There are ten T240s out of range, and some are about 6 times the maximun range of 0.3V.
There is one STS proof masses out of range at 4 times the maximum of 2V.

Averaging Mass Centering channels for 10 [sec] ...
2018-09-04 13:54:14.359578

There are 10 T240 proof masses out of range ( > 0.3 [V] )!
ETMX T240 1 DOF Z/W = -0.623 [V]
ETMX T240 2 DOF X/U = -1.175 [V]
ETMX T240 2 DOF Y/V = -1.114 [V]
ETMX T240 2 DOF Z/W = -0.52 [V]
ETMX T240 3 DOF X/U = -0.339 [V]
ETMX T240 3 DOF Y/V = 0.405 [V]
ITMX T240 1 DOF X/U = -1.244 [V]
ITMX T240 3 DOF X/U = -1.402 [V]
ITMY T240 3 DOF X/U = -1.12 [V]
ITMY T240 3 DOF Z/W = -1.949 [V]

All other proof masses are within range ( < 0.3 [V] ):
ETMX T240 1 DOF X/U = 0.164 [V]
ETMX T240 1 DOF Y/V = -0.273 [V]
ETMX T240 3 DOF Z/W = -0.08 [V]
ETMY T240 1 DOF X/U = -0.185 [V]
ETMY T240 1 DOF Y/V = 0.226 [V]
ETMY T240 1 DOF Z/W = -0.189 [V]
ETMY T240 2 DOF X/U = -0.06 [V]
ETMY T240 2 DOF Y/V = -0.173 [V]
ETMY T240 2 DOF Z/W = -0.088 [V]
ETMY T240 3 DOF X/U = -0.218 [V]
ETMY T240 3 DOF Y/V = -0.203 [V]
ETMY T240 3 DOF Z/W = 0.047 [V]
ITMX T240 1 DOF Y/V = 0.217 [V]
ITMX T240 1 DOF Z/W = 0.099 [V]
ITMX T240 2 DOF X/U = 0.035 [V]
ITMX T240 2 DOF Y/V = 0.158 [V]
ITMX T240 2 DOF Z/W = 0.211 [V]
ITMX T240 3 DOF Y/V = 0.122 [V]
ITMX T240 3 DOF Z/W = 0.045 [V]
ITMY T240 1 DOF X/U = -0.126 [V]
ITMY T240 1 DOF Y/V = -0.105 [V]
ITMY T240 1 DOF Z/W = -0.23 [V]
ITMY T240 2 DOF X/U = 0.033 [V]
ITMY T240 2 DOF Y/V = 0.012 [V]
ITMY T240 2 DOF Z/W = -0.051 [V]
ITMY T240 3 DOF Y/V = 0.007 [V]
BS T240 1 DOF X/U = -0.037 [V]
BS T240 1 DOF Y/V = -0.123 [V]
BS T240 1 DOF Z/W = 0.205 [V]
BS T240 2 DOF X/U = 0.0 [V]
BS T240 2 DOF Y/V = 0.197 [V]
BS T240 2 DOF Z/W = -0.102 [V]
BS T240 3 DOF X/U = 0.013 [V]
BS T240 3 DOF Y/V = -0.191 [V]
BS T240 3 DOF Z/W = -0.221 [V]
Assessment complete.

Averaging Mass Centering channels for 10 [sec] ...

2018-09-04 14:01:15.356812
There are 1 STS proof masses out of range ( > 2.0 [V] )!
STS A DOF X/U = -8.095 [V]

All other proof masses are within range ( < 2.0 [V] ):
STS A DOF Y/V = -0.856 [V]
STS A DOF Z/W = -0.389 [V]
STS B DOF X/U = 0.391 [V]
STS B DOF Y/V = 0.343 [V]
STS B DOF Z/W = -0.422 [V]
STS C DOF X/U = 0.842 [V]
STS C DOF Y/V = 0.922 [V]
STS C DOF Z/W = -0.55 [V]
STS EX DOF X/U = -0.128 [V]
STS EX DOF Y/V = 0.439 [V]
STS EX DOF Z/W = 0.098 [V]
STS EY DOF X/U = 0.094 [V]
STS EY DOF Y/V = -0.035 [V]
STS EY DOF Z/W = 0.51 [V]

Assessment complete.

The report shows that there was work on the PSL this morning, so locked times are short, and this is understood.  The HPO has no power.  The diffracted power at 1.3% is closer to what we plan to run during O3, so looks OK.

Laser Status:
SysStat is good
Front End Power is -0.003792W (should be around 30 W)
HPO Output Power is 0.1943W
Front End Watch is GREEN
HPO Watch is RED

PMC:
It has been locked 0 days, 7 hr 38 minutes (should be days/weeks)
Reflected power = 14.9Watts
Transmitted power = 51.21Watts
PowerSum = 66.1Watts.

FSS:
It has been locked for 0 days 6 hr and 5 min (should be days/weeks)
TPD[V] = 2.944V (min 0.9V)

ISS:
The diffracted power is around 1.3% (should be 3-5%)
Last saturation event was 0 days 2 hours and 11 minutes ago (should be days/weeks)

Possible Issues:
Front End Power is Low
ISS diffracted power is Low
LRA out of range, see SYSSTAT.adl

Maintenance concluded around noon (19:00UTC), and the current status/plans are:

• the ISS remains the same as Peter reported in along 4301
• commissioning plans are to lock DRMI and work tonight
• Peter plans to resume diagnostics on the ISS tomorrow

Maintenance Activities:

• 04-09-18 15:12 Richard to EX for ESD - looks OK
• 04-09-18 15:13 PeterK to the LVEA to take out the ISS card
• 04-09-18 15:14 Kyle to LVEA climbing on HAM3 and on beam tube between BSC7 and the termination slab
• 04-09-18 15:23 Patrick charge measurement on EY
• 04-09-18 15:28 Fil and Mark to EX to pull cables
• 04-09-18 15:29 Chris escorting Pest Control to LVEA
• 04-09-18 15:34 Ed to EX to pull cables
• 04-09-18 15:42 Chris and Pest Control done in LVEA heading ti X arm and then to Y arm
• 04-09-18 15:56 Betsy and Travis to LVEA to look for 3IFO parts
• 04-09-18 16:18 TVo to LVEA to start up CO2 lasers
• 04-09-18 16:21 Chandra to the LVEA for vacuum work
• 04-09-18 16:27 Betsy and Travis are out of the LVEA
• 04-09-18 16:32 Chris and Pest Control are done
• 04-09-18 16:44 Fil, Mark, and Ed, back from EX
• 04-09-18 16:51 Vanessa to EX to clean
• 04-09-18 16:51 Karen to EY to clean
• 04-09-18 16:52 Nutsinee to ISCT6 to open doors and work on the laser
• 04-09-18 16:57 Richard to Mechanical Room to look at TCS power supplies
• 04-09-18 17:07 Ed to wind fence
• 04-09-18 17:13 Mark and Tyler to crane items off H2 enclosure
• 04-09-18 17:35 Jason back from MY
• 04-09-18 17:50 Dave woking on EX to recover the SUS IOP that crashed last night
• 04-09-18 17:51 Fil and Ed at EX helping Dave
• 04-09-18 17:52 Betsy to LVEA to look at the items that were craned down
• 04-09-18 18:15 Chris to Out Buildings will call
• 04-09-18 18:15 jason to EY about OpLev
• 04-09-18 18:20 Chriss called from EY and it is showing 237
• 04-09-18 18:21 ETMX work to recover IOP started at 17:44UTC and is done at 18:20UTC
• 04-09-18 18:22 Georgia starting a charge measurement at EX
• 04-09-18 18:33 Richard says there was aglitch in the safety system - may have caused sqeezer laser to trip
• 04-09-18 18:38 Chris is done checking phones and is leaving EX
• 04-09-18 18:45 Jason is back from EY
• 04-09-18 18:45 Chandra is back from EX and EY
• 04-09-18 18:46 Terry and Nutsinee to optics lab
• 04-09-18 18:47 Danny to Hartman table in LVEA
• 04-09-18 18:48 Pest Control is done on site
• 04-09-18 18:53 Tyler and Mark done craning in LVEA
• 04-09-18 18:55 Kyle and all other vacuum activities are done for today in the LVEA
• 04-09-18 18:55 Richard to EX and EY to check on ALS lasers
• 04-09-18 19:10 Peter out of the LVEA
• 04-09-18 19:15 Georgia is done with charge measurements on ETMX
• 04-09-18 19:17 Chandra done visiting vacuum components in End Stations
   

Didn't want the stray Hartmann beam seen at the bottom left of the ITMX HWS image to interfere with upcoming measurements of ITMX lensing so we reinstalled an iris in front of the HWSX camera. 

Jeff K. emailed me about a suspicion that the digital whitening compensation for the ETMy oplev was incorrect, so I took a quick drive to End Y to check.  Sure enough, instead of the 2 whitening filters and 0dB of gain enabled as indicated in T1500556 (and as would be assumed from the 2 compensation filters enabled in MEDM), 1 whitening filter and 3dB of gain was enabled.  I corrected this, and the whitening filters and gain now match T1500556, with the proper number of compensation filters (2) enabled via MEDM.  The attached pictures show the Output Configuration Switch (OCS) as I found it and as it should be.  With the loss of 3dB of whitening gain, the SUM counts dropped from ~13k to ~9k.

Edited to add ISC and SUS tags.

Cheryl, Fil, Dave:

At around 23:06 PDT Mon 3rd September h1susex had a significant timing glitch which caused the IOP model to lose track of DAC channels, triggering it to enter its safe mode whereby it does not drive any DAC channels. This is indicated by the DACKILL (DK) bit being set on the stateword, and each 18bit DAC having bit 4 (right-most bit) set to red indicating the AI chassis have been remotely turned off.

We made a note of the SDF differences (h1susetmx=72, h1sustmsx=8, h1susetmxpi=0) and restarted the models. Fil was at EX and verified the AI chassis were operating correctly.

We "burt restored" using the SDF EDB-load back to the settings captured during shutdown of the user models, and now have the original number of differences in the SDF.

current activities:

• Jason at EY to diagnose the OpLev
• Betsy, Mark, and Tyler, in LVEA craning
• Chris visiting all outbuildings, about 1/2 way through
• Georgia just started a charge measurement on EX, now that DaveB brought the IOP back
• Nutsinee is in the LVEA working on the sqeezer table
• Peter King in the LVEA looking at the ISS electronics

I estimate 20-30 minutes for all regular Mantenance activities to wrap up, ISS work may or may not take longer.

Ion pump #1 (IP1) is a newly rebuilt pump that was installed and leak checked and finally valved in today.

Richard, Patrick, Thomas

Today we tried to turn on the laser but the 28V/28A power supplies on the mezzanine were completely turned off for some reason,  this is a new problem.  Richard tracked the problem down to a Beckhoff safety module on the interlock that was in error, this module is connected to the entire laser safety network so rebooting will cause all lasers to turn off.  The EE guys will wait till there is an opportune time to fix that module.  Until then, Richard plugged the power to both supplies directly into the outlets so we can still run the laser for commissioning higher power + preloading.

This morning I noticed that the first loop ISS went back to mis-behaving, for reasons unknown.
Attached are oscilloscope traces of the AOM control signal.  Whenever the first loop starts
oscillating, the AOM control signal behaves like this (scope_2.png).  A zoomed in trace is in
scope_3.png.

    scope_4.png shows the AOM control signal and the DC output of PDA.  The AOM driver is
deliberately turned off here.  The behaviour is present even when the light to the ISS PDs
is blocked.

    The ISS will be offline for a while, whilst I debug the board.

After talks with Gabriele today about CHARD, and his interesting find about ETMY, I checked the full actuation model for the quad suspensions.

This model takes into account the various cross-couplings we have in our DRIVEALIGN matrices:  If Gabriele was driving pitch at ISCINF, these signals get fed to length for some actuation stages.  Then we have to worry about the length-to-pitch coupling of the suspensions.

The code reads in every relevant SUS filter module at a given gpstime (ISCINF, LOCK, DRIVEALIGN), the on/off switch values for the lower stages, and txts of the MATLAB quad suspension model.

I plotted below the pitch-to-pitch and yaw-to-yaw couplings mirroring Gabriele's first two plots from alog 43797.  The model matches very well with non-ETMY test mass responses, and there is no cross-coupling term which explains ETMY's phase lag.

I also get all other DOF_to_DOF couplings, plotted here for the interested.

I was unable to lock today for several reasons:

Solved
-  DC centering caused RM2 was to rail both in pitch and yaw, which wrecked the PRM alignment while going through initial alignment.  It took me a while to figure out that RM2 was railed since there are no audible warnings and the suspensions monitor TV was frozen.  I reset everything to two days ago, seemed fine and I was able to get through initial alignment.

-The FSS was not locking for extended periods today.  The fast monitor was just sitting at 11 V while the loop rapidly shut itself on and off over and over.  I upped the oscillation threshold from 0.6 V to 3 V, this allowed the loop to close for a decent amount of time and actually lock the FSS.

Unsolved
- Something weird is going on with the fiber polarization: DIAG_MAIN reports ALS Y polarization is > 20%.  I haven't looked into this because of the next issue.

- At GPS 1220076426, I was locking arms green and X-arm transmission went to 0 and never returned.  The X-arm guardian gave messages "PDH; ReflPD A; Green input align": there is no green light coming back from ETMX.  It seems the HV driver for the ETMX ESD is off and cannot be reset.  The ISC_LOCK guardian in PREP_FOR_LOCKING is continually resetting the ETMX ESD HV, so I've paused the guardian for now.  I shut off control signals to ETMX L3 stage as well.


ISC_LOCK guardian repeated message
2018-09-04_07:33:42.929020Z ISC_LOCK [PREP_FOR_LOCKING.run] ETMX bias not at expected value
2018-09-04_07:33:42.929381Z ISC_LOCK [PREP_FOR_LOCKING.run] ETMX ESD Driver is OFF. Hitting RESET to turn it ON.
2018-09-04_07:33:42.929789Z ISC_LOCK [PREP_FOR_LOCKING.run] ezca: H1:SUS-ETMX_BIO_L3_RESET => 1
2018-09-04_07:33:42.930095Z ISC_LOCK [PREP_FOR_LOCKING.run] ETMX ESD Driver is being reset. Sleep for 2 sec.

Coming from Line 438 of ISC_LOCK:

else:  # Make sure ETMX ESD is on
    if abs(ezca['SUS-ETMX_L3_ESDAMON_DC_INMON']) < 20000: # ETMX ESD is not ready
        log('ETMX bias not at expected value')
        if -17000 < ezca['SUS-ETMX_L3_ESDAMON_DC_INMON'] < -15000: # Check if railed negative
            notify('ETMX ESD is potentially railed!')
        elif abs(ezca['SUS-ETMX_L3_ESDAMON_DC_INMON']) < 1000: # In case requested DC bias completely turned off
            if abs( ezca['SUS-ETMX_L3_LOCK_INBIAS'] ) < 5.0:
                log('SUS-ETMX_L3_LOCK_INBIAS too small. Check the requested epics value')
                self.timer['wait'] = 2
            else:
                log('ETMX ESD Driver is OFF. Hitting RESET to turn it ON.')
                ezca['SUS-ETMX_BIO_L3_RESET'] = 1
                log('ETMX ESD Driver is being reset. Sleep for 2 sec.')
                self.timer['wait'] = 2 # wait two seconds for the microcontroller to take action
        return # Exit and re-execute run to make check again

Since I could not lock the IFO due to the slow controls at X end, I decided to follow a different approach to characterize the CHARD yaw loop.

Single test mass measurements

First of all, I measured the pitch and yaw plants for each test mass, in standalone configuration, i.e. driving an excitation on the ISCINF pitch and yaw inputs, and measuring the motion using the optical lever. All measurements are high resolution (10 mHz) and gave me good coherence between 0.1 and 4-5 Hz. See below the results for pitch and yaw and all test masses:

The first observation is that ETMY behaves in a different way than all other test masses: the response has a steeper slope and there is an additional phase lag. To be more precise, the plot below shows the ration of the two ITMs and of the two ETMS, in both pitch and yaw. Again, the two ITMs have similar shapes, while ETMY is clerly steeper than ETMX, both in pitch and yaw. The response of ETMY changes more steeply than ETMX, in both pitch and yaw, by a factor of about 5 if we compare between 0.1 and 3 Hz.  A cursory check in the SUS screens did not show any good reason for this difference, but honestly there's a lot going on in those models. Nevertheless, this difference is worth investigating, since teh way we decoupled hard and soft modes relies in the assumption that all test masses have the same response.

Also ITMY seems to have a smaller response than the other test masses over all frequencies.

Reconstruction of hard and soft modes

Using the responses measured as explained above, I reconstructed the response in the DHARD, CHARD, DSOFT and CSOFT basis. The assumptions are

• the driving split between test masses is the one contained in the ASC output matrixes
• all optical levers are "cross calibrated" to the same units, so that I can really assume their output is in some physical units (the same for all test masses)
• the geometrical matrices to convert mirror motions into soft and hard degrees of freedom were computed from Sidles and Sigg

For some reason that I am currently not understanding, my reconstruction is ok in pitch, but swaps hard and soft modes in yaw. Unclear why. Nevertheless, I get a reasonable diagonalization. Below is an example of the CHARD pitch and yaw responses, reconstructed from the local measurements

Below I'm comparing the CHARD yaw transfer function measured in full IFO with this reconstruction. The magnitude (rescaled with a overall gain) matches quite well, but clearly the transfer function measured in full IFO shows a significant phase rotation between 1.5 and 2 Hz. Incidentally, I think this phase rotation is what is causing our problems when we try to increase the gain. Indeed, yesterday I tried to fit the CHARD plant transfer function, and discovered that it's not minimum phase: there is a zero with negative frequency, which is indeed needed to explain the excess phase rotation. We should investigate the origin of this non minimum phase behavior: my bet is on a wrong sign or gain somewhere in the driving matrix, or maybe it is coming from the weird behavior of ETMY. Of course I cannot exclude that my reconstruction of the d.o.f. responses from the local measurements is just wrong.

The Birmingham low-frequency workshop participants

Motivation:

The ASC noise dominates DARM below 30 Hz. To reduce this noise, we need to reduce the control bandwidth as much as possible (at least in the final low-noise state). In the first attached figure we show the aLIGO/A+ design sensitivity and ASC noise projections for different UGFs. Here we only consider a single DOF, assuming that the sensing noise is 5e-15 rad/rtHz and the a2l coupling is 1mm/rad. For each loop we low-pass it as aggressively as possible so that the phase margin is 30 deg. The point is that if we want to reach the design sensitivity, we can at most have an ASC UGF of 3 Hz. 

On the other hand, we need to have sufficient gain to suppress the residual mirror motion to maintain the IFO at its working point. Yet what defines 'sufficient gain', and how much RMS motion of each dof can be tolerated? Here we explore what kind of requirements should be set on the RMS angular motion, which can then be converted as requirements on the minimum ASC loop bandwidth given a seismic configuration. 

=======================================================

ARMS:

1). DARM sensitivity requirement -- ARM buildup

Note that while the shot-noise-limited DARM sensitivity scales with input power as sqrt(P_in), it scales LINEARLY with ARM buidup (see, e.g., https://arxiv.org/abs/1702.03329, eqs. 1 and 7).  This means that if we lose x% buildup, we will lose x% DARM sensitivity. 

In the second plot we show how the ARM buildup varies with respect to misalignment rms for different dofs. Here we define 1 HARD = 1 * ETM + 0.87 * ITM, and 1 SOFT = 1 * ETM + 1.15 * ITM. We see that the buildup is mostly sensitive to the hard mode misalignments and for CH/DH, 3 nrad rms for each dof seems to be good enough as we would only lose 0.5% DARM sensitivity. 

2). DARM sensitivity requirement -- A2L coupling

The RMS angular motion leads to a RMS spot position on the TM, which can then couple with the AC angular motion to become a length noise (i.e. a2l). The gain is dy/d heta = -4.5e4 m/rad for the hard mode, and 2.1e3 m/rad for the soft mode. This means that for a 3 nrad of CH/DH, it creates a spot motion on the TMs of 0.14 mm. This is smaller than the DC miscentering from the pointing dof ~ 1 mm, and thus is not a major limitation. Nonetheless, it sets a limits on how well we can reduce angular noise based on a2l feedforward. 

3). PR-CARM linear range

One concern people have in the workshop is that if the misalignment would reduce the linear range of high-finesse cavity PR-CARM. We thus perform a finesse simulation to see the CARM error signal with different CHARD misalignment. See the third plot. 

From it we conclude that the linear range is not affected. The decrease in the optical (PDH) gain is also mild <1%. A small offset appears in CARM yet this is not an issue as the longitudinal loop will correct for it. Consequently, 3) is trivially satisfied once 1) is satisfied. 

=======================================================

PRC:

4). PRC buildup

Here for simplicity we only consider misaligning PRM. The PR2/PR3 effects can be converted to PRM one accordingly (roughly speaking the conversion factor is the ratio of spot sizes on the PR mirror). In the forth figure we show the PRC buildup as a function of PRM misalignment. The shot-noise-limited DARM sensitivity scales as PRC build up as sqrt(G_prc). Thus it seems we can tolerate 7 urad of PRM misalignment, which corresponds to 2% decrease in PRG and 1% drop in DARM.

=======================================================

SRC:

5). SR-DARM pole frequency. 

The SR-DARM pole is affected by the SRC build-up. In the fifth plot we show how the DARM pole (assuming Tsrm=0.325, leading to a nominal pole at 426 Hz) varies with respect to SRM misalignment. If we want the darm pole to fluctuate within 1 Hz (3 Hz) then we need to control the SRC misalignment (after propagating SR3/SR2 to SRM) to 3 urad (5 urad). 

=======================================================

(Controlling the angular RMS to a certain level is just one aspect of the ASC bandwidth requirement. The other requirement coming from suppressing the Sidles-Sigg radiation torque. Specifically, the hard mode needs to be controlled around its resonance which can be as high as 3 Hz @ 125 W input. Using a regular 1/f-like controller would require a UGF of 5.5 Hz which clearly would not meet the noise requirement...)

=======================================================

All the analysis codes available at (requiring an installation fo finesse to run it):

https://ldas-jobs.ligo.caltech.edu/~hang.yu/ASC/general/work_min_asc/

The X arm green locking is not working: as shown in the screenshot, we can't connect to most of the slow controls. The guardians are stuck with dead channels in the SPM.

Probably a Beckoff problem? No idea how to fix it. End of the games for today.

J. Driggers, J. Kissel

I was deceived by some red lights on the CDS overview posted to the wall thinking that there were DAQ problems with the H1 SUS ETMX last night while I was gathering data to characterize the highest bounce and roll modes (see LHO aLOG 43713). However, I'm reminded that it's an inconsequential flaw with this version of RCG that the ETMs are running (see LHO aLOG 43039).

Long story short: I was looking at the CDS overview screens and found some filter files that were showing differences, indicating unloaded changes in a few filter banks. The list of front-end models with pending changes, and Jenne and my course of action taken is below.

    H1 LSC -- looks like a precision change of the sampling rate in the filters in MICH1 and SRCL1 banks, otherwise no changes to the actual function. The full filter file was loaded, and there are no longer differences.
    H1 SUS ITMX -- Small changes to the violin mode filter notching on the L2 LOCK stages; like the work of Sheila's finding out of the new yesterday. The filter file was loaded, and there are no longer differences.
    H1 ALS EY -- what looks to be substantial changes to the "ctrlHB" FM10 in the H1:ALS-Y_WFS_DOF_2_P filter bank (see attached screenshot for details). We know that Hang Yu has been working on this (see, for example, LHO aLOG 43516), but he's currently out of town, so we'll (for now) leave it unloaded and ask him about it.