• Dither TMSY in length
  • H1:SUS-TMSY_M1_LOCK_L_EXC; f = 0.3; A = 500
  • Definitely see the dither in power buildups, and also in yaw spot positions on TMSY QPDs.  Not really visible in pitch.  The yaw motion is coupling in to many ASC DOFs.
  • Marginal amount of improvement by going -5 urad in yaw, but very marginal.  (Looking at DARM BLRMS 3, 4, 5). No real change going +5 urad.
    • Did, however, seem to reduce the coupling of yaw motion to other DOFs.  Might just be that we're not falling off of the QPDs as much in this direction. 
• Use PEM shaker at EY
  • Kara set up a shaker injection, using the setup noted in alog 46524. 
    • awggui H1:PEM-EY_GDS_1_EXC, ellipBP, 4th order, 1-100 Hz, 10 sec ramp.  Starting amplitude = 50 counts (Robert recommends 50k counts).
    • Ramp up in amplitude to Robert's suggested 50k counts.
  • TMSY moved in yaw -5 urad, and also +3 urad, both are slightly worse than nominal.
  • TMSY moved in pitch.  -5 urad made things slightly worse, +4 urad made things slightly better.  Can't do much more than +4 without clipping on TMS QPD.
    • Fig 1 is time series showing slightly better BLRMS 3, 4, 5 with pitch +4 urad from nominal (-650 s through -380 s), as compared with nominal (-350 s through 0 s).
    • Fig 2 is the same data as spectra, with red as the nominal TMSY position, and blue is +4 urad in pitch. Both are 30 avgs.  Haven't done on/off tests yet.
    • Seems to make a small offset in the pitch ADS DOFs, not sure why.  It's very small though, so I'n not sure it matters.  The offsets are less than 1 count, when a normal starting point when we're acquiring lock is 100+ counts.
  • Move spot position on ETMY in pitch (nominal P2L gain value is 3.55)
    • going to 2.35, then waiting for ADS to converge.  High freq much worse.
    • going to 4.55, wait for ADS to converge.  High freq also worse.
    • 3.95, slightly worse than nominal.
    • 2.95, very slightly worse in the 30-50 Hz region, otherwise same as nominal.
    • Leaving at nominal.
  • Move spot position on ETMY in yaw (nominal Y2L gain value is 0.885)
    • 0.485, very slightly better than nominal, would have to do on/off tests to confirm.
    • -0.31 worse than nominal.
    • 1.485 a bit worse than nominal, but buildups were all much better than nominal.
  • Leaving TMS and ETM spots at nominal locations, since nothing seems dramatically better. 
    • Sometimes the spectrum seemed to get a bit better until the SRC ASC loops converged, then it was either the same as nominal, or a bit worse, as listed above.  So, maybe we should (as is on our whiteboard to-do list) look at SRC pointing.
• Dither TMSX in length, same settings as TMSY above.  Don't see oscillation in power buildups with the same amplitude of 500 counts at 0.3 Hz.
  • As with TMSY, when dithering TMSX I don't see any effect in DARM at frequencies above 7 Hz (I'm not looking lower), although I do start to see the power buildups oscillate a small amount when I dither length with 1000 counts (2x the TMSY dither). 

Lost lock trying to de-blend CHARD.  My TMS dithers weren't giving enough velocity to make any fringe wrapping show up at frequencies that are useful, but I can't push harder since the TMS motion is causing ASC signals to move the IFO.  Normally, CSOFT P, DSOFT P, as well as CHARD P and Y all use the TMS QPDs.  When I was shaking TMS in length, I was seeing a lot of yaw motion on the TMS QPDs, as well as a lot of yaw motion in other ASC channels.  This indicates that much of this coupling was through CHARD, since the SOFT DOFs are not using yaw right now. 

Recall DARM BLRMS 3 looks at 38 Hz - 60 Hz.  DARM BLRMS 4 looks at 60 Hz - 100 Hz.  DARM BLRMD 5 looks at 100 Hz - 450 Hz.

The OMC camera seems to have frozen sometime last week.  We've tried resetting it and restarting the service, but that hasn't worked.  

The DARM coherence with ASC and LSC is fairly low above 25 Hz, with the exception of DHARD_P having some coherence between 30-40Hz.  We should address this at some point, but it is not a high priority.  So, Danny's suspicions of the extra low frequency noise being due to his ASC change yesterday are exonerated. 

Also, we are not saving any signals from the ADS system, which is now being used to control the pointing of PRM and the SOFT degrees of freedom.  We need to add these in (at least the DOF[3,4,5]_OUT) before ER14.

I don't know if anyone has explicitly written this in the alog, but in the Saturday evening alog (46972) it is noted that while the DARM reference is mostly back to November levels, we're reporting a far smaller BNS range.  I'm quite confident that most of that range loss is due to the broad peak at 180 Hz from the OMC and PZT driver.  We already have plans to address this with the same solution that LLO implemented several months ago (LLO alog 41374 and comments).

• First lock:
  • made it up to nominal low noise but lost lock due to what appears to be CSOFT pitch (please see first attached figure).
  • right before the lockloss it looks like the ETMX L2 stage was periodically saturating every 5 seconds or so
• Second lock:
  • Decided to settle at LOWNOISE_ESD_ETMX to see if this might be because of our DARM actuator changes made yesterday
  • Lost lock at LOWNOISE_ESD_ETMX. ETMX L2 stage was saturating again before the lockloss.
• Third lock:
  • Commented out the final bit of code in LOWNOISE_ESD_ETMX that transitions the L2 stage actuator from ETMY to ETMX (alog 46969 and 46973). So the DARM actuator will be ETMX L1, ETMY L2, ETMX L3.
  • Stable at LOWNOISE_ESD_ETMX for about 6 minutes.
  • Transitioned to LOWNOISE_LENGTH_CONTROL. ETMX L2 started to saturate from CSOFT pitch ringing up so I reduced the CSOFT pitch gain from 30 to 20. (maybe the increase in gain from 15 to 30 at LOWNOISE_ASC might be too aggressive?)
  • Changed DARM actuator to ETMX L1, ETMX L2, ETMX L3 by hand.
  • After, I was able to make it to nominal low noise just fine.
  • Restored actuator changes in guardian.
  • Low frequency noise (10-50 Hz) doesn't look as good as yesterday (please see second attached figure).
    • Thought this might be increased ASC noise from me reducing the CSOFT pitch gain but after looking at the CSOFT filter at NLN it looks like it's the opposite (please see third figure) so I'm leaving the CSOFT pitch gain at 20.

The following is a short summary of an approach to commissioning the H1 ITMY CO2 mask, D1900030. The purpose of the mask is to reduce the scattering of sidebands into higher order spatial modes. However, when the mask is simply applied by itself, it creates a strong positive quadratic lens. A combination of the ITMY RH, ITMX CO2 central heating and ITMX RH must be used to minimize the overall effect of the COMMON & DIFFERENTIAL MICH lenses and the COMMON and DIFFERENTIAL ITM curvatures.

First Step: Mask application to reduce HOM and maintain current quadratic lens in ITMY 

The application of the mask is illustrated in the attached PDFs. An example of the application is shown here:

• Upper left: The single-pass (SP) optical path distortion from self-heating (point absorbers) scaled to 30W of input power and assuming PRG of 40. The Gaussian weighted RMS OPD of this distortion is 25nm (where the Gaussian beam radius = 54mm). Contour spacing is 5nm.
• Upper middle: "OPD Now": The SP OPD plus 0.75W of RH power. RMS OPD = 22nm. This is what we currently have on ITMY - hence the name "OPD Now". The scatter from this OPD to LG10 is calculated (i.e. the effective lens of this OPD) as that's a number that we're going to come back to.
• Upper right: The steady-state SP OPD from the CO2 mask when a total of 450mW is applied to the ITM. The RMS distortion from this is 25nm. Note that this is the power applied to the test mass (not the power transmitted through the mask. i.e. be sure to account for the efficiency of transmission from the mask to the ITM).
• Lower left: The "OPD Now" distortion plus the CO2 mask OPD. This removes a lot of the intermediate HOM but leaves some of the very high spatial frequencies. As can be seen, there is a strong positive lens in the OPD now. 
• Lower middle: The amount of additional RH OPD required to be added to the previous plot so that the scatter into LG10 (or the effective lens of the new OPD) is the same as what we currently have in "OPD Now".
• Lower right: the sum of "OPD Now", the CO2 mask OPD and the additional RH power. This has the same effective lens as "OPD Now" but has a much lower overall RMS wavefront error of approximately 8nm.

Note that (a) the color scales have been set to the same level [-70, 70]nm for comparison between different plots [so there is some saturation in some of the plots], (b) contours are set to 5nm spacing in all plots, (c) DC levels have been subtracted from each image so that the Gaussian weighted mean value is 0nm.

Once this step has been applied, the ITMY substrate lens should be same as it currently is. This will maintain the COMMON and DIFFERENTIAL MICH lenses. However, the application of ITMY RH will change the ITMY ROC and, hence, the COMMON and DIFF ITM ROC will need to be corrected. Which will be dealt with in step 2.

The attached PDFs show the effect for differing CO2 powers ranging from 50mW to 750mW. The minimum RMS OPD is achieved around 450mW. 

Craig, Danny, Georgia

• Locked with DARM control split between ETMX (L3 and L1) and ETMY (L2), and then manually transitioned L2 darm control to EX once at NLN using Sheila's instructions, this worked. I added a new final step in LOWNOISE_ESD_ETMX guardian which does the L2 transition from ETMY to ETMX. With DARM control on EY and EX we have had few glitches or whistles for most of the day. Towards the end of the evening glitches became more frequent.
• Danny changed the PRCL gain in INCREASE_POWER from 16 to 12, based on Sheila's observations yesterday.
• Dither line move
  • I moved the remaining dither lines back to the 20 Hz band, and saw an improvement in the DARM noise and in the coherence with the DHARD P and Y. Compare blue and red traces in first attachment. The coherence with DSOFT was not improved.
  • In the next lock after moving the dither lines, we saw that the extra 10-80 Hz noise in DARM had returned, even with the dithers at their new frequencies. It turned out the dither loops had not yet converged, and as they did the noise went away. We might benefit from tuning the A2L gains to find an even better spot position?
• Danny and Craig tuned the MICH feedforward, nominal low noise is now back to nominal.
• We had an unexpected fast lockloss from NLN at 02:59:11 UTC. There was a glitch in ETMX L3 ~0.7 seconds before the lockloss, and then some extra noise in the DARM input and all the actuators. Unclear what the cause was. Second attachment shows ndscope of the lockloss, actuator signals on the bottom row.
• We were planning on adding an offset to the OMC PZT3 (PZT1) and seeing if this reduced the RF9 RIN coupling to DARM. Currently we lock the OMC with 46 V on PZT2, and 10V on PZT1, if we want to explore voltage combinations which reduce the overlap between the carrier and the 9th order 9MHz sideband (eg 50V on PZT1 and 50V on PZT2, shown in the 3rd plot of alog 46667) we need to lock the OMC on the next FSR with the PZT voltage (~90V). I also noted that in order to see broadband coherence between the OMC QPD and DARM we need to go to higher-than-nominal modulation depth, which we already knew based on the coherence in the bottom right plot of attachment 1 of alog 46831.

Danny, Georgia, Craig

Danny retuned the MICH FF.  The coupling from MICH to DARM around 70 Hz was significantly reduced (Attachment one).
The filter comparison between Jan 11 and today is seen in attachment two.
The new filter is implemented as Feb16b in FM4 of MICHFF.  The AC (FM2) filter is no longer turned on with it as it is not needed.  This is implemented in LOWNOISE_LENGTH_CONTROL.

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

I also changed the DARM frontend calibration to reflect Georgia's DARM actuator flip (she put all DARM actuation onto ETMX, see an upcoming alog).  According to the PCAL lines we are good to 7%.
Our noise seems to back to November 2018 reference FOM levels after the MICH FF retuning and the dither alignment changes done by Georgia today, which improved the DHARD coupling to DARM.  
The November FOM says 92 Mpc, but our current calculations say 80 Mpc.

- Our high frequency noise is much improved with the increased ISS secondloop gain (+12 dB on the SECONDLOOP_GAIN slider)
- 180 Hz peak is still broad.  We are occasionally seeing what seem like harmonics of this peak in DARM, 
- ESD glitches are less frequent (1 every ~30 minutes)
- Scattering is gone when using the ETMX actuator.
- SOFT limits between 10 and 20 Hz, HARD still coherent beyond 20 Hz but is much improved.  

A plot of inspiral range hour-trends supports the impression that the rate of major glitches is, at present, greater than in O1 or O2 at LHO and possibly LLO as well. The minimum range per hour in Figure 1 (blue) appears lower now than in O1 and O2 (and the associated commissioning time) because fewer hours are free of major range drops. The plot on the second page of Figure 1 compares single recent days around the supernova alert, when the interferometers were mostly left free of commissioning glitches, to random days in O2, and these plots also suggest a higher big glitch rate at both sites. Hopefully, the high glitch rate will go away once the interferometers are in run mode, but I think we should start worrying, just in case.

One possibility is that the apparent increase in glitch rate is due to a new piece of equipment such as electronic or computer equipment, that was installed at each site during the O1-O2 break. Sheila pointed out that the possibilities might be narrowed down at LLO since the installation was staggered. I looked for a step increase, and, while it is not completely clear,  the best candidate appeared to be the March – September 2018 down-time (Figure 2). Suggestions of equipment to investigate would be appreciated.

I, and as far as I know, others, have not found channels that predict the majority of the major glitches. So, Kara and I set up magnetometer channels to monitor new equipment that might be too far from the permanent magnetometers for glitch source identification.

Robert, Kara

Sheila, Keita, Jenne, Daniel, Georgia, Craig

Today we have been having issues powering up due to large glitches in the CARM loop when lowering the IMC fast gain.  This has not been an issue in the recent past, and no changes have been applied to the CARM or IMC loops since the 6 dB gain redistribution back in January.  

We measured the IMC OLG in it's former nominal configuration (OLGs in attachment 1, nominal configs pictured below in attachments 2 and 3).

There was a feature at 150 kHz causing a second UGF in the IMC OLG in it's nominal configuration.
When we increased the FSS Common Gain, the feature was suppressed. (Attachment 1)
Changing the FSS Fast Gain did not change the 150 kHz feature.  (Attachment 4)

We increased the FSS common gain from 20 dB to 28 dB, and the FSS fast gain from 9 dB to 15 dB.  This suppressed the glitches associated with the IMC fast gain slider changes during INCREASE_POWER, and we were able to power up to 30 W.  
We suspect that the FSS common gain somehow fell significantly over the past week, causing some small feature in the FSS loop to approach a gain of 1, causing excessive oscillations in the IMC around 150 kHz, eventually leading to locklosses due to powerup gain slider glitches.

More investigation into the FSS is required to understand if the FSS gain really fell, and why.

Relevant alogs:
Peter King's last FSS OLG measurement (400 kHz UGF)
August 2018 test of the FSS common gain setting
August 2018 test of the FSS fast gain setting
Recent 2W IMC and CARM OLGs (with old FSS settings)

Relevant spectra:
Latest FSS Mixer Error Spectrum (alog 46631)
Latest CARM and IMC Error Spectra (alog 46635)

I looked at signals from the suspension noise monitors in the H1 PUM coil drivers, to see if they typically saturate during lock (result: yes they do), and to see if Duo Tao's monitor board redesign would substantially improve the situation (result: yes it would).

Attachment 1: signals from the existing noisemons, recorded during a Jan 18 lock.  Not all, but about half of them are exhibiting saturation (which sets in at ~25000 ct).

Attachment 2: projected output of the new board with the same drive signals.  The projection was made using the recorded MASTER_OUT data, filtered with the known transfer function through the new board (with the coil driver in state 1), as well as the coil driver's "LP" filter (necessary because the drivers actually run in state 3, which is the most aggressive dewhitening).

Attachment 3: since the noisemons on ETMY and ITMY were not continuously saturating, I ran a quick check of their coherence with the drives.  It revealed excess noise in the ETMY L2 LL channel.  This is unlikely to be a problem for the H1 DARM sensitivity, due to the state 3 dewhitening. But it lets us improve the estimated fault rate to 2 out of 12 (counting also the L1 ETMY PUM channels previously measured).

TITLE: 02/15 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC

STATE of H1: Commissioning

INCOMING OPERATOR: None

SHIFT SUMMARY:

16:00 (8:00) Start of shift

18:54 (10:54) Nutsinee to ISCT6

18:57 (10:57) Nutsinee out of LVEA

21:22 (13:22) Danny, Sheila to PSL enclosure -- investigate excitations on CM board

21:42 (13:42) Danny, Sheila back from PSL enclosure

21:52 (13:52) Gerardo to MY -- look at ion pump for shipping

22:36 (14:36) Gerardo back from MY

00:00 (16:00) End of shift

TITLE: 02/14 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC

STATE of H1: Commissioning

INCOMING OPERATOR: None

SHIFT SUMMARY:

13:00 (5:00) Peter to PSL enclosure -- refcav tweak

14:06 (6:06) Peter out of PSL enclosure

16:00 (8:00) Start of shift

16:08 (8:08) Richard to MY -- pick up shovel

16:30 (8:30) Peter to PSL enclosure -- turn off make-up air fan

16:40 (8:40) Peter back from PSL enclosure

17:50 (9:50) Corey to refill TCS chillers

18:05 (10:05) Corey back from TCS chillers

18:13 (10:13) Robert to LVEA -- pick up coil

18:21 (10:21) Robert to EX

18:22 (10:22) Nutsinee to ISCT6

18:31 (10:31) Chandra to MY -- VAC work

18:39 (10:39) Nutsinee out of LVEA

19:34 (11:34) Chandra back from MY

20:55 (12:55) Robert back from EX

22:00 (14:00) Leaving early due to weather conditions

Currently displayed chiller operating hours:

diode chiller: 8512 hours
crystal chiller : 8486 hours

The counter was reset to 41 hours for both chillers to coincide with when the laser was brought back online.

Jenne, Sheila, Keita, Jamie, Danny

Before leaving early because of the weather, we did a little bit of interferometer locking.  

• In the early part of the day there was some difficulty with ALS and locking which might have been related to the wind.  The winds stayed steady through the day but we were able to get through the locking sequence several times anyway.
• We had one lockloss while engaging the dither loops, so we reverted some changes:  In the PIT3 loop there was a factor of 10 more gain than last week due to an increase in the DEMOD_SIG gain, which we have taken out.  We also moved the dither frequency for PIT5 back to 6.9 Hz, and changed the gains, amplitudes and bandpass to the way it was last week.  We did this by hand and were able to get through it OK, changes have been made and loaded in the guardian but not tested. 
• We looked in more detail at the locklosses and glitches that we had while powering up last night.  The power into the IMC had a steady increase, the glitches only appeared in the mode cleaner transmission.  The glitches are approximately co-incident with the steps in IMC fast gain.  We can see large glitches which seem to saturate the readback of IMC-I (monitor after the sum of the IMC and refl signals on the IMC servo), and we can see that the output of the common mode servo is getting large each time the servo gain changes.  The attached plot is my attempt to show this, made from home.  As far as we know there haven't been any changes to the common mode servo or settings changes, although we can do a more thorough check. 
• The FSS transmission diode was reading around 2.1 V last night, and after Peter King adjusted the refcav alignment today we have about 3 V, which should is the same as when Peter measured the FSS loop in January.  Even a 6dB change in the optical gain should be OK with this transfer function, so we don't think that the change in FSS alignment explains our difficulties. 

We had one chance to try powering up today before getting off site, we actually did survive the power up but the large glitches were visible.  (Attached plot).  That lock was lost in the step LOWNOISE_LSC which is engaging the LSC feedforward, although it looks like the large pitch drive which saturated ETMX L2 starts earlier, when we are switching DARM control back to ETMX with the ESD in low noise.  1234219824

Using the optical path distortion measured by the HWS (provided by Aidan, see also 46127 and 46888) I simulated the mode content at various ports in a dual recycled Fabry-Perot Michelson interferometer. The simulation is done with MIST, using Hermite Gauss modes up to order 10, and locking the interferometer using simulated error signals. 

Only the optical path distortion in the ITM is included, there is no deformation of the HR surface.

Each of the attached plots show the distribution of power into each modes, assuming 26 W of input power, 60ppm or round trip losses per arm. The orange traces are there for comparison, to show that in a ideal IFO, all power is in the fundamental TEM00 mode.

Interestingly, the point absorber seems to create some 9MHz sideband power in modes of order 9 at the AS port, which we believe are the culprit for the high RF9 modulation noise coupling.

[Rana, Jamie]

We spent the evening trying to get more measurements of the 9MHz RIN situation, basically redoing what was done in LHO log 46586.  We went to ITMY single-bounce and locked OMC on carrier, then went to PRMI and locked OMC on 9MHz.  I'll post plots tomorrow.

FYI the OMC and PRMI configurations might be a little bit funky.  We didn't get to reset everything yet to get back to low noise, just in case any one tries to brave the snow to get back out here.