Using the latest BRUCO results, I've annotated a hi-res spectrum from last night's lock.  Peaks, bumps, and so on are labeled with the largest coherent channels.

There are a few peaks, at 46, 166, 420, and 689Hz, that are coherent with PRCL/SRCL, and they have changed since the blue reference (Mar 19th at 18:00).  This might be due to the POP --> POPAIR switch.

The source of the 300Hz lines has been identified, it's the BS violin modes.  The frequency is given in Mark Barton's table of predicted violin resonances (thanks Jeff!).

We turned off all the ring heater power supplies yesterday; this got rid of a line at ~74Hz but didn't change the 55Hz line and its harmonics.  These lines are certainly due to some electronics in the EX racks.

Features coherent with the IMC WFS and the PSL persicope are probably the same thing (input beam jitter), hopefully from the same source (PSL PZT mount).

== Activities ==

7:40 Cris to LVEA

8:00 Cris out of LVEA

9:00 Lock Loss

        Kiwamu to EY to reset ETMY ESD

9:22 Kiwamu back

11:14 Jodi to Mid X and Mid Y

14:50 Kyle back from mid stations (No notes of when he went out... Kyle and Jodi together?)

Best lock range at LHO ever. Happy Friday.

Kyle, Gerardo 

Pressurized lines -> no leaks.  

Attempting to clear a path for under tube pallet jack traffic and ease 3IFO storage and also to eliminate need for overhead crane.  

Instrument air and copper grounding cable still need to be re-routed off of the floor

Scott L. Ed P. Chris S.

The crew was able to complete tube cleaning to the X-1-7 double doors. 
Results are posted here.
The afternoon will be spent doing P Ms on the equipment and relocating to the next section to be cleaned.
  

I have added two buttons to the CDS OVERVIEW MEDM screen:

Press All Diag Reset Buttons

The name says it all. It opens an xterm window, and then sequences through all running models pressing the DIAG_RESET button on the GDS_TP screen

EDCU disconnected channels

This is a small yellow button, labeled with an exclamation mark,  next the the EDCU status LED. When the LED is purple, pressing the button will open an xterm and list the EDCU channels which are disconnected. The xterm is held open so you can read it at your leisure, please close it when you are done with it.

Here are some notes on the recent DARM calibration for future reference.

(A) We intentionally do not switch the simulated ETM actuators in the CAL-CS model when we switch to ETMY for low noise in the DARM control.

Even though we switch the actuator from ETMX to ETMY for the LSC DARM control to achieve low noise, the calibration filters for the actuators in CAL-CS remain using the *ETMX simulated actuator path*. Since we adjusted the ETMY ESD digital gain such that the response of ETMX and ETMY ESDs are the same with a precision of 10 % in frequency band from 20 to 60 Hz, the calibrated spectrum after the ETMY transition should be still valid with a precision of 10 %. In other words, we forced the actual ETMY ESD to be identical to that of ETMX so that we don't have to manipulate the filters in CAL-CS. In fact, when we transition from ETMX to ETMY, we do not see visible reduction or increment in the DARM spectrum at low frequencies below 100 Hz, which convinced us that the calibration remained consistent. Then, once we decrease the ETMX ESD bias all the way to zero, we see noise reduction in 20-100 Hz band due to lower ESD noise.

The adjustment of the ETMY ESD digital gain was done on the last Tuesday, Mar-24th (alog 17411). The following is some detail of what I did for the adjustment. First, I measured the transfer function from ETMX_L3_LOCK_L_IN1 to LSC-DARM_IN1 in 20-60 Hz band by swept sine while the interferometer stayed fully locked on DC readout. Then I measured the same transfer function but with the ETMY ESD driven. So the transfer function I took was from ETMY_L3_LOCK_L_IN1 to LSC-DARM_IN1. At this point, I noticed that the ETMY ESD response was weaker than that of ETMX by an overall scale factor of 1.25. Note that both ESDs use the linarization. So I increased the ETMY ESD gain by the same factor in ETMY_L3_LOCK_L_GAIN. So this gain is now 1.25 and this is already coded in the ISC_LOCK guardian. Then in order to check how good the matching is between ETMX and ETMY, I ran another swept sine on ETMY with the new gain. However this still gave me a bit too-weaker ETMY ESD by 10% (I attach the dtt xml file). Since we knew that the overall scaling factor of our calibration is already uncertain by the same level (on the order of 10%, see for example alog 17082), I did not try to get better matching between them. We will revisit the ETMY calibration at some point.

(B) The DARM spectrum below 2 Hz is not trustable.

There are two reasons.

1. We have not calibrated the L1 stages yet, the calibration below the cross over frequency (which must be somewhere between 0.5 and 2 Hz) is uncertain.
2. We intentionally do not engage two of the simulated suspension digital filters for the L1 stage (i.e. the ones simulating low frequency boosts in ETMX(Y)_L1_LOCK_L, specifically FM1 (zpk([0.3], [0])) and FM2 (zpk([0.1] [0])) ). This makes the calibration inaccurate below 0.3 Hz in such a way that the DARM spectrum becomes too good. Enabling one or both filters tends to accumulate a large DC offset over some time and eventually causes a spill over envelope into the DARM spectrum even if the DC component is subtratced in diaggui.

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.

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

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

Replaced Shutter Controller S1203610 with S1203612. Daniel reported CH1 on S1203610 is not functioning, thus we were controlling the shutter with CH2. I reconnected the shutter to CH1 of the new unit and changed the jumper settings to VS35 on both channels.