Editing: Daniel pointed out that I got the wrong pdf of the results, and reported the contrast defect from the wrong measurement. Corrected homodyne angle and the correct PDF are attached now.

I used Craig's scripts from labutils (also in gitcommon/labutils) to change the pcal lines and to sweep the darm offset for a contrast defect measurement.  I added an additional DARM offset step of 11 (40mA) to the list of steps that was in the code. 

to run this:

• cd /ligo/gitcommon/labutils/darm_offset_step/
• python set_up_pcal_for_darm_offset_test.py
• python DARMOffsetStep.py
• open the plotting script (plot_darm_optical_gain_vs_dcpd_sum.py) and add the filename of the log file the above script created, along with a description to the list of filenames and descriptions. 
• conda activate labutils
• python plot_darm_optical_gain_vs_dcpd_sum.py

Attached is a screenshot of the OMC trans camera when the DARM offset was at it's lowest setting, with 8.3mA on teh DCPDs.  It does not look like a 00 mode.  This camera was realigned a few weeks ago 70875, which may explain why we didn't notice this before, it could be a camera artifact.

The contrast defect seems to be 1.6 mW. Following Vicky and Craig's alogs 68870:

contrast_defect = 1.6 mW
total_dcpd_light = 46.6 mW
darm_offset_power = total_dcpd_light - contrast_defect = 45 mW

homodyne_angle = arctan2(sqrt(contrast_defect), sqrt(darm_offset_power))
homodyne_angle = 10.7 deg

In summary, the low frequency noise is improved and more stationary with the new CHARD_Y higher gain controller and reduced test mass damping gain in yaw. Also, the glitch rate is largely reduced.

Effect of new CHARD_Y controller

A new controller was designed based on the previous measurement of the CHARD_Y plant. This controller is implemented in FM9 (as an additional module that can be switched on with the other modeles). This can be engaged with the nominal gain of 60, and then the gain can be increased up to a factor 3 to 180. After a few tests I found that a gain of 100 seems ok, higher gain increase the amplification of a 3.4 Hz narrow peak. The amplification is expected due to a broad gain peaking of the new controller. However, the peak itself is already there and not related to the CHARD_Y controller. If we manage to track down the origin of this peak and improve it, we could increase the CHARD_Y gain even more. As it is now, more gain doesn't improve much the CHARD_Y RMS because of this 3.4 Hz peak.

With this new configuration, the CHARD_Y RMS is significantly reduced around 1 Hz (no more gain peaking) and 2-3 Hz (more suppression).

Effect of reducing the test mass damping gain

With the new controller in place, I repeated the old test of reducing the test mass damping gain in yaw. I realized that the 1 Hz oscillation I saw in my previous attempt was due to the CHARD_Y gain peaking at 1 Hz getting worse. the new controller solved this problem. Indeed, I could reduce all test mass damping gains from -1.0 to -0.5 without problems. This improves a bit the CHARD_Y motion, and improves significantly the DHARD_Y motion. So it's a good change to have.

I also tried to reduce the PR3 M1 yaw damping gain, since CHARD_Y was coherent with PR3 damping, but I did not see much of an improvement.

Noise improvements

Those changes were left overnight, and the noise was much better. On average, the DARM noise below a few tens of Hz is lower. The main difference is the disappearence of most of the non-stationay noise, as visible in a spectrogram. Comparing the omicron glitch plots from before and after the change, the number of glitches in the 20-50 Hz region is much lower.

Next steps

I suggest we leave the new CHARD_Y controller with a gain of 100 as the default configuration. I also suggest that we run with reduced test mass yaw damping. I would leave the PR3 damping at -1. I would also keep the current value of -1.50 for ITMY Y2L gain.

Next things to check:

• Compare the CHARD_Y plant with the reduced damping gain with the one with nominal gain. I noticed that the 1 Hz peak is increasing, so there might be a change in the CHARD_Y plant due to the change in damping  gain. This is expected. We might want to re-measure carefully the CHARD_Y and DHARD_Y plants and further improve the controllers with reduced test mass damping.
• Find the origin of the 3.4 Hz peak that would be limiting the CHARD_Y RMS wiht higher gain. Also, maybe worth trying to increase CHARD_Y gain all the way to 180 and see if things are better or worse
• Look into the Y2L decoupling. More details in another alog entry, but it is evident that there are two coupling paths from CHARD_Y to DARM: one with a steep frequency dependency below 20 Hz, and one flat-ish above 20 Hz. Changing ITMY Y2L coefficient changes the two paths in opposite directions

TITLE: 08/03 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 145Mpc
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 3mph Gusts, 2mph 5min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.04 μm/s
QUICK SUMMARY:

• 14:06 lock time
• CDS/SUS/VAC/Dust/SEI looks good

TITLE: 08/02 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Commissioning
SHIFT SUMMARY:

Most of the action was at the beginning of the shift.  Commissioning work ending, a lockloss, recovery, and then sorting out post-comissioning items as well as calibration issues.  Happily handing off a nicer H1 to Tony tonight!  (Also saw/heard group of 5 coyotes at "lunch" time.)
LOG:

• continued:  H1 COMMISSIONING for CHARDyaw meas (Gabriele)
• 0001 Lockloss (nothing obvious environmentally & Gabriele didn't think it was his measurements either since H1 was OK for minutes before the drop.
• 0157 Back to OBSERVING
• Road out earthquake from 0143 - 0211.

After a lockloss and more Commissioning time, then needed assistance from Louis & JeffK to restor Calibration Lines (i.e PCal x&y).  Once all of this was complete H1 rode out an earthquake and has been observing for just over 1hr (and been locked 2+hrs).

....Back to OBSERVING just as a M5.9 Panamanian earthquake rumbles!

(Louis, Jeff K, Corey)

After addressing Gabriele overnight test SDF Diffs, now had alot of SDF diffs for CALEX & CALEY (basically PCAL channels).  And on the DARM FOM, could not see any (green) PCALy lines or (pink) PCALx lines.  At this point, started working with Louis on TeamSpeak and he started texting Kissel.  Below is what I did (via Louis instructions) for the CALEY & CALEX SDF nodes:

H1CALEY:

• 26-Diffs were listed
  • I forgot to take a screenshot of this before REVERTing, but attached is a photo Louis sent to me.
• REVERTED all 26 Diffs
• Clicked on "SDF RESTORE SCREEN" on CALEY
• Then on this window, Clicked "! SELECT REQUEST FILE"
• In pop-up window, selected "safe.snap" & clicked OPEN (this closes pop-up)
• Then on SDF RESTORE SCREEN, clicked "LOAD TABLE" and after a couple secondsit looks like the safe.snap was updated with a time stamp of Aug 2, 2023 at 18:25:59 (PT).
• With Louis on the phone texting with Jeff, we think we are good....we have green PCALy lines on DARM FOM.

H1CALEX:

• 16-Diffs were listed
  • see attached screnshot
• REVERTED all 16 Diffs
• Clicked on "SDF RESTORE SCREEN" on CALEX
• Then on this window, Clicked "! SELECT REQUEST FILE"
• In pop-up window, selected "safe.snap" & clicked OPEN (this closes pop-up)
• Then on SDF RESTORE SCREEN, clicked "LOAD TABLE" and after a couple secondsit looks like the safe.snap was updated with a time stamp of Aug 2, 2023 at 18:34:18 (PT).
• Louis continued texting with Jeff.  The pink PCALx on DARM FOM might look odd....waiting to see what Kissel thinks.
• At this point, Louis and Kissel took over to restore PCALx....so I think we are about ready to go back to OBSERVING

Several CHARD_Y tests today during the commissioning time. A more detailed analysis will follow.

Went go to NLN_CAL_MEAS

## Test new CHARD_Y ##
- load new filter OK
- engage with gain 60 OK
- gain increase to 100 looks OK: what is that big peak at 3.x Hz? It's not gain peaking of the CHARD_Y loop

## Check A2L ##
- inject line at 22.1 Hz and check demodulation of DARM. Large fluctaations, hard to tune
- inject noise [CHARD_Y noise ampl 20  butter("BandPass",6,10,100)]
  coupling at low frequency changes differently than high frequency (-1.50 is a good compromise). Also, 22 Hz is right at the transition between the two noise coupling regions

## Test Mass damping ##
- reduce gain looking at TM signals and also CHARD_Y DHARD_Y

all test mass M0 Y gains to -0.5
from PDT: 2023-08-02 16:23:37.085598 PDT
     UTC: 2023-08-02 23:23:37.085598 UTC
     GPS: 1375053835.085598
to   PDT: 2023-08-02 16:32:40.068152 PDT
     UTC: 2023-08-02 23:32:40.068152 UTC
     GPS: 1375054378.068152

left gains at -0.5

## PR3 damping gain reduction ##
M1 Y damping gain to -0.5
from PDT: 2023-08-02 16:33:56.677335 PDT
     UTC: 2023-08-02 23:33:56.677335 UTC
     GPS: 1375054454.677335
to   PDT: 2023-08-02 16:44:18.190283 PDT
     UTC: 2023-08-02 23:44:18.190283 UTC
     GPS: 1375055076.190283
     
Lowering the damping gains might have changed a bit the plant? Measured another CHARD_Y plant [saved CHARD_Y_shaped_exc_2023_08_02.xml]

I've spent a little more time working on the HAM1 ground to HEPI feedforward and did another test. I can get pretty good improvement on the HEPI L4Cs, but it doesn't make much of an improvement on the interferometer. DARM doesn't see any improvement, but CHARD P sees a bit of an improvement over 5-10hz, see attached plot. Top is the table HEPI Z L4Cs, middle is the tabletop L4Cs,  bottom is CHARD P. For each, red is with the FF on, blue is with the FF off. The HEPI and table top L4Cs see some reinjection 1-2hz, but this doesn't show up in CHARD. CHARD P does see a not quite factor 2 improvement at 8hz.

I haven't had a chance to see how this interacts with the HAM1 TT to ASC feedforward, but that, I think, is generally a bit higher in frequency.

I've talked to Jenne and Sheila, I'm going to leave it on overnight to get some good low frequency measurements.

If there is concern this is somehow causing problems (it really shouldn't!) it can be turned off by setting the gain to 0, in a terminal :

caput H1:HPI-HAM1_3DL4C_FF_Z_GAIN 0

The new gain would then need to be accepted in SDF. But, this really shouldn't hurt anything.

TITLE: 08/02 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Commissioning
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 16mph Gusts, 14mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.04 μm/s
QUICK SUMMARY:

Arriving to an H1 still locked from lockloss recovery I handed over to Tony at the end of my shift.  And Ryan C filled me in on H1 also currently being in COMMISSIONING (mainly while L1 was out for logging & storms...but they appear to be back to NLN now though).

Jim also mentioned there is a changed status for HAM1's HEPI for a new L4C servo he is testing out (it will be kept in and he ACCEPTED sdfs).

94degF and mild (under15mph) winds.

Now to catch up on chat to see how things are looking/going.

TITLE: 08/02 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Commissioning
SHIFT SUMMARY: Lots of squeeze work today, and some other comissioning items (HAM1FF, CHARD_Y controller, contrast defect...), handing off to Corey with a locktime of 15:06

From 15:00 to 16:00 there was some work going on in the MSR, including moving items and cables (tagging DetChar). The MSR racks' 1 & 2 temperatures saw an increase in temperatures seeming to correspond with the times the work was being done, rack2 had a sharp increase, but it was colder than nominal beforehand and now seems to have settled around its nominal temperature (22C).

• Out of Observing at 16:00UTC for squeeze work back into Observing at 19:54 UTC
• We went out of Observing again for more planned comissioning at 22:00UTC which is still ongoing as of 23:00UTC

LOG:            

Sheila, Naoki, Vicky -- SQZ data with FIS and FDS.

NLG~11.0 (Gen SQZ=14.7dB), according to calibration from OPO_TRANS = 80 uW (this calibration is reasonably accurate).

Started 8:05 hours into lock. 3-4 hour set of measurements. Data times in bold.

Total change in squeezer configuration: SQZ angle has changed from 145.2 --> 150.2 deg.