Looking over the past 3 weeks of data for the Laser Room temperature, the attached plot shows 4 deviations
from the norm.  The first two coincide with maintenance activities carried out by Jason and myself.  The
third from the left by Cheryl and Robert doing some IO work.  The fourth one from the activity this week.
Each incursion results in a change in the pre-modecleaner body temperature with perhaps the largest change
occuring this week.

Since most times we probably touch up the pre-modecleaner alignment a little, this probably masked the
effect of the pre-modecleaner body length change on the alignment.

This is a follow up to this entry about the excess noise in the EX TR QPD signals.  The OSEM fix did not help this, so they seem to be unrelated.  I looked at the PIT and YAW signals, and found that they are very coherent with SUM in the 5-100 Hz band where the excess noise appears (plot 1), and that the phase of the transfer function in that region is 0 (e.g., SUM, PIT and YAW all have the same sign and phase).  This appears to point to a problem in segment 1, though I cannot confirm that with offline data.  I looked at the OUT16 channels for all segment and didn't see anything obviously wrong (plot 2).  Interestingly, the same signal appears in QPD A and B, so this is not a single channel problem.

To do: investige the individual segment signal in the online data... is this just sement 1?

Most of the night IFO was with commissioners.

Earthquake about 2 hours ago kept us from relocking for a while.

IFO has made it through to Engage ASC a few times, so transition to CARM is ok.

I've been having the IFO sit in Engage ASC, which I thought was very stable, but it has not been this morning, and we have not had any locks that are long or that make it up to DC Readout+.

The main story of the day is related to the non stationary low frequency noise first seen early in the morning. It seems to come from CHARD noise, which could be coupling to DARM more now because of a change in alignment.   

• Once we were stable at 24 Watts this afternoon, we didn't see the terrible low frequency noise that was seen in the early morning (at least it was not as bad).  
• Jenne and I worked a bit more on the CHARD loops, adding 23 Watt boosts, a lead filter that gave us some phase to make cut offs.  The first attached screen shot is a comparison of CHARD PIT at 3 Watts, and at 24 Watts before and after the changes.  Jenne has similar measurements for yaw.
• The terrible low frequency noise came back.  
• We undid all of the CHARD changes we made yesterday and this afternoon(keeping only the leads and cut offs) .  The terrible low frequency noise did get better, although some extra non stationary low frequency noise remains below 50 Hz.  The non statinary noise was reduced when we did this, although we still had some excess non stationary noise below 50 Hz, and coherence with CHARD.  We did another round of on/off test to be sure CHARD was involved.  
• We decided to check on alignments that we thought moved durring monday's PZT power off and PSL temperature excursions.  We could see that we had moved on IM4 trans after monday, so in full lock we moved IM3 to bring ourselves back to the old location on IM4 trans.  
• We then redid inital alingment, carefully, and relocked, using the low bandwidth CHARD loops and our new cutoffs.  After this the noise does seem better, but there is still excess noise that is non stationary.  

A few ideas for next steps:

• see if we can find a better CHARD sensor.  Do we need to use trans mon QPDs or is there a way to find a better SNR on the refl WFS?
• can we do a better job with A2L?
• We could try to change our alignment to see if we can reduce this noise.
• DHARD resonant gain for the 0.46 Hz instability.  This instability only seems to come up when we have a bad alignment, but a little more gain can probably help us avoid it. 

We also worked on a few other things today...

• Between Evan and I we reverted the phase of the 45 WFS to what they were a week ago (before TCS tuning)
• Gabriele and I saw this morning that we think that a SRC1 YAW input matrix of -3 for AS A 36 I and no signal from AS B is good.  We watched all of the AS 36 Yaw signals as we powered up to 17 Watts, and saw that AS B sees something that drifts as we power up.  When we removed AS B from the input matrix, the AS 90 power increased.  
• The SRC2 Yaw loop was painfully slow (several minutes reaction time).  It now has a factor of 2 more gain (-40 is fm gain now, it was -20 before).  This is in gaurdian. 
• Gabriele had a look at doing frequency dependent A2L for ETMX.  We have reverted it for now, but it seemed promising. 
• Our locks today seem quite stable, we have been loosing lock by making mistakes, and when we have a combination of driven measurements and PEM injections.  
• ETMY ESD LP had been turned off at some point, most likely unintentionally.  It's on again, and now monitored in SDF.  We also turned the PUM coil drivers back to their low noise state.  We needed more range for DHARD when the roll mode was rung up very badly last week (because of DOWN not runnning for extended of periods of time twice.)  These were a mixed bag of monitored and not in SDF, I think I've set them all to monitored now, with the requested state as 3.  However, this gets over written by the gaurdian.  
• I had put offloading of full lock ASC in the normal guardian path, but this seemed to make the DRMI alingments for relocking worse (possibly because the full lock ASC is compensating for some wire heating).  So it is now removed from the normal path, but can be choosen as an option after transitioning to DC readout.  

I ran Hang's latest A2L script (see aLog 20013), after the realignment work that was done tonight (Sheila is writing up her entry as I type). 

We stil have excess noise at low frequency, but maybe there's a bit less than when I started the script?  The noise we're seeing is totally non-stationary, so it's hard to say.  Certainly the A2L didn't eliminate it.

Dan, Nutsinee

Tonight we identified and damped more ITM first harmonics.

They will be added to the violin wikipage.

All Times in UTC

• Beginning of the shift:  Various commissioning activities going on
• 23:29 (UTC) (16:29PT):  Violin work (Nutsinee)
• 0:45 (17:45):  PEM injection work in LVEA (Robert)
• 5:30 (22:30):  ITMy Roll mode damped
• Did some work learning how to run current lockloss tools.  Added some info about the lockloss tool to the Useful Scripts wiki.

(Dan, Corey)

Around 5:30UTC (22:50PT), Dan noticed a rung up roll mode on DARM spectrum, and from the Bounce/Roll monitor, the culprit was ITMy. 

Brought up the bounceroll.stp StripTool from the Ops Template & could see ITMroll channel high.  From the ITMy SUS screen, opened the DARM BR DAMP filter bank screen.

Initial Values:  -60degrees & a gain of +40.

New Values:  +60degrees & a gain of -80.

This took care of ITMy, and should be fine for this current lock.  Whether we want to keep ITMy like this remains to be seen.  Should see how we look after a few locks.

After the PSL temperature adventure on monday afternoon, it seems as though the PMC alignment shifted.  We now get less transmitted power, although the sum of refl and trans has not changed much. 

FRS 3247

The h1hwinj0 computer has been renamed to h1hwinj2. 

Scott L. Ed P. Rodney H.

8/11/15
After filling the water tank, the crew moved the fans and re-strung the lights. 45 meters of tube and bellows were cleaned ending at station HSW-2-012. Cleaning results posted here.

8/12/15
60.6 meters of tube and bellows cleaned ending at station HSW-2-009. 

I took a look at the scattering noise we see in all lock since last night .

I computed the band-limited RMS between 20 ans 120 Hz, and this is a good indicator of the scattering noise level. Then I looked at correlations with all suspension motions (using M0 and M1 signals, as Keita did for the OMC).

So I'm able to reconstruct the noise variation over time, using a linear combination of all the suspension signals and their squared values. However, I'm not able to pick point one single mirror which is moving more, as shown in the ranking of the most important channels for the BLRMS reconstruction.

I compared the suspension motion spectra from tonight (GPS 1123422219) and few days ago (GPS 1123077617). The most relevant difference is that all test masses YAW motion have now a large bump at 3 Hz. ITMY also has large lines at 0.45 and 0.63 Hz. Finally ETMY pitch shows a large line at 6 Hz and some excess noise above that frequency.

Not sure if all of this is really relevant...

Some random commissioning tasks from tonight:

LSC rephasing

In full lock, the phases of POP9 and POP45 were adjusted to minimize the appearance of PRCL in POP9Q and the appearance of SRCL in POP45Q. Then the input matrix element for POP9I→SRCL was tuned to minimize the appearance of a PRCL excitation in the SRCL error signal. New settings attached.

We should take a sensing matrix measurement sometime soon.

LSC OLTFs

I took OLTFs of PRCL, MICH, and SRCL. The data are attached.

[I also did some noise injections into CARM for frequency budgeting purposes. Those are attached too.]

Front-end LSC triggering

Jamie and I started this a few weeks ago, and now it is completed.

There are occasions when the DOWN state of the ISC_LOCK guardian (which, among other things, turns off feedback to the suspensions) is not run immediately after a lockloss (e.g., because the guardian is paused or in manual mode). Therefore, Jamie and I set up the LSC trigger matrix so that PRCL, MICH, SRCL, DARM, and MCL are turned off if POP DC goes below 100 normalized counts. This is set in the DRMI_ON_POP state.

CARM gain redistribution in the Guardian

The state REFL_IN_VACUO now redistributes the CARM gain slightly in order to improve the noise performance of the CARM loop. This state has not been tested and has been left commented out.

I looked into the glitches created by Robert's dust injections. In brief: some of the glitches, but not all of them, look very similar to the loud glitches we are hunting down

Here is the procedure:

1. select all drops of the range in the two hours of injection
2. for each one, load three minutes of data, compute the 30-300 Hz BLRMS and find the glitch tims as the maximum of the BLRMS peaks

In this way I could detect a total of 42 glitches. The last plot shows the time of each glitch (circles) compared with the time of Robert's taps (horizontal lines). They match quite well, so we can confidently conclude that all the 41 glitches are due to dust. The times of my detected glitches are reported in the attached text file, together with a rough classification (see below)

I then looked at all the glitches, one by one, to classify them based on the shape. My goal was to see if they are similar to the glitches we've been hunting.

A few of them (4) are not clear (class 0), some others (14) are somehow slower than what we are looking for (class 3). Seven of them have a shape very close to the loud glitches we are looking for (class 1), and 16 more are less obvious but they could still be of the same kind, just larger (class 2).

See the attached plots for some examples of classes.