J. Oberling, P. King

Spent today installing and testing the new HPO water manifold.  The mainfold is now installed and the valves for the MOPA, PWR, and Laser Head water circuits are set to provide the proper flow rates.  While we were doing this we figured it was a good idea to implement ECR E1500408; this ECR is for installing valve on the outlet side of the Laser Crystal water circuit.  This is now also complete.  A picture of the new water manifold and valve is attached.  This completes this ECR.

Once everything was installed and verified that it wasn't leaking, We noticed the flow sensor for laser head #1 (part of the Laser Head water circuit) had stopped reading.  Opening up the HPO box we saw that the turbine was not spinning.  We drained the circuit and removed and replaced the flow sensor.  Before installing the new flow sensor, Peter found an ~1/2" piece of black plastic (looked like a piece leftover from cutting the threads on the main water manifold.  Recall we pulled out a bunch of these yesterday while prepping the new manifold.) sitting in the output side of the flow sensor (in the small black manifold that sits above the HPO resonator cavity).  We installed the new flow sensor, turned on the chillers, and watched for leaks.  After several minutes no leaks were observed, so we left the crystal chiller running overnight to test the system (the diode chiller is still OFF).  The HPO and FE lasers are both OFF.  Will continue in the morning.

Activity Log:All Times in UTC (PT)

15:00 (08:00) – Start of shift

15:41 (08:41) Kyle – Going to End-Y mechanical room

15:52 (08:52) Gerardo – Going into the LVEA looking for cables

15:57 (08:57) Jim & Corey – Going to HAM6

16:05 (09:05) Jeff K. – Going to HAM6

16:10 (09:10) Peter & Jason – Going into the H1 PSL enclosure

16:15 (09:15) Gerardo – Out of the LVEA

16:22 (09:22) N2 delivery to the X-Arm

16:49 (09:49) Richard & Gerardo – Going to End-X

17:10 (10:10) N2 delivery to Y-Arm CP4

17:30 (10:30) Kyle – In LVEA near BSC4 (WP #5817)

18:15 (11:15) Jeff K. – Out of LVEA

18:16 (11:16) Ed – Terminating cables at HAM1, Vertex, and HAM6  

18:32 (11:32) Richard & Gerardo – Back from End-X

19:36 (12:36) Filiberto – Going to End-Y mechanical room

20:00 (13:00) Jeff K. – Going into LVEA then Optics lab

20:01 (13:01) Jim – Going to HAM6.

20:15 (13:15) RO alarm – John notified. No alarm – Dave doing burt restore to fix alarm handler

20:41 (13:41) High dust counts at HAM6. Stand down ISI work while Kyle & Jeff were sealing up East Door curtains for door install

21:20 (14:20) Krishna & Michael – Going to End-Y for BRS

21:39 (14:39) Bob's Heating on site to work on VPW HVAC

22:10 (15:10) Kyle, John, Chandra, Jeff – Reinstall HAM6 east door.

23:03 (16:03) Jeff K – Going to HAM6 to install tuned mass dampers

End of Shift Summary:

Title:04/07/2016, Day Shift 15:00 – 23:00(08:00 – 16:00) All times in UTC (PT)

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Incoming Operator:

Shift Detail Summary:Work on HAM6 is going well and should wrap up tomorrow. East HAM-6 Door has been reinstalled. 

Michael, Krishna

We did more sensor correction (SC) tests today with mildly windy conditions. This was similar to the tests reported in 26455. However, we had made one important mistake in that test - the CPS value reported was before the blend filter input which is measured after sensor correction. This was wrong, it needs to be measured before SC (using H1:ISI-ETMY_ST1_SCSUM_CPS_X_IN_DQ). This is a more accurate measure of the local table motion.

As before, the four configurations were: a) 90 mHz blends, b) 90 mHz blends and SC using BRS, c) 45 mHz blends, d) 45 mHz blends and SC using BRS and we also tested e) 90 mHz blends and SC without using BRS.

The two measurements for End Y (BRS-2) and End X (BRS-1) are shown in the attached pdfs. We saw very similar looking results in both.

The wind-speed varied between 5-20 mph with a rough average of ~12 mph for EY and ~9 mph for EX. First page shows the Stage 1 T240 motion and as before 45m+BRS_SC gives the best performance, with 45m, 90m+BRS_SC or 90m+SC configurations giving roughly the same performance. The next page shows the RMS of the CPS signals before the sensor correction. 90m has the least CPS motion with 90m+BRS_SC being the next best. SC using BRS and not using it (with or without tilt-subtraction), can be compared by using the blue and yellow/orange lines respectively. The third page shows the ground motion during each configuration and the corresponding tilt-subtracted signal.

Some comments:

1) The sensor correction filter used here (Mitt_SC) is a broadband filter going down to 30 mHz. We may want to tune it for 40-50 mHz instead, to reduce the low-frequency motion.

2) Based on the results so far, the best configuration for 0-10 mph wind-speeds (LOW wind) might be 45 mHz blends+BRS_SC which gives the best isolation (a factor of ~50-100 at the microseism!). And for winds above 10 mph (HIGH winds), 90 mHz +BRS_SC might be best. This is the same configuration that was followed for O1 but with the addition of SC using BRS.

This afternoon, we recentered the DC position of the beam-balance. Due to the process, the amplitude is very high so we are using this opporunity for a Q measurement.

Corey, JeffK , Jim

This morning, while Corey put doors on the south side of the chamber, Jeff and I set up the B&K and got before measurements for the last corner. I then installed the last of the new damping elements, and we got the final B&K measurements for the ISI. Corey then helped me close up the last corner. After lunch, Corey and I went back out, unlocked and floated the ISI, while Jeff took the the old TMD's to the lab for retuning.  Jeff will probably be logging results for TMD's and B&K soon. I'll add that we used the "hard" tip for the B&K for this mornings measurements. We should have started with that, it worked a lot better than hte soft tip, with coherence out to 2khz. Jeff says he will hang out and reinstall TMDs later tonight.

Per Hugh's suggestion, I looked at the ISI's operating CPS position over last week (before the vent) and rebalanced the table as close as I could get. Looking at the CPS in the cartesian basis made this very easy as any mass we added only changed RX,RY and Z. I'd heard this suggestion from others in the seismic group, but this was the first time I'd tried it. Recommened. 

Currently, the vacuum group is putting on the East door on HAM6. This will still allow us to access every thing we need to on the ISI tomorrow. 

Tomorrow, we still need to unlock the ISI again, do a sweep of the chamber, pull the septum cover and do close-out tf's. We should also check the beam diverter still actuates and that the OMC survived the rough-housing it got while Corey and I rebalanced the table.

S&K electric converted single receptacles to duplex today which allows us to power fans and the HAM1 and HAM6 ion pump controllers (without extension cords!!!)

Chart updated to include both high power beam dumps.

For reference here is the last HAM6 pumpdown in June/July 2015.  From atm to stable turbo running was ~3.5 hours.

This log is duplicated in LLO alog 25563.

Summary

Further to my alog 25932, I have calculated approximate TCS power levels for O2, this time including the effect of the ring heaters. The results are presented in tabular form.

The bottom line:

1. the RHs are used predominantly to correct the surface deformation on the test masses.
2. The CO2 lasers are used to correct the residual lens in the test mass after the RHs have been applied. 
3. We might need to commission annular heating on CO2Y at LHO.
4. ETMY_RH at LLO requires a larger increase in power due to the relatively high absorption in ETMY

Calculation:

Surface curvature

To correct the surface curvature errors, we use the RH. It is straightforward to show that the required change in RH power is given by:

dP_RH = - (absorb*dParm) * dSD/dP_self / (dSD/dP_RH),

where 'absorb' is the absorption in the surface of the optic, dParm is the change in the power in the arm, dSD/dP_self (H1:TCS-SIM__SURF_DEFOCUS_SELF_GAIN) is the steady-state change in the surface deformation in diopters per Watt absorbed power, and dSD/dP_RH (H1:TCS-SIM__SURF_DEFOCUS_RH_GAIN) is the steady-state change in the surface deformation per Watt power from the RH. These values are available on the TCS SIM MEDM page.

Substrate thermal lens

The same calculation can be done for the CO2 laser power:

dP_CO2 = - [ (absorb*dParm) * dS/dP_self + dP_RH * dS/dP_RH ] / (dS/dP_CO2),

where dS/dP_self, dS/dP_RH, dS/dP_CO2 are the change in the substrate lens defocus per Watt for self-heating, RH and central heating CO2 laser respectively. Note that the RH power has, nominally, been fixed by correcting the surface curvature in the previous step.

Note the distinction between the responses for the surface deformation, dSD/dP and the substrate lens, dS/dP.

LHO settings:

Based on the best estimates for the absorption in the test masses, the changes in actuator settings are:

Obviously, we can't apply negative power with central heating on CO2Y. The reason CO2Y was set to 0W for O1 was because it wasn't working during that science run - therefore, this is probably not the best operating power for CO2Y at 100kW of arm power.

• A recommended commissioning activity would be to optimize CO2Y at 100kW in the arms and then recalculate the required TCS at 200kW in the arms.
• If we find we do need more negative lensing in the substrates of the ITMs we can do one of two things:
  • Use more RH power and move the ITM surface curvature away from the nominal operating point
  • Or, commission an annular heating mask with the CO2 lasers.

LLO settings:

Notice the relatively large increase required for ETMY - this is due to our measurements indicating an absorption on there of the order of 1.6ppm, or about 5 or 6 times larger than the average of the other optics.

Krishna, Michael

Due to the slow wind day, we decided to take a look at an 6.7 magnitude earthquake that struck near Australia last night. All three STS seismometers (ETMX, EMTMY, and ITMY) and the BRS picked it up very clearly. The first plot in the attached pdf shows the time series of both the z component of the STS at ETMY and the BRS2 also at ETMY. The BRS shows clear coherence with the STS at the earthquake frequencies. The second plot shows the ASD of the same two signals along with the possible acceleration coupling of the BRS assuming a d value of 0.5 microns. The BRS signal is a factor of two or three above the possible acceleration coupling around the earthquake which suggests that it is seeing the real tilt component of the Rayleigh waves of the earthquake.

Along with studying how the BRS sees earthquakes, we used z components of the STS seismometers to estimate the velocity and direction of the primary wave. By measuring the phase between the seismometers at the end stations and the seismometer at the corner station, we were able to get the time delay of each arm. Using this we get an estimate for the velocity of 4700 +- 800 m/s and the angle of 71+-10 degrees from the X-arm. The third and fourth plots in the pdf show how the angle and velocity measurements change with different number of averages in the phase calculations. The fifth and sixth plots show how the measurements change over 125 second chunks of time.

Earthquake info: http://earthquake.usgs.gov/earthquakes/eventpage/us20005fsi#general

Edit: We realized that yesterday's calculations of the acceleration coupling had an extra factor of g so the BRS signal is actually a factor of 30 above the possible acceleration coupling. The first plot in the Update pdf shows the updated ASD of the z component of the STS at ETMY, the BRS, and the correct acceleration coupling. Also, using the ratio of the z component of the seismometer and the tilt signal we were able to get another estimate for the velocity which is consistent with the previous analysis.

We also decided to take a look at how the different STS seismometers reacted to the earthquake to ensure they were calibrated correctly. The second plot of the Update pdf shows the ASD of the z component of all three seismometers. The final four plots show the magnitude of the transfer function at the earthquake's primary frequency between the ETM seismometers and the ITMY seismometer with varying number of averages and over time of the earthquake. This suggests that the ETMX seismometer's calibration is ~7% less than ITMY and ETMY's calibration is ~15% less. Coincidentally, we had to add a factor of 0.85 to the BRS to get the gain to match the ETMY seismometer.

J. Warner, N. Kijbunchoo, C. Gray, J. Kissel, K. Kawabe

We've made good progress today. Two of the corner's new damping systems are completely installed and characterized (analysis of data to come). That's Corner 1 and Corner 2's blade tip dampers, and the Horizontal and Vertical GS13 can dampers on Corner 2 and Corner 3. We've also re-installed the hardest of the inner and outer walls on Corner 1.

Schedule Status:
On the docket tonight:
- Process and post today's B&K hammer results
- Re-tune tune the smaller Tuned Mass Dampers

Up for tomorrow:
- Characterize the free blade and free cans again (it's quick, and we want to be consistent)
- Install of Corner 3's blade tip damper (the last one)
- Characterize the blade damper
- Install of Corner 1's GS13 can dampers (horizontal and vertical; the last one)
- Characterize the cans
- Re-install all of the walls and trim mass
- Install newly-retuned tuned mass dampers on all blades
- Float and balance the table

For Friday:
Begin close out checklist.

This puts us maybe ~1/2 a day behind schedule from E1600092. We'll discuss if we've made it back on schedule by lunch tomorrow.

Attached are some pictures of the days work, both of the damper installation, as well as some publicity photos of the stuff on top of HAM6. To entice you, I've attached the best pictures from both .pdfs in their raw form.

Stay tuned for characterization results of the two corner's blade tip dampers. I can tell you right now that we have too little coherence with the B&K up at ~1-2 kHz, so there won't be much to show on the Can Dampers. However, we've audibly compared damped vs. undamped cans with impacts from a metal wrench and there's a satisfactory "clunk" instead of multi-tone "ding."

The HPO survived overnight without any problems.

This morning the HPO was turned off to allow for testing of the pre-modecleaner setup
with the front end laser.  After that was completed the HPO was turned back on.  After
being on for ~20 minutes, a leak developed in both flow meters leading to turning the
HPO off (the flow meters being for the power amplifier and the power meters).  Replacement
of the water manifold is in progress.  Fortunately no damage was done to the HPO.

Examination of the MOPA flow meter showed a large rust stain on the flow meter body.
In retrospect this partly explains why in recent weeks the topping up of the crystal
chiller was occurring more frequently.  In the short time between turning off the laser(s)
and the chillers, the flow meter for cooling the power meters leaked water profusely.
Examination of that flow meter showed a break in the body.

It should be noted that the flow meters, which are part of the water manifold, are located
on the floor under the PSL table and are typically not inspected every day.

The spare water manifold is being prepped for installation.  In doing so it was noticed
that there were a number of material strands left from when the threads were tapped.  As
many of these were removed as possible, thereby reducing the possibility of one of the
coming loose and jamming up the plumbing else where in the system.



Jason, Peter

   Installed the new Met One GT521S dust monitors in the PSL enclosure and in the PSL Anit-Room. They are up and running but not connected to the network yet. Will finilize the installation over the next couple of days.

Filiberto and Richard went to end X to work on the fiber to the X2-8 gauge. Richard had me try to undisable the gauges in TwinCAT. Somewhere in this process the rest of the channels stopped updating. I had to restart the system and the IOC to get them running again.

(Covering for Nutsinee)

15:43 UTC Joe D. to LVEA to check batteries
15:47 UTC Jeff B. to LVEA to take pictures
15:52 UTC Jason to PSL enclosure
15:54 UTC Corey and Jim W. to HAM6 for ISI work
16:13 UTC Nutsinee to HAM6
17:03 UTC Karen and Chris moving from end Y to end X
17:06 UTC Gerardo to LVEA, H2 vacuum diagonal
17:11 UTC Jeff B. done in LVEA
17:38 UTC Corey done at HAM6. Nutsinee, Jeff K, Jim W. at HAM6 running B&K hammer before measurements related to tuned mass dampers
18:01 UTC Karen and Chris leaving end X
18:09 UTC Kyle to LVEA to remove and replace vibration isolators on vertex turbo pump by HAM5 (WP 5816)
18:54 UTC B&K hammering team out for lunch
19:25 UTC Vern to TCSX table
20:13 UTC Jeff K. and B&K hammering team back in
20:20 UTC Jeff B. and Mitchel to PSL enclosure to work on plumbing for dust monitors
20:26 UTC Joe D. to LVEA
20:30 UTC Nutsinee to HAM6
20:35 UTC Nutsinee back
20:49 UTC Richard and Gerardo to X2-8 to work on ion pump high voltage cable
21:07 UTC Nutsinee to HAM6
21:30 UTC Dick G. to LVEA ISC racks to retrieve lab book
21:53 UTC Corey to HAM6 to drop off tools
22:37 UTC Richard and Gerardo back

3:50-4pm local time:

Took 2:18 min to overfill CP3. Next fill due Friday.

Michael, Krishna

Winds are very low today which has given us an off-day to look at boring stuff like instrument noise and other techinical details. We also got a loud and interesting earthquake which Michael will post about later.

Quiet period data

The attached pdf shows an ASD of 5K seconds of data during quiet conditions last night with wind-speeds between 0-5 mph. The blue and green show the BRS_in (raw) and BRS_OUT signals. The seismometer Y signal (converted to angle units) is shown in red. There is very little coherence between the two sensors. BRS-2's signal level is improved over that shown in 26387, but is still seeing some excess noise/signal compared to the STS.

The BRS ref signal is the angle of a stationary reference mirror in vacuum and is representative of the autocollimator noise. However, unlike BRS-1, here the calculation of this angle is done at a slower rate than the main mirror angle, hence it's white noise floor is higher. It is still useful as a measure of the noise at lower frequencies (below ~ 0.1 Hz). In this case, it looks like the BRS_OUT may be partially limited by the autocollimator noise near 10-30 mHz.

BRS_DRIFTMON

The image file attached (BRS_DRIFTMON.png) shows the DC position of the beam-balance over the last 7 days. The inital rise corresponds to when we first closed the foam-box, which lead to a 2 deg C increase in the temperature inside the box. The beam-balance appears to still be equilibrating slowly. The range of the autocollimator is +/- 16K counts as shown on the Y-axis (~ 2 mrad range). Going by the trend, it may get too close to the edge of the range and we will likely try to position it a bit more to the center. Once it does settle, the DC position does remain fairly constant, unless there are big changes in VEA temperature.

BRS2 Damping issues

The initial scheme for BRS-2 capacitive damping was that it would turn ON when driven above a HIGH threshold, would damp with a Q of ~5 below a LOW threshold and then is turned OFF. Brian L. had suggested considering leaving it on with a Q of ~50 all the time. We tried this for some time and found it doesn't work currently. There are at least two reasons - 1) There exists a potential difference between the grounded beam-balance and the capacitior plates even when they are grounded, (Contact Potential Difference). This is on the order of ~0.1 to 0.2 V and appears to vary very slowly with time (may get smaller). This creates issues when we are trying to damp very small amplitudes as the sign of the actuation force changes near this potential 2) The capacitor plates on the left and right side are not matched well and we do not account for the actuator gain mismatch when we apply damping creating uneven actuation. This could be fixed with careful testing in the future.

So, as things stand, just enabling Q=50 damping all the time doesn't work and adds more noise than expected. Careful analysis of the actuation may enable this in the future.

Looking around at the suspension damping for my ASC models, I noticed that there are 3 different damping shapes used for the 4 test masses.  The ITMs have the same damping for all degrees of freedom, but each ETM has a different shape.  The differences are in the L, P and Y degrees of freedom.  The R, T and V degrees seem to all be the same. 

Probably this is not so critical since it's way up on the top stage, but I think we should certainly make them all the same.