- Duty Cycle: 54%

- range: 75 - 85 Mpc

- PRM M3 LL coil driver caused noise in 10-60 Hz range on Friday, may have been responsible for some loud glitches

- Also on Friday there were some strange lines in the strain spectrogram at around 10Hz

- loud glitches that cause brief, large drop in range that we saw in ER7 continue; the rate is improved

- link to full DQ shift

JeffreyK, Kiwamu, Darkhan

Overview

A DARM OLG TF model and its parts, sensing and actuation functions, are used for calculating the interferometer strain, h(t), and estimation of uncertainty in reported h(t).

On last Thursday we put together a DARM OLGTF Matlab model for ER8/O1 and compared it to a DARM OLGTF measurement taken on Aug 17, 2015. This model is mainly based on a similar model for ER7 (LHO alog 18769). Currently the model agrees with the measurement to only about +/-10% in magnitude and +/- 5 deg up to 200 Hz. So there's still work need to be done, probably changing parameter file needs some fine tuning of possibly following parameters: optical gain, CC pole frequency, ESD zeros and poles, ESD gain.

Details

Please, see a summary of things to be aware of when using this model (mostly listed differences from ER7 model):

• The following parameters at this point were fit by eye:
  • optical gain: 1.6*10^6
  • CC pole frequency: 338 Hz
  • ESD gain was adjusted by factor of 1.4
  • moved ESD driver pole to 138 Hz (not sure if this helped significantly)
• One major difference from ER7 model is that the new model generates all of the frequency dependent transfer functions in the form of LTI objects (zpk, ss, sos). This should make it more convenient to obtain frequency response of DARM parameters at a desired frequency vector.
• In ER7 time delays have been included only into overall OLGTF, but not into C, D and A. In ER8 model we explicitly included time delays at the places where they occur, i.e. SUS computation delay is included into discrete frequency response of SUS digital filters, total IOP downsampling TFs in C and A include their respective computation time delays, etc. E.g. below you can see the difference when comparing calculation of OLGTF in ER7 and ER8 models:
  • OLGTF from ER7 model is: G = C * D * A * time_delays
  • OLGTF from ER8 model is: G = C * D * A       (time delays were included into C, D and A)
• Since not all of the frequency dependent TFs that contribute to the DARM OLGTF are coming from discrete (computation) or analog/continuous (electronics, optics, mechanics) sources, but rather from mix of the two kinds, there is no a single LTI object for OLGTF (G), actuation (A) and sensing (C) functions. For user convenience this model includes inline functions that generate C, D, A and G transfer functions at a user requested frequency vector. E.g. if we want to obtain TFs in the range [10 .. 100] Hz with 1 Hz frequency resolution, following commands can be used:

[ol, par] = H1DARMmodel_ER8('par_file');

freq = 10 : 1 : 100;

G = par.G.getFreqResp_total(freq);

A = par.A.getFreqResp_total(freq); % total actuation function

% frequency responses of actuation stages can be obtained similarly

A_tst = par.A.getFreqResp_TST(freq);

% frequency responses of C with and without CC pole

C = par.C.getFreqResp_total(freq);

C_res = par.C.getFreqResp_noCavPole(freq);

• In ER7 for analog AA and AI filters both LHO and LLO sites used averaged frequency response of measurements taken at LLO. Recently Kiwamu and I processed AI filter measurements taken at LHO EY during calibration week before ER7 (LHO alog 18639), and produced a new zpk model of AA/AI filters based on these measurements (LHO alog 20769). Now we are using this new analog AA/AI model. One assumption that we are still making is that analog AA and AI filters have the same frequency response. To ensure that this assumption holds we will need to compare other AA and AI chassis measurements from pre ER7 (LHO alogs 18628, 18639) with the AA/AI model.

• In this DARM model the suspention TF is taken from a tagged suspension model that was recently created by Kiwamu and Sudarshan; this tag was also installed in calibrated Pcal RxPD and TxPD channels (LHO alog 20334).

• Another minor change is that parameter file for the measurement from 2015-08-17 uses OMC and SUS filter files that are copied into calibration SVN, this makes the scripts ready to run outside of control room.

We still need to take more DARM OLGTF and PCAL to DARM TF measurements and compare them to better estimate DARM model parameters.

The model was uploaded into calibration SVN (r1095):

CalSVN/aligocalibration/trunk/Runs/ER8/H1/Scripts/H1DARMOLGTFmodel_ER8.m

The parameter file associated with measurement taken on Aug 17 is in the same directory:

CalSVN/aligocalibration/trunk/Runs/ER8/H1/Scripts/DARMOLGTFs/H1DARMparams_1123894143.m

I believe that these scripts are in a reasonable shape to try it with LLO DARM parameters.

The fluid levels are essentially unchanged since the end of July.  The EndX is down <1/16" but I'll wait for more data to claim a trend from a leaky Accumulator.  No further HEPI Maintenance needed tomorrow.

BRS software crashed at the end of last week. I got a chance to head to EX and restart the code from the desktop in the rack room.

I kept the damper OFF for now to see whether or not it is rung up.

J. Kissel, K. Izumi, S. Karki, D. Tuyenbayev, R. Savage

I attach a picture of the whiteboard where we've sketched out our plan for the week. We've gone through T1500443, taken off items that we've already managed to capture before this week, and prioritized the remaining tasks accordingly.

Stay tuned for daily updates on progress.

J. Kissel, K. Izumi

At 16:02 UTC, we've taken the IFO down to begin calibration measurements.

On today's docket:
- Actuation function frequency dependence checks
    - UIM, PUM Coil Driver TFs
    - ESD LVLN Driver TFs
- Sensing function frequency dependence checks
    - OMC DCPD AA Chassis
    - OMC DCPD PreAmp (with single bounce IFO)

ALL TIMES IN UTC

Science Mode Checklist: (beginning of shift)

• Guardian:  NOMINAL_LOW_NOISE

• Inspiral Range: 62Mpc

• LVEA Sweep: N/A

• Ops Overview: Clean and Green (except for the beam diverter caveat)

• CDS Overview: Green except for Cal injections

• SDF Overview: All Diffs cleared except for  SUSPRM, OMC  and CALCS.

• SYS DIAG:  the usual BRS message

• Calibration Lines: Calibrations are running.

• ODC Master Observation Ready Bit: GREEN

• Observation Intent Bit: UNDISTURBED

• Ops Observatory Mode: Observing

Activity Log:

• 12:10 EY .3µ Dust Alarm Major

• 12:21 EY .3µ Dust Alarm Major

• 12:22 Set the Observation mode to ‘Environment’ while the earthquake settles down

• 12:26 Christina on site

• 12:26 Muted annoying EY dust monitor alarm

• 12:45  Took ISC_LOCK to down while Z-axis settles. Incessant OMC DCPD saturation Verbal Alarm after Lockloss and OMC still flashing. I called Evan and he instructed me to slide the ‘OFFSET’ slider in the OMC CONTROL Screen to the left a bit until the flashing stops. Guardian will touch this again when it’s time for locking. Verbal Alarm for this should be addressed as it was sounding excessively for an innocuous event according to Evan.

LOCK LOG:

• 11:42 IFO Locked at NLN. Range ~62Mpc.

• 11:59 Observation Intent Bit and Observatory Mode set

• 12:07 Lockloss.  There appears to be a mag 5 earthquake in the North Pacific off the coast of Russia

• 12:08  Begin locking sequence

  • DRMI - may take a while. mag 5 quake N Pacific/Russia

    • DRMI 1F locked after 15 minutes but came unlocked. I’m pretty sure it was the earthquake now

• 12:32 DRMI LOCKED

• 12:32 Attempt to proceed failed

• 12:57 Begin sequence (EQ calming) we’ll shoot for DRMI for starters.

  • DRMI Locked 1F in about 2 minutes

• 13:02 Lockloss. Never made it to 3F.

• 13:03 Begin sequence

  • DRMI Locked 1 min

• 13:19 Locked at NOMINAL_LOW_NOISE. 62Mpc

• 13:28 Set OIB and OOM to Undisturbed/Observing

Shift Summary:

• Most of the night was spent commissioning to resolve a problem with stability at “high” power.

• locking resumed at 11:42UTC and went well until an earthquake off the coast of Russia shook things up for about 1.5 hours.

• The wind stayed down all night and another good lock was achieved and hopefully will hold as I hand off to Jeff B. Only 1 ETMY saturation noted during this last lock, so far.

13:28UTC OIB and OOM set to Undisturbed/Observing

ALL TIMES IN UTC

Science Mode Checklist:

• Guardian:  NOMINAL_LOW_NOISE

• Inspiral Range: 62Mpc

• LVEA Sweep: N/A

• Ops Overview: Clean and Green (except for the beam diverter caveat)

• CDS Overview: Green except for Cal injections

• SDF Overview: All Diffs cleared except for  SUSPRM, OMC and CALCS.

• SYS DIAG:  the usual BRS message

• Calibration Lines: Calibrations are running.

• ODC Master Observation Ready Bit: GREEN

• Observation Intent Bit: UNDISTURBED

• Ops Observatory Mode: Observing

Activity Log:

• 11:42  got the “go ahead” to go to NOMINAL_LOW_NOISE. Range -60Mpc
• 11:59 Observation Intent Bit and Observatory Mode set
• 11:50 Evan has cleared most of the diffs in SDF Overview. PRM will stay red due to script workaround for current problem with LL OSEM signal and OMC will stay red because he wasn’t sure that the changes effected were meant to be permanent.

Sheila, Evan

We looked again at the situation with the 45 MHz REFL WFSs, which are used as sensors for the PR3 ASC loop. In the end, we didn't implement any changes to the sensors or the associated loops.

We were motivated by the following:

1. The current demod phases for these WFSs simply do not make sense; we expect that they should be similar (since the analog delays should be fairly well matched), but instead they are scattered by 100+ degrees.
2. The cHard and PR3 loops are strongly cross-coupled. We would like to be able to turn up the gain of cHard without impressing extra motion from other optics into DARM. [20523, 20497]
3. Any perturbation in the PR3 seems to couple into the SRC loops. We already know that the SRM loop is quite delicate, and we would like to get rid of this coupling if possible.

We tried the following:

• We changed the demod phases of the 45 MHz REFL WFSs, and then closed the PR3 loops.
  • We chose phases so that cHard pitch appears entirely in the Q phase (thereby leaving I dominated mostly by PR3 motion, hopefully). This was done previously, but loop retuning was not investigated in detail. Also, the phases of A3, A4, B3, and B4 seem to need an extra 180° phase shift in order to produce correctly phased signals (see screenshot).
  • We then found that only REFL45B gave a sensible error signal in response to PR3 motion (both pitch and yaw), so we closed the loops around B only. Additionally, the required digital gain went from 2 ct/ct (with the old phasing) to 40 ct/ct, perhaps indicating that the "old" PR3 configuration is actually dominated by cHard motion.
• This seemed to produce a constellation of bad things:
  • The sideband buildups (POP18 and AS90) were slightly suboptimal (i.e., fuzzy and not maximized).
  • The soft loops reduced the recycling gain (to 36 W/W or so) when they came on.
  • Switching the SRM yaw loop input matrix elements at 3 W seemed to make POP90 worse.
• We tried using new trans QPD offsets for the soft loops, but this led to the familiar angular instability when going to 20+ W.
• We also tried to find a new SRM yaw matrix element, but this didn't work either.
• We also turned off the dc oplev coupling on SR3, since we didn't want the optic position to be dragged away by the ground.
• In the end, we simply reverted all the changes we made.

After that, we couldn't get to full power because of an oscillation that showed up in dHard pitch when going to 20+ W. (We've seen this before, and it seems to be distinct from the angular instability mentioned above.) To get around this, we had to slightly beef up the resonant gain that gets turned on in dHard pitch when the power is increased.

Also, there were some small maintenance tasks that we did:

• Improved the filter hygiene of the DC centering loops (there were some integrators that didn't have ac gain of 1, some low-pass filters that didn't have dc gain of 1, some filters with ambiguous names, etc.)
• Added an optional ISC_LOCK guardian state called REDUCE_MODULATION_DEPTH, which implements the 3 dB modulation depth reduction that Stefan and I have carried out before.

ALL TIMES IN UTC

On my arrival, Evan, Sheila and Dan on site (of course Jim also). Not really any wind to speak of (~10mph). Minor earthquake activity in the last couple of hours after about 5 hours of quiet. Everyone gone except for Evan.

Science Mode Checklist: (since beginning of shift)

• Guardian:  actively running lock sequence while commissioners are troubleshooting

• Inspiral Range: N/A

• LVEA Sweep: N/A

• Ops Overview: In flux due to commissioning work

• CDS Overview: mostly green except for the typical OVF errors and the Calibration Line Excitation

• SDF Overview: Diffs showing on: SUSPRM, SUSSR3, LSC, ASC, OMC, ISCEX & ISCEY. Others are ODCX, ODCY and CALCS.

• SYS DIAG:  the usual BRS message

• Calibration Lines: It appears that Calibrations Lines are running.

• ODC Master Observation Ready Bit: RED

• Observation Intent Bit: Commissioning

• Ops Observatory Mode: Commissioning

Activity Log:

• 7:00 Evan and Sheila continuing work on ASC.

• 7:32 ETMX Dust Monitor giving Invalid Alarm

• 8:08 Refreshed the Operating mode FOMs

• 9:32  ETMX Dust Monitor giving Invalid Alarm

• 10:52 Still working on ASC issues

Quiet night again.

IFO was locked when I arrived, but was knocked out by an earthquake.

Sheila and Evan have been working on ASC improvements since.

Lock loss where SRCL went first.

Guardian code issue stalled progress to Low Noise, now fixed.

ETMX PUM needed to be reset.

IFO has been locked for 2 hours and range is above 60MPC.

Currently in commissioning mode - Sudarshan, Sheila, and Evan are here.

Plot attached shows SRCL goes at -30 seconds, then PRCL goes at -12 seconds.

Lock Loss right after PRM saturation - lock loss plot shows an issue in SRCL came first, then PRCL responded, then lock loss

- plot attached shows PRM _M3_LOCK_L_OUTPUT 

--- signal changes directions at 17:46:14UTC

--- exceeds it's normal range at 17:46:17UTC

--- abrupt change of the signal at 17:46:22UTC

--- signal exceeds it's normal range (negative) at 17:46:25UTC, Lock Loss

Relocked:

- didn't make it through RF_DARM

Relocked:

- didn't make it through RF_DARM, and I tried to diagnose it, but couldn't, so put the IFO Mode to "unknown,"

Guardian Code issue, corrected:

- Sheila arrived and she diagnosed the problem - Guardian code was waiting for OMC_LOCK to be in "ready to hand off" but OMC wasn't ready.

- Sheila corrected the code so now it only looks at the two arms to see if they are ready.

LSC_LOCK was waiting for OMC to be ready, but OMC wasn't ready, so we cleared that and tried to go on t DARM_WFS and the IFO made some progress but then lost lock.

Relocked

- lost lock at DARM_WFS again - reason unknown.

ETMX Coil issue, corrected:

- after lock loss, ETMX coils died, Sheila went to EX to fix.

Back in Observing/Undisturbed Mode:

- ETMX fixed, relocking went well, and as of 20:36UTC Obs/Und Mode bit set.

NOTE: on the observatory mode screen

I used the UNKNOWN mode for locking issues (since the cause was unknown to me) and for the ETMX fix (because Corrective Maintenance just didn't seem to fit what was an equipment failure).

Sudarshan reports that a PCal line was turned off sometime last night.  He is turning it back on at 17:53.

Using the calibrated DRMI channels created and described by Kiwamu in entry 18742, I grabbed data from the lock of August 3, 2015, starting at 04:20:00 UTC. The attached 4 page PDF shows spectra of the open loop and residual displacement noise for SRCL, MICH and PRCL. The 4th page shows the coherence of SRCL with the other 2 degrees of freedom.

The SRCL spectra has a curious shape: it comes down quickly with frequency to 10 Hz, then is fairly flat from 10 Hz to 50 Hz, then falls by a factor of 5 or so to the (presumed) shot noise level that is reached above 100 Hz. What is this noise shelf between 10 Hz and 80 Hz? That is exactly the region where the SRCL noise coupling to DARM is troublesome. Our usual approach is to send a SRCL correction path to DARM to reduce the coupling, but this spectrum shows that there should also be some gain to be had by reducing this noise shelf.

The last page of the PDF shows the coherence between SRCL and MICH & PRCL, and it indicates that the SRCL noise shelf could be coupling from PRCL noise -- the coherence is fairly high in this band, though not unity. This suggests that the DRMI signals could use some of the demodulator phase and input matrix tuning that Rana has recently done on L1, reported in LLO log entry 19540.

To complete this log entry, it would be useful if someone at LHO could add the open loop transfer functions for each loop (models), and other pertinent info such as DC photocurrents for these detectors and the input matrix coefficients.

Kiwamu, Hang

We did an estimation of the beam position on test masses based on the a2l gains that gave us best decoupling.

The result was shown in the first image attached. The blue line indicated the boundary of L3 and the red spot the position of the beam on the test mass. It seemed that the beams were <~1 cm off center.

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

In case that you are interested in how we obtain the results:

The basic idea is to excite the pitch (yaw) motion of L2 stage, and let this excitation go through both

1): the L2->L3 P2P (Y2Y) path, and

2): L2->L2 P2L, and then L2->L3 L2L and L2P.

The ratio of L3's L over L3's P will then give us the vertical position of the beam on test masses. See the second picture for a graphic representation.

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

The code to re-run this analysis is available at:

/opt/rtcds/userapps/release/isc/h1/scripts/a2l

You can do the analysis by entering

./run_GrabBeamSpot.sh

in the command line