TITLE: 04/10 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Jim
CURRENT ENVIRONMENT:
    Wind: 19mph Gusts, 16mph 5min avg
    Primary useism: 0.07 μm/s
    Secondary useism: 0.22 μm/s
QUICK SUMMARY:  H1 lost lock at 15:01 UTC, possibly related to Safety System issues that Richard is currently working on. 

TITLE: 04/10 Owl Shift: 07:00-15:00 UTC (00:00-08:00 PST), all times posted in UTC
STATE of H1: Observing at 93Mpc
INCOMING OPERATOR: Travis
SHIFT SUMMARY:
LOG:
11:20 Starting suite of cal measurements

13:30 Cal measurements done, back to observing

14:30 Safety system has some sort of failure, killing all of the lasers except for the PSL, Richard is on the floor trying to fix it

I was left with a small novel describing some calibration measurements that needed to be run. I tried to follow Jeff's instructions, but I don't think everything ran as it was intended. Two measurements described as "Sensor measurements", one doesn't look like the reference and the other doesn't look like it actually ran the excitation properly.

2019-04-10_H1DARM_OLGTF_5to1100Hz_30min.xml <-- this TF is just flat and doesn't look like it actually went.
2019-04-10_H1_PCAL2DARM_TF_5t1100Hz_15min.xml <-- this looked like it ran, but the measurement doesn't look like the reference.

Everything else seemed to go okay, other than the implied times in the file names didn't seem to actually reflect how long the measurements would take. Often a "25min" measurement was more like 10 minutes. I've saved all the new data as requested and left all the measurements up on the workstation that was set up for the measurements.

IFO just relocked, there are some SDF difffs, that I'm not sure the origin of. The ADS diffs I know come from TJ struggling with wind induced scattering, but there is an MC2 M3 LOCK L filter changer and a SQZ LO SERVO SLOWOPT. Near as I can tell, things are otherwise fine, so accepting to go to observe.

TITLE: 04/10 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Aligning
INCOMING OPERATOR: Jim
SHIFT SUMMARY: Winds were a problem the entire shift, but might be at a managable level now. I just finished an initial alignment and will hand off to Jim.
LOG:

• 2330 Betsy, Nicole From MY to MX
• 2340 Georgia, Danny to LVEA to check CO2Y mask
• 0030 Betsy, Nicole leaving MX
• 0430 Reached NLN
• 0509 Observing but with increase ADS lines
• 0545 Lock loss

The wind is causing a scatter shelf larger than the ADS lines much of the time, so it was suggested that I turn up the ADS lines. I accepted the larger lines in SDF so we could go to observing for a bit.

Other things I had to accept in SDF:

LSC - Not sure about these, didn't see anything in a alog about it.

CALCS - For the measurements that I will be taking after we thermalize, I was instructed to change these, but it seems that they were already accepted as changed at some other time. Accepted in this configuration for now.

ASC - The larger ADS lines

We've measured the DARM plant to have a prospring at 6 Hz and a Q of about 4. About the spring frequency, the phase goes through around -90 degrees, and not the expected +180 degrees alog 48083 

This +180 degrees is not typical for causal control systems, but it is expected from SR IFOs as discussed in Section II B from BnC.

Using the Ward DARM model (Eq 3.83) I was unable to achieve a satisfactory fit of the H1 DARM plant at low frequencies, so I made some sliders to see if I could get a heuristic match.  I was not able to for reasonable IFO parameters.

I discovered that our Q is far too low given our optic transmissions.  One can lower the Q of the optical spring by increasing the SRM transmission or reducing the ITM transmission.  However, changes to these parameters also change the frequency of the optical spring and the DARM pole.  The pictured plot shows the best Ward model I was able to come up with to explain the current plant, featuring detuning of -0.5 degrees.

DARM Plant Measurement
I began questioning the measurement itself, but the procedure is pretty simple.  A PCAL to DARM measurement gives C/(1 - G), where C is the DARM plant, and G is the DARM OLG.  Then a DARM OLG is taken to get 1/(1 - G), and these two measurements are divided to give the DARM plant C. 
 
The PCAL calibration into meters is just two real poles at 1 Hz.  This has phase of -160 degrees at 6 Hz, i.e. there is some dynamic phase rotation happening at LF due to the calibration which may not be real.  

We had several locklosses early in the CARM offset reduction sequence tonight. In the CARM_150_PM state we servo the ASC_AS_A_RF45_Q_SUM_NORM to zero using the DIFF_PLL_OFFSET. In the past Sheila and I have lowered the gain on that servo (set in guardian) as it seemed to be injecting noise and causing locklosses.

I had a look at these channels and it seems like turning the servo on is not helping to stabile AS_A_RF45. Something in this process needs retuning for these windy conditions (see attached screenshot).

The gain is nominally 0.004 (ISC_LOCK guardian line 1587), I tried decreasing it, and while we did survive a little longer we still lost lock shortly afterwards. I tried increasing it, and we did make it through the state, so I am leaving it at 0.01.

Do we actually need this servo? If this state continues to cause locking issues perhaps future operators could just comment out line 1598 of ISC_LOCK and see if just not turning it on helps.

Georgia, Danny

With different ITM spot positions we have changed how the point absorbers contribute to the overall optical path distortion. This makes the first CO2Y mask design (Mask 1) less helpful, Aidan designed a second iteration of the CO2Y mask (Mask 2) in order to better accommodate for the new optical path distortion. We installed this new mask today into the annular mask beam flipper.

We believe the mask should be installed in the flipper as indicated in the first figure. 

Some notes on the installation of Mask 2:

• Based on the installation orientation, we think the major axis of the elliptical aperture may be along the wrong axis. 
• Installation with inital flipper position
  • Attached FLIR images show some centering differences between Mask 1 and Mask 2 after initial installation.
  • Measured optical path distortion after turning the CO2Y on with Mask 2. (.9 W of CO2 above nominal)
• Translated the mask to acquire better overlap of the aperture positions between Mask 2 and Mask 1
  • Some FLIR images showing the new centering differences after translating
  • Measured optical path distortion after translating Mask 2 (2W of CO2 above nominal)
  • It looks like we translated the flipper to far in the vertical direction (Horizontal on the HWS).
• We still need to adjust position and mask rotation before testing. 

Jenne, Craig

We are wondering why our range did not go up when we increased the power from 30 to 35 watts.  
Assuming responsivity = e λ / (h c) = 0.858 A/W, I used the 330 Hz PCALY line to find the optical gain today (April 9, 2019) and before the 30 to 35 W power input increase (which happened March 18, 2019):

35 W DARM Optical Gain = 3.87 mW/pm
30 W DARM Optical Gain = 3.71 mW/pm
Optical Gain Increase = 4.3 %


I checked the actual input power measured according to IM4 as well:

35 W Input Power = 30.8 W incident on PRM
30 W Input Power = 26.5 W incident on PRM
Power Input Increase = 16.0 %


We servo the DARM offset to always keep 20 mA on our OMC DCPDs.  DARM offset decreases like the sqrt(Antisymmetric Power) increases: Pas ~ DARM offset2:
35 W DARM offset = 10.1 pm
30 W DARM offset = 11.0 pm
DARM offset Decrease = 8.1 %


Checked the power recycling gain:
35 W PRG = 45.0
30 W PRG = 46.3
PRG Decrease = 2.8 %


According to Kiwamu Eq 11, DARM optical gain goes like
dPas/dLDARM = 8 * k2 * Input Power * DARM offset * PRG * Signal Recycling Gain * Arm Reflectivity Derivative

where 
k is the wave number 2π/λ
PRG = (tPRM/(1 - rARM * rPRM))2
SRG = (tSRM/(1 + rARM * rSRM))2
Arm Reflectivity Derivative = drArm/dφ = ( tITM2 rETM / (1 - rITM rETM)2 )2 


DARM Optical Gain goes linearly with PRG, DARM offset, and Input Power.  From the changes above, we find our DARM optical gain should have increased by around 4 %.  This is pretty much what we see.

So why didn't the range increase?  My guess is, it did, but on the night of the power increase we didn't see any immediate improvements due to bad spot positions and TCS for higher power. 
Later with the calibration changes and other commissioning tasks happening at the same time we got confused about what our range really was.  
In any case, we did win with the power increase (after ~month of ASC/TCS commissioning), and we have no reason to believe that going up further would not help us.

Shifter: Sumeet Kulkarni

Fellow/Mentor: Greg Vaughn-Ogin

• The overall duty cycle was 73.6% Observing at a BNS range of ~110 MPc.
• There was a large amount of low-frequency scattering persistent around 10 Hz. band throughout. The noise levels dipped on Wednesday, April 4 from 10:00 UTC up until 3:00 UTC on Thursday, April 5 (Seen before during ER13 (alog47931). These glitches were picked out by HVETO from the Output Mode Cleaner ASC POS_Y and POS_X channels.
• Loud glitches appeared at a significant rate (compared to O2) throughout and were picked out prominently by the witness channel H1:LSC-POP_A_LF_OUT_DQ in HVETO.
• High winds and microseism lead to increased scattering at around 30 Hz. and loss of lock on April 6 and 7. alog48288
• Three Earthquakes were logged: 2 lead to lock loss (on April 5 and 6) and one did not affect the re-locking stage (April 7). alog48262 alog48288 alog48302

Complete details can be found at https://wiki.ligo.org/DetChar/DataQuality/DQShiftLHO20190401

Nutsinee Daniel

Plot 1 shows the open loop gain of the servo. Blue and brown represent the original TF using the OPO TRANS and REFL as error signals, respectively. Ugf is 100 Hz. The red curve is after we added a 200 Hz low pass filter to reduce high frequency noise.

Plot 2 shows the noise of the OPO TRANS and REFL photodetectors: the green curve shows the noise with the servo off, the red curve is with REFL as the error signal, the brown curve with TRANS as the error signal, and black represents the dark noise.

Plot 3: Coherence for the above spectra. There is a lot of uncorrelated noise below ~10 Hz.

The default error signal is now the transmitted power of the OPO. Nominal power in transmission is 325 nW, and 0.945 mW in reflection.

Daniel, Nutsinee

Current|Temperature from before: 1.955A | 33.72C

Current|Temperature now: 1.935A | 33.73C

This was a quick fix just to get away from the multimode given the amount of time we had. Hopefully it's good until next Tuesday. A proper mapping of good current/temperature region still needs to be done.

Due to less current we are also putting less red into the SHG. Daniel adjusted the SHG temperature to optimize the green output (was 35.8C, now 36.9C). 35.8C was set for 100mW of red input to the SHG. He also tweaked the red alignment into SHG, upped the power by 2%. Alignment tweaking hasn't been done at least since the last time the laser current was adjusted. Changing laser current/temperature might have changed the alignment into the SHG.

Craig, Danny, Georgia

This week (nominally tomorrow) we plan to try taking some small steps down in power with the SR3 heater. We will run several injections before taking each step, and to leave the interferometer in Observing for an hour at a time between steps, while the system reaches thermal equilibrium.

Before taking heater steps

    * Engage SR3 cage servo
    * Let IFO thermalise
    * Injection: DARM plant (DARM and PCAL excitations)
    * Injection: Frequency noise (Band-limited Craig injections)
    * Injection: Intensity noise (Noise budget style broad band injections)
    * Injection: 9 MHz RIN (Broad band injection)
    * (Maybe) turn off ADS (caused problems in the past when SR3 heater serring changed)

Take a 0.5 W step down on SR3 heater

    * Reconcile SDF, return to observing for 1 hour

After an hour has passed

    * Check for offsets in SRC ASC
    * Rerun all injections listed above
    * If ADS is off, maybe let it come back on and converge

We will repeat this for ~3 steps of the SR3 heater

Marc Nutsinee Daniel

Servo board readbacks:

All common mode boards in the squeezer rack (CLF S/N S1700344; OPO S/N S1700345; SHG S/N S1700346; LO S/N S1700348) as well as the 2 spares (S/N S1700347 & S/N S1700349) were modified according to E1900103 (high pass filtering of DAQ channels to avoid slew rate limitations in the AA chassis).

AM modulated RF amplifier:

Installed the AM modulated AOM driver chassis D1900045 (S/N S1900202) and removed the temporary ifr RF synthesizer and Mini-Circuits RF amplifier.

Squeezer model:

Updated the model to add a dedicated integrator at the output of the green pump power stabilization. This prevents the filter output from increasing to very large numbers, when the actuator is out of range. The servo can now be turned on and off with a trigger from the OPO transmitted power.

The bad:

When we tried to relock the squeezer, we had to fix several problems with broken equipment!? Cause unknown.

1. The SHG wouldn't lock because the I channel of the IQ demodulator chassis was not working (replace with spare S1000780).
2. The CLF wouldn't lock because both channels of IQ demodulator chassis were not working (replaced with spare S/N S1000774).
3. The excitation channel for the CLF is not working and both differential legs are railed. Since there is no powered equipment for this in the squeezer rack, this must be caused upstream (cable, AI chassis or DAC).
4. The PZT driver for the SHG has a ~40V offset. This is not good, since it limits the range of the actuator. However, we could lock the SHG at ~80V and left it at that.