ETMY single arm test first two fibre welds

Doug, Jason, Travis and Angus spent the afternoon welding in the first two fibres on ETMY. The ETM is currently set with approximately 600 microradians pitch down. Both welds were straightforward with no particular issues. S1106461 is welded in position HR side right (looking from HR side), S1106459 is at AR right (looking from HR side).

H2 DAQ MSR Sataboy RAID lost disk

We had our first Sataboy RAID disk failure yesterday. H2 DAQ MSR SATABOY disk 7 (counting from 1) failed. Dan replaced with spare 2TB SATA disk, it is now rebuilding the RAID6 using the new disk.

Should be able to link to comments

Main entries have a link in the upper right corner such that one can provide direct links to log entries in emails, etc. This should also be the case for comments. Perhaps it's best if the link takes you to a page that has both the main entry, the comment itself, and any other comments associated with that entry (I fear that a direct link would show *only* the comment on the resulting page, like it does for the main entries -- I don't want this, it's imperative to see the context of the comment). However, the comment should somehow be highlighted to show that "it's *this* comment I wanted to show you."


On a related note, if you try to link directly to a comment by replacing the "callRep" at the end of any normal entry's URL for with one for a comment the page turns up blank.

i.e. Take the URL for entry 1874,
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=1874

and replace the callRep for the corresponding comment to that entry,
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=1880

and you get zilch.

Jeff,

This is implemented in test test aLOG.  It will be moved to production in the next few days.

LVEA DAQ channels now being recorded

We rerouted the fiber optics line from the H2DAQ out to the LVEA via the H2EE building. All fast channels are now back in the DAQ.

DAQ data from LVEA not being recorded

This afternoon a CDS multimode fibre optics cable was pinched against the cable tray near BSC8, causing the fast DAQ data from the LVEA to be stopped. For the rest of this week the aligo DAQ will record EY channels and slow channels from the LVEA. On monday the H2 racks will move into the H2 EE building and the missing DAQ channels will be restored. 

FMP/ICC Prep for BSC8 Cartridge Install

The Y arm cavity bottom was lightly vacuumed, using the same procedure that we typically use on BSC domes (HEPA vac with custom stainless steel brush attached). Mark L. was in the tube and Chris was on the outside. Vacuuming started at BSC8 and proceeded toward GV5. No significant issues were encountered and final inspection showed that the large debris (relative term) that had littered the bottom of the tube was gone. As anticipated, the very fine (mostly metal?) particulate "rain" from the top of the tube was not significantly improved by vacuuming.

Since the Apollo crew was in the neighborhood, we also installed the BSC flooring (without hardware at this point) and a 60" dust barrier to facilitate the upcoming Arm Cavity Baffle install.

BSC8 ISI Prep for Cartridge Lift to Chamber

SEI--Jim Corey & Greg
Once we got the all-clear from SUS for their tests and Vincent for our ISI tests we started preparations for transport.

Trillium cable end repairs were made.
Cabling was disconnected at the Feed thrus and tied off back on Stage0--we may need to move some of this for insertion clearance.
Dummy Feed-thrus were removed from the Test Stand to ease access clearance for future activities.
The Keel Mass was removed along with the other Stage2 balance weight on the sides.

-Hugh

ISI-BSC8 Tests

The ISI-BSC8 was tested on December 6 and 7. It went smoothly. I have attached a sum-up of this 2-day test. Further details will be given in E1100845.

BSC8 SUS Cartridge Install Prep

This afternoon, after the final B&K hammer measurements were complete, and SEI locked the ISI and began their preps, I began securing the FMy and ITMy for lift-off.  Because the First COntact that was on the ITMy HR was many months old, and had been peeled down for IAS purposes numerous times over the last 2 months, I removed it and put a fresh coat on, including a new tab at the top.  I observed a lot of particulate on the optic after the peel and attempted to remove them with alpha swabs and the N2 gun (gun also used intermittently during FC removal).  This was cumbersome and while doing it I (and Corey over my shoulder) noticed some streaking pattern not from the First Contact, as well as some First Contact PEEK mesh patterning on the optic.  More pictures to come.  So, I gave up on the dabbing and blowing and reapplied the new FC coating.

Then, I secured all of the EQ stops on both the FMy and ITMy, with the exceptions of:
- 2 nuts (missing) - one on each UIM side stops, and
- the ITMy Top Mass Blade Stops, which require removing the Top Mass BOSEMs.  The masses and blades above and below are rock solid however, so this is fine.

I then added the new "finger" assembly which acts as a 20mm gap stop between the ITMy AR and the CP HR.  This assembly, however hangs down below the QUAD structure and may be a problem for the cartridge, but is easy to remove tomorrow if needed.

I also added the transport pins to the vibration absorbers on both suspensions.

I covered the FMy.

Further to Corey's elog regarding the contamination pictures of ITMy, following is my note to COC:
Yesterday, I removed the old FC from the ITMy HR and reapplied a new coating with a thin tab at the top which can be peeled in-chamber.  Corey managed to take some great pictures of this and they are posted at the link on ResourceSpace below.  (Note, the pictures are always uploaded in reverse order so the first picture is my new FC coating.)  Long story short, there are 4 things to note regarding the surface of this optic:

1) Overall particulate - lots still on the surface - like 10-20 per square inch - Ugh.  Performed the dabbing technique but gave up after a short stint because it seemed futile.  (Used lots of N2 filtered DI gun flow throughout, which helped some but not enough.)

2) PEEK Mesh pattern seen down front of optic (recall, we applied a long tab back in Oct when we bantered about the idea to tear down a strip for IAS purposes.  In the end we didn't do this and the full tab just pulled the whole top of the circle down for IAS).  You can see the "matrix" like pattern in the center of the optic in some of the pictures.

3) When I pulled the FC circle, a little square tab stayed on the optic when I got down to just below center.  Weird.  It's like it had a cut and the FC peeled around it.  I stopped pulling and pulled the circle in such a way to pull up the tab.  A small horizontal line roughly 3mm in length remained on the optic almost on center line and a 1-2 inches to the right of center (when looking at the face).

4) A very strange "watermark" was apparent streaking across the top of the optic - very apparent in some pictures.  It looked very reminiscent to me of the purple markings we observed on many iLIGO optics.  Not sure what this is.  Defect in the coating maybe - I have not looked up the CSIRO report.

As stated above, all of this was observed and then I reapplied a new FC coating as shown in picture 1 on the link.

Today, Cheryl and I re-inspected the ITMy HR surface, which now has the ~week old First Contact sheet on it.  My subsequent email to GariLynn:

Hi GariLynn -
So, the good news is, the blue streaking that ran horizontal in a band across the ITMy HR peeled off with the new FC.  The bad news is, Cheryl has pictures of a newly observed band of contaminant running around the surface of the HR surface within 1" from the edge (so outside of the FC ring).  She'll post pictures soon of today's observations.

I will indeed need to do a fresh application/pull after all IAS needs are complete in order to pull any more streaking likely to be induced when we do the pull-and-close technique a few times over the next few weeks with this new FC sheet.  Not sure how we can get away from doing this in the future - maybe we just leave it exposed?  Then we risk particulate accumulation which seems worse (as FCing over particulate may scratch, and the amount of particulate is likely to be too much to remove via dabbing).

Not sure what the new stuff is - I'll make a larger diameter FC sheet next time.

-Betsy

Cheryl's pictures from today:

https://ligoimages.mit.edu/?c=883

H2 PSL dust counts

On the night of the 5th, the HEPA fans were turned off for noise measurements. Dust levels still look good during this period. The attached file is a 3 day trend, with the time with no HEPAs roughly indicated by the black lines. 14 is the anteroom, 13 is the laser room.

CP1 and CP2 overfilling

The recent installation of permanent heat traces around the LLCV needle valve valve bodies for CP1 and CP2 solved 1/2 of the nuisance freezing problem.  Now the actuator box is freezing up (These units were installed upside down for some reason and are prone to moisture entry and subsequent freezing) -> I am using drop lights with 25 watt bulbs as general heat sources as an interim solution for now.  

Operators note that I'm am monitoring CP1 and CP2 levels periodically and additional alarms are likely overnight.  No action is required.

Ops Summary

I covered from ~12:45 - 4:00.

Work on upgrading the FMCS system.
Preparation for cartridge install.
Fiber from LVEA H2 electronics rack to H2 DAQ accidentally cut.

plots of dust counts

Attached are plots of dust counts > .5 microns.

Y Arm Beam Tube Pictures:

This is a follow up to Jodi's alog here, showing the pictures I took of the stuff we found.  Images show the range of particulate that was found, which includes white thread, small bundles of glass fibers, metal, and some stuff we couldn't identify.  

White fuzzy / thready particulate was very prevalent.  Other particulate was rare, so for example, only one red item was found, I only took two pictures of what looked like bundled glass fiber, and there was only one area where there was brown stuff stuck to the beam tube wall.  The pictures of the o-rings show that there was a significant number of particles on and in between the o-rings.

Picture names have the description of what's in the picture.

H2 ITMY Tap Tests

Today, impulse response tap tests on the ITMY QUAD were performed with the ISI floating.  The following plots are of the response for the 7 locations with each X,Y,and Z DoF plotted. Descriptions of the tap locations are below.

ITMY 

location1 - cross brace on reaction side in front of PUM - 
location2 - just between pum and uim vertical brace from clean side to beam tube
location3 - straight cross brace between uim and R0 
location4 - cross brace beside pum on clean side downwards 
location5 - cross brace beside R0 clean room side hitting upwards 
location6 - beam tube side - vertical brace beside M0 hitting towards clean room 
location7 - straight cross brace between M0 and UIM downwards. on ITM side 

Test of ESD Cableing Integrity

Performed a test of the ESD cabling associated with the BSC8 cartridge.  A time domain reflectometer was used to verify the integrity of the coaxial cable from the vacuum side connector down the suspension chain leading finally to the reaction mass ESD actuator.  Discovered that 3 out of the 5 coaxial paths were bad.  Cause traced to a failure of the solder joints used to attach the coaxial cable to the PEEK custom connector.  The joints were baked at 200 degrees C in the vacuum bake process.  The solder used has a melting temperature of 184 degrees C, which resulted in a complete failure of these connections.  Even the two that tested good rapidly failed when tension was applied to the connections.

After a conversation with John Worden and Mike Landry, we elected to leave the majority of the cabling intact and to re-terminate the coaxial cables in a new connector after the cartridge is installed.  The 5 coaxial cables will be drawn through the aperture of the conflat feedthrough and a new connector will be installed in situ.

All of the five cables appear intact and correct aside from the failure of the vacuum side conflat mate.

For reference, here are some pictures of Rich's setup:

 1. The front panel of the TDR (time domain reflectometer) box used by Rich. This particular unit is very old and failing, and a modern replacement is being procured, but the new one will be similar in concept. The screen shows the output for a 15' test cable with an open circuit termination. The horizontal scale is set to 2" per major division, and a fairly clean reflection from the end of the cable can be seen. (A short circuit would have given a reflection of opposite sign, and a impedance-matched termination would have given little or no reflection.)

2. The output for channel 1 of the ESD (viewing the connector as a boat shape and counting left-right, top-bottom). The horizontal scale is now 5' per division and the horizontal position has been set to put the section of the trace representing the 15' of test cable on the outside of the vacuum flange offscreen to the left, so that the visible portion represents only the in-vacuum cable. There is a more complicated shape reflecting the different impedances of the conductors in the chain and the capacitance of the electrodes at the end.

3. The output for channel 3 of the ESD. It is quite similar to ESD 1. These traces can serve as a provisional reference for what a working channel should look like. (There may be slight differences when the connector is repaired, and/or the TDR is replaced.)

4. The connector falling apart in Hugh's hands. There is supposed to be a gold pin on the end of each inner conductor, but the solder has melted and several of the pins have come off.

Mark B.

Rich spotted a typo in my earlier comment: the horizontal scale in the first picture is 2' (feet) not 2" (inches) per division.

H2 SUS ITMY M0, Long to Yaw Coupling Investigation

In order to investigate whether the Length modes coupling into H2 SUS ITMY M0 Top2Top Yaw transfer functions are real or noise, I've taken a high resolution (2 mHz) measurement of the same transfer function (same amplitude, BSC-ISI unlocked but undamped, ITMY M0 damping OFF, ITMY R0 damping ON).

I attach three plots for discussion. 
(1) A full-frequency-range plot measurement itself, 
(2) A zoom in on the resonance that we've been concerned with, and
(3) A plot of what cross-coupling we expect from the model (i.e. zip, nadda, zilch).

Note that neither of the first two plots are calibrated properly, but the relative amplitude should be accurate

One can see from the full-range plot that not only is the lowest Longitudinal mode present (at 0.43 Hz), but the second L mode (at 0.98 Hz) also creeps in. Regrettably, I'm now convinced that this (these) resonances are actually a measurement of physical motion, not just unlucky in coherent noise.

Now, is it a show stopper? No (yet).

A useful tip from the good Dr. Lantz: physically cross-coupled modes typically show up as pole-zero pairs, as opposed to what we see here -- just a sharp pole.

Other pertinent information: the excitation for this drive is a continuous, broad-band, white noise excitation across the measurement band, for the duration of the measurement. You'll note in the second plot attached (upper right panel), that the coherence (i.e. the measure of the *linear* coupling) between the Y drive and this particular L resonance is ~0.25, which is roughly consistent with what we know to be noise in the rest of the band. 

However, the lower right panel shows the OSEM basis response of F2 and F3 to Y (in PHASE); the sensors that compose this DOFs Euler basis signal. Here, (though it's tough to see with the black cursor overlayed -- sorry) the sensors are identically in phase, implying real longitudinal motion.

Why don't I think this is a show stopper (yet)? We have found from experience that moving around these suspensions, after locking and unlocking, that these sharp cross couplings come and go. Case and point -- we don't have a smoking gun of what might have happened between the 2011-11-19, 2011-11-29, and 2011-12-02 measurements that might have caused such a gradual increase in coupling, except for *better* aligning the chains. Further, I expect that the coupling will be significantly reduced once we take a similar measurement with damping loops ON (we'll be sure to confirm this of course) -- which is the default "plant" upon which we'll apply ISC control loops (if there are any at this stage). 

But most importantly, let's just see what we get after we install the cartridge. We'll have to lock and unlock the suspension, and will have to do another round of BOSEM centering (in and out, not necessarily laterally). We may get lucky and the coupling may be reduced, or we could get unlucky and have much worse coupling. Further, we have yet to use what's in our digital back-pocket: diagonalizing the drive using sensors. This may help as well. From what I've seen of the remaining degrees of freedom, I'm confident that the suspension's mechanical system is behaving well.

--------------------

Data for this measurement can be found here:
{SusSVN}/sus/trunk/QUAD/H2/ITMY/SAGM0/Data/20111207_1700_H2SUSITMY_M0_Mono_Y_0p002to50Hz_TF.xml

B. Lantz, J. Kissel, B. Shapiro

Brian guesses that this excess cross-coupling maybe be from air currents in, on, and around the suspension.

The notes leading up to the hypothesis:
- The amplitude at this frequency (0.43 Hz) in both the Yaw2Yaw and Yaw2Long transfer function is incoherent (~0.2 coherence, consistent with what we know is noise, or non-linear coupling at other frequencies).
- One difference between the 2011-11-29 measurement and 2011-12-02 measurement is that the BSC ISI is unlocked (and undamped), and we know the BSC-ISI "is a big sail" when it comes to air currents**.
- The clean room forces air current to move in, on, and around the QUAD, as well as the BSC-ISI.
- Remember F2 and F3 are the Long (in common) and Yaw (in differential) sensors; they're in line with the vertical center of mass at the top stage.
- OSEM response to linear drive goes incoherent on *expected* resonances, because the SUS is swinging with large amplitude outside the (linear) range of motion of the Flag/LED/PD system (think -- at the edge of the range, the signal flat-lines at open or closed light and is no longer proportional to the drive). Non-linear response to drive = still get amplitude, but no coherence. 
- "The OSEMs are linear to "+/- 0.7 mm" peak to peak." I put in quotes, because though this is the number we always quote as a spec, this number is eye-balled from the curves measured of a few OSEMs, on an independent jig, ideally aligned. Mark has shown the linearity to vary with alignment (see T1100455) and we know OSEMs can have ~50% variability in sensitivity). 
- Suspension Q's are "a billion," so we often cannot resolve their actual absolute motion.
- Another plot is attached -- the calibrated amplitude spectra of the motion during the transfer function excitation, and after late at night during a quiet time (thank you data stored in frames!).

The hypothesis:
- Air currents are exciting the longitudinal mode by lots, but in an incoherent manner (such that it might be misconstrued as yaw). Because there is so much incoherent motion, it bleeds into the yaw sensors, and therefore into the amplitude of the transfer function.

Devil's Advocate questions:
- Why would there be so much more motion at longitudinal, vs. other degrees of freedom?
     (Not sure. BSC-ISI Y [not yaw but cartesian Y, aligned with IFO arms, and therefore ITMY's L direction] resonances are at )
- Wouldn't the air current excitation be broad-band? 
     (Well -- so is the intentional excitation. We insert uniform white noise across the measurement band as our excitation)
- Is there really a mechanism where longitudinal motion can be sensed as yaw? 
     (If, for example F2 goes non-linear before F3 as the pendulum swings through the edge of OSEM range in L, then you'll get more amplitude in F2 than in F3; a differential signal, which appears as yaw.)
- Why don't we see the same coupling on the reaction chain? 
     (We did -- in the 2011-11-29 measurement (see page 6, magenta curve of allquads_111202_H2SUSITMY_ALLR0_TFs.pdf), arguably just as strongly, but it went away in the 2011-12-02 measurement)
- Why don't we see anything on FMY?
     (Maybe because FMY is not aligned with any of the fundamental modes of the BSC-ISI?)

**Auxiliary/Curiosity Questions: 
- What're the BSC-ISI Modes in the L degree of freedom?
     (See second attachement -- for this QUAD and ISI, the L and Y/RX modes are roughly aligned. for the BSC-ISI, those are at [1.0, 1.75, 5.15, 6.95 ] Hz)