SudarshanK, RickS

Yesterday, we adjusted the transmitter module optical layout to address the s-pol light downstream of the AOM (see notes appended below).

We then calibrated the system using Working Standard WS1.  The details are in LIGO-T1500129.

The calibration of the TxPD output (H1:CAL-PCALX_TX_PD) is  8.517e-13 *1/f^2 (m/V).

The calibration of the RxPD output (H1:CAL-PCALX_RX_PD) is  6.799e-13 *1/f^2 (m/V).

Notes:

LHO Xend calibration

Every time commissioners improve the sensitivity, I have to run again my brute force coherence. Luckily, it's fast enough now. Here is the sumamry page:

https://ldas-jobs.ligo.caltech.edu/~gabriele.vajente/bruco_1111482016/

MICH is dominant between 20 and 150 Hz (first plot). PSL periscope peaks are prominent (third plot). Intensity noise is a factor of few below DARM at frequencies above 100 Hz (fourth plot). There are many lines coherent with suspension or environmental signals, too many to list all of them here.

SRCL and PRCL show a broad band coherence basically everywhere (second plot), giving a noise projection a level of few below the DARM signal. This is the usual thing we already saw, and I believe is due to the IMC locking offset, somehow converting frequency noise into intensity noise. Still to be proven though.

Updated all the BSC ISI snaps to reflect Jim's current Blends.  Elliptical blends have been added to and turned on to all the St2 for the 4 DOFs we are isolating.  I also had to edit unchanged filter banks due to the FE/SDF mapping of SW2 down onto SW1.  This was an issue just at the ETMs and seems related to the blend switching for the winds (45 vs 90mhz, what's up with that?)  Safe.snaps committed to svn.

Similar to my mods at ETMX in alog 17488, I thought I would try add some low pass filters to one of the HAM's CPS blend filters. So far I've gotten mixed results. HAM6 shows a pretty clear improvement, HAM5 is about 50/50 good and bad. First plot shows HAM6, second is HAM5, solid is before, dashed is after, black is ground, blue is CPS, red is GS13. HAM6 shows improvement between  1 hz and 10, but HAM5 is better up to 3 or 4 hz, then worse. At least the HAM 5 data shows nothing worse below a HZ, the HAM6 data was taken really quick so I didn't get the low frequency part.

Not really sure what is going on. Maybe insufficient loop gain or something?

Previously posted as comment to 17504.

Note that ISI Stage2 was a State3 trip meaning that the Damping Loops were still functional.  It would be nice to know when/why the stage tripped.  But I'd guess that the Guardian was set to fully isolated before the ~0700utc short lock and was untripped during the short lock, likely triggering during acquisition and then triggering again at the trip.  That is what I first thought.

See attached--It looks like the stage2 when isolated survived the IFO lock loss but not the MICH reacquisition.  This means, we can use the Guardian to transition the ISI between Isolated Damped and Fully Isolated with tripping nor requiring operator intervention.

This is a 50 minute stretch so the IFO lock Loss is only a couple minutes before the St2 WD trigger but there may be enough time to deisolate stage2.  Looking at a zoomed in full data, looks like a full 70+ seconds after lock loss based on this CAL_DELTAL channel.  The second lock loss had even more time so I don't think it is tied to the lock loss but more to the reacquisition.

Of course, we also need to show that turning Stage2 Isolation loops on is a positive thing.

J. Kissel, J. Warner, J. Romie, H. Radkins, N. Kijbunchoo, K. Izumi, G. Moreno

SUMMARY: We just finished ~7 HOUR lock stretch at our best sensitivity ever, between 32 and 34 [Mpc]!

We've all been pleasantly surprised this morning to see that the lock stretch that Sheila Evan, Dan and Lisa started last night lasted the entire night. Unfortunately, as of ~10 minutes ago (~8:40a PDT, ~15:40 UTC), there are GIANT glitches and non-stationarity that keep popping up, spoiling the sensitivity. There's no one in the LVEA, so we're not at all sure what's caused the sudden change in behaviour. Wind seems fine at ~5 [mph], ground motion is still pretty low, the 1-3 [Hz] hasn't even come up yet.

Anxious to explore things, Jim installed some low-pass filters in the HAM5 and HAM6 ISIs at around 8:45 to try to reduce scattering / acoustic coupling to the ISI, and Kiwamu began exploring MICH coupling to DARM. 

But, as I write this log, we lost lock. However, for DetChar purposes, one can assume the detector was undisturbed from March 27 9:00 UTC to March 27 ~15:00 UTC.

model restarts logged for Thu 26/Mar/2015
2015_03_26 00:32 h1fw1
2015_03_26 08:55 h1calcs
2015_03_26 08:57 h1omc
2015_03_26 09:03 h1broadcast0
2015_03_26 09:03 h1dc0
2015_03_26 09:03 h1fw0
2015_03_26 09:03 h1fw1
2015_03_26 09:03 h1nds0
2015_03_26 09:03 h1nds1
2015_03_26 14:44 h1fw0

two unexpected restarts. CAL and OMC model work, with associated DAQ restart.

Scott L. Ed P. Chris S.

My apologizes for this late report from yesterday. I had to leave early to get to town and pick up oil filters for the new generator, already time for P Ms.
The cleaning crew was able to clean 76 meters of tube yesterday towards X-1-7 double doors. Good day.

The whistles in DARM are still quite prominent in this lock. As briefly summarized in this alog, they happen whenever the PSL VCO frequency crosses 79.2 MHz. This points to the likely cause. This is a reliable enough indicator that we can get some statistics. In the first hour of the current lock (Mar 27 9 UTC to 10 UTC), the whistles happen at a rate of 4 per minute.

Below are four spectrograms. The first two show some whistles identified this way. A new feature is that there seems to be a second oscillator very close by, or maybe some harmonic of the beat note. The next two spectrograms show a minute with several whistles, and the next minute where none occurred. Even when none go through zero frequency, you can still see the beat note hovering up near Nyquist.

Evan, Sheila, Dan, Lisa

We made it to 34 Mpc by managing to do at the same time all of the things we have tried before (low noise ESD on ETMY, low noise coil drivers for all the optics, POPAIR for vertex length DOF, more aggressive SRCL cut-off), plus some more ASC cut-offs. Implementing all of these things at the same time happened to be more challenging that expected because of a few problems that slowed us down today:

• trip of EY ESD driver at every unlock happening from the final low noise state (requiring a trip to the end station for resetting the driver);
• trip EX PUM whatchdog (not immediately recognized from the control room, also requiring a trip to the end station);
• some new which required some effort to get damped;

Some more details

• The improvement below 20 Hz in the sensitivity is entirely due to the cut-offs we added to the CHARD loops;
• Even after transitioning the BS M2 coil driver to low noise, and moving to POPAIR, we still have some coherence with MICH below 100 Hz. We tried to engage the MICH subtraction path, but we unlocked in doing so. Since unlocking from low noise costs us a trip to the end station, we didn't try harder..
• We closed the OMC REFL beam diverted;

Final IFO & Guardian state

• We promoted the SRCL 20 Hz UGF + cut-off in the Guardian, as it seems to work well;
• The transition to ETMY ESD low noise + DARM boost is still done by hand (it is written in the Guardian; we are just not brave to try it)
• The transition to BS low noise is also done by hand, and since it has failed at least once in the past, we decided not to engage it in this last lock
• Stage 2 ISI on BS is tripped..
• Sheila prepared some more cut-offs for the ASC DHARD loops, but we haven't tried those yet.

We leave the interferometer locked at 34 Mpc, starting at March 27 9:00 UTC

Evan & Sheila, Dan & Lisa

Tonight some new failure modes of the violin damping manifested themselves, and we found new ways to damp them.

On ITMY, the following modes and settings were identified:

Note that in the earlier catalog the 504.875 line was mis-identified as an ETMX mode, and the 503.119 line was not paired with an optic.

Earlier in the evening we tripped the RMS watchdog on ETMX, and had to drive out the end station to power cycle the coil driver.  

This wasn't obvious from the control room.  Three things that would help are to 

1) add this to the OPS overview screen

2) add it to the SYS_DIAG gaurdian

3) add it to the SUS guardians

Rich A., Lisa, Sheila, Jeff, Evan

The EY ESD driver has tripped twice today, apparently in the same failure mode as described previously. Each time we have had to drive down to the end station to reactivate it.

The supplies are set at ±430 V, each with a 75 mA current limit. When the driver is active, it draws 23 mA dc from the positive supply and 20 mA dc from the negative supply. When tripped, it draws 3 mA dc from each supply.