No restarts reported.

Kiwamu, Stefan, Lisa

After talking with our LLO locking friends, spending some more time trying to further reduce the CARM offset, and thanks to the fact that tonight everything else was working fine, we think we know why our CARM offset reduction is so painful.

At LLO, the transition to 3f signals can be done with a very large offset (~ 3kHz), and once the transition to 3f signals is done, there is no particular issue in reducing the CARM offset down; no adjustments are done in the DRMI control.

Here, first of all we can transition to 3f signals for PRMI only after having passed the 18 MHz resonance in the arms (~970 Hz). This implies using the REFL 45 I&Q signal down to 700-800 Hz, which can be done only by tuning the demod phase on-the-fly .

Second, once on 3f, without constantly tuning the MICH loop (gain, offset, demod phase), we can't keep the PRMI locked while reducing the CARM offset.

We realized that the problem is that here we are using REFL 27 Q for controlling MICH, instead of REFL 135 Q. This is bad because REFL 27 Q is much more sensitive to the CARM offset, and offset and gain changes for this signal are indeed predicted by Kiwamu and Anamaria's simulation (though we don't have on hand plots for the exact CARM offsets we are currently at; Kiwamu is in the process of producing more plots).

The reason why historically REFL 135 Q was not used here is that there was essentially no signal. By comparing the LLO parameters with the ones we are currently using, it looks like we should increase the modulation index by at least a factor 2 and increase the light on the BBPD.

On the other hand, once we realized what was going on, we could reduce the CARM offset down to 250 Hz, by keeping the MICH loop happy monitoring offset, gain, and demod phase, and adjust all these parameters by hand. We could probably keep going, but there is no much point in doing that if we believe that we are just making our life harder by using a hostile signal.

Here is the roadmap to reach 250 Hz:

CARM OFFSET / MICH OFFSET
700 Hz / +200 cts
600 Hz / +400 cts
550 Hz / +800 cts
400 Hz / +900 cts
350 Hz / +900 cts
250 Hz / +1300 cts (PRCL offset -1000 cts)
MICH GAIN = 2
PRCL GAIN = 1.5

Other changes we did tonight:
    1.    Stefan relaigned the full IFO (X arm green, X arm red, TMSY single shot to beat note, Y arm green, PRMI)
    2.    We added a notch in the PRCL loop for the 70 Hz periscope resonance
    3.    We realized that theTMSY YAW damping loop has been off since May 15.. we re-closed the damping..
    4.    We modified the ALS slow path to include a 40 dB 5 second ramp for smooth engaging
    5.    We re-commissioned the Y arm ITM dither alingment loops, 1 dof only, in PITCH and YAW (the PZT loops are broken for both arms since the WFS software upgrade)

ISS was in a state where he tries to engage the loop but keeps failing. So I re-adjusted the reference DC signal to -1.631. It fixed the issue. The diffracted power is now at 8-ish percent. Good.

Hope this will help our locking activity tonight.

CO2X:
- Turned on laser at 10:00 AM PT, mysteriously turned off around 3:24 PM PT.  Still investigating causes, but we opened up the table and didn't see any problems.  We're leaving this on overnight tonight.

CO2Y:
- Calibrate the on table power meter.
- We're not leaving the laser on tonight, but we are leaving the chiller and the power supply on.

HWS HAM4:
- Aligned part of the X side on the in air table
- Retrieved spare in-vac temperature sensor for install by SUS

RHs:
- We wanted to commission the ITMX ring heater today without bothering the integration team.  Since the time constant of the ring heaters is on the order of many hours, quick impulses of very small powers (1-4 Watts for 1 or 2 seconds) we figured that it wouldn't be a problem.  We left the ITMY ring heater alone because it is actively being used to lock the PRMI so we focused solely on ITMX.

Complication: We saw some problems with the ITMX RH.  First off, the power we request gets translated into a current request which should match pretty closely to the current measured.  When we request 3.5 Watts, we expect to get .29 Amps and 12.0 Volts but we get .14 Amps and 6.00 Volts with an output wattage of .8 Watts. Not good.  Then we noticed that turning on the upper segment of the RH affected the read back on the lower segment.  This is really strange since we expect that the two segments are electronically isolated from each other.
Test:
We tested the ITMX ring heater continuity out to the floor and got 50.2 Ohms for both the upper and lower segments so that is what we expect.  Then to the ring heater on the floor from the RH driver chassis, we saw that it was driving the correct amount when we used a breakout board to measure the voltage across the ring heaters.  The ring heater driver also provides the monitoring tools for the RHs as well such as voltage_mon and current_mon and this could be wired wrong in the Beckhoff chassis.  So we carefully measured the continuity of the connection between the feed through and the EtherCAT modules to make sure that they match our drawings and this is where we found the wiring mistake that had us confused.  Basically, there was a wiring switcharoo between the readouts of the upper and lower segments on ITMX but in a unique way: the positive read back terminal was connected to the upper and the negative read back terminal was connected to the lower.  That would explain why the two segments were coupled when we know that they shouldn't be.  The good news is that ITMY seems to be working just fine and weird up correctly, also, this mixup happened only on the read back side of ITMX RH, which means we don't think that it's actually driving the ring heaters in some unexpected way.  At the first available opportunity, we want to fix this wiring and test the RH again.  Before the next vent, we hope to do some serious testing with the ITM ring heaters, namely turning them on and off in 30 minute intervals for 24 hours to see their response.

With a woefully underestimated increase in the payload, I removed a bunch of wall mass from the ISI.  It unlocked pretty easily and then I commenced to removing more and yet more mass.  But I got there with the table locking/unlocking quite smoothly with well within spec shifts.  A 10Kg D0901075 even had to be removed from the table top.  In the end, the added payload & balance mass is lower by 52.45Kg.  I have red-lined D1001132-v3 with the changes and current mass distribution and added that to the DCC.

The ISI is unlocked with the C3 covers pulled away from the ISI.  HEPI remains locked.

Between the times of 3:24-3:27 PM PT, we saw that the laser on CO2X was turned off when we were trying to initialize CO2Y.  It's not clear exactly what caused this glitch because we had not yet started touching either system during this time frame so we're not sure if this glitch was due to a human interaction or some sort of electronics malfunction.  All we know is that the laser gate was off but that the emergency shutoff had not been pressed on either table.  Also, the laser itself was not shut off but the laser controller had somehow closed the gate.  We're still investigating this issue, we turned the laser on at 10:00 AM this morning so it had been running for about 5.5 hours or so.

08:50 Corey – Working around the squeezer area on laser enclosure
09:20 Hugh – Working on HAM4 ISI alignment & balance
09:42 Dave – At HAM4 area working on Hartman table
10:00 Jason & Betsy – HAM5 for SRM alignment
10:05 Travis & Gerardo – Working on ACB alignment
10:18 Peter – Working in the H2-PSL enclosure
12:50 Karen – Going to End-Y and Mid-Y
12:57 King Water Systems on site to work on RO system
13:17 Thomas – In and out of LVEA working on TCS
13:51 Gerardo & Travis – Working on ACB alignment 
14:22 Hugh & Scott – HAM4 ISI alignment & balance
14:30 Justin – Transition LVEA to laser hazard 
15:45 Hugh – Turned down purge air at HAM4 and HAM6

Today, Jeff is on operator duty so I tagged back in on HAM 5.  While Jason was resettting his equipment, I worked on -

- cable routing for SR3, including switching the cables in the bracket since they were mounted backwards.

- positioning all of the lower stage AOSEMs on SR3.

- removing yaw adjustment hardware and torqued remaining dog clamps.

- cable routing on SRM.

- resetting the SRM open light gains/offsets with Arnaud (and creating the safe_snap once set) - Note, this was done because it was last done on a different set of electronics/cables.  Currently, all of the OSEMs are backed out and reading open light - I'll resume setting these tomorrow.

- staging the dog clamps for the upcoming OFI and 3-baffle installs on this table.

On friday night, the wind was high(~25mph), and the arm was hard to lock. Although the angular motion of the test masses was not particularly different than on a quiet night. First attachement shows the oplev spectra from friday night, when the wind was ~25mph. second attachement shows spectra from yesterday night with a 5mph wind.

To note :

• RMS of ETMY (blue curve) in pitch and yaw are consistently higher, even though the ISIs are in the same config (level 3 controller and Tbetter blends on St1 and St2 except for Rx and Rz)
• ITMX (pink curve) seems to perform better, but it's actually because the oplev beam is offcentered from the qpd, sitting mostly on S4 quadrant. SUM is ~5900

(Stefan, Lisa, Chris)

Looking through the locked stretches from the weekend, we noticed that the ALS slow feedback -- intended to relieve the VCO control signal of low frequency seismic and tidal motion -- was failing in its mission.  What we saw is plotted in the first attachment.  The green trace shows the VCO control signal, which should be forced toward zero when the slow test-mass feedback (red trace) is enabled about halfway through the timeseries. Obviously this wasn't happening. Meanwhile the VCO frequency servo that actuates the tune slider (blue trace) was running away along with the VCO control signal. When the tune slider hits its limit at +/-5 the lock is broken.

We tracked it down to a missing integrator in the ALS-X_ARM filter bank, without which the slow loop didn't have enough oomph at DC to null the fast control signal. I think this filter was removed intentionally (but without realizing its true purpose) during some earlier automation work. We put it back and, taking advantage of the improved test mass plant inversion, we were able to increase the gain upstream (in the ALS-X_REFL_SLOW filter bank) from 1 to 30. This should help prevent the arm from being blown away by the wind.  When we lose lock the integrator is switched off by the Beckhoff, and the drive bleeds away through a 0.01Hz pole.  The improved behavior is shown in the second attachment (where the gain was cranked about 20 minutes in).

Here is the list of commissioning task for the next 7-14 days:

Green team (XY-arm):

• Hand-off to 3f lock signals.
• Common mode hand-off.
• Hand-off ALS signals to interferometer signals.
• RF phase for MICH.
• Add CM Sum in chain.
• Noise hunting.

Blue team (X/Y-arm):

• Revisit the WFS with the now improved beam quality.
• High BW feedback to input PZTs?
• EY WFS alignment sening matrix.

Red team:

• Center the red QPDs in EX/EY.

SEI/SUS team:

• EY ESD drive is broken.

In-Vacuum preperation:

• IMC/PRCL adjustment: Prepare to move MC2.
• EY ESD fix: What measurements can we do now?
• Conflat for mirror discharging.
• EX QPD centering: Can we get the beam centered?
• EY QPD centering: Will work.
• POP beamsplitter.
• Change mode of ALS/POP periscope in HAM1.
• Are all picos working?
• Test photodetector pods for leaking?

As of 12:00

PSL Status: 
SysStat: Green, except VB
Output power: 26.7w  
FRONTEND WATCH: Good
HPO WATCH: Red  

PMC:
Locked: 12min
Reflected power:   1.5w
Power Transmitted: 9.8w 
Total Power:      11.3w 

FSS:
Locked: 12min
Trans PD: 0.94v

ISS:
Diffracted power: 3.833%
Last saturation event: 12m

Jason & Betsy – SRM fine alignment at HAM5
Gerardo – Putting the OFI into storage box and fly over beam tube
Hugh – ISI balancing at HAM4
Travis – ACB balance and alignment
Richard & Filiberto – Chassis work in EE shop & cabling at HAM6
Peter & Olli – In H2-PSL working on ISS assembly
Dave – TCS Hartman table alignment

The problems we noted over the weekend with the ETM SUS (and sometimes SEI) systems tripping on lock loss (alog 11957) can maybe most accurately be characterized as a watchdog problem.  The trips are caused by large drive transients after lock loss.  It's hard to imagine that there's much we can do to prevent this from happening.  Even if the DARM (CARM, etc.) control signals could be shut off immediately, the residual impulses would still produce large impulse response in the LOCK filters in the suspensions.    We could try to shut off the drive signals in the SUS controllers, or hold the outputs at their current value, but that's a bit more difficult to implement.

In general, though, the watchdogs should probably just not be tripping on transients.  If the watchdogs were a bit smarter and only tripped on sustained saturations or oscillations, this would likely not be an issue.  I vote that we solve the problem in the watchdogs, but increasing the amount of time it takes before they trip.

Just for a bookkeeping purpose:

I recentered the beam on the IMC WFSs on this past Saturday. I used the picomotors. Both of them had been off by 0.2-ish counts in the normalized pitch and yaw.

No restarts reported.

I made a couple of improvements to the IMC guardian:

• maybe most importantly, I filled in a lot of comments and inline documentation
• cleaned up the code quite a bit
• added GuardStateDecorators for handling fault conditions and lock loss
• cleaned up edges around the FAULT state
• broke out a BOOST state from the LOCKED state

The final point was to make it so that there is no activity in the LOCKED state, so that reaching the LOCKED state means that the IMC is fully up.  In general, I think we should start making all requestable states be "idle" states in that they don't do any action other than monitoring for exit conditions.  This idea here is to make them true markers of a steady state of the system.

We end up with just two requestable states now: DOWN and LOCKED.  The DOWN state doesn't actually prevent the IMC from locking briefly, so we may want to change the DOWN state to something that actually prevents the IMC from locking.

Next, I want to make the IMC guardian the manager of the SUS_MC{1,2,3}, so IMC is actually in control of setting the MC suspensions to their ALIGNED states.  This will also allow us to achive the point above, since we can then make the DOWN state into something where the SUS are misaligned, thereby preventing the IMC from locking.