Which ECR is this done under ( I assume it is the ITM ESD install)?

I'm assuming it is covered by ECR E1600064 though it is not clear if that ECR shows the additional ADC channels for the sus-aux system needed to support the PI-ESD install on the ITMs. 

I should have made it apparent that there are now 8 ADC cards installed in the h1susauxb123 I/O chassis. My original post omitted this important detail.  The newly installed card is ADC7.

It appears that the MySQL process on h1conlog1-replica stopped at around the same time:

/var/log/mysql/error.log
160603  8:28:54 [Note] /usr/sbin/mysqld: Normal shutdown

I have powered off both computers until after the power outage.

To be more clear regarding the HEPI task I will perform Monday morning, see WP 5910.

This is the Capacitive Accumulator Pressure checking which requires the HEPI Pumps off.  This is done only every 3 to 6 months.

I disabled the Pause functionality (and added this status message) in the last update of the code, about 12 months ago. The rationale was that it was far too easy to inadvertently pause the code via epics and not realize that it had happened. It's not impossible for the user to pause the code. The current stationary behavior is not related to the lack of pausing.

SR3 is not the problem after all. 

KIwamu and I unplugged the cables from the Sat amp to the chamber for both M2 and M3, and the locklosses and glitches still happened.  The good news is that Kiwamu seems to have found a good clue about the real culprit.

Our current theory is that locklosses are due to the ISS which shuts itself off for some reason at random times at a rate of once in 10 minutes or so. This causes a glitch in the laser intensity. Before a lockloss, there was a fast glitch (~milliseconds) in PRCL, SRCL and CARM error signals. That made us think that the laser field may be glitching. Indeed, we then found that the ISS had gone off automatically at the same time as the glitch and seemingly had caused the subsequent lockloss. We then tested the stability of ISS in a simpler configuration where only IMC is locked. We saw glitches of the same type in this configuration too.

In order to localize the issue, we are leaving the ISS open overnight to see if some anomaly is there without the ISS loop.

Conclusion: it was the ISS which had a too low diffraction power.

According to the overnight test last night, I did not find a glitchy behavior in the laser intensity (I looked at IMC-MC2_TRANS_SUM). This means that the ISS first loop is the culprit. Looking at trend of the recent diffraction power, the diffraction power kept decreasing in the past few days from 12-ish to almost 10% (see the attached). As Keita studied before (alog 27277), a diffraction power of 10% is about the value where the loop can go unstable (or hit too low diffraction value to shut off the auto-locked loop). I increased the diffraction power to about 12% so that the variation in the diffraction power looks small to my eyes.

Note that there are two reasons that the diffracted power changes, i.e. intentional change of the set point (left top) and the HPO power drift (right bottom). When the latter goes down, ISS doesn't have to diffract as much power, so the diffraction goes lower.

In the attached, at the red vertical line somebody lowered the diffraction for whatever reason, and immediately the ISS got somewhat unhappy (you can see it by the number of ISS "saturation" in right middle panel).

Later at the blue vertical line (that's the same date when PSL air conditioning was left on), the diffraction was reduced again, but the HPO power went up, and for a while it was OK-ish.

After the PSL was shut down and came back, however, the power slowly degraded, the diffraction went lower and lower, and the number of saturation events sky-rocketed.

Craig is working on a WFS rotation matrix script so that we can easily software rotate the WFS into the correct up/down left right arrangement.

Today we also tried to balance the hard/soft actuation. Looking at the aLIGO T0900511 ASC design document, we see that the dHard signal is 10x bigger than dSoft in AS. So we adjust the output matrix elements for the ITMs until we minimized the 6 Hz soft excitation in AS45. The matrix elements before/after:

Before:  ITM = 1,   ETM = 0.87

After:     ITM = 1.12,   ETM = 0.87.

The previous numbers were set by using the RoC from the metrology and the arm length. I assume that this 10% correction is due to actuator strength and not RoC. Hopefully now that common/diff and hard/sfot are balanced the WFS loops will be more smooth. Tomorrow, we need to propagate these numbers into the ASC Output Matrix.

C. Cahillane

The WFS rotation matrix script is done.  This code is designed to rotate the WFS pitch and yaw signal quadrature together by the same angle over 5 seconds.

It is located here: 
/ligo/home/craig.cahillane/Public/ASC_WFS_P_Y_Signal_Rotation.py
This code should be accessible for read write and execution by anyone.

To run it, choose how much you want to rotate in degrees and then the WFS you would like to rotate. The first argument is rotation in degrees, and the second is the channel name. (You must separately rotate I and Q.)
For example, I choose to rotate REFL_A_RF45_I by -10 degrees. 
To run this, type:

python /ligo/home/craig.cahillane/Public/ASC_WFS_P_Y_Signal_Rotation.py -10 ASC-REFL_A_RF45_I

Once run, this code takes 5 seconds to spin the WFS signal orientation to the one you desire.  

Nutsinee, Kiwamu,

We cleaned up and rearranged the violin filters today. Unnecessary filters (e.g. 1000 Hz and higher order modes) are removed. As suggested by Evan, we are trying to assign one filter for each fundamental mode. For doing so, we also rearranged the filters so that they line up in ascending order.  We did not try getting rid of any of the broadband filters yet; we can still use then when necessary. ISC_LOCK is edited accordingly although we have not gotten a change to test the code.

The attached screenshots show the old settings for ITMY and ETMY, as well as their gain settings. Nutsinee will post the setting information on ITMX and ETMX.

Attached screenshots show the old setting of ITMX (except MODE1 and 2) and ETMX (except MODE1). I splitted all the broadband filters but left those new filters turned off (gain=0) until we have a chance to test them. I only let the guardian turn on what was already turn on before this arrangement. ISC guardian doesn't touch ETMX violin filters so all gains should be 0 there.

I created another wikipage for the new violin mode table with updated filter information to live in. The old table can still be found here.

The peak is also visible in the DARM spectrum. In this plot the peak is at 3335 instead of 3340 Hz. Why is there a 1.5% frequency shift?

Here are projected SRM thermal noise curves for structural and viscous damping.

Given a typical SRC coupling into DARM of 1×10⁻⁴ m/m at 40 Hz, 20 W of PSL power, and 13 pm of DARM offset (25019), this would imply a noise in DARM of 1×10⁻²⁰ m/Hz^1/2 at 40 Hz if the damping is structural.

When I modelled the optics in https://dcc.ligo.org/LIGO-T1500376 and in particular the surrogate SRM I had assumed optic was bonded. After looking again earlier with Rana and Betsy realised it is held with 2 set screws (Peek?) on barrell at 12 o'clock and two line contacts at 4 and 8 o'clcok. See https://dcc.ligo.org/LIGO-D1200886.

The previous bonded model for the SRM surrogate (I believe) had a fisrt mode predicted around 8k Hz. However, from a quick model I ran today (with the set screws etc ... ) the first mode appears to be around 3400 Hz. The mode is associated with the optic held with the peek screws. (Now I was doing model using remote desktop so I will need to check it again when I get a better connection, so more to follow on this. I will also post updated model, once I get back to Caltech.) 

The ~3340Hz peak is also clearly visible in the PDA/PDB x-correlation spectrum. See alog 26345.

A couple of comments on this topic:

• There is no feature at 3340 Hz in the L1 DARM spectrum, nor within several hundred Hz of this. So the main mode of the L1 composite SRM seems to be at a different frequency, though I think there has never been a transfer function measured there above ~1 kHz that would indicate the mode frequency (put on todo list). The first attached plot shows Kiwamu's full-O1 DARM and cross-correlation spectra for H1 and L1, zoomed in to the several kHz region. There are some peaks in L1 in the 4700-5100 Hz region, but it's fairly complicated in that region.
• The thermal noise peak in Evan's SRM plot is at a level of 2e-15 m/rtHz, which is a bit above the SRCL sensing shot noise level, so we should be able to see it in SRCL. The second attached plot shows a spectrum of the SRCL error signal from January 9, 2016. From the Aug 2015 entry 20270, the shot noise corresponds to a displacement noise of 1.3e-15 m/rtHz. In the attached spectrum, the mode peak (which is at 3320 Hz here - ?), is 2.5x above the shot noise level, putting it at about 3e-15 m/rtHz. This is a bit higher than in Evan's model, but it is actually remarkably close. (I didn't include it in this plot, but the DARM spectrum also shows this peak at 3320 Hz at this time, and there is 0.8 coherence with SRCL at the peak.)

Danny, Matt (Peter F remotely)

Due to the issues currently seen at LHO, we were asked how the LLO SRM surrogate was put together and if we could add to the alog for a record of the process. The easiest way is to do it via photos (which we have of the assembly process).

IMG_1462....There are only two setscrews that hold the optic in place. Can be seen putting these in place below in the "cup" that holds the optic (eventually). Im not sure of the material but Peter F's speculation is that "I think those set screws must be the carbon-loaded PEEK type. The only other option I can think of for a black set screw would be carbon-steel, and it surely isn’t that."

IMG_1455...Here you seen the three main parts. The optic, the “cup” that the optic goes into and then the main mass the cup goes in. Note in the “cup” you see the two raised parts at around 4 and 8 o’clock that the setscrews ‘push’ the optic onto. So its not 'really' a three point contact, its 2 points (set screws) and 2 lines (in the holder)

IMG_1466...Here is the optic going into the cup making sure the fiducial on the optic lines up with the arrow on the cup

IMG_1470.....Optic now in the cup and doing up the setscrews that hold it in place. I cant remember how much we torqued it up (we only did it by hand). But as Peter F again speculated that perhaps we just did the setscrews up tighter than LHO

IMG_1475....Flipping the cup (with the optic in it) over and placing in main mass

IMG_1478....Cup now sitting in Main mass (without screws holding cup into main mass)

IMG_5172......the SRM surrogate installed into the suspension

It looks like there might be a mode in the L1 SRM at 2400 Hz. See the attached plot of SRCL error signal from January, along with DARM and the coherence. There is also a broad peak (hump) around 3500 Hz in SRCL, with very low coherence (0.04 or so) with DARM. The SRCL data has been scaled by 5e-5 here so that it lines up with DARM at 2400 Hz.

Here are two noise budgets showing the expected DARM noise assuming (1) structural (1/f^1/2) SRM damping and (2) a hyperstructural (1/f^3/4) SRM damping. This hyperstructural damping could explain the DARM noise around 30 to 40 Hz, but not the noise at 50 Hz and above.

I also attach an updated plot of the SRCL/DARM coupling during O1, showing the effect of the feedforward on both the control noise and on the cavity displacement noise (e.g., thermal noise). Above 20 Hz, the feeforward is not really making the displacement noise coupling any worse (compared to having the feedforward off).

Note that the PEEK thermal noise spectrum along with the SRCL/DARM coupling is able to explain quite well the appearance of the peak in DARM.

I am attaching noise budget data for the structural case in 27625.