IO Work Day Summary Nov 8th 2017

J. Kissel, E. Merilh, C. Vorvick

Below is a summary of what Cheryl led us through today:

 - PRM and PR2 Irises placed in-vacuum
 - Performed daily alignment of IMC by adjusting PSL PZT, and IMC Mirrors
 - IMC flashing speed reduced by turning down HAM2/HAM3 purge air
 - IMC alignment fine-tuned by driving MC2 broadband in L from 0.2 to 0.25 Hz (to have RMS velocity dominated by a slower pulse than the 12 Hz HEPI pier resonance noise)
 - IM1&2 alignment finalized (via sliders / actuators) using IR card views of flashing beam at Faraday Isolator input and output apertures 
 - Flashing beam routed through to PR2, but found that IM3 needs entire DAC range in Yaw (consistent with what was seen during first observing runs)
 - IM3 alignment mechanically offloaded in Yaw using OSEM sensors
 - Re-tightened all IM3 cage / structure bolts

A video of the flashing can be seen here: https://youtu.be/8DJnQ45cmK0. The speed at which the IMC is flashing through alignment fringes is reflective of the 12 Hz pier resonances transmitted through the locked HEPI and ISIs in HAM2 / HAM3 (see LHO aLOG 39328).

Attached are screenshots of:

 - The evolution of alignment sliders during the daily re-alignment of the IMC in Pitch and Yaw
 - Screenshots of OSEM positions and alignment sliders after we finalized the IMC alignment 
 - Screenshots of OSEM positions and alignment sliders after we finished alignment of IM1 and IM2, and after mechanically offloading IM3

We ran out of time today given the extra work with IM3, but we will resume tomorrow morning around ~10a, with the end-goal to install the IMC bypass and hand off to further down-stream alignment of the IFO.

Any work that needs laser safe will be free to work laser glasses free for a few hours in the early morning.

LVEA is LASER SAFE; Purge Air Restored

J. Kissel, G. Moreno, E. Merilh, C. Vorvick

The IOO HAM2 / HAM3 crew is done for the day.

The LVEA is LASER SAFE.

The HAM2 / HAM3 purge air is being restored by Gerardo.

J. Kissel for G. Moreno

Purge air has been restored.

Ops Day Shift Summary

 

BS HR Elliotical Baffle Alignment

Since Monday, Jason, Travis and I have been working on (amongst other things) the BS elliptical baffle rebuild and realignment.  Once all parts were in hand, the rebuild was straight forward.  Travis used the removed HR and AR baffle assemblies to line up and preassemble the mounting brackets so that the new baffles went in roughly where the old ones used to be positioned on the BS suspension structure.  However when we put the target on the HR panel, we discovered one of GariLynn's earlier worries - the baffle was off center by many millimeters.  Looking at the baffle relative to the structure seemed to indicate the same thing - the beam was left and down when looking at the HR surface target (meaning, the baffle was potentially too far up and right relative to the simulated IFO beam).

Unfortunately, this target-mounted-to-the-elliptical-baffle is what was used to align the entire BS SUS/ISI cartridge in the chamber install in ~2013, as per IAS procedure E1200795.  This fact lead us to spend a day or 2 sorting out how to tell if the BS optic is misaligned in the chamber (without any IAS measurement ability), and how we possibly could have installed the elliptical baffle out on the cartridge in the first place many years ago.  During this we went back in-chamber to make "precise" measurements.  We used Class B rulers to measure where the IFO simulation beam was hitting the BS, how well the BS is centered in the structure, and exactly where the beam was hitting the target.  Attached are actual sketches and pictures with detailed numbers.

Here's what we were able to measure to within ~1mm error since it's by-eye and other knowns:

1) The beam is hitting the center of the BS optic 2mm to the left of the optic centerline.

2) The optic is suspended in the structure to within 1mm or less of error.

3) The beam is hitting the HR target baffle 5.5 mm left of the target center.

4) Our Y-arm IFO simulator beam which runs between the ITMy center and the SR3 center ran dead center on the ITMY elliptical baffle (prior to it's removal) and the HWSY path a few weeks ago when HAM4 work was checked.

5) Per IAS procedure E1200795, the BS suspension to ISI locations were performed via more direct methods which did not involve the Baffle target, so we believe the BS to ISI mounting is correct.

Point 1) and 2) give us some confidence that the error of the BS optic placement is not as bad as how the baffle target indicates.

Some consult with GariLynn and Jenne, to understand what centering is most important from various aspects (including looking at some modeling done by Hiro in T1400055) and we have come to the conclusion that we will carry on as planned.  Namely, to first order it is best to have the baffle aligned very well to the beam.  Our next steps will be to recheck the IFO simulation beam pointing again, align the HR baffle to it, and take a series of pictures to ensure that the edges of the baffle are lined up correctly with the edges of the BS optic from the beam POVs.

Also during our walkabout over the last 2 days, we re-interpreted Keita's BS centering/beam clipping alog 28196, pointed out by Sheila.  Because it is difficult to see the edges of the BS optic when the baffle is installed, it seems Keita made some geometrical analysis of the HR and AR baffle positions to determine the position of the BS center.  However, since we believe the baffle was mounted in the wrong position by a few mm, his centering numbers likely are not correct.  Still, his numbers indicate the same directions of error as we see - the beam is hitting left and low of the baffle/optic.  I think we can repeat this measurement in the future by scaling the known diameters of the baffle holes and BS optic size on the camera view pictures.  Will think on this more.

 

End Station Temperature Control

Krishna

The End Station VEA temperatures are currently locked to H0:FMC-EY_VEA_AVTEMP_DEGF, which is an average of various sensors mounted to the walls of the VEA. As has been discussed before, what we'd like to hold constant is the temperature of the suspensions or the vacuum chambers. The attached plot shows various temperature sensors (refer to Jeff's alog for calibration) in the VEA which all show a rising trend (the M0 has a negative temp coefficient), whereas the FMC average sensor shows a constant trend. The reason for this is it is getting colder outside, so the walls are cooler. Therefore to keep the walls at the same temperature, the inside has to get warmer.

Robert and others had noted this for the corner station earlier and I've been told that this was fixed at the corner station but not at the end stations. I would recommend fixing this problem for both the end-stations as well. One possible solution is to simply mount the FMC sensors on or closer to the vacuum chamber.

BRS-X upgrade: Complete. Monitoring Mean Position.

Krishna

The reconfiguring of BRS-X is complete. The new resonance frequency of BRS-X is 5.6 mHz (T ~180 s) and d is zero for all practical purposes. The BRS-X calibration filters have been modified. I have also modified the tilt-subtraction filter banks. The big change is that there is no acceleration correction for the finite d.

The pdf attachment shows the tilt-subtraction achieved under mild wind speeds of ~10-15 mph. The one noteworthy change is that the tilt-subtraction is slightly better in the 5-20 mHz frequency range, likely due to the lower resonance frequency.

I have also modified the C# code, which calculates the Beam angle, to also make an online subtraction of the reference beam angle. Previously, we did not do this since the reference beam angle noise was usually much smaller than the main Beam angle, hence it didn't help much. However, I have recently noticed that during times of excess temperature noise in the VEA, the reference beam angle noise is worse and does contribute to the main Beam angle. In order to do the subtraction (requires extra calculations), I had to reduce the update frequency of the C# code (from 140 Hz to 70 Hz). I have confirmed that this does not negatively affect the tilt-subtraction, though it does increase the high frequency noise floor slightly (by ~sqrt(2)). This code change will also be implemented at BRS-Y.

The pressure in the vacuum can (BRS_X_PumpPressure.png) is currently at ~1e-6 torr and going down steadily. The mean position (driftmon) of BRS-X was reset on Monday (see BRS_X_DriftMon.png). Acceptable range is +/- 16k counts. It seems to be stable now and I will continue monitoring.

Edit: The capacitive damper/actuator on BRS-X now works the same as that on BRS-Y. The Q is set to ~10 when the angle exceeds the high threshold (which is nominally set to 2000 = 2 micorad). Below that, the Q is set to ~100. It is time to say goodbye to the gravitational damper! It was fun while it lasted !

LVEA purge-air dewpoint

As measured just before the low pressure regulator; -31C when supplied by left drying tower and -28C when supplied by the right drying tower.  

Also, the Kobelco compressor portion of the LVEA vent/purge supply has had a "Service Alert" in effect for the past few days.  We have a field service technician from Roger's Machinery coming out on Monday.  

Beam Tube port Y2-8 ion pump back up and working

Richard M., Filiberto C. 

The EE guys installed a new King's SHV pump-end HV connector (modified?) in place of the shorted unit from a week or two ago.  I energized the IP and everything seems to be working again.  

HAM4 transfer functions also look clear

Was able to run long transfer functions on the HAM4 ISI last night and got the data this morning. Again, I don't see anything unusual for the chambers state. Attached plots are for the tf last night (first plot, act to gs13) and the best similar tf from 2014 I could find (second plot). Unfortunately it looks like there was some rubbing or something on the old measurement, cause the data around suspension mode looks bad. Jeff hasn't posted B&K measurements of the new baffle yet, but unless there's something nasty hiding in the high frequency stuff (hidden by the purge air or whatever), looks okay.

BRS-Y and the Platform Seismometer

Krishna

The attached pdf file shows the comparison between BRS-Y, the ground seismometer (an STS-2) and the platform seismometer (a T240), called a PEM signal in this case (since we are using spare PEM channels for it). Also shown are the online tilt-subtracted super-sensor output (online residual) and a second tilt-subtracted signal between the T240 and BRS-Y (PEM residual). Page 2 shows the coherences between various signals and Page 3 shows the wind-speeds. As I showed before, the coherence between BRS-Y and the platform seismometer (T240) is better than that between BRS-Y and the ground seismometer (STS-2).

Note that in this plot I have used the normal calibration factor for BRS-Y and STS-2. For the T240, I matched its output to the STS-2 at the secondary microseism. You'll notice that while the STS-2 and BRS-Y are coherent below 0.1 Hz, their outputs differ by 20 percent. Initially some had suspected we got our calibration wrong, but this is now known to be due to differential floor tilt. For the online tilt-subtraction we use a factor of 0.78 for BRS-Y to correct for this. However, the platform seismometer agrees very well with the raw BRS-Y calibration (we did get our calibration right!). This confirms that the two instruments are now seeing the same tilt.

The tilt-subtracted T240 signal (PEM residual) is now marginally better than the tilt-subtracted STS-2 signal in the 15-50 mHz range. It is possible that this is still limited by temperature noise on the T240, since the tilt-subtracted noise looks similar at lower wind speeds too (not shown). Hugh will attempt to improve the thermal insulation when possible.

The most important test is to now see if the two residual curves diverge even more when wind speeds pickup above 20 mph. If so, this would confirm the differential floor tilt hypothesis. If not, it would suggest some other noise/nonlinearity limits the tilt-subtraction. Unfortunately, it looks like we'll have to wait till next week for higher wind speeds.

PSL weekly status

Not sure how relevant this is right now.

 

Laser Status:
SysStat is good
Front End Power is 35.66W (should be around 30 W)
HPO Output Power is 154.0W
Front End Watch is GREEN
HPO Watch is GREEN

PMC:
It has been locked 0 days, 0 hr 27 minutes (should be days/weeks)
Reflected power = 26.11Watts
Transmitted power = 50.55Watts
PowerSum = 76.66Watts.

FSS:
It has been locked for 0 days 0 hr and 27 min (should be days/weeks)
TPD[V] = 2.491V (min 0.9V)

ISS:
The diffracted power is around 0.71% (should be 3-5%)
Last saturation event was 0 days 0 hours and 26 minutes ago (should be days/w

Possible Issues:
PMC reflected power is high
ISS diffracted power is Low

Monthly seismometer centering FAMIS 6092

All the STSs are okay. Corner station ISIs are in air. ETMY is somewhat out of spec, though.

2017-11-08 10:52:36.354536
All STSs prrof masses that within healthy range (< 2.0 [V]). Great!

Here's a list of how they're doing just in case you care:
STS A DOF X/U = -0.718 [V]
STS A DOF Y/V = 0.064 [V]
STS A DOF Z/W = -0.195 [V]
STS B DOF X/U = 0.388 [V]
STS B DOF Y/V = 0.944 [V]
STS B DOF Z/W = -0.609 [V]
STS C DOF X/U = 0.368 [V]
STS C DOF Y/V = -0.065 [V]
STS C DOF Z/W = 0.938 [V]
STS EX DOF X/U = -0.164 [V]
STS EX DOF Y/V = 0.47 [V]
STS EX DOF Z/W = 0.151 [V]
STS EY DOF X/U = 0.144 [V]
STS EY DOF Y/V = 0.169 [V]
STS EY DOF Z/W = 0.51 [V]

Assessment complete.
 

 

Averaging Mass Centering channels for 10 [sec] ...
2017-11-08 10:52:39.355680

There are 17 T240 proof masses out of range ( > 0.3 [V] )!
ETMX T240 2 DOF X/U = -0.327 [V]
ETMX T240 2 DOF Y/V = -0.574 [V]
ETMY T240 3 DOF Z/W = 0.347 [V]
ITMX T240 1 DOF X/U = -0.418 [V]
ITMX T240 1 DOF Z/W = -0.337 [V]
ITMX T240 2 DOF Y/V = -0.37 [V]
ITMX T240 3 DOF X/U = -0.652 [V]
ITMY T240 1 DOF X/U = -0.386 [V]
ITMY T240 1 DOF Z/W = -0.549 [V]
ITMY T240 2 DOF Z/W = -0.654 [V]
ITMY T240 3 DOF X/U = -1.001 [V]
ITMY T240 3 DOF Y/V = -0.389 [V]
ITMY T240 3 DOF Z/W = -0.604 [V]
BS T240 1 DOF Z/W = -0.564 [V]
BS T240 2 DOF Y/V = -0.491 [V]
BS T240 3 DOF X/U = -0.683 [V]
BS T240 3 DOF Z/W = -0.469 [V]

All other proof masses are within range ( < 0.3 [V] ):
ETMX T240 1 DOF X/U = 0.296 [V]
ETMX T240 1 DOF Y/V = 0.19 [V]
ETMX T240 1 DOF Z/W = 0.222 [V]
ETMX T240 2 DOF Z/W = 0.125 [V]
ETMX T240 3 DOF X/U = 0.171 [V]
ETMX T240 3 DOF Y/V = 0.284 [V]
ETMX T240 3 DOF Z/W = 0.223 [V]
ETMY T240 1 DOF X/U = -0.003 [V]
ETMY T240 1 DOF Y/V = 0.109 [V]
ETMY T240 1 DOF Z/W = -0.123 [V]
ETMY T240 2 DOF X/U = 0.201 [V]
ETMY T240 2 DOF Y/V = -0.161 [V]
ETMY T240 2 DOF Z/W = 0.0 [V]
ETMY T240 3 DOF X/U = -0.132 [V]
ETMY T240 3 DOF Y/V = -0.004 [V]
ITMX T240 1 DOF Y/V = -0.046 [V]
ITMX T240 2 DOF X/U = -0.106 [V]
ITMX T240 2 DOF Z/W = -0.093 [V]
ITMX T240 3 DOF Y/V = -0.047 [V]
ITMX T240 3 DOF Z/W = 0.016 [V]
ITMY T240 1 DOF Y/V = -0.178 [V]
ITMY T240 2 DOF X/U = 0.263 [V]
ITMY T240 2 DOF Y/V = -0.239 [V]
BS T240 1 DOF X/U = 0.131 [V]
BS T240 1 DOF Y/V = -0.262 [V]
BS T240 2 DOF X/U = -0.041 [V]
BS T240 2 DOF Z/W = 0.032 [V]
BS T240 3 DOF Y/V = -0.024 [V]

Assessment complete.

 

 

Weekly H1 ISI CPS Noise Spectra Check

FAMIS Task #6923

   Attached are the plots for the BSC and HAM ISI CPS checks.  

Monthly PSL Chiller Filter Inspection

   FAMIS Task #8302 

   Both Crystal and Diode chiller filters look good. No debris or discoloration noted. Added 100ml water to Crystal Chiller. Added 200ml water to Diode Chiller. 
   No problems or concerns noted with either chiller. 

IO activities for Tuesday, November 7th

Activities in IO Land:

• installed PRM and PR2 irises
• first real issue
  • found huge signals in IMC/ASC signals for all IMC optics
• tracked this down to the IMC flashing enough to trigger the ASC, which pushed the optics
• this feature was disabled - see alog 39319
• optic sanity restored, aligned the beam to the IMC using the PZT
• noticed MC2 Trans at 30 counts - has been 1.6 to 2-ish counts without flashing
• noticed that PSL-Periscope-Power-In remained unchanged from yesterday
• was unsure of the power coming from the PSL
• closed the shutter to investigate
• found two beams on the bottom periscope mirror
• the first red herring of the day
  • the iris, which I found fully open, is the beam dump for the second beam, when the iris is about 1/2 closed
• tweaked the AOM beam alignment to maximize PSL periscope power, it increased from 0.06 to something (will alog later)
• this new alignment was centered on the iris/beam dump that's before the HWP that's before the bottom periscope mirror
• a issue to be looked at later
  • measured the power at the bottom periscope mirror - the current power into the IMC is 170mW
  • this is not accurately represented by any current DC PD signal
• exited the PSL
• aligned the beam to the IMC
• found the reason for the second red herring - MC2 trans SUM increase
  • while checking the MC2 iris, found the strong work light was on at the chamber, and when turned off, MC2 trans returned to it's normal values
• aligned the IMC to flash
• optic motion prevented all but a sparse few 0-0 flashes
• without 0-0 mode flashes, IMC and IM optic alignment through HAM2 will be difficult
• unclear what changed (reboots, restarts, mechanical...)
• see alog 39328
• will resume investigation/alignment tomorrow morning

- Cheryl, JeffK, Ed

Completed permanent installation of 55 L/s ion pump at CP2

Kyle, R., Rakesh K. 

Today we coupled the ion pump assembly to the 1.5" Vent/Purge valve at CP2.  Upon testing, the ion pump was found to be shorted (50 ohms).  Ughh!  This is a newish pump that had passed testing when it was briefly used as an emergency backup a few years ago -> Oh well.  It had to be replaced nontheless.  Again the new joints were leak tested and the turbo pump removed.  

Now both CP1 and CP2 have permanent, dedicated 55 L/s ion pumps installed.  The purpose of these are mostly to pump hydrogen and nitrogen for those times when the 80K pump has to be isolated from adjacent volumes for prolonged periods.  Nominally, these ion pumps are running but valve-out from the 80K pumps until needed.  

All that remains now is for final power and signal cabling to be routed.  For now we have no read back and are using extension cords to power them.  


This completes WP #7204

beckhoff vs front end timing of slow channels from DAQ NDS

Sheila, Jonathan, Dave:

Sheila had a question about the relative timing of an analog event which was recorded by both a front end computer and a Beckhoff slow controls computer. When looking at the two channels from the DAQ, there was a time difference of about a tenth of a second.

As a test, I have some slow signals coming from front end models and being a acquired by the DAQ through two paths: one direct alongside the fast data, and an equivalent channel coming in via the EDCU. To show the delay, I looked at the h1ioplsc0 model's state word, and manually changed it by running an excitation to set the EXC bit. In the attached plot, the signal being sent directly to the DAQ data-concentration is the upper red plot, the signal being acquired over the network via the EDCU is the lower purple plot. As can be seen, the front end data is packetized into a 1/16th block before sending to DC, which in turn packetizes the data into a 1/16 block and adds the Beckhoff data point. This results in an apparent 2 sample delay (0.125S) in the red plot. In actuality, the red plot is timed correctly, and the Beckhoff event is incorrectly time stamped as preceding the event by 0.1 S.

We think moving the EDCU to a front end would resolve this.

The use of a front-end based EDCU (instead of the DAQ Data Concentrator) is already implemented in the CDS code base.  It has already been tested extensively on test stand and, and briefly on L1. There are installation instructions in the DCC.  This change is required to ensure EPICS data agreement when multiple Data Concentrators are used to increase redundancy.  

Large ~11.3 Hz Displacement in HAM2/HAM3 SUS

J. Kissel, C. Vorvick

While Cheryl and I were aligning the IMC this afternoon, we noticed that we were getting much faster fringing than we saw yesterday. However, comparing spectra of all suspensions in HAM2 / HAM3, in L, T, and V from yesterday evening after work (2017-11-07 02:20 UTC) vs this evening after work (2017-11-08 00:20 UTC) show that there is a large, high Q feature at ~11.3 Hz. Comparing the spectra from over the weekend, in which HAM2 was unlocked, it becomes obvious that the problematic feature dominating the RMS is the HEPI cross-beam resonance, transmitted directly through the locked platform.

Our best supposition is that yesterday, the lower frequency motion (0.5 Hz < f < 5 Hz) was much *larger* than it currently is, dominating the RMS velocity of the IMC, resulting in slower fringing.

So, we'll think more about how we can slow the suspensions down enough to get alignment done tomorrow.