Last night we noticed, looking at the real time spectrum of DARM, that there was a wandering line. The attached spectrograms show the peculiar behavior: about every 270 seconds (not regular) this line enter the spectrum from the high frequency range and moves down in a quite repetible way (the frequency has quite perfect exponential evolution with time). Then there is some sort of burst of noise before the line starts again from the high frequency.

This behavior seems different from the wandering line related to IMC-F seen at Livingston.

The dmtviewer on projector0 used up all available memory on projector0 (it takes over a month to do this), so I rebooted the computer and restarted the dmtviewer display of seismic data.

End X PCal camera lost connection last night. The camera control software crashed and didn't detect the camera when I restarted the software. I went in to restart the communication unit this morning and that solved the problem.

Jason spotted the RefSignal voltage was 2.07V and Diffracted power was over 14%. I adjusted the RefSignal voltage to 2.13V bringing diffracted power to ~ 7.5%

model restarts logged for Tue 24/Feb/2015
2015_02_24 05:42 h1fw0
2015_02_24 09:03 h1lsc
2015_02_24 09:03 h1omc
2015_02_24 09:09 h1alsex
2015_02_24 09:09 h1iscex
2015_02_24 09:11 h1alsey
2015_02_24 09:11 h1iscey
2015_02_24 09:16 h1omc
2015_02_24 09:31 h1omc
2015_02_24 09:39 h1asc
2015_02_24 09:49 h1lsc
2015_02_24 09:51 h1susmc2
2015_02_24 09:56 h1calcs
2015_02_24 10:06 h1lsc
2015_02_24 10:14 h1asc
2015_02_24 10:19 h1susetmy
2015_02_24 10:19 h1susitmx
2015_02_24 10:24 h1susitmx
2015_02_24 10:26 h1susetmx
2015_02_24 10:28 h1oaf
2015_02_24 10:28 h1susitmy
2015_02_24 10:34 h1susbs
2015_02_24 10:38 h1dc0
2015_02_24 10:38 h1fw0
2015_02_24 10:38 h1fw1
2015_02_24 10:38 h1nds0
2015_02_24 10:38 h1nds1
2015_02_24 10:39 h1broadcast0
2015_02_24 12:01 h1pemex
2015_02_24 12:16 h1omc
2015_02_24 12:32 h1lsc
2015_02_24 12:35 h1omc
2015_02_24 12:52 h1pemex
2015_02_24 12:57 h1pemex
2015_02_24 13:34 h1broadcast0
2015_02_24 13:34 h1dc0
2015_02_24 13:34 h1fw0
2015_02_24 13:34 h1fw1
2015_02_24 13:34 h1nds0
2015_02_24 13:34 h1nds1

one unexpected restart. Maintenance day: work on ISC and SUS and CAL. PEM restart for RFM testing. Two related DAQ restarts.

model restarts logged for Wed 25/Feb/2015
2015_02_25 06:45 h1fw0
2015_02_25 10:18 h1fw0

two unexpected restarts.

04:57 Turned on the HEPA fans in the H1 PSL Laser Room.  I would like to run this test for at least
      a couple of hours.

      It is noticeable that as soon as the fans are turned on, the minimum and maximum values of the
      ISS percent diffraction vary by ~1%.

06:55 Turned off HEPA fans.

    In running this test, I had forgotten that running the HEPA fans generates heat, and is not a good
idea without turning on the air conditioning.  I switched on the air conditioning to bring the
temperature back down and switched it off after about 40 minutes.

    Attached is the output of the quadrant photodiode that is located inside the power stabilisation
photodiode box.  Assuming that DY is vertical and DX is horizontal, it appears that the vertical
alignment does not recover, whilst the horizontal alignment does.

    Also attached is the reference cavity transmission signal during the same period.  It seems to
recover.

Sheila, Alexa, Gabriele, Evan

Summary

In addition to the differential ETM loops, we now have closed the common ETM degrees of freedom using REFLA9I + REFLB9I. These loops are slow, with bandwidths of a few tens of millihertz.

Details

Previously (LHO#16883), we had closed loops around IM4 in order to reduce the amount of reflected light into REFL_A_LF. However, tonight we decided instead to close the common ETM DOF, so that the ETMs are nominally controlled in all four angular degrees of freedom. This (hopefully) leaves us free to pursue more loop-closing with the corner optics.

The common ETM loops are implemented in the CHARD filter modules. These modules are stuffed with the same filters as for their DHARD counterparts.

• For CHARD pitch, we have FM3, FM4, FM6, FM7, FM9, and FM10, with a gain of −14 ct/ct.
• For CHARD yaw, we have FM3, FM4, FM7, FM8, FM9, and FM10, with a gain of −5 ct/ct.
• For DHARD, the gains are 12 ct/ct for pitch and 15 ct/ct for yaw.

Gabriele, Sheila, Evan, Alexa

Summary

We now have new green alignment references for the WFS that should bring us to a better alignment while on resonance.

Details

Now that we have enaged more ASC loops and touched up the alignment while on resonance (i.e. we acheived a recycling gain of 29), I have updated the green QPD offests and the ITM camera nominal positions in hope that this will improve our initial alignment. For reference, I have also included the old values that we have been using.

Note: we had touched up the ITMX camera nominal position once before (LHO#16825).  After one of our locklosses we ran the green wfs on the y-arm ONLY with this new configuration, and went through our inital alignment procedure. These new values seemed to be good. After another locklos, we then ran the green wfs on the x-arm to test this new configuration, and went through the inital alignment once again. This also seemed to be fine.

There's nothing on the USGS website, but we have been riding out some seimsic disturbance that reached 10 um/sec in the 0.03-0.1 Hz band, locked with DARM on RF.  

Nice!

During all today locks, we could see from time to time the AS beam shake.

It seems that the cause is ETMY, which gets quite often kicked in pitch. Nothing is visible in yaw or in the other mirrors.

Today we have changed the plant inversion for the DHARD pit loop (which is really differential ETM).  

The first two attachments show the data collected, the data used for fitting, and the fit both at a CARM offset of 50 pm and on resonance.  The third attachment shows the fit after some poles and zeros were removed by hand.  Our strategy was to invert the plant for the on resonance case, and aim for a stable but very low bandwidth loop to engage durring the CARM offset reduction.  The resulting controller is plotted in the 4th attachment, this includes FM3,4,6,7,9,10 in the DHARD filter bank.  We are using a gain of 16 and the signal is AS A 45 Q.  

On resonance, we now have a ugf of about 150 mHz, a gain margin of 10dB and plenty of phase (last attachment).  The RMS of the error signal is still dominated by fluctuations between 0.5-0.1 Hz.  This was measured with the oplev damping on at full bandwidth. 

We later turned the OpLve damping down and saw an instability at 0.55 Hz, which could be due to multiple UGF crossings in this loop.

Today Betsy brought to our attention that PR3 had moved yesterday durring model restarts.  We have now moved it to bring the ALS beatnote back to 5dBm, and we have since locked the full IFO with a recylcing gain of 29.  The attached screenshot shows that the OPLev is still miscentered, so it is probably still a good idea to recenter it in the morning.  

Summary:

RIN of X arm green beam everywhere (input measured by QPD, transmission measured at corner, reflection measured by WFS) is much larger than Y arm for a broad frequency range, the descrepancy peaking at around 10Hz.

Looking at various things, the beam might be clipping somewhere between ISCTEX green Faraday and TMSX M3 (that's the HR/partial for IR/green to split the green main path and green QPD path).

This is not an ultra serious clipping, causing additional 1%-ish pk-pk RIN, but could be an issue for our initial alignment scheme. Needs more investigation.

Details:

First attachment, top panel shows various RIN when the arms are locked with reasonable alignment (ALS-TRX and TRY both more than 0.95).  Thick lines = X, thin ones =Y.

X arm RIN for input (QPD), transmission (ALS TR) and reflection (WFS DC) are all about 2 orders of magnitude larger than Y at 10Hz. The middle panel shows that the QPD signals for X arm shows similar structure, and it's mainly PIT.

On the bottom panel you see that the PIT to NSUM coherence is really high. This means that the structure is not due to some intensity noise from the laser, it's more likely that the PIT clipping is causing the RIN and increasing (or decreasing) PIT signal at the same time.

Perfect coherence between X QPDA and QPDB means that the clipping location is upstream of the QPD sled. High coherence between the QPD RIN and transmission RIN at 10Hz should mean that the clipping is upstream of TMSX M3 where transmission and QPD path are separated.

Back to the middle panel, the reflection RIN (WFS DC) is larger than input and transmission by a factor of 1.5 or so. This should mean that the clipping location cannot be upstream of the green Faraday on ISCTEX.

So the conclusion for now is that it's likely clipping between green Faraday and TMSX M3.

The noise is not stationary, it goes up and down, but it never comes down to the same level as Y arm.

The second plot shows that X arm has been like this for the past 6 months except for two brief periods.

(Note that I needed to set a factor of 0.685 calibration for X WFS DC NSUMs, as the DC value for these was about 1.45, not 1.00. I didn't have to do this to any other RINs.)

LVEA: Laser Hazard
Observation Bit: Commissioning  

07:15 Karen – Cleaning in the LVEA
08:00 Alarm on PY-199 – Notified Bubba & Kyle
08:11 Jim – Running testing on ETM-X, ITM-X, and HAM4
09:15 Kyle & Gerardo – Installing vacuum gauge on HAM1
09:25 Kyle & Gerardo – Out of the LVEA
12:09 Ken M – Going to Mid-X to recover parts
13:04 Filiberto – Working on Test Stand near Y-Arm spool
13:16 Kyle – In LVEA checking the HAM1 vacuum gauge
13:22 Kyle – Out of LVEA
13:40 Filiberto – Out of LVEA
15:17 Bubba – Going to Mid-X to receiving area
 

Just for referecne. If you want to decode a SWSTAT value use the following, and replace '#' with the SWSTAT value:

cdsutils sfm decode #

(Kiwamu, Dave, Jim, Jeff, Daniel)

The LSC and OMC models have been re-partitioned, so that DARM and CARM (to the ifo) are processed in the OMC.

• New input and output matrices have been added. We are upgrading the guardian to use Jamie's new matrices which uses channel names rather than numeric indices as rows and columns. This should make us more robust against changes in the future.
• All DARM signals are now processed in the OMC model, ie., ALS_DIFF, ASAIR_A_RF45 and DCPDs. This should eliminate 62µs of delay in the DARM path.
• A new MCL feedback path was added to the LSC to take over what has previously been done by the CARM module (feedback to MC2).
• We fixed the long standing naming conflict in the IMC servo, the filter module is now called IMC-MCL.
• All references to OAF have been replaced by CAL (mainly in names of IPC modules).
• The IMC-F signal is additionally routed to the OMC model and out as the common tidal signal to the end stations. The tidal script is no longer required.
• New medm screens are available.
• And committed to svn.

The current processing times are:

Only the OMC sends data to the ETMX/Y, and only ISCEX/Y send data back to the LSC. With no more than 13µs processing time one might expect that there is plenty of time to send the DARM signal to the ETMs without an IPC errors. But no! We still have one every couple of seconds. This is down from a ~10Hz error rate. Strangely, the ALS, which picks up the common tidal signal and is located after the SUS in the fiber loop, does not see any errors. We now suspect a problem at the receiving end. More investigations ongoing.