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. 

Michael, Krishna,

This evening we tried using the tilt-subtracted ground sensor for sensor correction(SC) in the Y-axis on Stage 1 at EndY. Wind speeds were between 0-10 mph. We tried four configurations:

1. 90 mHz blends (Quite_90) only

2. 90 mHz blends and broadband sensor correction using BRS-2

3. 45 mHz blends only and

4. 45 mHz blends with broadband sensor correction using BRS-2.

The results are shown in the attached pdf. The first plot shows the ASD of Stage 1 T240 seismometers. As expected 90 mHz blends do not provide any isolation at the microseism, and 45 mHz blends do well there. But 90 mHz blends and SC performs nearly as well as the 45 mHz blends. The second plot shows the rms of the ST1 capacitive sensors, which is a measure of the net DC motion of the platform. 90 mHz blends + SC does a factor of ~5 better than other configurations. The third plot shows the ground motion during the four configurations and the tilt-subtracted sensor signals in each case, showing the factor of 3-5 improvement.

Bottomline: 90 mHz blends and sensor correction using BRS-2 does nearly as well as 45 mHz blends above 0.1 Hz and improves the low frequency rms by a factor of ~5, even under mildly windy conditions. We will repeat this test under higher wind conditions, where performance is expected to be even better.

(Bubba is the primary contact for this alarm) but I think that this can be dealt with in the morning as long as water use is kept at a minimum tonight.

J. Kissel, J. Warner

After getting all of the mechanical labor out of the way (see LHO aLOG 26452), Jim and I took to the B&K system for our first attempt at characterizing the resonant frequencies of ISI HAM6 blade springs and GS13 cans. No excitingly awesome results here; mostly just me writing stuff down for future reference. Stay tuned for more substantive results after tomorrow's work is complete.

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

We hit in two locations with accelerometer as close to the blade spring and GS13 can hit locations as possible. The blade hit location was roughly in the middle of the blade, stroking the hammer upward into the blade. Today's data is from Corner 3's blade alone. The accelerometer location was very similar to what's shown in pg 1 of LHO aLOG 25472's attachment. The GS13 Can hit location -- the H1 GS13 -- again suffered an awkward hammer stroke from beneath the can (because we didn't take the outer wall off). The accelerometer for this hit was mounted on the outer side wall just above the can.

We hit in two locations simply because it was the first data we'd seen and it wasn't processed well enough to confirm that we can see both systems of resonance in the blade-spring hit location. Attached are the data, processed. Though the three axes indicate different mode shapes, we weren't particularly careful about aligning the DOFs with any other reference set of coordinates. We'll try harder tomorrow.

The processed data is attached.

We expect the blade spring's 1st bending resonance to be at ~153 [Hz], and indeed that's exactly what we see. No surprise there. We see some more resonant features in the blade-hit location data which I have not specifically called out with data tips. Those resonances are a function of the blade modes vs. other body modes of the table will be more clearly identified once we damp them, so I'll wait for that.

As far as the GS13 can location, we expect its resonant modes to be around ~1.2 and 1.6 kHz. However, with the accelerometer close to the GS13 can there don't really appear to be any features in the data other than a 1.1 kHz mode. Looking back at the blade-hit location, there're feature more akin to those expected. Again, we'll see once we apply the damping material what modes are truly of these structure, but the message is that we can stick with the one blade-spring location for the accelerometer in each corner.

Much more to come tomorrow!

------------
Details:
The data has been exported from the B&K laptop and ported over to Sei SVN, the data lives here:
/ligo/svncommon/SeiSVN/seismic/HAM-ISI/H1/HAM6/Data/BandK/
2016-04-05_1315PDT_H1ISIHAM6_BladeSpringHit_Corner3_X_Reference.txt
2016-04-05_1315PDT_H1ISIHAM6_BladeSpringHit_Corner3_Y_Reference.txt
2016-04-05_1315PDT_H1ISIHAM6_BladeSpringHit_Corner3_Z_Reference.txt
2016-04-05_1322PDT_H1ISIHAM6_GS13CanHit_H1_X_Reference.txt
2016-04-05_1322PDT_H1ISIHAM6_GS13CanHit_H1_Y_Reference.txt
2016-04-05_1322PDT_H1ISIHAM6_GS13CanHit_H1_Z_Reference.txt

and the script to process the data lives here:
/ligo/svncommon/SeiSVN/seismic/HAM-ISI/H1/HAM6/Scripts/BandK
process_bandkdata_20160405.m

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

For those who can imagine the B&K software window and have gotten as far as finishing the measurement:
In order to export the data after the measurement is taken, one must 
- go the "Validation" step on the left bar
- go to the upper left corner and click the "display" button
- choose the measurement number of your most recent measurement, selecting one of the accelerometer's DOFs at time
- right click on the resulting plot, select "properties" from the bottom of the menu, go to the "options" tab of the pop-up window
- make sure that the options are set to export as a PULSE ASCII format 4.2 (it doesn't really matter which one of the two of those options; I chose the upper one. I think the lower just adds more info to the header, which we don't use anyways).
- hit the copy to clipboard button.
- open up a text editor (the windows default is "notepad"), paste in the ASCII, and save as text.
- You *can* then wrestle with Tortoise SVN, but I didn't bother. I just pulled out the external disk and brought it over to sensible machine, and loaded in the data there.

The high power oscillator (HPO) is currently on and injection locked.  The watch dogs for both the
front end laser and the HPO have been engaged.

SHOULD THE LASER TRIP OUT, FOR ANY REASON, PLEASE DO NOT ATTEMPT TO RESUSCITATE IT.

No real progress towards locking the pre-modecleaner to the HPO.

Completes FRS ticket 5254 

NOTE - Vented BSC4 annulus with no response to PT140B, i.e. no inner O-ring leaks for BSC4 annulus volume.  

J. Warner, N. Kijbunchoo, T. Shaffer, B. Weaver, T. Sadecki, J. Kissel

Good progress today on the HAM6 Damper Install, a la E1600092. Starting on the Tuesday steps:

10) Remove all three chamber doors DONE
11) Pick up floor CC wafers.  Take particle counter measurements and record DONE (see LHO aLOG 26450)
13) Pick up table top CC wafers. DONE (see LHO aLOG 26450)

12) Lock HAM ISI DONE 
14) Install Septum Window Cover DONE 
15) Evaluate, mark and Move Beam Diverter ONLY IF ABSOLUTELY NEEDED for ISI work.  IF CABLES of Beam Diverter get removed, a test of the Beam Diverter function will need to be made before closeout. 
           Beam Diverter did not need to be moved. Nice!
16) Start ISI damper install work. 
   a) Remove outer walls and internal "window" access panels in order to access the blade-springs. DONE 
   b) Remove Tuned Mass Dampers (TMDs) DONE
We Stopped Here for the day.*
   c) Install new spring damper assemblies
   d) Measure new spring modes using the B&K System
   e) Retune TMDs with new info
   f) Reinstall TMDs

* After removing the TMDs from the blades, we took reference B&K hammer measurements to be sure we'd gotten all the data we need and we understood how to use the B&K system (all of us are relative newbies to the software interface). We have pre-assembled all spring-damper assemblies, but we were at a good stopping point for the day with the reference measurements and will pick up with the installation of the spring damper assemblies tomorrow morning.

Stay tuned for processed reference data.

The attached image is of Jim removing the inner wall from the -X/+Y corner (to access Corner 3's blade tip), with Nutsinee's knees visible as she's doing the same to the +Y corner (to access Corner 1's blade tip).

TITLE: 04/05 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:
LOG:

Peter was already in the PSL and Kyle was already at HAM6 area when I arrived.

15:12 (8:12) Krihna and Michael to EY checking BRS pump

15:25 (8:25) Gerado joining Kyle at HAM6 area.

15:41 (8:41) portable potty here -- they couldn't get through the tumbleweed so I think they turned around and left.

15:47 (8:47) Jason and Ed joining Peter in the PSL

15:49 (8:49) Betsy to Optics lab

16:10 (9:10) Ken the electronics guy to both ends checking air compressor cabinets (if he could get through tumbleweeds).

16:13 (9:13) Keita to HAM6.

16:33 (9:33) HVE-EY:INSTAIR_PT499 alarm handler went off

17:01 (10:01) Travis to LVEA

17:10 (10:10) TJ to HAM6

17:12 (10:12) Travis out

17:19 (10:19) Richard to LVEA

17:20 (10:20) Dave to beer garden checking on ITMY hardware watchdog

17:32 (10:32) Ken back from end stations

17:40 (10:40) Dave out, going to CER to replace WD.

17:53 (10:53) Calos working on the net box in the CER. Will affect the internet.

18:26 (11:26) Calos done

19:05 (12:05) Dave swapping out ITMY WD chassis.

19:08 (12:08) Jason, Peter, Ed out of PSL for lunch.

20:13 (13:13) TJ and Nutsinee to LVEA

22:02 (15:02) TJ out

22:27 (15:27) Nutsinee out

22:40 (15:40) Ed out of the PSL for the day.

22:43 (15:44) Jeff and Jim out of HAM6 for the day

16:02 (23:02) Jason and Peter done for the day. HPO box is left on but the shutter is closed.

J. Oberling, P. King

LHO WP #5810.

Short Version

IT'S ALIVE!!!

Long Version

Today we began the HPO turn on procedure.  First things first, we put a water cooled 200W power meter head in the main beam path after the PMC (see attached picture 200W_power_meter_20160404.jpg).  This way no light is getting out of the PSL enclosure until we are ready for it, and once we have a recovered PMC we simply need to plug in a power meter so we can set the available power with IO_MB_HWP1. 

In an abundance of caution we began by repeating the HPO Laser Head turn on test we did back on March 22nd (see LHO alog 26193).  Everything came up without issues, just as in the previous test.  We then removed the HR mirror that sat in front of the HPO Output Coupler (OC); it is currently left in the HPO box, set to the side and out of the beam path (see attached picture OC_removed_20160404.jpg).  This taken care of, we set all the laser heads to 30 A of pump diode current and turned on the HPO.  As the currents were coming up we saw the HPO go through the first, low power stability range, but nothing at the high power stability range (which is what we expected, not enough pump power yet).  We repeated this at 35 A, 40 A and 45 A with the same results.  Getting a little discouraged we input the previous operating currents (from Peter's alog here) and turned on the HPO.  This time the laser came on!  It started at ~120 W of total power (~70 W in the forward direction and ~50 W in the backward direction).  We then increased the diode currents individually until they all read ~100% power and then let it sit for ~10 minutes so everything could come to thermal equilibrium; the output power settled at ~145 W.  As a final check we moved the pump currents up and then down slightly (~0.4A in both directions) to check that we were on the correct side of the stability range; we are.

Now with a running HPO we decided to try injection locking the 35 W FE.  Following the instructions in T1200259 we powered up the FE laser and pressed the "Lock" button on the PSL Beckhoff computer control screen.  It locked, without issue.  Total output power now read 208 W.  This seemed really high, and looking at the HPO diode currents it seemed the diodes for head 4 were suddenly delivering more power without changing current; power changed from 100% to 105% at the same diode current.  This is very odd and we currently cannot explain it.  We lowered the current back to 100% power and the total power out of the full system was reading 183 W.

It was at this point that we realized we had forgot to align mirror M5, which controls the beam out of the HPO.  This is important as this mirror needed to be tweaked when the HR mirror previously in front of the OC was installed back in 2014.  In the process of trying to realign this mirror we lost the alignment entirely and spent the afternoon trying to recover it.  We eventually turned the HPO off, reinstalled the HR mirror and used it and M5 to mostly recover the alignment.  We are currently at a state where spending more time recovering this alignment is a waste as we are going to have to do alignment work with the HPO on anyway.

We left the system with the HPO OFF and the lid on; as a safety measure we wrote down the last used HPO diode currents and set the current input fields to 0 A.  We the left the FE laser ON but shuttered, so there is no laser light available to the IFO.  We left the environmental controls (HEPA fans, AC, and Make-Up air) ON.

Tomorrow

Tomorrow we plan on once again removing the HR mirror and then beginning the recovery of the PSL subsystems downstream of the HPO; PMC, ISS, FSS, DBB (likely in that order).

Keita, Sheila, Jenne, Evan, Hang

The mystery about AS 90 WFS may be (partially) due to the drift of dark offset.

We checked a time of today when IMC-MC2_TRANS_SUM was 0, and found that the output of a segment of AS 90 WFS was as large as ~100 cts when it was dark. As a comparison, the total sum of 4 segments at DC_readout was ~ 1000 cts. After corrected for it, the AS 90 WFS signal looked more reasonable.

We then checked the dark offset of the same WFS roughly days ago, and found that it drifted by ~ 100 ct (see, e.g., two seg1s in the attached plots). This large drift seemed make it not a very reliable sensor as the drift of dark offset was at least comparable to the signal we looked for. If we wanted to use it, we might have to check the offset frequently.