After seeing the reflected spots on the PSL Quad display this morning and the "ISS diffracted power low" notification, since no one was using the beam today I performed a remote beam alignment tweak for both the PMC and RefCav.  I started shortly after 10am, after Masayuki and I finished his PMC measurements and sufficient time had passed for the PMC to recover.  The PMC Refl spot looked brighter on the left side vs. the right, indicating a potential alignment shift in yaw, while the RefCav Refl spot looked like it needed a pitch adjustment.

Starting with the PMC, with the ISS OFF there was ~103.3 W in transmission and ~25.0 W in reflection.  Tweaking beam angle (entirely in yaw as expected based on the Refl spot, pitch adjustment acheived nothing) resulted in ~105.2 W transmitted and ~22.7 W reflected; walking the beam got things a little better, with ~105.5 W transmitted and ~22.3 W reflected.  Seems this drop in PMC transmission was due to a slow alignment drift as the enclosure recovered from our NPRO swap ~10 days ago.  With the ISS ON and diffracting ~3.8% (I had to adjust the RefSignal to -1.97 V from -1.95 V due to the increase in PMC transmission) the PMC is now transmitting ~105.7 W and reflecting ~22.4 W.

Moving on to the RefCav, with the IMC locked the RefCav TPD was ~0.79 V.  Adjusting the beam angle got things a little better, with a TPD of ~0.82 V; as expected this adjustment was almost entirely in pitch.  While walking the beam alignment the IMC unlocked and was having a hard time relocking, so I asked TJ to take it to OFFLINE while I finished the alignment; I note this as with the IMC unlocked the RefCav TPD is generally a little bit higher than with the IMC locked.  With the IMC now unlocked I was able to get the RefCav TPD to ~0.86 V by walking the beam alignment.  While I was not able to get the TPD higher than this, the Refl spot on the PSL Quad display still looks like there's some alignment work to do; the central spot is usually centered in the ring that surrounds it, but now it looks a little low and left.  I don't have an explanation for this currently, we'll keep an eye on this in the coming days and see if/how things change.  TJ relocked the IMC and it did not have a problem this time.

Following from last week (alog81493) I've now replaced the Increase_Flashes (IF) state calls with SCAN_ALIGNMENT (SA). The former still exists, I've created parallel paths in the ALS arm nodes, but it's not called by ISC_LOCK or INIT_ALIGN. If there are any troubles, then reverting ISC_LOCK and INIT_ALIGN should be all that's needed (no need to touch ALS nodes).

Last week I wanted to return the functionality to immediately stop if it sees a flash above threshold. I added this back in, but since it has to watch slow channels, it rarely happens. Still though, SA seems to be slightly faster than IF, accuracy seems similar.

I've also added some more fault checking and a way to "gracefully" escape the state. I would still like to go through and clean up the code a bit since it's currently a Frankenstein of comments from me integrating this. This includes some log and notifications that might still reference IF. For other time.

Maintenance wrapped up, the most notable item was an internet outage. We are back to Observing.

The LHO offsite network has been down since 06:30 PST this morning (Tue 03 Dec 2024). Alog has just become operational, but network access to CDS is still down.

TITLE: 12/03 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 156Mpc
INCOMING OPERATOR: Ryan C
SHIFT SUMMARY:
LOG: Quiet shift, been locked for just about 10 hours. DIAG_MAIN has been notifying "PSL ISS diffracted power is low" its around 2.8 right now.

J. Freed,

On Wednesday Nov 20th, the Double Mixer topology for SPI D2400315-x0 was taken, and it works how we intended as a way to gerenrate a 80MHz - 4096Hz signal it to but with alot of noise.

DMPrototype.png Is a diagram of the Double Mixer Design

DM_First_Test.png Is a diagram of the test done on the Double Mixer, this inital test was just to check that the Double Mixer produces the expected output signal frequency, as such, the amplifier was ignored. 

DM_FT_Result.png Shows the output on the scope.  Blue is the double mixer output. White is a reference of SRS SG382 (sync with 80 Mhz OCXO via 10 MHz Timing) with a frequency of 79,995,904 Hz and power of -0.91 dBm. The SRS signal, timed with the OCXO, and the double mixer correctly locks with eachother. This gives credance that this design will work for the goal of the double mixer; a 79,995,904 Hz signal frequency locked to a 80MHz OCXO. However there is a lot of noise in the double mixer signal. An ongoing investigation is currently underway to find and reduce this noise.

ZMSCQ_Wave_Shape.png Shows a possible source of the noise, the Double Mixer requires phase delayer for the Sin path, we used a MiniCircuts ZMSCQ-2-90B for this. I tested the ZMSCQ-2-90B by puggining the input of the signal and the signal from the 2 ports into osciloscope. I split off the input signal with a Minicircuts ZMSC-2-1BR+ (Summer/Splitter) and I had to normalize input power pickoff in postprocessing by a factor of 0.68 due to the power difference. The results show that the output of the ZMSCQ-2-90B has a sligtly different shape than what was plugged in. With the delay port (orange) having a slight "hump" on the rise. Will retake with a faster osciloscope, as the signal is very noisy.

The investigation is continuing with the next step of checking the double mixer output signal with a network anaylizer to check the frequencies around 79,995,904 Hz. A Phase noise measurement would also work with the caviot that the phase adjust to destructivly interfere the double mixer signal with the reference signal would have to be adjusted manually.

Sheila and I were looking at one of the most recent ETMX glitch locklosses and found something interesting. About 150ms before this particular lockloss there is a glitch that saturates L3, which seems to be between a few hundred hz and 1khz. The glitch is big enough to propagate to L2 and L1 very quickly. The IFO rides out one glitch, but seems to lose lock during a similar glitch immediately after. There were also 4 other glitches that looked kind of similar during this lock, that didn't cause a lockloss. The open loop for the ESD is around 70 hz, so we think it might be possible to add some more low pass to reduce the drive on the ESD, and reduce the chance of saturating the dac. I'm looking at that.

While trying to understand the path to the dac on this SUS, Sheila and I had a hard time finding the custom screen for the parts added to the top of the ETMX sus model for the 32-bit (-ish?) DAC on that suspension. It lives on the WD tab on the sitemap, it's called DAC_TEST. Shown in the second image. There are calibration gains of 275.310 applied to top level filter banks on the output of the model, these filter screens can be opened by clicking on the rows of black OUT GAIN and OUT VAL epics readbacks on the bottom of the screen. I don't think clicking any of the 0|1 buttons in the middle of this screen is safe.

TITLE: 12/03 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Observing at 157Mpc
INCOMING OPERATOR: TJ
SHIFT SUMMARY:  Currently Observing at 157Mpc and have been Locked for 4.5 hours. Today we had some trouble getting DRMI to lock, and a lockloss from TRANSITION_FROM_ETMX, but nothing too difficult to fix and bypass.

LOG:

15:30 Observing at 157Mpc and have been Locked for over 2 hours

16:33 Out of Observing for Commissioning
16:58 Lockloss due to commissioning activities
    - During relocking, stopped at DRMI_LOCKED_CHECK_ASC because SRM M3 and M1 LF/RT were railed. Clearing SRCL1 history fixed M3, but not M1 LF/RT. We cleared the history on the M1 locking filters, leading to a lockloss and SRM trip. This issue happened because during the commissioning before the lockloss, SRM was accidentally moved so far out of alignment that during DRMI, ISC_LOCK thought that the lock it caught was DRMI when it was actually PRMI, which caused it to push super hard on SRM
    - Lockloss from LOWNOISE_ESD_ETMX
        - Next time we finished TRANSITION_FROM_ETMX, I waited 9 seconds after it completed before moving on to LOWNOISE_ESD_ETMX
    - Multiple locklosses from lower states like ALS and IR

20:02 NOMINAL_LOW_NOISE
20:08 Observing                                                                                                                                                                                                                                                                                                                                    

TITLE: 12/03 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 157Mpc
OUTGOING OPERATOR: Oli
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 0mph Gusts, 0mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.34 μm/s
QUICK SUMMARY: Observing for over 4 hours, calm environment.

Closes FAMIS26449 ,last checked in alog80350

BRS-Y temperature looks to be slowly trending upwards since ~10/22.

WP12223 FRS32776

Jonathan, Erik, Dave:

cdslogin is currently down for a rebuild following a disk failure yesterday. Alarms and Alerts are currently offline. EDC has 58 disconnected channels (cdslogin epics_load_mon and raccess channels).

Lockloss @ 12/02 16:58 UTC after 3:39 locked due to commissioning activities

TITLE: 12/02 Eve Shift: 0030-0600 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 142Mpc
INCOMING OPERATOR: Ibrahim
SHIFT SUMMARY: A long relock today from DRMI locking struggles and lock losses at Transition_From_ETMX. Once back up to observing the range hasn't been very stable, hovering between 140-150Mpc. I was waiting for a drop in triple coincidence before trying to tune squeezing, but that didn't happen before the end of my shift. The 15-50Hz area in particular looks especially poor.
LOG:

• Relocking notes
  • MICH and PRMI caught no problem, but DRMI would not catch. I tried moving SRM but nothing seemed to work. MICH and SRCL were triggering and flashes looked good. I ended up doing an initial alignment but skipping green alignment since this looked good before.
  • DRMI had basically no flashes after initial alignment. Odd. Did MICH and then couldn't lock PRMI. Trying a full initial alignment.
  • Flashes better this time, but it still took 4 min to lock. Finally locked DRMI though.
  • Lost lock at Transition_From_ETMX
  • And again.
  • One more lock loss at Transition_From_ETMX. I had it sitting in this state for 5 min while I was looking at the state code, then there was an ASC pitch ringup. I'm not sure which was the worst of the ASCs.
  • Another initial alignment. Another struggle for DRMI after PRMI and with seemingly great flashes.
  • Bumped SUS-ITMX_L3_LOCK_BIAS_TRAMP to 25 from 30 during the transition to ETMX state, similar to what Sheila did on Nov 22. The hope was to move faster to a safer place and avoid the CHARD P ringup.

We've now had two lock losses from the Transition from ETMX state or immediately after while trying to reacquire. Unlike back on Nov 22 (alog81430), SRCL seems fine. For the first one, the locklost tool 1417133960 shows the IMC-SERVO_SPLITMON channel is saturating ~5sec before lock loss, then there is some odd LSC signals 40msecs before the tool tagged the lock loss (attachment 1). This might just be the lock loss itself though. The second one (locklost tool 1417136668) hasn't tagged anything yet, but ETMY has a glitch 2.5 sec before lock loss and ETMX seems to move more from that point (attachment 2).

Oli, Camilla WP12203. Repeat of some of the work done in 2019: EX: 52608, EY: 52636, older: part 1, part 2, part 3.

We misaligned ITMY and turned off the ALS-Y QPD servo with H1:ALS-Y_PZT_SWITCH and placed the Ophir Si scanning slit beam profiler to measure both the 532nm ALSY outgoing beam and the ALSY return beam in the HWS path.

The outgoing beam was a little oblong in the measurements but looked pretty clean and round by eye, the return beam did not! Photos of outgoing and return beam attached.  Outgoing beam was 30mW, return beam 0.75mW. 

Attached is the 13.5% and D4sigma measurements, I also have photos of the 50% measurements if needed. Distances are measured from the optic where HWS and ALS beams combine, ALS-M11 in D1400241. 

We had previously removed HWS-M1B and HWS-M1C and translated HWS-M1A from whats shown in D1400241-v8 to remove clipping. 

Ansel reported that a peak in DARM that interfered with the sensitivity of the Crab pulsar followed a similar time frequency path as a peak in the beam splitter microphone signal. I found that this was also the case on a shorter time scale and took advantage of the long down times last weekend to use  a movable microphone to find the source of the peak. Microphone signals don’t usually show coherence with DARM even when they are causing noise, probably because the coherence length of the sound is smaller than the spacing between the coupling sites and the microphones, hence the importance of precise time-frequency paths.

Figure 1 shows DARM and the problematic peak in microphone signals. The second page of Figure 1 shows the portable microphone signal at a location by the staging building and a location near the TCS chillers. I used accelerometers to confirm the microphone identification of the TCS chillers, and to distinguish between the two chillers (Figure 2).

I was surprised that the acoustic signal was so strong that I could see it at the staging building - when I found the signal outside, I assumed it was coming from some external HVAC component and spent quite a bit of time searching outside. I think that this may be because the suspended mezzanine (see photos on second page of Figure 2) acts as a sort of soundboard, helping couple the chiller vibrations to the air. 

Any direct vibrational coupling can be solved by vibrationally isolating the chillers. This may even help with acoustic coupling if the soundboard theory is correct. We might try this first. However, the safest solution is to either try to change the load to move the peaks to a different frequency, or put the chillers on vibration isolation in the hallway of the cinder-block HVAC housing so that the stiff room blocks the low-frequency sound. 

Reducing the coupling is another mitigation route. Vibrational coupling has apparently increased, so I think we should check jitter coupling at the DCPDs in case recent damage has made them more sensitive to beam spot position.

For next generation detectors, it might be a good idea to make the mechanical room of cinder blocks or equivalent to reduce acoustic coupling of the low frequency sources.