loops still unstable.
- Turned down / off purge are in HAM six. Amplitude of GS13 motion went down, but still the loops were unstable.
- Performed the radical -- flipped the sign of loops in the DAMP filter bank, AND IT WORKED.

We can't think of any reason that there would be a sign flip in the chain, but for now, we leave it and move on checking out SUS.

yesterday we noticed that ITMX has been tripping, it seems to happen within a minute or so of becoming fully isolated.  HEPI seems to have position loops running, there is no feedback from ISC to the suspension or HEPI.  The last few trips have been just stage 2, actuator trips.  It looks like something is ringing up.

The stage 2 blends were on Tbetter expect RZ, which was on Tcrappy for the two trips plotted in the first screenshot attached.  I've tried setting stage 2 blends to start, this also caused a trip which is the second attached screenshot.

Now I have set the guardian to isolated_damped, so that stage 1 is isolated and stage 2 is damped.  So far its not tripped.