Matt, Terra

We have 2 modes which are very close in frequency (both around 15540kHz) and we have had some trouble damping them.  To help with this, I modified the PLL filters for these modes to support a lower bandwidth loop, which I hope will be less easily "distracted" by the nearby mode.  The low-pass in FREQ_FILT1 (usually a 1Hz pole) is a modified elliptic which provides significant attentuation at 0.5Hz (ELF0.5), and requires a UGF of about 100mHz.  To support this, the integrator in FREQ_FILT2 is moved down to 30mHz and the gain is reduced to 0.3.  (Note that ELF0.5 has a gain of 0.5 below the cutoff.  This helps to move the UGF down when this filter is on.)

So far this configuration has been working, but should it prove problematic the old filters can be moved back from FM2 to FM3 (which is the FM operated by the guardian).

I used Evan's script to step the 9 MHz modulation depth down by 6 dB.  This was inspired by Koji's alog pointing out that the 9th order 9MHz HOM lines up pretty well with the carrier TEM00 mode (alog 29399), and so is probably what we're seeing on the camera view of OMC Trans.

This noticeably improves the image at OMC Trans - see attached screenshot of camera views.  Both have an exposure of 35000.  Left is nominal, right is -6dB for the 9MHz. 

It also reduced the DARM noise between 900Hz-1kHz.  In the attached spectra, dark purple is the nominal 9 MHz modulation depth of 16.8 dBm, and bright red is the lower modulation depth of 10.8 dBm.  There's perhaps a bit more frequency noise at several kHz, indicating that the CARM gain isn't being increased quite enough (it was increased for this screenshot by 7dB from a slider value of -5 to +2 on the common mode board's IN1 slider).

Tomorrow I'll add this to the ReduceModulationDepth guardian state.

Title:  09/19/2016, Evening Shift 23:00 – 07:00 (16:00 - 00:00) All times in UTC (PT)
State of H1: Working relocking after Lockloss. Environmental conditions are OK. Microseism is low and stable. Seismic activity is a bit rung up in Y. X is also elevated but less than Y. This is consistent with a Gentle to Moderate Breeze (11 – 18 mph).     
Commissioning: Commissioners are working on improving stability at higher powers 
Outgoing Operator:  Ed
 
Activity Log: All Times in UTC (PT)

23:00 (16:00) Start of shift
06:59 (23:59) End of shift


Title: 09/19/2016, Evening Shift 23:00 – 07:00 (16:00 – 00:00) All times in UTC (PT)
Support:  Jenne, Sheila, Lisa, Matt,      
Incoming Operator: N/A

Shift Detail Summary: IFO locked for almost the entire shift. Currently at 51.1W and 35 plus Mpc. Environmental conditions are better than at the start of the shift, with both wind and seismic lower. Commissioners continue making improvements.   

J. Kissel

Now that we're approaching ER10, and the noise is getting back to O1 levels, we need to start tracking the time dependence of the SRCL detuning in the DARM response. As such, with only intuition to guide, I've added a new calibration line at 7.83 Hz, driven by PCALY at a requested amplitude of 20000 [ct] (corresponds to a DAC [ct/rtHz] of 28909, and 8.8e-13 [m/rtHz] of DARM displacement). For a 10 [sec] FFT, with the current sensitivity, this has about an SNR of 10. We can explore driving the line harder, but let's see what we get out of this -- we're already close to the limit of the PCAL AOM, and that's what I used to tune the excitation amplitude. Also note that, although we often use a 10 [sec] FFT as our SNR metric, in practice, we often use 60 or 120 [sec] FFTs (i.e. the time scale on which we expect optical plant parameters to vary), so we'll win there.

I've checked to make sure that this new line
- Does not saturate the PCALY DAC
- Does not saturate the PCALY OFS
- Does not saturate the DARM actuator when trying to control this line (ETMY SUS) 
- Does not generate any substantial harmonics or other non-linear noise in DARM

And I've also accepted the settings for this new line in the safe and OBSERVE snaps for PCALY.

Let's get this line into SLM tool and start analyzing to see if the SRC detuning moves!

P.S. We expect fisher-matrix back-up that this is roughly the "optimal" location for the SRCL line, given that we suspect the optical spring frequency to be around 9.8 [Hz]. Of course, we cannot put the line right on 9.8 [Hz], since that's exactly the frequency of the QUAD's highest vertical mode (a.k.a. "bounce" mode). I've compared 7.93 [Hz] against all of the "do not put a line here" criteria used for the original calibration lines (see LLO aLOG 15870), and this frequency does indeed satisfy those criteria especially since the line is below the astrophysical analysis band.

   Took a 12 hours trend of the PSL Chiller vital signs after this mornings flow adjustment. The various pressures and flows changes in the manifold, chillers, AMP and PWRMETER are not out of the range of expectation. The change in the PWRMETERFLOW is a bit larger than the changes in the other parts. Will monitor this over the next few weeks to make sure all is well. 

   The interesting result is the changes in the four head flows and temperatures. On heads 1 through 3 the flow was reduced by about 0.1 l/m. On HEAD1 the temperature remained constant. On HEAD2 and HEAD3 goes up by 0.1 degree. What is interesting about this is the change in temperature actually smooths out the variation of the high/low temperature range. Need to monitor to see if this is holds up over time.

   HEAD4 has always been the PSL poster child of different, and continues this trend. When the flow was first adjusted it took a relative large drop (0.2 l/m) and over the next three hours the flow recovers to within 0.02 l/m of its original value. The temperature at first goes up and then settles down to its normal value. Whereas on HEAD2 & HEAD3 the temperature goes up and smooths out the high/low fluctuations; on HEAD4 the temperature goes up, then down and then smooths out the high/low fluctuations.  

   It should be noted these changes are actually relatively small. The Crystal Chiller flows around 22 l/m and the Diode Chiller flows around 32 l/m.        

First attachment shows the ISS 1st loop sensors and second loop sensor when 1st loop was engaged but 2nd loop open.

Solid lines are now, and dashed lines are from Friday (the same reference time used in alog 29778).

Even though the ISS state is the same between solid and dashed, 1st loop out of loop sensor (PDA) is much larger than it was on Friday.

It's not like the loop was crazy, as the in-loop sensor (PDB) didn't change, and the second loop sensor didn't change either.

The second attachment is a one-day trend of pointing into the ISS 1st loop QPD (ch1 and 2), various environment signals (ch3 to 11) and PMC trans.

Pointing changed a bit, mostly in DX (this is probably YAW in PSL speak) though PMC transmission increased.

ISS QPD spectrum didn't change much (third attachment).

It's as if the jitter coupling for PDA changed.

Jeff K, Sheila, Chris Whittle

Having recently taken measurements for the CARM and IMC loops with the newly installed 200 kHz pole (aLOG 29735), we have begun an investigation into whether we can boost the gain in CARM to help mitigate frequency noise in DARM without compromising loop stability. We used the following form of the CARM open loop gain:

G_CARM ~= g_CARM * H * ( g_IMC * G_IMC / (1 - g_IMC * G_IMC) )

where g_IMC and g_CARM are tweaked, and G_CARM and G_IMC were measured (see above). H is a combination of the electro-optical CARM plant of the IFO and the electro-optical IMC plant, and is calculated from the above measurements. We are ignoring the slow path here as we are far above the 30 Hz crossover. See aLOG 22188 for more details.

Note that the closed loop gain of the IMC was extrapolated back to 1 kHz from 10 kHz (assuming a unity CLG below 10 kHz).

The OLG of the IMC loop shows that we can't get away with an IMC gain much grater than 2 dB without hurting our phase margin too much. Similarly, the loop suppression of the IMC loop significant gain peaking above 2 dB.

With g_IMC = 2 dB, our CARM phase margin suffers above g_CARM = 2 dB. This gives us a a factor of 2.08 dB suppression in our CARM loop suppression. We therefore propose increasing CARM and IMC loop gains to g_CARM = 2 dB and g_IMC = 2 dB. Although this introduces some additional UGFs, all are stable, and the worst of which has a phase margin of 31.6​​^∘​.

The script for producing these plots can be found at:

   Posted are the ISI HAM & CPS Spectra Checks. Did not notice anything that appeared out of the ordinary. 

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

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.

Since the lock was so stable, I could not avoid measuring the DARM open loop for calibration purpose tonight. I have tuned the excitation amplitudes of the 4-1200 Hz DARM OLTF template because some frequency points had too high excitation causing saturation on ETMY DACs. Also for completeness, I have taken a Pcal sweep as well. I will analyze the data later.

The dtt files can be found at:

/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER10/H1/Measurements/DARMOLGTFs/2016-09-15_H1_DARM_OLGTF_4to1200Hz.xml

/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER10/H1/Measurements/PCAL/2016-09-15_H1_PCAL2DARMTF_4to1200Hz.xml