We've been having trouble isolating ITMX. The punchline is, I think I need to collect a new with the seismometers in low gain and redo the loops. The rest of this post is summary/posterity/flagellation.

-Last week, Sheila complained about the performance of the ITMX ISI.

-To fix this, I took a new transfer function, but in response to something somebody said somewhere, I used a different configuration than previous rounds. This time I left the T240 and L4C in high gain, where before I had usually run all the seismometers in low gain for the tf. 

-I ran through all the commissioning scripts, load new cart matrices, new blend filters, new damping loops, and new isolation loops. Loading everything went off with no problems.

-Turning on the isolation loops was a different story. When I left on Tuesday, St1 was partially working, I never made it to St2. Kiwamu and Jaime were able to wrestle St1 into a semi functional state (alog 13746).

-I've continued to wrestle with this. JeffK suggested less aggressive loops, which I have spent a lot of time making successively more and more conservative loops. The first two attached images show a representative old and new loop. The old loop (that Sheila complained about originally) is more aggressive: higher UGF, more gain peaking, more aggressive boost, less phase at UGF (14 degrees!). The newer loop seems pretty "easy" in comparison, but it took a lot to turn it on, and it still rings a little.

-Another clue, suggested by BrianL, comes from looking at the damping filters. The third image shows one of the loops from ITMY and ITMX. The ITMX loop has 7X less gain, but otherwise looks the same; phase looks the same. The 7X is suspicious, because that is exactly the difference in the gain between the high and low gain of the L4C. I had noticed earlier that the DAC outputs when the ISI was only damping looked low (i.e. never higher than a count, when I thought a few tens of counts was more normal).

-So, this afternoon, I tried turning up the gain on the St1 damping loops to 7x. The outputs of the DAC increased to what I thought were more normal numbers, and nothing went crazy. I tried turning loops on at this point, and it was still difficult, but eventually we got everything on for St1. Additionally, some of the ringing was alleviated by upping the gain on a few of the loops, so that is how I have left it. St2 is damping only still, but St1 has been running for the last 4-ish hours.

-I looked at the St1 & St2 seismometers, as well as the op-levs to compare these not-so-great loops and the just damped state and it looks like the current arrangement is a little better than just damping. My last 3 images are the op-lev spectra, and the St2 seismometers. Pretty sure the big peak at 30hz is Kyle's pump cart, so a temporary issue.

-I have scripts set to launch the tf at about 1 am. I may come in to work on this some more this weekend, I'll let the appropriate people know if I do.

S. Dwyer, G. Grabeel

Completed the alignment of the HWS on the ISC table and end-Y for TCS. The green laser had some alignment issues after the power outage that a burt restore didn't fix. Sheila and I put the PZTs in the middle of their range of motion and realigned the beam onto the QPDs. After the green beam was aligned with the irises and centered on the QPDs I began aligning the TCS HWS side of the ISC table.

The new layout worked really well and I was quickly able to get a good looking beam on the HWS. Unfortunately there is an issue with an incorrect pinout on the HWS cable so I will not be able to get the camera running just yet.

on OPSWS1.  Please don't disturb the matlab session.  The TFs should complete before noon.

Closed these loops with the controllers designed from the TFs taken yesterday.  They turn on fine with Guardian and the ISI (w/ Lvl1 Controllers) only gets marginally excited during the process.  The HEPI and ISI Guardians are not SEI Supervised and are each in EXEC control as there is no ROBUST_ISOLATED choice in the SEI Manager.

A safe.snap was taken.  The only thing there is the open loop drive OFFSETs are still in place although the OFFSET is off.

I still want to study some performance but the positions are locking so good first step.

IP3 and IP4 need to be pumped with pump cart prior to energizing them -> These two IPs haven't been energized since aLIGO de-install/install activities required that they be unbolted from the iLIGO output MC tube a few years ago -> IP3 was found to be < 1 torr, was assisted with the pump cart while energized initially and was able to match its own outgassing after ~30 mins -> IP4 was found to be >> 1 torr and will need prolonged pumping assistance

Rick, Peter, Gerardo, Dave

We captured the settings of the four PSL models this afternoon and updated the SVN repository safe.snaps. To follow other systems' standards, we renamed the configuration controlled files h1pslxxx_safe.snap and symbolically linked them as safe.snap in the target burt directories.

J. Kissel (after talking with R. McCarthy, J. Oberling, D. Barker, H. Radkins, J. Warner)

The ever useful ISI table optical levers for ISIHAM4 and ISIHAM5 are read out by the susham34 and susham56 computers. As such, one needs to distribute the the lever signals from the SUS computer to the desired consumer on the ISIHAM45 computer via the Dolphin network IPC. A long time ago, h1susmc2 had been determined as the "master" for the susham34 front end, and h1sussrm for the susham56, and therefore in charge of distributing optical lever signals, binary IO interactions, etc. As such, a similarly long time ago, I'd installed IPC senders for these optical lever signals from h1susmc2 and h1sussrm but receivers never made it into the h1isiham4 or h1isiham5 front-end models.

Jason has just now getting around to bringing these levers online, and he's discovered the lack of infrastructure in SEI land.

Realizing the problem and simple fix, I've installed the necessary parts in the top levels of the HAM4 and HAM5 (copied from HAM3, with the appropriate name changes). However, because we're already trying to commission six things at once today (SEI ITMX, REFL WFS, SR2 Coil Balancing, HAM5 HPI), and a DAQ / FB restarted did not sound appealing to anyone, we elected NOT to install and restart the front-end code with the new parts. However, I've confirmed the model compiles and committed it to the userapps repo. These models should be make-installed and the front-end process restarted at the next earliest convenience.

Also -- why don't these optical levers have their screens linked from the HAM ISI overview screen? I notice that the ISI levers are still using Ryan DeRosa's optical lever infrastructure (both in Simulink and MEDM) instead of the generic QPD part that all SUS and ISC use... The generic screen is independently linked from LHO's sitemap for HAM2 and 3.

*ahem*...

8:53 am Sudarshan to X-End VEA, Mic check.
9:38 am Cyrus CS control room, reconnect switch for SUS test stand build up.
10:27 am Travis CS VEA, West bay, SUS test stand.
11:45 am Filiberto to CS VEA, BSC1 connect ACB photodiodes.
1:42 pm Dale + 1 Visitor, CS VEA, tour, then roof.
3:10 pm Jason CS VEA, West bay for ITMY OL.

Yesterday, we found that the multi-ton, white mechanical test stand that the Q6 QUAD was mounted to was out of level.  Eh, it's been a while since we've used it.  So today, Travis rolled up his sleeves and releveled it to the QUAD structure.  All ~3 tons of it.  Don't forget to check the level of the test stand when you mount stuff to it!

Jeff K, Betsy

While the SR2 M3 stage coil had previously been balanced using coil sensors, we tried to use the AS_C PD to repeat the measurement.  AS_C is an in-vacuum PD on HAM6 behind SRM.  Keita helped me center the beam on the PD with SR2 bias.  We then used the SR2 LOCK-IN to drive the SR2 in the pringle mode at 5Hz, with 100k aplitude, at varying coil imbalance states.  Unfortunately we could not see much change in the response when the M3 coils were balanced or unbalanced.  Attached shows the unchanged peaks between the 2 states of coil unbalanace.  SR2 pointing was restored to how we found it when we started.

Things to try next:

- Try on SR3

- Try using AS_B PD - a nearby WFS which does not have a lense in front of it - which maybe caused us a problem

GerardoM and RickS

GUIDANCE FOR A SYSTEM THAT IS ALREADY LOCKED

On the PSL_ISS.adl MEDM screen (see attached image), look at the strip chart in the top-right corner.
The diffracted power level should be about 7%. 
A few percent more or less is OK, but I suggest setting to near 7% at least once per week, say Tuesday during the maintenance period.

To change the diffracted light power, one adjusts the “REFSIGNAL” field in the lower left corner. 
A change in this parameter of 0.01 changes the diffracted power by about 1%, so make small changes.
A larger negative number (say going from -2.00 to -2.01) will decrease the diffracted light level.

This REFSIGNAL field is the DC laser power level (ignoring the minus sign) that the servo compares with
the “Output AC” level on the PD that is selected in the middle-left portion of the screen.

Note that in the screen snapshot the REFSIGNAL is at -2.03 and the PD A Output AC signal is at 2.03.
This indicates that the loop is operating properly; the loop tries to make the PD output be equal to the
reference level (without the minute sign, of course).

Notice that the diffracted light level is varying a bit but is close to 7% on the strip chart. 
At the middle-right edge of the screen the Diffracted Power field indicates 7.38%.  This is the field that is plotted in the strip chart.

GUIDANCE FOR WHEN THE SYSTEM IS NOT LOCKED

In the case that the ISS servo is not locked and you are having difficulty locking it, I suggest the following:

With the loop unlocked (Autolock OFF), observe the PD A AC output level. This may be a bit hard to do if the value is swinging a lot quickly.  
Set the REFSIGNAL level to about ten percent below this observed mean value.
Close the loop (Autolock ON) and observe the diffracted light time series in the strip chart.

If the diffracted light level increases and goes off screen at the top, then your REFSIGNAL setting is too low (absolute value is too small)
so you are not requesting enough light and the servo is trying to diffract a lot of light to give you the low level you requested.
Increase the (absolute value) of the REFSIGNAL field.

If the diffracted light level decreases and goes off screen at the bottom, then your REFSIGNAL setting is too high (absolute value too large)
and you are requesting more light than the servo can give you and still maintain some diffracted light headroom.
Decrease the (absolute value) of the REFSIGNAL field.

Once the system stabilizes, set the diffracted light level to be close to 7% by making small adjustments to the REFSIGNAL value.
Be patient, the time constant is pretty long and small changes make a big difference (on order one or two percent per 0.01 increments in the REFSIGNAL value).

Once the diffracted light level is near 7%, observe a few minutes of the strip chart data. 
The variations should be on the order of what is shown in the attached screenshot.

If all else fails, feel free to call me (Rick) at any hour, any day, and I will try to help over the phone.  My numbers are in the site directory.

Connected photodiode readouts from BSC1 Flange F1-3C1 to Baffle Photodiode Amplifier D1301017 Chassis (SN S1400065) in rack SUS-R5.

Updated the IMC guardian node:

• renamed to IMC_LOCK, in a move towards a more standardized naming scheme.
• specified that a NOMINAL state of LOCKED.
• added indices for all states:

jameson.rollins@operator1:~ 0$ guardutil states IMC_LOCK
100 LOCKED *
20 DOWN *
0 INIT
40 BOOST
30 ACQUIRE
10 FAULT

Screens and links were updated where appropriate (GUARD_OVERVIEW, IMC_CUST_OVERVIEW).

As reported before, ITMY OL is making a huge fake triangular wave motion of 10 minutes period mainly in YAW (CH1).

We know that the optic itself is not moving because we cannot see this anywhere else, e.g. look at CH7 (AS_C QPD) and CH8 (L2 stage OSEM of ITMY).

We know that this is not the intensity noise. The RIN of OL SUM (CH6) for this 10min thing is about 0.3% pk-pk while each quadrant (CH2-CH5) sees two orders of magnitude larger signal. In addition, the phase of SEG1 and SEG4 are the opposite of SEG2 and SEG3.

It appears that  either the OL laser or the receiver or both are moving in YAW (unless the electronics of all four channels are conspiring together, which is very unlikely).

We could not find any apparent correlation between this fake OL motion and various FMCS and PEM channels. AOS people, please investigate.

(Borja)

It has taken me a bit longer than I thought to write back here the final results to proof that the ion pumps are the main chargers of the ETMX and ETMY masses at LHO.

But finally here is the proof. This entry completes my previous entry here. In that entry we saw that when closing the ion pump gate valve at ETMY the charge values for all the quadrants and both orientations (pitch and yaw) became stable. The next obvious question was; what would happen when the ion pump gate valve was opened again?

The answer, shown next, is that the charge in all quadrants begin to vary again as you would expect if the ion pump was the main charger.

The next plots are a summary of all measurements I took at ETMY. The first set of 2 plots is Veff values in pitch and yaw and the second set of 2 plots is the slopes in pitch and yaw respectively. In pink are the set of measurements when the ion pump gate valve was closed (see the stability of the charge for nearly 6 days!) and in red are the measurements when the gate valve was reopened. It took almost a day of having the gate valve open to be able to see charge variations in all quadrants but these changes are considerable. In particular notice the quadrants UR and LL which changed charge from -140 to nearly discharge values. Remember that the labelling of the quadrants in these plots corresponds to the quadrant labelling on the CDS models which does not correspond with the real quadrants being driven. In particular the quadrant labelled LL is actually the driven quadrant UL. Which means that the quadrants suffering higher charge differences when opening the ion pump gate valve are the upper quadrants of the ETMY mass.

The question now is; How can the ion pump have such a quick charging effect in ETMY but we observed no charging effect at ETMX? Again I have the answer here: because we did not wait long enough at ETMX to see the charging effect. Fortunately despite not observing a charging effect in ETMX I did keep taking regular charging measurements on that mass with the ion pump gate valve open for 6 days. Next I plot the summary of all my measurements at ETMX (like I did above for ETMY). The area in pink shows all the measurements with the ion pump gate valve open. It is obvious the charge variations in comparison with all previous measurements at End-X with the ion pump gate valve close. In particular, for the first time at ETMX, we observe negative charges in some quadrants during the time in which the ion pump gate valve was opened.

I have attached to this aLog a compilation of the Veff and slope values for both pitch and yaw of all the measurements I did at End-X and End-Y and the time of those measurements. These data is given as a word file and as a Matlab file for easy operation. I also have included the Matlab figure versions of the above summary plots.

And finally for completeness I have also attached the pdf files with the last set of measurements both at ETMY and ETMX.

(Alexa, Sheila, Keita)

• X-arm locked on green (see Keita's alog 13740 for more detail on alighment).
• We had to realign Green REFL B on ISCTEX.
• We plugged the 24.407079 MHz RF oscillator source back to the RF Amp, with the demod phase at 120.6deg. The ifr was set to some wrong value, and we didn't bother resetting it for now. For reference, the HIFOX configurartion was Mod Freq: 24.407363 MHz, Demod phase: 120.7 deg (alog 10227).
• COMM beat note was well aligned on ISCT1, we measured 1.5Vppk.
• DIFF and COMM demod controls cable was plugged into the wrong slot in the back of the concentrator. (We moved from slot 3 to slot 1).  This is now consistent with the pull list.
• There is a LO mon error for COMM demod. Will investigate tomorrow.

The new H1 ITMs ROC (ITM03 and ITM11) are similar to the ones in L1, but they are swapped (the wavefront error is larger from X than from Y). 

Based on  T1300954 (table 3) and Hiro's wisdom, the effective ROCs of the H1 optics, as measured in reflection, going through the bulk, are:

R_ITMX (ITM03) = 1939.3 + (-10.92*2*1.457); 
R_ITMY (ITM11)= 1939.2 + (1.56*2*1.457);

By looking at the L1 data in single bounce without TCS (below), one should expect something like ~20% mode mismatch for X and something somehow better for Y.

L1 Mode mis-match:
NO TCS:
ITMX    14.5%
ITMY    22%

Even with an input beam perfectly matched to the PRM, I would expect something like:

modematching asX with OMC = 0.8408
modematching asY with OMC = 0.91229

[Dan, Nic, Koji]

After we tamed the OMC QPD spot motions by the alignment servo, we turned on the high voltage supply
as the vacuum pressure allowed to do that.

Then we did notice that the OMC is already locked. WHAT? Did we miss the most exciting moment!?
Well, it was okay. It was a higher order mode. We shifted the PZT offset and locked at the highest peak that gave
us about 13mA total current.

We went down to LVEA and checked the mode shape. Yes. It was TEM00.

Statement: The OMC was locked

The position of the OMC trans spot was checked at ISCT6. Unfortunately the spot was hitting a pillar of the ISCT6 enclosure.
It is not nice to make a hole on the pillar. We probably need to move the table and think carefully how to connect the tube
to the table enclosure...

The OMC REFL with the best alignment looked a bull's eye as we suspected (attached photo #1). Dan is now measuring the mode scan for the mode matching ratio.

For the celebration, Nic cut open an OMC locking cantaloupe. Thanks Gerardo!