Thermalization guardian commented out of ISC_LOCK for now.

Reverted the change to ITMY A2L gains from 69082

I've turned *ON* the "thermalization" calibration lines, via the CAL_AWG_LINES guardian for this power up, in order to track the thermalization of the sensing function during a 60W power up (we did not turn on these lines until we were regularly at 75W, so we don't really have as clear of an analysis [e.g. LHO:69593] of the thermalization behavior during 60W)

Recall, the eight line frequencies (the highest at 24.5 Hz) are listed in LHO:69284.

They've been on and running since 2023-06-21 15:18:04 UTC.

Note, I have *not* recoded this up to be turned on automatically in ISC_LOCK, as I hope that we'll get a few thermalization runs during these next two 8 hour periods, and I'll be present for them.

As per discussion in LHO:70650, I've edited 
    /opt/rtcds/userapps/release/isc/h1/guardian/
        lscparams.py
in order to change the hard-coded value to which we set the SRCL offset, changing it from -265 [ct] that we've been using at 75/76W PSL input power, to -175 [ct] which we'd used at 60W PSL input power. This is line 526 (at the time I edited the params):

    offset = {'SRCL_MODEHOP':-800,
              'SRCL_RETUNE':-175  # updated 20230621
             }

While we're not confident this is the perfect value, it's certainly a fine place to start.

Reverted LSC FF filters, as noted by Elenna's config alog.

SRCLFF1 again uses FM2. MICHFF again uses FM6-9.  PRCLFF gain is commented out (so, should be left at zero from Down).

PRCL OLG measured after the loop changes in LOWNOISE_LENGTH_CONTROL

Sheila measured the PRCL OLG, having left the 'new' filters in place, and letting lownoise_length_control set PRCL1 gain to 6, and not using the thermalization guardian.

Our UGF is about 25 Hz, so a little lower than the target of 30 Hz, but stable and fine.  We'll re-check after a while of having been at full power.

Lowered CARM gain by hand by 6dB (lowered H1:LSC-REFL_SERVO_IN1GAIN and H1:LSC-REFL_SERVO_IN2GAIN by 1dB each, alternating, until I was down on each slider by 6dB).

When we just ran through LaserNoiseSuppression, we saw lots of excess noise, and Sheila measured the highest CARM UGF to be around 27 kHz, which is too high.  We the lowered the overall gain by 6dB.  Not yet in guardian.

EDIT: Lowering by 6dB brought our lowest UGF to ~12kHz, too low.  We re-increased by 3dB, so that in the end we've only reverted the 3dB increase that Elenna mentioned in the config alog.

EDIT2: this is now in guardian.

PRCL OLG remeasured longer into the lock, and the UGF was quite low.  I increased the PRCL1 gain to 10 (from the nominal, without-thermalization-guardian, 6), and the UGF is back to 30 Hz. 

We can likely afford to just put this gain of 10 into lownoise_length_control, but that would put our UGF at the beginning of the lock at 37 Hz with 24 deg of phase margin.  Probably fine, but much higher starts to be not fine.

I increased the gain of the SRCL FF (and measured that I did not need to change the gain of MICH FF).

Attached shows the reduction in coherence with SRCL when the gain of the SRCLFF1 filter bank is set to 2.1 (rather than 1.0). Blue is the old coherence, green is the updated coherence.  You can see that if we want to keep the coherence reduced at lower frequencies, we'll have to make a frequency-dependent change to the feedforward, but so far this at least helps.

I did this by injecting noise into SRCL (by just using the SRCL OLG measurement template's excitation, just set to exponential rather than fixed averages), and changed the feedforward gain until the noise in DARM seemed minimized above 30 Hz.  I did the same also for MICH, but found that the existing gain value of 0.97 was already the best.

This means that I incidentally got SRCL and MICH olg measurements, which are the second and third attachments.

Accepted FF-related SDFs.  Also accepted PRCL1 gain at 2 sec, since the thermalization guardian is off and won't set it to 30 sec.

Not shown, I also accepted the OAF-WHITENING gain at zero (which means that there's no NonSENS cleaning going forward).

Another PRCL measurement, UGF is just a bit under 30 Hz.

Sheila plugged in the SR785 to the ISS second loop chassis similar to the photo in alog 61721.

Keita confirmed that Err1Mon is equivalent to our digital filter banks' In1 (so, before the excitation), and Err2Mon is equivalent to In2 (so, after the excitation).  The excitation BNC is likely the one plugged into the port under Err1Mon on the photo.

And, since the two monitor points have different gains, the UGF of the loop should be read off of the TF at the -20dB line.

With the ISS second loop gain H1:PSL-ISS_SECONDLOOP_GAIN at the 75W value of -5 dB, Sheila measured that we had a UGF of about 17kHz.  With the gain increased to -2dB, we have a UGF of about 21.7kHz.  I've accepted the value of -2dB into SDF.

Attached is a photo of the SR785 with the IFO at 60W and the ISS second loop gain at -2dB.

We've changed the PRCL1 gain in lownoise_length_control to be 10.  Since this means that we don't need the Thermalization guardian, we'll just leave that in IDLE, and TJ has set it's nominal to be IDLE (see alog 70694).

Sheila has written a separate alog 70692 for what to do if this is too much gain for PRCL at the beginning of the lock.

I did a simple caget to find out what the values of H1:LSC-SRCLFF1_GAIN & H1:LSC-SRCLFF1_TRAMP and a caput to change the gain to 2.1. 
After the change I saw a noticable increase in SENSMON Range.

IFO Current Status : NOMINAL_LOW_NOISE & OBSERVING  with a range of 140.6 Mpc

This is a photo of the CARM OLG measurement refered to in 70662