[Jenne, Hang, Gabriele]

We noticed that when we switch the DRMI length loops from 3F to POP_1F, the recycling gain gets lower and less stable, like we had a longitudinal offset. Indeed before we switch the POP_RF9 and POP_RF45 signals have large offsets, in the 100-1000 counts range.

We tried to switch back to 3F after all ASC loops were on and the alignment was good, and we saw a similar behavior.

We checked the dark offsets and they are small. We also checked POP_9 phase and tuned it from -22 to -19.5.

For the moment being we don't feel like leaving those large offsets. More investigations needed.

I thought that we had fixed this, but AS_B_RF45 seems to have a difference between the request and readback of the whitening filters or gain. We're not currently using AS_B for anything, so not urgent, and can likely wait until next week. 

TITLE: 09/12 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
INCOMING OPERATOR: None
SHIFT SUMMARY:
LOG:

Gabriele and Jenne working on locking

15:00 PSL meeting via TeamSpeak

15:46 Nutsinee driving down Y-Arm to have a look at the burned area of the desert

16:11 Nutsinee back and going out to ISCT6

16:16 Guest for Chandra on site

16:38 Mark, Tyler, and Chris to MY to install grease lines for fans and to seal up areas where bats may be getting in

17:00 Safety Commission tour into LVEA for tour.

17:24 Vanessa to MX

17:45 Chandra and guest to mid-stations

18:00 Kyle out to LVEA to recover light equipment. He'll be entering through man door at Lg equipment entry

18:40 Tour out of LVEA

18:51 Karen back to corner

19:04 Mark, Tyler , and Chris back for lunch and are setup at MX for same work.

19:40 Karen to EY

20:00 Mark, Tyler, and Chris to EY

20:32 Karen leaving EY

20:32 Tour group leaving EY

20:41 TVo out to LVEA to turn on CO2X LASER

22:00 Site meeting

After Gerardo regenerated three corner station NEGs yesterday, the isolated pressures in their housings continues to drop. The drastic slope change you see in attached is a gauge thing - these full range hot cathode ion gauges change emission current at 5.6e-6 Torr and can be deceiving when running an experiment like this.

After today's commissioning meeting I was asked to look into the FSS oscillation threshold setting and why the FSS guardian was not detecting when the FSS was oscillating (thus necessitating by-hand adjustment of the FSS common gain every time the IMC loses lock and throws the FSS into oscillation).  Looking at the FSS model (1st attachment, middle of the picture), H1:PSL-FSS_OSCILLATION is set when H1:PSL-FSS_MIXER_PP is greater than H1:PSL-FSS_OSCILLATION_THRES.

Knowing this, I trended back a couple hours, looking for times when H1:PSL-FSS_FAST_MON_OUTPUT was oscillating, and compared them with the value in H1:PSL-FSS_MIXER_PP; see 2nd attachment.  This makes it clear why an oscillation threshold of 3 was not working to set H1:PSL-FSS-OSCILLATION; the mixer peak-to-peak voltage never exceeded 2.5V during times of oscillation, therefore the threshold was never crossed.  From talking with Jenne, apparently a value of 0.6 doesn't always catch an oscillation, so for now I recommend a value of 0.5 for H1:PSL-FSS_OSCILLATION_THRES.  This change has been made and accepted in SDF.

[Jenne, Hang, Gabriele]

This morning, when we were locked at 2W, we saw that a line at 28.45 Hz was ringing up, and visible mostly in MICH / PRCL and SRCL, and a bit less in DARM. After checking all loops for possible instabilities, we decided it was a mode of some suspension. We added band-stop filters at 28.4 Hz in all angular degrees of freedom of all suspensions, and this solved the problem, letting the mode ring down. We haven't identified which suspension is responsible.

The mode (actually it looks like a doublet) was also visible in the two ITMs optical levers, but at that time we saw the same excitation in the hard angular loops.

model restarts logged for Tue 11/Sep/2018
2018_09_11 10:22 h1iopiscey
2018_09_11 10:24 h1pemey
2018_09_11 10:26 h1iscey
2018_09_11 10:28 h1caley
2018_09_11 10:30 h1alsey
2018_09_11 10:58 h1iopiscey
2018_09_11 10:58 h1pemey
2018_09_11 10:59 h1iopiscey
2018_09_11 10:59 h1pemey
2018_09_11 11:00 h1alsey
2018_09_11 11:00 h1caley
2018_09_11 11:00 h1iscey

Restart to recover h1iscey from a timing glitch. First unsuccessful restart was done remotely, second at EY itself.

model restarts logged for Wed 05/Sep/2018 - Mon 10/Sep/2018 No restarts reported

J. Kissel

Noticed the calibration line spectrum on the main sensitivity wall FOM (nuc3) showed no calibration lines. Opened PCAL Y overview screen and found the OFS railed at ~7.5V (as quickly seen by the trend on the MEDM overview screen; see attached). Trended the OFS PD channel (H1:CAL-PCALY_OFS_PD_OUT16), and found that it railed at Sep 11 2018 @ ~18:00 UTC or at ~11a PDT. This is likely a result of the timing glitch at EY (referenced in LHO aLOGs 43932, 43928).

In order to fix, I merely needed to toggle the Loop Enable Switch, H1:CAL-PCALY_OPTICALFOLLOWERSERVOENABLE.

Also -- we (Travis and I) didn't store the new amplitude settings for the calibration lines in the SDF system. Upon restart I found calibration line heights at their O2 values. 
I've also re-changed the line heights to their temporarily higher values while we measure the optical gain with our current, not-yet-amazing, sensitivity.

For the record,
             Former   New    Change
36.7   OSC1  500      1000   x2
331.9  OSC2  5000     20000  x4
1083.7 OSC3  15000    5000   /3
7.93   OSC4  5000     5000   no change

See 2nd and 3rd attached files confirming the change and the capture into SDF.

All BSC spectra looks to be nominal except for a slightly elevated offset in the BS_ST1_CPSINF_H1_I channel. All HAM spectra appears to be nominally sound.

It was not necessary to add water at this time.

TITLE: 09/12 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    Wind: 5mph Gusts, 3mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.10 μm/s
QUICK SUMMARY: Safety committee meeting today

Hang Sheila Georgia

• Tuesday maintenance recovery - with the EY power glitch at roughly 1800 UTC, the ALS EY camera references and QPD offsets got reset to outdated values. Sheila updated many many ALS and ISC SDF differences to help prevent this kind of thing happening again.
• X arm initial alignment - with the ETMX L1 lock gain fix, WFS DOF3 now takes a long time to converge and can do with some extra gain. We have not fixed this problem in guardian yet, this is just a note to tomorrow morning's initial alignment team.
• Violin mode guardian - last night Sheila and Hang left the IFO locked with the violin mode damping guardian running. 27 modes were successfully damped, and 5 undamped modes have been identified. Attachment 1 shows DARM spectra at the beginning and end of the lock. Another close doublet has been identified at 504.885/504.891 Hz (bottom plot attachment 1). We're working on putting gain adjustment in the guardian, so that the gain is increased when the monitor filter is low, and decreased when the monitor filter is high.
• Hard loops improvement - we took quick transfer functions of the DHARD pit and yaw loops, they seem to match O1 levels now. We increased the gain of the CHARD loops massively. CHARD yaw gain was increased from 0.3 to 2, giving a UGF of ~6-7 Hz; CHARD pit gain was increased from 0.3 to 60 (!!), giving a UGF of ~7Hz. These changes have been included in the guardian (REFL_POP_WFS state), with the +30 dB filter module now being engaged for CHARD_Y.
• Soft loops - we left the soft loops unchanged, including the low bandwidth CSOFT_P.
• Power up! - We first powered up to 9W. The increased hard loop gains increased the low frequency DARM noise, so we ran the A2L script to reduce angular coupling to length. We then gradually powered up to 17 W, we started to see reductions in recycling gain and on POPAIR18 at 10 W, as we're not using TCS yet. The OMC suspension saturated when we tried 20 W and we brought it back to 17 W but lost lock anyway.
• We lost lock at 08:12:50 UTC, and left the IFO in the down state so that the HWSs can record cool-down data.

[Nutsinee, Haocun]

After putting ND filters before the OPO REFL due to the saturation issue, the OPO can be locked without problems, and the I and Q phases look good. (Nutsinee can give more details on this.)

Later on we took more squeezing measurements under this good locking condition, and I plot the data with some fitting curves as attached.

Homodyne Visibility: 97% and 96.87% (We had to do this, and before any adjusting it was ~86.7% with ~2mW unbalancing.)

So the estimated optical efficiency is 65% and 50mrad phase noise.

According to our budget here, our optical efficiency should be around 85%, which means we need to find out where are these ~20% loss from.

Next step:

- Swap PD or tweak electronics to have proper set-up for the saturation problem, instead of using ND filters.

- We'd better to adjust the crystal position again with OPO locking properly.

- Measure the optical loss on SQZT6, and dig out other potential losses.

[Sheila, Hang, Gabriele]

In brief, the L1 LOCK gain in ITMX was 10 instead of 1 (as it used to be during O2). Therefore the reallocation of pitch and yaw to M0 was ten times stronger, and it modified the suspension angular response as seen by the ASC at the lower stages. This created a crossover at about 1 Hz that produced the right-half-plane zero we measured in CHARD and DHARD. This wrong gain was there only in ITMX. We reverted it to 1 as it was during O2. The gain was changed from 1 to 10 on Saturday June 2nd 2018 at about 21:55 UTC. Nothing relevant written anywhere in the elog.

The plot below shows the yaw to yaw response of ITMX, measured with the optical lever, in a few different configurations.

• Blue: M0 reallocation on, as it has been for the past 3 months (ten times stronger than it should be). This transfer function deviates from the expectation (and from other suspensions) below a few Hz. You can also note the large phase rotation at about 1.8 Hz, which corresponds to the non-minimum-phase zero
• Green: M0 reallocation off, this is the expected response of the suspension, and there is no weird phase rotation
• Red: M0 reallocation, turning the L1 lock gain back to 1 from 10. Note that we are not using L1, but this is a pass-through gain
• Brown: M0 reallocation plus a 0.6 Hz Chebyshev low pass filter, that Hang designed to reduce the impact of the reallocation. The design is based on the suspension model, which seems to match reasonably well the measurement (at least qualitatively)

The expectation is that this will fix the DHARD/CHARD plants (43844)

We implemented the low pass filters in all test mass M0 stages, since it gives us some more phase and gain margin at about 1.8 Hz, where there is still a zero.

The story of how we found this problem is long and convoluted. A brief summary below:

• we noticed that there was a large coupling of yaw actuation to pitch motion for the two ITMs, much larger than the ETMs
• we wanted to measure and fit it, so we repeated optical lever measurements of all angular transfer functions of all four test masses
• we noticed that the ITMX pitch to pitch was clearly different from the others, and we traced the difference w.r.t. ITMY to the fact that M0 was on for ITMX and off for ITMY
• we then took a ITMX measurement with M0 reallocation off, and found that ITMX was now behaving
• Hang added the low pass filter in the M0 path, and we found that the yaw transfer function was much better
• We finally found the wrong gain looking at the conlog

TITLE: 09/11 Day Shift: 15:00-23:00 UTC (08:00-16:00 PDT), all times posted in UTC
STATE of H1: Preventive Maintenance
INCOMING OPERATOR: None
SHIFT SUMMARY:

Maintenance from 8am - 1:30pm PDT this morning.
LOG:

• 13:18-18:15 Test Stand disassembly (Mark, Tyler, Chris)
• 14:50 LVEA transitioned to LASER SAFE (Richard M)
• 15:00 PREVENTATIVE MAINTENANCE & SEI_CONFIG transitioned to SC_NO_BRSXY
• 15:04 Pest control beginning exterior work (until 11am)
• 15:13 VAC crew beginning work
• 15:20 T240 centering & CPS tuneup/investigation(jim)
  • 15:42 Power cycling in CER for CPS (Jim)
• 15:28-16:20 Vanessa cleaning LVEA
• 15:29-17:19 EY pulling cable for ESD Power supply (Fil & Ed)
  • Dave noticed an EY electrical glitch occurred (as seen on CDS Overview)...determined to be tripped from power cord being bumped.
• 15:40-16:50 ETMX charge (corey)--probably did not have ESD ON
• 15:42-18:30 IMC VCO investigation (Marc)
  • box pulled & being inspected/tested in lab
• 16:00 Electrical inspector tour by Ken around site
• 16:13 PSL work (jason)
  • 17:00 Cheryl joining
• 16:20 Cleaning end stations (vanessa & Karen)
• 16:52 Inventory check (Betsy)
• 16:55 Guardian reboot (tj, dave)
• 17:07 Workstation swaps in LVEA (carlos)
• 17:20 EX taking down high voltage for junction box for ESD (fil, ed)
• 17:25 Fixing EY elec glitch (dave)
• 18:20-21:13 EY grease pipe work cont. (mark, tyler)
• 18:20-19:08 ETMY Charge (georgia)
• 18:40 Restoring FSS (cheryl)
• Conditioning of Neg pumps (gerardo)
• 19:05-19:25 ETMx cross coupling measurements (hang)
• 19:15-30 Measuring VCO cable length (marc)
• 19:48 All LVEA gate valves open
• 20:00 VAC out, but still need to power down Turbos & check Neg pump temps (chandra, gerardo)
• 20:08-20:26 ETMx charge again (georgia)
• 20:26 Back to Commissioning!
• 20:40 back to laser HAZARD in LVEA
• 20:41 SQZ6 & ISCT6 work (Nutsinee & Haocun)
• 21:45-22:10 Checking on Well Pump at EY, he's been filling our big tank here at the corner due to it being depleted from weekend's fire (Richard)
• 21:49 Checking on temps for NEG pumps (gerardo)

• Jason measured the beam after the 70W amplifier, for mode matching
• He and I measured power before and after the AOM, and he has the details, I recall there's about a 5W drop in power
• From after the AOM, almost no power drop to the PMC, and Jason has power measurements from after the PMC
• I took a measurement just before the bottom periscope mirror
  • A request of 2W gave 2.4W on the power meter
  • A request of 10W = 11.4W on the power meter
  • A request of 20W = 23.1W on the power meter
  • A request of 30W = 35.0W on the power meter
  • A request of 38.5W = 45.5W on the power meter, this is the rotation stage max power, at 20.02deg
  • real max power was found at the angle 20.5deg, at 45.9W
• All measurements taken with the ISS off
• All measurements take with the water cooled power meter

At 19:10TUC,  I'd restored the ISS and FSS to locking.  At 19:22UTC, unlocked, Mark and Keita are out making measurements.

[Hang, Craig, Gabriele]

Summary

We moved PR3, PRM and the soft degrees of freedom to improve the beam centering on all four test masses and increase the recycling gain.

We started with a recycling gain of about 38.2 and finished with a recycling gain of 47.4 [+24%]

A lock loss terminated our work, so there is still some re-alignment to do to get the test masses centered. And there might be more recycling gain.

We added dithering lines in yaw to all four test masses, and we could improve the centering significantly. At the end all Y2L coefficients are zero, and the dithering signals are quite close to zero. The two ITMs are reasonably centered, as is ETMX. Instead ETMY seems to have a larger mis-centering.

If we need to put back the Y2L coefficients, we probably only need to set ETMY to about 4.

Details

• We moved PR3 as we did in the past days.
• We had to compensate the PR2 alignment offset since the offload was clipped at the limiter
• From time to time we also adjusted the soft degrees of freedom position, by opening the loops, optimizing the power, and adjusting the QPD offsets
• We did the same with the POP QPD. Finally we were hitting a large offset, so we pico'ed the QPD
• We also moved the ALS POP QPD to keep the green beams in ggo shape on the cameras
• We also updated the green references, by moving the green QPD offsets and adjusting the camera set points [not quite to the last position, since we lost lock, but it should be quite close to good...]

We finally lost lock after more than 6h continuous lock.

(In this post I mean "railing" as "parked at the maximum actuation range", where "oscillation" means "PZT is fighting the EOM")

The FSS Fast Path has been railing recently, preventing the FSS from locking.  (Pic 1)

It seems as though FSS_OSCILLATION does not in fact monitor the FSS RMS, but triggers on a threshold.  When the FSS voltage would pass a certain value, the PSL_FSS guardian would send it to state FSS_OSCILLATING.
This state brings the common gain down to -10 dB, then slowly back up to wherever it started.  This works great for stopping oscillations, but not for permanent rails.

I modified the PSL_FSS code to increase the oscillation threshold from 0.6 to 3 V for five seconds whenever the fast voltage is railed at greater than 10 volts with extremely low RMS.  This should allow the FSS loop to close and bring the temperature within range.  Railing hasn't happened again, so I haven't had a chance to test the state, but it does still suppress actual oscillations.

J. Kissel, M. Pirello

Applied the following ECR's to the primary chassis (S1101627) and the spare (S1101603).

The existing Whitening Amplifier (D1002559) needs modification to accommodate the violin modes of the main LIGO optics in the vicinity of 500Hz that have a tendency to saturate the existing whitening chain’s pole-zero filters.  (E1600252-v2)

Implement separate higher bandwidth readbacks for the OMC DCPDs to support PI damping. (E1600192-v2)

Both ECR's implemented to both chassis, the primary chassis testing is complete and the data is attached to this report.