The updated mode-matching solution to account for the noise eater alog(44783) assumed a waist at the coupler of 750um (because that was in the thorlabs documnentation recommended). However a measurement indicates a waist of 500um out of the coupler.

I adjusted the solution SHGtoFiberAM.pdf alog(44783) to move the  ROC75 lens 6cm closer to the SHG the ROC200 lens 1-2 cm further away from the SHG and the fiber coupler 10 cm further away from the SHG to get a waist of 550um.

To get a waist of 500um would take a relatively major path rearrangement and with the vent only hours away it was a little risky to do it now, I will fine tune after the vent and hopefully the proper solution will be significantly above 85%. 

Turned ON air compressors in chiller yard for instrument air, QDP80 is ON, and purge air skid is ON.

Hard closed GV 1,2 this morning and then vented HAM6 (~45 min. vent). Dew point measured -45degC just before valving in purge air.

I've put in a temporary bypass for HAM6. We'll bypass others as the vent progresses.

Bypass will expire:

Tue Nov 13 08:36:07 PST 2018

For channel(s):

    H0:VAC-LX_Y0_PT110_MOD1_PRESS_TORR

TITLE: 11/12 Day Shift: 16:00-00:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    Wind: 8mph Gusts, 6mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.30 μm/s
QUICK SUMMARY:

15:00 Peter out to PSL

15:17 Chris S out to LVEA to fix scaffold

15:18 Cheryl out to PSL

15:40 Cleaning crew out to LVEA

16:16 Chris S out

In prep for this weeks vented volumes followed M1300464 and shut down High Voltage and other system of concer.

EY

Ring Heater switched off

+-430V  ESD supplies shut off

Pico Motors disabled.

Corner station

Ring Heaters for ITMs and SR3 where shut off.  ITMX was already off.

Fast shutter controller HV disabled chassis powered down Power supply off

PZT unit powered down PZT power supply off.

ESD Power supply off

All pico motors confirmed to be or placed in disabled.

OPO TEC servo turned to the off position.

The LVEA has transitioned to LASER SAFE.

    This is under work permit #7934, and facilitates the venting of the corner station.

n.b.
  

    
 The PSL and ALS light pipes are locked and tagged out.
    
 Both TCS CO2 lasers are on.  No work is to take place on either TCS or HWS tables unless barriers are set up.
    
 The squeezer laser is off.  The power supply key is inside the table enclosure and the laser shutter is closed.
  

    Verification that no PSL light is entering the vacuum system is attached in Transition.png

On site now.  Will head out to lock HAM 6 HEPI and disable the ISI to disconnect cables from feedthrus.  Will comment here when complete.

Georgia mentioned yesterday that the fast shutter lockloss guardian was failing it's check.  We saw this again today, after we powered up and then reduced the power with the interferometer still locked. 

The problem here was that the shutter lockloss check guardian watches the transmitted arm powers, and if they go above a threshold it watches for the shutter to fire when we loose lock.  We went below this threshold when we reduced the power again to do OMC scans, which caused the LOCKLOSS_SHUTTER_CHECK guardian to go into the failed state, which it stays in until a human intervenes by taking it to init. 

The shutter has passed it's test a few times today.  

We observed some improvement with larger PD current yesterday. It was not clear to us why. There is some chance that a calibration issue is fooling us, but at the low frequencies we were looking at the calibration should only depend on the actuator.

Either way, to get to the bottom of this, we revisited the whitening of those PDs.

Currently, we are using 10mAmp per diode in regular operation. If the violins are smaller (as the were yesterday) we can increase the DARM offset to operate at about 15mAmp per diode, but that becomes a problem when the violin modes are high.

Attached is a plot of the whitening situation of out OMC DCPDs in full lock, with about 14mAmp per photo diode.

ndsope inset top: ADC signed of the photo diode
ndsope inset bottom: photo current on the photo diode
dtt red: PD signal in cts ADC (which is loop gain suppressed, hence the dip at 30Hz amd the peak at 100Hz)
dtt blue: dark noise
dtt green: possible option with current whitening filters: additionally engage a 2nd whitening stage plus the low-pass. Reduce the DARM offset by 3.2dB to get the violin mode peaks back down where they were.

It would be worth testing the green configuration, just to exclude that we have some load-dependent dark noise after the whitening stages.

Had same issue initially (as on Tuesday) trying to start the Kobelco this morning - namely, "RTD Error" and all displayed temperatures showing "-115F".  Cycled power, wiggled RTD wires and eventually it reset but it isn't clear what fixed the issue.  Also, the right drying tower failed to switch initially but began working after manually forcing it to switch. 

I did not turn on the HAM6 cleanroom as it is thought that Hugh R., had volunteered to do this when he came later today and, at least a few, commissioners could use more "low noise" time this morning. 

A BruCo scan of 500 seconds with a sensitivty around 93 Mpc (45197) can be found at the link below

https://ldas-jobs.ligo.caltech.edu/~gabriele.vajente/bruco_1225937545/

• below 15 Hz the sensitivity is completely limited by ASC (CHARD and CSOFT pitch) (fig. 1 and 2)
• between 15 Hz and 25 Hz there is significant coherence with REFL_A_RIN and with INP1_Y and PRC2_Y (fig. 3, 4 and 5). Slightly lower coherence with INP1_P.
• this coherence between 15 and 25 Hz  is also seen in some IMC signals, for example IM4_TRANS_YAW_OUT and the second loop QPD, so this is likely to be input beam jitter
• between 20 and 40 Hz DHARD_Y shows coherence, although not very high (fig. 6)
• At 500-600 Hz there is coherence with PSL table accelerometers (fig. 7)

Georgia, Craig, Peter, Stefan

Tonight we worked on increasing the input power to 28W.

- Along the way we found MICH marginally stable at 5-ish Hz - we increased the final MICH gain from 1.7 to 2.5.

- Initially we increased the power by AC-coupling the ISS 2nd loop in low-noise, and manually stepping the power up using the POWER guardian.
  That method actually increased the light level on the DCPDs (as the DARM offset is not reduced to compensate).
  Interestingly, that seemed to slightly improve the the low-frequency noise too - we don't really understand why. We believe thee effect is there if we only use the DARM offset.

- We tried going to 30W input, but started seeing increasing recycling gain fluctuations, followed by what seems to be a lock-loss due to CARM.
  So we left Guardian at 28W. We directly go there in the regular power-up step.

- Initially, at 25W, we tried to increase Hang's radiation pressure compensation by stepping up the RPC gains by a factor of 1.5, as designed for 25W. (see Hang's alog 44709).
  That actually led to an instability. We were successfully able to increase it by a factor of 1.2 using 
    z step H1:ASC-RPC_DHARD_P_GAIN *1.2 H1:ASC-RPC_DHARD_Y_GAIN *1.2 H1:ASC-RPC_CHARD_P_GAIN *1.2 H1:ASC-RPC_CHARD_Y_GAIN *1.2
  However, in the end we did not need to do that to go to 30W, so that is not in the Guardian.

- We ran an A2L at 28Watt.

- At 28Watt input we noticed a significant decrease in the CARM gain - an we had to compensate by adding 11dB of gain in the CM board. After roughly 30min we lost lock due to ASC: CHARD_Y, PRC2_Y and SRC1_Y started running away.



Attached is a DARM spectrum of the best we saw today - H1:CDS-SENSMON_CAL_SNSW_EFFECTIVE_RANGE_MPC called it at 93Mpc.

From Nov 10 2018 09:13:41 UTC to 09:19:27 UTC, the interferometer heroically rode out a fairly large earthquake for as long as it could.  The ASC performed beautifully for about six minutes, handling the seismic waves as if they were the GW stochastic background.

While this free seismic noise injection was happening, we saw the same exact scatter shelf in DARM that we saw earlier when we were injecting frequency noise around the OMC dither line.
Green in the attached plot is DARM during the frequency noise injection, the linear coupling visible from 3.5 to 4.5 kHz, the nonlinear seen at DC.  Red is DARM during the earthquake.  Grey is our reference.
It could simply be elevated ASC controls noise, but it was eerily close to the same OMC noise we had just seen.  Could OMC ASC be responsible?

We have also been having timing system errors H1:SYS-TIMING_Y_PPS_A_ERROR_FLAG audible updates every two minutes.  

Fil Marc Daniel

We modified the spare CM board (s/n S1102622) according to E1800338 and swapped it with the existing one (s/n S1102621). This modification includes low pass filters for the DAQ readbacks, and a frequency change in the first two boost stages to 10Hz/500Hz.

The figure shows spectra from the 4 angular IMC WFS DC channels with labeled peaks. Eight of the peaks between 80 and 1000 Hz are from optics or structures on the PSL table, two were from IOT2 and four haven’t been identified. The unidentified peaks were not excited by our PSL injections, even the global ones. It is possible that they are associated with structures that weren’t excited on IOT2 or in HAM2, or they may be associated with structures on the PSL table that we weren’t able to excite.

The identified sources are table resonances, periscope resonances and optic mount resonances. All optics that produced peaks in the spectrum were downstream of the PMC and were mirrors rather than through-optics like lenses, as would be expected.

The figure also shows the location of the sources in the PSL, as well as samples of the bowing and tapping data used to make the identifications.

Robert, Craig