Kiwamu, Daniel

The two Thorlabs PDs that measure the power after the EOM and at the bottom of the PSL periscope were originally intended for low frequency only. However, they can be useful for intensity noise characterization as well, so we used the two spare channels on the PD interface box to acquire AC coupled and amplified versions too. The AC coupling is at 4 Hz and the gain will be 200. The ascimc model has been updated with separate AC, DC and normalized channels. These are then used to form relative intensity noise channels.

Terra, Evan

We continued our examination of  EY body mode Q factors  and made a quick estimate of the resulting coating loss.

This time, we simultaneously rang up one of the butterfly modes and two of the drumhead modes during a 50 W lock and watched them ring down for about 45 minutes. The resulting Q factors are as follows, with the uncertainties determined by the χ² of the fit.

• Butterfly mode (6054 Hz): Q = 25.3(2.6)×10⁶
• First-order drumhead mode (8158 Hz): Q = 21.3(4.5)×10⁶
• Second-order drumhead mode, vertical (9830 Hz): Q = 46.9(5.9)×10⁶

Plots of the ringdowns, along with the fits, are attached. The script to generate the numbers and plots in this alog is also attached.

We have also used the rough FEA numbers given previously for the surface-to-bulk energy ratios to estimate the loss angles of the EY coating and substrate. We assume both losses are structural. The resulting posterior (assuming a log-uniform prior on each loss) is shown in the attached plot. The 1d marginalized loss estimates are as follows:

• Substrate loss: 1.56(39)×10⁻⁸
• Coating loss: 2.8(0.8)×10⁻⁴

Using the formula from Nakagawa et al., this implies a thermal noise of 8.1(8)×10⁻²¹ m/Hz^1/2 at 100 Hz, which is about 14 % higher than direct audio-band measurements on witness samples.

Future work:

• Remeasure these modes at a different interferometer power, to make sure the parametric gain is not affecting the measurement
• Measure the same modes on other test masses
• Use better FEA to extract the energy ratios
• Go beyond the Nakagawa approximation (coating has uniform loss, has material parameters identicaly to the substrate, and has no light penetration)

• The early morning found Cheryl and myself investigating  bad alignment of the IMC which is going to result in a seperate Ops Wiki page on how to deal with it and very possibly a future training session for Operators
• The PSL team took the PSL down to decrease the water flow on the table in an attempt to discover some excess intensity noise
• There was a DAQ restart. In the wake of it, the IMC WFS not triggering properly
• I got my first opportunity to add a user to the new RACESS system
• Locking this afternnoon is a daunting task as many Guardian edits have to be made to get past TR_CARM step. I expect this will be correctted for the evening shift.

17:07 Jim to EY to check on the BRS power supply and to change a setting so that it will come back up after a power outage.

17:11 BRS at EY switched off.

17:15 Jason and Peter ou to the PSL enclosure to begin work reducing flow to possibly mitigate intensity noise.

17:30 Betsy out to LVEA to do TCS inventory

17:31 Travis out to LVEA to retrieve ITM Pcal camera

17:32 Jim back from EY

17:32 Jeff K to begin charge measurements

17:36 Jason called from enclosure - LASER is going DOWN

17:59 Travis back from LVEA

18:33 Travis headed to end stations for Pcal camera work. Switching BRS Guardian to VERY_WINDY as per Jim's wiki page under the SEI tab

18:59 Jason and Peter out of the enclosure. THe LASER is ON.

19:00 DAQ restart

20:28 Start initial alignment

20:45 Switched BRS back on at both ends

21:00 Begin locking sequence

A quick inspection of the PMC output mirror and window was done whilst the PMC was
locked and unlocked.  No obvious bright scattering points or marks, spots .... etc.
were apparent.

    Nothing was spotted on the optics between the PMC and the IO EOM either.




Jason/Peter

The neutral density filter that was installed in front of the ISS photodiode box was removed.
The half waveplate inside the ISS photodiode box was adjusted so that the output voltage of
PDA was ~5 VDC when the ISS was unlocked.



Jason/Peter

LN2 at exhaust after 6 minutes 26 seconds of having the LLCV bypass valve opened 1/2 turn -> restored bypass valve to as found (closed) state.  

Increased manual setting for LLCV from 16% to 17%

Next CP3 overfill to be Wed., Sept 21st.  

As requested, the flow rates through the laser heads was reduced from ~0.7 lpm to 6 lpm.
The minimum flow rate was dictated by the flow rate on head 4, which was lower than the
others from the outset.  Its flow was set so that the flow rate was ~0.5 lpm.  The flow
rate was reduced by adjusting the bypass valve on the cooling manifold.  The flow rate
out of the chiller is already set to its non-zero minimum value.

    The flow rate in the power meter cooling circuit was also reduced by adjusting the
pressure regulator.





Jason/Peter

2nd loop QPD output alignment signals didn't make sense (attached top), and this turns out to be whitening mismatch.

This QPD goes through the QPD interface and standard whitening, and there is one unswitchable zp=0.4,40 analog whitening. This is supposed to be compensated by zp=(40,0.4) anti whitener (which is unfortunately named 0.4:40), which was off.

I turned them ON (attached left) and now it makes sense (bottom).

J. Kissel 

I've measured this week's charge assessment early, just to get it out of Tuesday's way while opportunity struck during ISS improvements this morning. 

All is well: charge continues towards zero, and it looks like in a few weeks -- at the start of ER10 -- we can try regular ESD bias flipping again. 

Impressively, but perhaps inconsequentially, the rate of charge on ETMX has increased substantially over the past few bias flips. However, this may also be a function of how much time we've spent over the past few months commissioning with the DARM drive still on ETMX. The fluctuation of actuation strength of ETMX is not important to calibration, and lock acquisition is not-so-sensitive to it, but this fast rate may confuse our assessment of the charge from week-to-week while it hovers around zero. Perhaps we should consider -- during ER10 at least, if/when we begin regular flipping -- measuring charge twice a week, just to get more that one data point per flip. 

WP6168. Daniel:

A new h1ascimc model was installed. This replaces two SPARE DAQ channels with 3 PWR_EOM channels in the commissioning frame (all at 2kHz). Additional filtermodules were added (no DAQ inclusion).

Model and DAQ were restarted at 11:55 PDT.

Pressure comparison between hot IG and cold cathode gauge on diagonal volume. Tomorrow CC will be decommissioned via WP 6166.

(green trace is hot IG; red is CC that has been flaky and turning off periodically)

J. Kissel reporting for D. Sigg, K. Kawabe, L. Barsotti, M. Evans, K. Izumi, R. Savage, P. King, J. Oberling, J. Driggers, R. McCarthy

The following ideas / action items were discussed at this mornings 9a LHO commissioning meeting to battle / reduce intensity noise; the primary high-frequency noise contribution/ limitation to the DARM sensitivity at the moment. I don't know every detail, so hopefully you can glean the action from the words I was able to capture from the meeting. The list is also in no particular order, but the hope is to accomplish most of these tasks over the next few days.

- Look at recent DBB scans for any evidence of free-running intensity noise badness.
- Reduce PSL HPO chiller flow rate from 0.7 [L/min] to 0.5 [L/min] returning to O1 level flow rate
- Remove ND filter that had been recently installed to rule out scattering noise from the 1st loop PD array
- Inspect PMC output ports for excessing scattering / badness
- Move EOM on its translation stage, checking for changes in intensity noise output.

- Install high-sensitivity electronics on EOM PD (IO_AB_PD3 in D0902114, read out as H1:IMC-PWR_EOM_OUT16) and IMC PWR IN (IO_AB_PD2 in D0902114, readout as H1:IMC-PWR_IN_OUT16)
- Install extra high-sensitivity PD in ALS path on PSL table. (This path is upstream -- toward the front-end laser -- of the EOM. The PD will be used to compare the intensity noise upstream vs. downstream of the EOM  which is currently an area of suspicion. The worry is that there is too much between the pickoff on the PSL and where this pickoff is already captured on ISCT1, which may confuse the intensity noise measurement)

- ISS front-end model reboot in order to improve channel naming conventions for ISS channels (e.g. INNERLOOP / OUTERLOOP to FIRST/SECOND LOOP-like changes)
- PEM front-end model changes to store PSL accelerometers at higher sampling rate
- ASCIMC front-end model changes / or create a new front-end model to process/store EOM PD, IMC PWR IN PD, and IM4 TRANS at higher, (4? 16 kHz?) rate. 

- Modify new ISS 2nd loop analog electronics (drill a few holes in front panels) to pull out more signals to analog BNC spigots

- Move IMC / IFO alignment offsets to find jitter coupling minimum.


Hope this helps!

No restarts over this 3 day period. Test frame writer did some restarts Friday morning, none since we installed RCG3.2-daqd (aka Jonathan's code) Friday afternoon.

• Tuesday maintenance will be a busy one, possibly taking all day. Thursday might be used as maintenance as well. 
• ER10 begins end of next week.
• SEI - Everything looks good. Nothing to report
• SUS - Nothing to report. Charge monitoring, ongoing.
• CDS ELE - Intrusive work to be done regarding end station Beckhoff. Ongoing ISS work.
• PSL - Intensity noise investigation to be don this morning
• VAC - Experimentation on CP4 (Tues). Kyle doing RGA bakeout at EX. PT140 can be turned off.
• FAC - Flushing RO system. Punch list items found during safety review to be addressed.
• GC - No internet Tues between 8:00-9:00AM PDT. Final stage of process.

Here is the current state of the H1 DAQ.

h1fw0 and h1fw1 have been completely stable for several weeks, and following the code fix on Wednesday 9/7 the frames written by both are 100% identical. These systems have the same hardware and are running the same code, but h1fw0 occasionally asks for retransmissions and h1fw0 never does. The OS install is slightly different between the machines, and we will try cloning fw0 from fw1 next week.

h1fw2 is a front end computer, running U12 with a local disk system for frames. It was running the original daqd code, but went unstable after the Sat 9/10 power outage. We upgraded it to the rcg3.2 daqd this afternoon to see if this improves stability. It is now connected to UPS power.

Now that h1fw2 has the new set of EPICS diagnostics channels I have expanded the DAQ overview medm screen to show these.

Sheila, Kiwamu, Evan, Matt, Lisa, Jenne, Corey

Tonight the locking has been stable enough that we were able to try several low noise steps.  We ended up with a range of about 20 Mpc, and were locked for 3.5 hours.

• Earlier this afternoon Matt, Evan, Kiwamu, and reduced the ISS loop gain by 4dB, to reduce the gain peaking visible in Peter King's plots (29725)
• We've used the guardian states LOW_NOISE_ASC (for reducing arm loop bandwidths, which Jenne checked out earlier), COIL DRIVERS (after a few additional bug fixes), LOWNOISE_ESD_ETMY, and ran the A2L script for the test masses.
• Kiwamu noticed that the AS WFS DC have been close to saturation at 50 Watts.  This might have been part of the reason the OMC alignment was railing in some locks.  To help with this he reduced the modulation depth for 45 MHz by 3dB, and moved the REDUCE_MODULATION_DEPTH state to before the power up. The OMC drives are not large right now.
• Kiwamu reduce the DARM gain by a factor of 2 (in guardian at DC readout) because there was gain peaking.
• We reduced CSOFT PIT back to 0.2 for the digital gain, and CSOFT Y from 3 to 2.
• We have not used the third loop tonight.  We accidentally powered up with it off, and that has been fine.  With the 3rd loop off we don't have the low frequency ISS oscillations that caused us to DC couple the ISS last night.
• I also made a few changes in the IMC LOCK guardian. After talking with Keita, we realized that if the 1st loop saturates and turns off, the second loop would not be turned off.  The guardian is now written to handle this, but I don't think this has happened tonight so we haven't tested it. 
• We measured the SRCL and MICH loops (screenshots and data attached). SRCL still has 6dB of gain peaking, the MICH loop would have been unstable with the boost that gets engages in the state NOISE_TUNNINGS, so we increased the gain by 3dB to a digital gain of 2. 
• When need to move SRM ASC loops off the dither before we reduce the gain of SRCL.  We were sucsesfull for PIT, using 4*ASA36I-ASB36I, and a gain of 3 (FM1 off).  We picked this matrix about 3 hours into a lock, after the thermal state had stabilized.  The next lock we tried it shortly after powering up, and it seemed fine.  We haven't added this to the guardian but probably could.  We tried a similar procedure for YAW, but about 2 hours into the second lock we opened the loop because SRM was slowly becoming misalinged. 
• We tried MICH and SRCL FF, MICH worked fine with the old settings, and improved the noise around 100Hz, we are now limited by SRCL at 50 Hz and below.  We tried SRCL FF, but it made things unstable so we need to check on it tomorow.
• Evan updated the calibration. It was off by 20%. 
• For our last lock, the violin mode damping was somehow off the whoel 3 hours.  Rung up violin modes ended up breaking the lock.  If tomorow's operator has a chance to lock at 2Watts and damp violins using the instructions on the wiki, that would be great.

The BRS at EY has had a long term drift requiring periodic recentering. That drift seems to have stopped or changed sign, following the power outage on Saturday. Attached image is a 60 day trend for H1:ISI-GND_BRS_ETMY_DRIFTMON. The black streaks are from when the BRS went out of range and when it was recentered during Krishna's last visit. The little blip up to zero at the end is from the power outage, before the commissioners recovered the BRS code. Second image is the last 6 days, outage is when the signal goes to zero. Definitely looks like the drift has changed sign.

I have updated the correction filter for the dtt DARM spectra that are projected in the wall and screens in the control room. I hope Evan will like it.

This does not affect the CAL-CS or GDS calibrations. This is only for display purpose in diaggui.

[The DARM spectra]

Here is a comparison of the newly corrected and previous DARM spectra.

As shown in the attached screenshot, the high frequency excess wing that has been shown above 3 kHz is now gone. The noise level at around 7 kHz now seems a bit too low compared with the f-shaped GWINC curve (shown in green). This maybe a real calibration error because I have applied the best and latest knowledge about the sensing chain for correcting the spectrum.

The correction filter is made by a matlab script:

/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PreER8/H1/Scripts/ControlRoomCalib/H1DARM_FOM_correction.m

This script creates a text file which contains the correction filter in [freq, dBmag, phasedeg] format from 1 Hz to 7444 Hz. The text file can be found at

/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PreER8/H1/Scripts/ControlRoomCalib/DARM_FOM_calibration.dat

Both script and text files are checked in to the svn. Also I updated the latest FOM dtt template, H1_DARM_FOM_20150722.xml so that it now uses the new correction filter.

[Corrections newly included]

Here is a list of what I newly included.

• Analog anti-aliasing filter
  • See this plot from alog 17951
• Unconmpensated OMC DCPD poles
  • See this plot from alog 18037
• True zpk([355], []) cavity pole, instead of zpk([355], [7000]) in the IIR filter
  • See some discussion in G1501013

Note that the previous correction was made only from the IOP down sampling filter and the numerical whitening zpk([1,1,1,1,1], [100,100,100,100,100]) which are still included in the new correction.