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.

Dave, Patrick

Restarted all web medm screenshots on script0.

And all other driver dofs are quiet as well.  Remember, Monday night 29667, this channel, H1:ISI-BS_BIO_IN_CD_ST1_V3_STATUS, was dropping to zero, indicating a thermal problem.  Checks suggested the coil driver was not actually sending the bad signal and the BIO Chassis was responding appropriately to simulated state changes.  The I/O computer cards were reseated and by default, all the machines were power cycled.  Maybe we've seen the last of this issue for the time.

Sheila, Matt, Lisa

The ISS has been oscillating a couple of times when reaching 50W in the last two locks. Sheila fixed that by turning off the AC coupling.

We leave the IFO locked at 50W with the ISS AC coupling off, at Sep 15, 9.45UTC. It has been locked for about 20 minutes, powers are stable, no PIs.

Matt updated SDF with the latest PI settings.

We just noted that the PSL NOISE EATER is oscillating -- so please fix that in the morning.

Sheila, Lisa, trying to summarize the work of many people today

* More  Intensity Stabilization Science   made possible to engage all of the ISS loops and lock several times at 50W;

* The lock at 50W had been broken earlier today due to the inability to damp the ETMY Mode 27 (18041 Hz). This triggered the decision to turn off the EMTY ring heater (see  Terra's elog ). After that we had a couple of stable locks at 50W, when Terra and Matt were able to keep all the Pis damped, and the sideband power and the recycling gain were stable. As Kiwamu already observed, it looks like the current combination of ITM ring heaters and CO2 powers is good (enough) to prevent the sideband power and the recycling gain from dropping (note: Corey and Kiwamu noticed a drop in AS90 in another 50W lock later in the evening (see   Corey's entry ) and they had to deal with some PI damping, but that lock was done with no CO2 X power, instead of 400 mW, as Kiwamu was exploring CO2 tuning);


* After more than 2 hours at 50W we started some low noise steps. Evan engaged the OMC whitening filters, but that didn't help at all unfortunately, as we are entirely dominated by intensity noise above 300 Hz. Looking at the noise budget from O1, a by-eye estimate tells us that the current level of intensity noise is at least ~300 times worse than during O1, even more at some frequencies. The noise is also worse than what it was during ER9 (when the HPO was operational). Sheila's entry  shows indeed that the intensity noise coupling to the interferometer is about 3 times worse than it was during O1; also, the ISS out of loop sensor is about 3 times higher than previously measured, showing coherence with PSL accelerometers. If you add that the current ISS loop has a factor of 2 less gain than during O1, while the intensity noise with the HPO is 30 times higher, well..the factor of 300 worse noise than during O1 makes sense.

So the bottom line is:

* we are close to a stable 50W configuration, it looks like PIs can be controlled, and the sideband power can be stable; need to work on robustness from lock to lock;

* the intensity noise is huge, and it dominates the noise above 300 Hz; trying to get more gain out of the current ISS loop didn't prove successful tonight, so we need a better strategy. Probably we should start by going in the PSL and realign the PMC and see if it improves the ISS out of loop PD spectrum.

Lisa, Sheila

We have had 2 more incidents of locklosses where the ISS autolocker unlocks the interferometer in response to an ISS saturation. (described last night as well)

Here is a plot very similar to last nights, showing one of these locklosses. 

Sheila, Lisa, Keita, Daniel, ...

Here are a few plots ilustrating our intensity noise situation.

• The first attachment is the spectrum taken after 1 hour at 50 Watts, with ASC in the high bandwidth state, so the ASC noise dominates up to 300 Hz.  You can see that there is a high coherence with intensity noise (yellow) above a few hundred Hz, and frequency noise coherence is large above a few kHz. At the peaks of intensity noise there is coherence with all the PSL accelerometers, microphones, ect.
• The coupling of intensity noise (measured passively) is shown in the second attachment. This is about a factor of 3 worse the the coupling measured by Evan durring O1 (25476)
• The alingment of the PMC was better in July than it is now. (last attachment).  This may explain some jitter to intensity noise coupling on the PSL table which shows up as more noise in the ISS loop.
• The intensity noise from the first loop is worse than when Evan and Keita measured it in February 26773.  (last attachment, PDB is now the out of loop sensor, this was measured with the second loop off so it should be comparable to the attachment from February).  There are several broad accoustic peaks in the new spectrum that aren't in the February spectrum, and have coherence with PSL table accelerometers between 100Hz and 1 kHz.  The out of loop sensor is a factor of 5 more noisy at 100 Hz, and there are frequencies where it is a factor of 10 worse, after the IMC things are a factor of 3-5 worse. 

It seems possible that a worse alingment on the PSL table since July (ER9) is contributing to our worse intensity noise.  It might be worth considering a PSL incursion to align through the PMC better to take care of some of these peaks, as seen by the first loop PDs at least. 

Walked in to a locked H1 and several tests going on.  After a while H1 dropped out & then Daniel/Keita ran some ISS arm power scaling tests.  

After these tests I wanted to get H1 locked up at High Power.  Similarly to last night DRMI & PRMI locking looked quiet.  So I went & used Sheila's trick of pushing the BS (see note in her alog about this & how to end the excitation).  This seemed to work in that PRMI was able to lock up...but I also tweaked the BS to bump up the PRMI flashes.

Took H1 up to INCREASE_POWER (I assumed it would take H1 to 30W, but it actually kept on going....at around 54W, I went ahead and selected 50W.).  I kept H1 at 50W for some high power locking.  Here are some notes from the lock thus far:

• After a few minutes, the PI MODE27 rung up, but it went back down without any action.
• MODE26 slowly started to ring up.  Since I had never dealt with PIs before, I grabbed Kiwamu for help.  This mode was using PLL to damp the mode.  When we looked at the mode, it wasn't large enough to lock the PLL so it could damp it out....BUT, Kiwamu noticed that if the PLL were to lock it up, it would excite the mode, because it had the wrong sign (+1.00).  Kiwamu changed it to -1.00 and then this damped out (after a quick test which Kiwamu showed me regarding the sign).
• MODE25 & MODE17 then rung up.  After some sign changes, Kiwamu determined that MODE17 did not have a small enough band pass & was observing crosscoupling from the true culprit:  MODE25.  Kiwamu worked on damping this guy out, but then we lost lock surprisingly (we had been noticing AS90 drifting down over our 90min lock.

FOM/Nuc5 Note:

I tried to fix nuc5, but after reboot, the seismic DMT viewers  were not getting data from correct time.  Is this a kerberos ticket issue?  Do we have instructions on this?

Seismic Config Note:

EX was taken to Windy NO BRS because Nutsinee was going to go in the VEA & just wanted to be safe.  EX ISI was returned to Windy config after she exited the VEA.  In hindsight, looks like we didn't need to do anything (her incursion wasn't seen on the STS).

We are having trouble relocking the modecleaner, with FSS oscialltions. 

This could have something to do with the new ISS 2nd loop, but the ref cav alignment seems to have drifted in the last few days. 

4:20pm local

Went out to overfill CP3 and found that the exhaust is dripping LN2 and the exhaust pipe is frosty. I did not open the bypass LLCV, and instead lowered the LLCV value from 18% to 16% open. Picture attached.

Title:  09/14/2016, Day Shift 15:00 – 23:00 (08:00 –16:00) All times in UTC (PT)
State of H1: IFO is unlocked.  
Commissioning: Daniel & Keita working on ISS Second Loop
Outgoing Operator:  N/A
 
Activity Log: All Times in UTC (PT)

15:00 (08:00) Start of Shift
15:55 (08:55) Karen – Cleaning in the Optics Lab
16:45 (09:45) Dave – PSL ISS Model change and DAQ restart

 

Title: 09/14/2016, Day Shift 15:00 – 23:00 (08:00 – 16:00) All times in UTC (PT)
Support:  Jenne    
Incoming Operator: Corey

Shift Detail Summary:  Relocked the IFO at DC_READOUT on the first attempt without running an Initial Alignment. Commissioners are working on the ISS Second Loop. After initial lock was broken, had to rerun Initial Alignment. Once complete the IFO was relocking with little operator’s intervention. The interferometer was locked for most of the day while the commissioners continued improving the system.    

Jeff K, Chris Whittle

Following on from aLOG 29400, which suggests a very large negative bias voltage zero-crossing on ITMX, we have repeated ITMX charge measurements at excitation frequency 20.1 Hz in an attempt to produce results more comparable to those in aLOG 27752 (zero-crossing at 3k counts). Defying expectation, we found the bias voltage zero-crossing to depend on the excitation frequency. Repeating this measurement for multiple frequencies gives the first attachment, which shows the bias voltage zero-crossing as a function of excitation frequency.  This plot seems to suggest a f^-2​ dependence. The second attachment shows results from a separate measurement in which we sweep over multiple frequencies at different bias voltages. The two plots seem consistent in that dips in the transfer function seem to correspond to the frequencies with the associated bias voltage zero-crossing.

Limited studies of ITMY show similar behaviour:

These results are also reproducible day-to-day, varying by <10%. We have not looked closely at these fluctuations, however.

Further investigation is required to determine the cause of the frequency dependence, and to understand the large difference between current measurements and those taken in June.

We turned the ETMY ring heater off (.55 W --> 0 W top and .55 W --> 0 W bottom) at 21:00 UTC. 

Change was made since we seem unable to damp ETMY Mode 27 (18041 Hz). 

Keita Daniel

We were able to engage the outer loop ISS after the mode cleaner was locked and power up to 50 W in full lock. The third loop was intended to be engaged around 10 W, but due to a scaling error in the arm powers, the gain was too low. We were able to adjust the gain, when we reached 40 W. And then power up to 50  W.

How to engage the outer loop:

• To turn the outer loop off, set the OUTERLOOP_ENABLE switch, the OUTERLOOP_BOOST_1 switch and  and the output switch of the THIRDLOOP_SERVO to off. The input switch of the OUTERLOOP_AC_COUPLING_SERVO should be on. The SECONDLOOP_CLOSED switch in the first loop ISS may or may not be off.
• Once the first loop ISS is working, the SECONDLOOP_CLOSED can be turned on.
• Once the IMC is locked, the OUTERLOOP_ENABLE can be turned on.

How to engage the third loop:

• When the input power reaches 10 W, set the gain of the THIRDLOOP_SERVO to 0 and the TRAMP to 3.0 sec. Now turn the output switch of the THIRDLOOP_SERVO on and set its  gain to 1.0.

This is now coded on the guardian. However, the arm power scaling error needs to be fixed with an LSC model reboot.

New features in the digital ISS model:

• The input switch of the OUTERLOOP_AC_COUPLING_SERVO also switches the corresponding AC coupling filter in the third loop.
• When the OUTERLOOP_ENABLE is off, the integrator in the AC coupling bleeds off its offset.

We did not test turning on the boost or turning off the AC coupling of the outer loop. Changing the ISS main gain is problematic due to electronics offsets. The same goes for the boost stage.

Lately we have been aligning DRMI by hand before letting the ASC come on because the ASC engagement has been rough and caused many locklosses. 

Tonight I watched WFS signals while Corey alinged by hand (and the BS drifted in pitch while cooling off from a 50W lock).  It looked like AS45Q was a better signal for the BS than the 36 WFS, with much less sensitivity to other optics.  Hoping that this would help DRMI ASC acquire more smoothly, I tried it out by eyeballing the relative gain.  (where ASB36Q using a 2 in the input matrix, we used a -100 for AS45Q). 

This seems to be working quite well, we have acquired lock with bad alingments about 3 times durring these earthquakes,  and let the gaurdian handle the ASC without aligning by hand. 

We need to switch back to AS36 before we do the CARM offset reduction.

I've moved the DRMI ASC offloading, fast shutter testing, and waiting for BS ISI out of the CARM on TR guardian state (this state was getting crowded with things that are not related to CARM.)  There is now a new state called DRMI_ASC_OFFLOAD that switches MICH to AS36, waits for the ASC to converge, tests the fast shutter if needed, and waits for the BS ISI to isolate stage2.  This happens before CARM on TR. 

Corey, Sheila

Tonight we have very low ground motion (useism band 10^-1 um/second earthquake band 10^-2um/second)

We have been using awggui to add an 8000 count sine wave at 0.1 Hz to the BS M1 LOCK L filter bank (which has a gain of 0.1).  This is helping us to catch fringes more often tonight, and we are manually ramping it off once DRMI locks.   This would be a good idea for operators who find themselves havign trouble locking DRMI in low ground motion.

To do this, use a terminal and type awggui.  Set it up like the attached screenshot.  It is a good idea to start with the gain (bottom middle) set to 0, hit set/run, then ramp the up to 8000 by hitting set in the gain box. 

Evan H., Jenne, Matt, Kiwamu,

We locked the interferometer at 50 W with the latest ring heater setting (RHX = 0.5 W, RHY = 2.5 W, 29588). So far the interferometer has been locked at 50 W for roughly 1 hour.

P.S. we have now having difficulty damping a PI mode (mode2, 15520 ITMX) and decreased the PSL power back to 30 W.

[DRMI lock on POP sensors]

As reported yesterday (29601), we had a difficulty in switcing the sensors from the 3fs to 1fs earlier today (29603). In the end, I manually executed the sensor switch process one by one and for some reasons this was successful. I then measured the open loop transfer functions of the DRMI LSC degrees of freedom, but they looked OK. See the first attachjment. This may be due to that we did not wait for long enough time to let the new CO2 setting settle (29603) for lock acquisition ([CO2X, CO2Y] = [500 mW, 1000 mW]). Not sure.

Also, in lock acquisition, I manually kept aligning PR3 when the interferometer was at ANALOG_CARM in order to maintain the lock.

[CO2 tuning at 50 W]

This is not well tuned, but the below is an OK CO2 tuning for 50 W which gave us a 30% imbalance at the AS port OSA.

[CO2X, CO2Y ] = [300 -400 mW, 0W]

This time I did not spend time for tuning the dCO2 at 20 W or 40 W. Maybe I should have done that to collect more data points.

[PIs]

MODEs 17 and 27 needed a sign flip. Mode 27 seems tricky -- every time when it rang up we needed to flip the control sign.