WP #5094

The NDS2 client software has been updated to nds2-client-0.11.4 for Ubuntu 12.04 workstations.

J. Kissel

Came in and IFO had been unlocked for ~1.5 hours. In preparation for today's maintenance activities, I've brought the IFO_LOCK guardian to DOWN, and saved any alignments that had not yet been saved -- specifically the ITMs, SR3, the OMC, and the three OMs. 

Such that @DetChar can get a few hours of undamped / fre-swinging SUS before the DAQ restart that will be needed after this morning's front-end model changes, I've requested the IMC_LOCK guardian to DOWN, and turned off the input to the IMC common mode board, and requested all of the following suspensions to be in SAFE:
PRM, PR2, SRM, SR2, SR3, MC1, MC2, MC3, BS, ITMX, ITMY.
This has been the case since 14:26 UTC (7:26a PDT).

I plan to leave the SUS in this state until 17:00 UTC, or 10a PDT -- THEN we can do a DAQ restart to capture all of the channel name changes, but we don't need to wait to make the model changes.

In this state, we need NOT halt any LVEA incursions. Go on in at your leisure.

Evan, Alexa, Sheila, Chris, Dan, Stefan

It was hidden under an ITM...

Today we moved the remaining uncontrolled DoFs, looking for power recycling increase. This first required:
 - Offloading ASC loops to top stages for ETMs. Note that since the green WFS were using the HOLD OUTPUT button, they are now no longer compatible.
 - Offloading all other ASC loops to top stage as well.

Then we moved ITMs (mostly differential, but more Y than X), as well as a little PR3, looking for more recycling gain. Indeed we increased the arm build-up: the Y-arm went from 900 to 1150, the X-arm from 800 to 1020. The recycling gain thus went from roughly 26 to 32.

However, at that point we started seeing a decrease in DRMI build-ups (the arm power seemed to continue to climb). Also, once there, the current ASC loops started pulling us away from the best spot.

We set the IR TRANSMON QPD Offsets to zero the QPD signal in this best arm power configuration. The attached plot shows the "good" position for PR3, ITMX and ITMY.

The PR3 optical lever beam is on the edge of the QPD.  It needs to be realigned. 

Something happened to the SRM guardian.  First we had the "can't proceed suspending" problem described in alog 16880.  Evan logged into the guardian machine, killed the process, and restarted it. 

It came back, but with some states we don't expect (like align to PD4?).  Also, there seems to be something wrong with the drop down list of requestable states, for example, "tripped" is an option in that menu.  In the attached screen shot you can see that the drop down menu doesn't correspond to the actual requested state.  I've closed and opened the medm screen several times with the same result. 

Sheila, Evan, Alexa, Stefan

The LSC MICH loop was a little marginal with phase, so we replaced its roll-off filter in FM5:
  Old:
    zpk([2.73333+i*81.9544;2.73333-i*81.9544;10+i*299.833;10-i*299.833],[16+i*27.7128;16-i*27.7128;4.0625+i*64.8729;4.0625-i*64.8729],1,"n")
  New:
    butter("LowPass",2,80)
We successfully reacquired twice with this filter, so we left it as a drop-in replacement for FM5. The old one is in FM1 for now.

The plot shows old and new filter.

Alexa, Sheila, Evan, Chris, Stefan

We implemented Peter's DARM 'SUScomp' from alog  16728. Since we can't lock with that filter directly (see alog 16840), deleted the old 'LLO' filter, but instead loaded a difference filter called 'acqLP' that makes the 'SUScomp' look like the old 'LLO' filter:
  zpk([80;500-800i;500+800i],[50;70;200],1,"n")

Guardian was updated to turn off acqLP' in FM8 instead of turning on a lead.



A note on the previous filter is also found in alog 16381.

To prepare for power increase durring full lock, we have made a few changes:

• THE IMC ugf is moved from 30 kHz to 50kHz, this increases the gain margin as shown in the attached plots.
• THE IMC guardian now calculates the gain that it should use to keep the ugf the same to within 1 dB, in the locked state.  
• We changed the minimum power angle for the rotation stage to -25 from -24.  This makes the power you get a bit more similar to the power you request.  

Scott L. Ed P. Chris S.

Today we were able to clean 50 meters of tube moving towards X-1-5 double doors. The afternoon was spent traveling to town to fill the diesel tank and fueling the support vehicles.
Continuous monitoring of beam tube pressures by the control room operator.  

07:00 - 08:00 Cris M. in LVEA
~ 8:00 Reverse Osmosis in alarm, notified John W.
08:10 Hugh transitioning BS ISI stage 2 to isolated, running measurements
08:54 Ed to H2 building
09:06 - 9:11 Sudarshan at end Y blocking PCAL beam
09:22 Elli to LVEA to align ITMX and ITMY spool cameras
09:56 Elli back
11:08 Jodi to mid station
12:30 Jodi back
13:33 Ed and Peter to H2 PSL enclosure to work on Livingston PMC
15:58 Ed and Peter done

SudarshanK and RickS

Since first noticed during the LLO Yarm commissioning effort two weeks ago, we have been chasing a subtle problem that is confusing the Pcal calibrations.

Today, we finally found the source of the problem, and fortunately it has a relatively simple remedy.

The Pcal transmitter modules use uncoated, 3 deg., BK7 glass wedges to generate the sample beams for the Optical Follower Servo (OFS) and Transmitter (Tx) Monitor photodetectors

The wedge is operated near Brewster's angle to reflect only about 0.1% for the OFS PD (first surface) and 0.5% for the Tx PD (second surface).  We have been observing slow (few to tens or even hundreds of seconds) transients in the OFS and Tx PD signals that have apparently resulted from fast, large-amplitude changes in the OFS signals, e.g. from changes in the loop gain or offset.

We have been making measurements to eliminate potential offenders and today we tracked the source of the slow variations we have been seeing to small, time-varying depolarization of the Pcal beams caused by the acousto-optic modulator (AOM) that generates the Pcal beams that are directed to the ETMs.  This depolarized light, while only a few tenths of a percent of the incident light, is in S-pol when incident on the wedge beamsplitter, so about 10% of it is reflected to the photodetectors.  By installing a polarizing beamsplitter cube downstream of the AOM the slow transients in the Pcal beams were eliminated (or at least significantly reduced - we will investigate further).

The attachment below shows StripTool trends of the H1 Y-end Pcal OFS, Tx, Rx (receiver), and AOM drive monitor signals when the AOM drive level was changed (left half of figure, up to 450 seconds), when the loop switch was closed but the loop had not locked (490-910 dseconds), then when the loop locked after the offset was adjusted (910 seconds).  Note that the OFS PD signal (blue trace) goes flat when the loop closes, but the drifts in the OFS PD signal due to the AOM-generated S-pol light is imposed on the other "out of loop" signals.

The second attachment is an oscilloscope screen photo taken after installing a polarizing beamsplitter (PBS) cube downstream of the AOM.  The green trace is from a temporary photodetector that was installed in the beam reflected from the PBS (s-pol light), yellow is the OFS PD, the blue trace is the Tx PD, and the magenta trace is the monitor of the drive to the AOM modulation input (modulates the amplitude of the 80 MHz RF).  Note that the s-pol light exhibits the long (10s of seconds) transient observed at LLO and at LHO.

The third attachment is a photo of the lab setup with the PBS and temporary photodetectors installed.

We have packaged two complete PBS hardware setups along with beam dumps for the reflected beams.  They will go out to LLO to Shivaraj's attention via overnight delivery tomorrow for installation ASAP at LLO.  We plan to install an identical setup at LHO Yend later today or tomorrow morning.  If we find that this is a suitable remedy, we will procure more hardware for LHO Xarm and the 3rd. interferometer.

One of the working standards is currently at LLO.  The Pcal calibrations will have to be repeated.  This should take about two hours at each end station.  We plan to repeat the LHO Yend calibration tomorrow.

Guardian state indices have now been added to all of the requestable, and some of the "static" non-requestable, states in the seismic guardians.

The SEI guardian state index mapping can be found in LLO Log 15748.

The indices have been added to the code, and the code has been committed to the USERAPPS SVN, but the SEI nodes have not been restarted/reloaded yet, to pull the change.  This will happen during maintenance period tomorrow.

J. Kissel, A. Staley, S. Dwyer

While investigating the MICH OLTF on resonance, I noticed that the bounce mode notch in the oplev damping loop (ellip("BandStop",4,1.5,40,19.3,19.9)) was not the same as the M2_LOCKING_L notch FM10 (ellip("BandStop",4,1.5,40,17.7,17.9)). However, the roll modes were idenitcal (ellip("BandStop",4,3,40,25.7,26.4)). Using the oplev, I measured the bounce mode to be at 19.636 Hz and the roll mode to be at 26.211 Hz. So, I added another Bounce Roll M2 lock filter FM8 that matches the filter in the oplev damping. Using FM8 instead of FM10, seemed to have improved the MICH OLTF. However, later when we lost locked and tried re-acquiring DRMI the bounce mode rung up and we immediatly lost lock. I have reverted back to the original FM10, and we can now lock DRMI again. Unclear ...

Sudarshan, Rick

We saw some transient in Pcal laser power in our recent observation. The power variation in these transients are about 20% at its max. We are working on to find where the issue is. Until then, donot trust Pcal calibartion to more than 50% (over-estimation) of what it reports.