H1 Manager called because it couldn't get ALSY to lock in initial alignment. The flashes were barely below being able to catch. I paused INIT_ALIGN and touched ALSY in yaw and we were able to lock green and are on our way back up.

TITLE: 04/27 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
INCOMING OPERATOR: Oli
SHIFT SUMMARY:
H1 is locked and Observing for 4 Hour now.
Relatively quiet night.
 

LOG:
No log

FAMIS 26297

H0:VAC-MX_FAN1_370_2_ACC_INCHSEC has a very Strange looking reoccuring ingrease in its noise.
It looks like this fan wasn't being used until about 100 days ago. 100 days ago it seemed to be fairly noisy as well, but this is strange looking and very different.
it seems like the fan is noisy for 12-16 ish hour and quiet for 8-16 hours. Maybe this particular fan isnt on for 8 hours,
It's likely it turns on at 1Pm and turns Off at 9-10 pm.

I think this is a new noticable development since the last time I checked on the Vibrometers.

TITLE: 04/27 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 152Mpc
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 4mph Gusts, 2mph 5min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.17 μm/s
QUICK SUMMARY:

00:52 UTC Intentional Drop from Observing to adjust squeeze angle.

Requested SQZ_MANGER to go to SCAN_SQZANG saw the phase slider move around a bit and it created https://lhocds.ligo-wa.caltech.edu/exports/SQZ/GRD/SQZANG_SCAN/SQZANG_SCAN_240426175458.png

00:56 UTC Back to Observing

2:04 UTC  Lockloss  https://ldas-jobs.ligo-wa.caltech.edu/~lockloss/index.cgi?event=1398218686

Unknown cause but ETMY L2 Master out starts to change behaivor about a second before the lockloss.

---Relocking--
Increase flashes ran for YARM
Happened automatically without any input from me.
Nominal_Low_Noise reached at 3:01 UTC
Observing reached at 3:04 UTC

Ibrahim A, Oli P, Mark B, Betsy W

Context:

M3 on the beam splitter has secondary prisms that are placed along the barrel below the primary prisms. These secondary prisms are placed at a location below the primary prism, and if placed in the correct spot, act as a clamp, damping the oscillations moving down the wire loop into the optic. We've been working on finding the optimal secondary prism position for the BBSS.

Experiment:

The experiment for determining this position was developed for the BSFM in 2011(T1100086), and we used a similar setup for our three (successful) runs for the BBSS. This is basically how the experiment is set up to work:

1. A biased solenoid is placed a few millimeters away from one of the M2-M3 loop wires. The solenoid is driven at the wire’s predetermined resonance frequency using a waveform generator.
2. The wire goes from M2 down through M3’s fixed primary prism and (the reason for this experiment) moveable secondary prism.
3. Phonograph needle is rested on wire below the secondary prism and the other end is connected to a spectrum analyzer. Five FFT averages are taken to give us an attenuated peak at the resonant frequency. This is a reading. We took 4/5 measurements for each location, where each measurement consisted of five 8-second averages.
4. We move the prism down by a millimeter or two and take more readings.
5. From the results, we determine the lowest amplitude peak/highest attenuation and note the prism position.
6. This becomes the new BBSS secondary (glued on) prism position.

Results + Commentary:

Note: Mark has an upcoming alog about the run of data and issues that we took when he was here, but in LESS IMPORTANT Auxiliary Investigations we will be focusing on the data from the second and third runs, but here in the results will still be showing the data we got with him.

The plot attached shows the attenuation measured versus the position (positive distance relative to the mass’ centerline) of the secondary prism. Each color is a separate run, and the more negative the attenuation, the quieter the reading was, so we are looking for a location with the lowest values where the secondary prism would do the most damping.

We found that there is a region between ~29.00mm and ~31.5mm below the horizontal center of the mass where the amplitude is minimized. There are approximately three anomalous data points in between, with one confirmed being due to cross-coupling of above wire. As of now, we’re still working on understanding this data and have spoken to Mark B and Jeff K about how we can go about accurately interpreting the raw data (including essential questions about the calibration and setup. See below.)

LESS IMPORTANT Auxiliary Investigations - Details, Details, Details

    Read for Clues/Hints (things we noticed, changed etc.):

• Mass Locking: When Mark Barton was at LHO, we “almost locked” the Test Mass in order to help damp any motion that we caused when we adjusted the experiment for a new reading. This locking was not meant to take the load off the wires but we realized that given differing amounts of “just touching”, our attenuation amplitudes changed by over 20dB systematically. Importantly, the attenuation difference did not change the resonant frequency, which is what really matters. Given this, we proceeded with an “almost locked” Dummy Test Mass.
• Cross Coupling: The expected behavior for this experiment is that there is a minimum/dip in the resonant frequency amplitude where we can optimally glue the secondary prism. At certain positions along this trend however, we noticed a marked and visible vibration in the wire. Upon further investigation, we found that the wire segment directly above it (Top Mass - PUM) was also visibly vibrating. Upon meeting with Mark and checking records, we found that this was more than likely an nth harmonic of that upper wire causing cross-coupling. Thus, these “anomalous” positions should be avoided.
• Needle Changes: One of the three data sets we have was taken with a different needle because the one used for the first run had broken, and we had another needle become permanently cocked out of place and give us erroneous readings before we swapped the needle again and were able to get a good second and third run. We took “no contact” or noise floor measurements for each new needle. The noise floor measurements for each run were taken and we are working on calibrating the two needle sensitivities to better represent our data.
• Needle Touching: We tried to see if there was an effect in noise with the needle touching head on vs. on the side of the wire. We found that while the location of the needle on the wire didn’t really matter, the amount of tension between the needle and the wire does add some damping to the wire. As such, we attempted to ensure that the needle was resting on the wire rather than applying any force to it. We also tried to replicate the location/contact area of the needle for consistency.
• Cable Changes: We noticed that moving BNC cables too close together or having them sway in the cleanroom air contributes to noise. To tackle this, we used small weights to secure them to the ground and separated them as much as possible.
• Solenoid Distance Changes: For unknown reasons, and despite our wave function generator having the same output throughout, the wire would vibrate visibly at certain times than others for the same frequency. After playing with certain distances, we landed on the original 2.5mm for the sake of consistency. An effect we did notice is that if the solenoid was actuating too strongly, it would move the wire laterally back and forth with some oscillatory behavior. This would move the entire mass. At our 2.5mm, we tried to ensure that the wire was still visibly vibrating but not so much as to cause translation movement in the masses or the wire.
• Resonant Frequency Experimentation (Largest Persistent Confusion):
  • Mark gave us this suggestion to see the effect of frequency changes on the wire for different prism positions. We realized that when we sweep the frequency over +-2Hz, there was definitely more oscillation in some points than others. This was the case for each position we tried. I.e. The resonant frequency of the wire changed slightly as the prism moved down (and even just with a prism in vs. without), and as such, the actuation frequency from the solenoid was not (and could not have been) exactly at the resonance of the wire. 
  • What is confusing to us here is that if the entire point of the experiment is to shake the wire by some constant amount to measure the attenuation below the prism, how can we be sure that this attenuation is maximized if the amount that the wire is shaken changes and in fact, depends on the prism position? (by virtue of the res. Freq. moving slightly by each move).
    • E.g. At position 16, the wire was vigorously shaking (due to coupling) so obviously our reading was just … louder.
    • E.g. At position 18, the wire was so far away from the attenuation frequency that it was not moving at all so obviously our reading was just … quieter. We spanned the frequency at the same actuation strength and found that the resonant frequency had moved all the way from 303 to 307 Hz - so obviously the wire isn’t resonating/shaking things as much.
  • We tried taking readings where we just match the visible vibration at each prism point but quickly realized that this would just yield us the same results each time because it tells us nothing about the attenuation of the actual resonant frequency we want to damp just how good this prism system was at damping any vibration. 
  • With 2 needles, this effect would be negated because we could just take signal A and signal B and compare the attenuation before and after the prism. We have the tools for this if it is worth doing.

TITLE: 04/26 Eve Shift: 23:00-07:00 UTC (16:00-00:00 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
OUTGOING OPERATOR: Ryan S
CURRENT ENVIRONMENT:
    SEI_ENV state: SEISMON_ALERT
    Wind: 9mph Gusts, 6mph 5min avg
    Primary useism: 0.04 μm/s
    Secondary useism: 0.19 μm/s
QUICK SUMMARY:
H1 is locked for 2 hour 52 minutes. 
When H1 has been locked for 4-5 hours I will follow the instructions out lined by Sheila's Alog 77447 to adjust the SQZ angle after the IFO has been thermalized.
The will take us out of Observing for a short time.

TITLE: 04/26 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 150Mpc
INCOMING OPERATOR: Tony
SHIFT SUMMARY: Commissioning for most of the morning which ended in a lockloss. Relocked easily and have been observing for the afternoon.

• 15:20 - S240426dl
• 16:01 - Dropped observing for commissioning
• 18:55 - Lockloss - alog77442
• 20:12 - Reached NLN
  • During this acquisition, Jenne re-enabled the PRMI ASC loops in the ISC_DRMI Guardian after we realized they were not turning on during PRMI_ASC
• 20:34 - Started observing after Sheila retuned SQZ angle (alog77447, will need to do this again this evening after H1 is thermalized)
• 22:32 - Saturation callouts for ITMX, ITMY, and BS simultaneously; PRG, CSOFT_Y, DHARD_P all saw motion at this time

LOG:

After the changes in our output arm this week (77427) we took some time to check the level of backscatter from the AS port, as a way to check the health of the OFI. 

I tried to reproduce Camilla and Eleonora's excitation from 71354, using a 0.65 Hz excitation on OMC L, and adjusted the amplitude until I saw about 12um peak to peak motion of the OMC (peak to peak amplitude measured by OMC M1 DAMP IN1, in um, are listed in the legend.) 

Comparing this plot to 71354, the amplitude of reflected light does seem higher now by about a factor of 2. We didn't repeat this measurement after the OMC was swapped, before the apparent changes in the OFI.

Thanks to Elenna for the instructions!

The BRUCO can be found here and ran on 400s seconds starting at 1398159599.

Analysis in progress.

I've just retuned the SQZ angle with a freshly locked IFO, which will not be well tuned once the IFO is thermalized.  Once we have been locked for ~4-5 hours, it would be good for the operator to re run this so that the squeezing angle is set for a thermalized IFO.

Please, go out of observing, from sqz manager select SCAN_SQZANG.  This will create a folder (named by the time you run it) https://lhocds.ligo-wa.caltech.edu/exports/SQZ/GRD/SQZANG_SCAN/

The plot should look something like this, with a minumum of squeezing at some CLF phase, which should now be where H1:SQZ-CLF_REFL_RF6_PHASE_PHASEDEG is set to. 

There had been a suggestion (passed to me by Sheila) that we should measure the beam positions on SRM and SR2 after the big move that we made this week (which is summarized in alog 77427). 

We don't have a premade script to do this like we have for the test masses, so I just did it by hand.  One at a time, I put in a line using the ADS screen to SR2 or SRM pit or yaw, then changed the corresponding A2L element to minimize the line height in CAL-DELTAL_EXTERNAL.  I was also watching SRCL_IN1 and SRCL_OUT, but the lines disappeared in the SRCL signals before they disappeared in the DARM signal, so I just used DARM. 

All A2L values for SR2 and SRM had been 0.0, so I'm not going to bother putting in a 'before' column in the table below since they were all the same value of zreo.

After finding those values, I ran /opt/rtcds/userapps/release/isc/common/scripts/decoup/BeamPosition/CalcSpotPos.py to get from A2L coefficient to beam spot.  This script had been made for IMC optics, but since SRM and SR2 are the same style, the calculation should be the same.  Reminder of where this calc comes from (it's referenced in the script): alog 31402.

We don't have any 'before' measurements to compare to, but at least we now have some amount of information of where we are on these optics after the big move.

I'm pretty sure that these new A2L values can only be good, so I've accepted them in both safe and observe snaps for SR2 and SRM (see first and second attachments, only 2 rows per SDF table are accepted).  These A2L gains for non-test mass suspensions are not under guardian control, so this should be good enough to keep them in place.

In the table below, the Cal-Deltal line reduction factor ends up really just being the ratio of the peak height in DARM before I started doing anything to that dof, and the noise level.  To do a better job of measuring this, I would have had to increase my excitation amplitude, but that didn't seem important enough to do given the limited commissioning time we had. 

I don't have time right now to think through the whole left-vs-right sign convention (it's discussed in alog 31402), but it does look like we're rather 'diagonal' in the SRC now, since the signs of the spot positions are opposite for SR2 vs SRM (eg one positive P2L and one negative P2L means the beam is on opposite sides of center).

First I ran SCAN_SQZANG from SQZ_MANAGER, result is here

Then switched to anti squeezing by flipping sign on CLF servo and adjusting sqz angle to 98 (roughly watching the DTT template), and ran SCAN_ALIGNMENT_FDS.  Results are here: https://lhocds.ligo-wa.caltech.edu/exports/SQZ/GRD/ZM_SCAN/240426111805/

In that scan it looked like some of the degrees of freedom didn't end at the place that was really maximizing anti-squeezing, perhaps because the best alignment was at the edge of the scan range.  I manually moved AM4 + ZM6 to try to increase the anti-squeezing based on these plots (and watching in dtt). I also noticed during this that a lot of time in SCAN_SQZ_ALIGNMENT is taken up with scanning the squeezing angle, which is necessary if we are using squeezing to align, but seems like it will be less necessary for anti-squeezing.  I looked at the sqz angle the script was choosing, and indeed it wasn't changing much at each alignment step.  I've added logic to the state that it does this sqz angle scans if the fom is sqz, but skips it for asqz. This cuts the time that the script takes in half, so it now takes 5 minutes.

Re-running the script (without scanning sqz angle) produced this set of plots: 240426115056/ which show that we seem to have maximized anti-squeezing for differential alignment, but the plots for common seem like noise.  We may need to make a larger scan for common.

We lost lock right as this scan finished, but don't think that the scan was the cause of the lockloss. We will need to retune the sqz angle when we relock, and may also need to retune it after the IFO has thermalized.

Lockloss @ 18:55 UTC - link to online lockloss tool

This was at the tail-end of commissioning time, but commissioning activities happening at the time don't seem to be the cause. At this point, no obvious cause.

In alog77427, Sheila notes that our optical gain and power at the AS port PDs dropped 4% Monday night. On Wednesday after we moved SR3, SR2 to recover the throughput into HAM6, in a full lock our AS port PDs are now 12% lower than out last good lock Monday night before the optical gain drop. This number might be confusing with an alignment change, getting more or less 45Mhz down into HAM6. Another good comparison is from a no SQZ single bounce that Jennie Wright did in alog77204 a few weeks ago, compared to just after Jenne moved SR3, SR2 (alog77395).

PSL single bounce comparision

started scan of OMC alignment started with no squeezing: April 26th 2024 16:36:47 ended at 17:30 UTC

We've asked Tony to try locking the IFO with SR3 and SR2 in these very different positions.  With these optic positions, we don't want the AS_C offsets in place that we used to get locked yesterday.  So, I have now accepted in safe.snap for the ASC model that the AS_C offsets are off (but I've left the numerical values). 

If we're unable to lock, then the plan is to ask Tony to revert SR2 and SR3 and turn back on those offsets.  Since the offset switches are part of SDF revert, to turn them on the plan should be to go Sitemap -> ASC -> Overview -> AS_C (bottom left) -> Turn on the offsets and save the diff in SDF.

First attachment is my saving the safe.snap file with the offsets off.  Second attachment is where the offset buttons are.

We're still working to understand why we've got problems, but we've at least found *an* alignment of SR3 and SR2 that seems to prevent clipping at the AS port when we're centered on AS_C.   To get here, I had to move SR3 and SR2 by very large amounts, much more than they ever drift.  In order to more accurately see changes in power levels on the AS WFS, I had the DC centering loops engaged in this single bounce off of ITMY configuration.

In the attached plot, the bottom row is the slider values for SR2 yaw and SR3 yaw (so, in microradians).  As a reminder, folks have been checking all day and there is no indication from suspension sliders, OSEMs, or where applicable oplevs, that any of our optics have moved nearly this much, so this should not have been necessary.  That said, we've often found that (normally at least) we have lots of leeway clipping-wise when chosing SR3 and SR2 positions.  There's no reason a priori that I can think of that would prevent us from locking with these SR2 and SR3 positions, but TJ and Camilla point out that having moved SR3 this much may make it challenging to also have the HWS paths aligned. These moves are basically my moving SR3, then moving SR2 to re-center on AS_C.

The top row of the attached plot is the centering on AS_C.  So, we would like to only evaluate the amount of power on AS_A or AS_C (middle row) when the beam is centered on AS_C.  It turns out that it's the low-ish part of the power curves that are the values when AS_C is centered. 

I have highlighted using a blue line on the AS_A curve (middle row right side) roughly the trend.  When we started (at about -42 mins) the power on AS_A when AS_C is centered is at about 1.64 units on this y-axis, and as we move SR3 and SR2 in yaw, I can increase the power on AS_A to about 1.85 units.  Jennie found that a time of equivalent single bounce configuration from a week ago, we had 1.87 units on this y-axis.  (This y-axis is just AS_A_NSUM * 0.001).   I didn't take the time to go to the 'other side', but the trend of power on AS_A seems to show that we're into the plateau region, and at the same time the AS AIR camera looked much more normal and unclipped.

EDIT to note that part of the reason it's helpful to wait to evaluate AS_A power until AS_C was centered, is that that also gave time for the DC centering loops to catch up to my big SR3 moves.  I think that the reason AS_A sometimes is higher than the blue marker curve, is that the beam was clipping on AS_A while the DC centering loops were catching up.