TITLE: 05/29 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: TJ
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 13mph Gusts, 7mph 3min avg
    Primary useism: 0.03 μm/s
    Secondary useism: 0.10 μm/s
QUICK SUMMARY: Work continues to close ASC loops. We've been able to close about seven of them so far with new input matric values, and we'll continue this evening.

Work at the EX windfence has been completed. While laying out the last panel (furthest North) it was discovered that the new panel had been stitched incorrectly. An old panel that was in good shape was reused.

Ibrahim, Rahul

Attached below are the B&K (Bruel & Kjaer) measurement results of A+ HRTS (suspended config.) mounted on BBSS structure - see picture over here. We used a tri-axis accelerometer mounted on the BBSS frame as shown in this zoomed-in picture - X axis is along the longitudinal side of the BBSS, Y axis is the vertical and Z is transverse.

At first we measured BBSS alone (without mounting the HRTS) - see results posted here. Using a hammer (force transducer attached to a front end - recording the hammer and accelerometer data on the B&K software) we hit BBSS structure in X, Y and Z direction (of the accelerometer). The hit was hard enough to not cause a soft hit, while taking care its not saturating the sensors. We see a small spike at around 68Hz on X axis hit, which is similar to what Jim saw in his measurements few months ago - LHO alog 79930. However, at that time BBSS was without its side braces for providing structural rigidity.

The second plot represents BBSS with HRTS mounted on it. Here as well we see some peaks below and around 70Hz.

Both the suspensions were unlocked and suspended during this measurement.

I am processing and analyzing some additional data (taken for sanity check) by moving the accelerometer to a different location on the BBSS, and will be posting those numbers soon.

S. Dwyer, R. Short

While in PREP_ASC_FOR_FULL_IFO this afternoon, Sheila and I re-phased REFL9 similar to Georgia's attempt in alog84646, but we think we had a better result this time, maybe because alignment is a bit better now.

SDFs of gains and new phasing screenshots are attached. Phasing template has been saved with updated references as /opt/rtcds/userapps/release/asc/h1/templates/phasing/phase_REFL9_mrtodd.xml

TITLE: 05/29 Day Shift: 1430-2045 UTC (0730-1345 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY: The morning was spent trying to get back to PREP_ASC_FOR_FULL_IFO as it was found this morning. Locking DRMI was proving to be tricky even though camera flashes looked good and the POP 18&90 flashes also looked good. I would wait 5-10min, make minor adjustments to BS, PRM, or PR2 and try to increase the frequency or magnitude of the flashes. Sometimes this worked, sometimes it wasn't needed, and sometimes we gave up and ran an initial alignment skipping green. We've ran 3 initial alignments so far. We are now sitting at PREP_ASC_FOR_FULL_IFO and control room users are rephasing POP, tuning loops, and checking on other loops. I've had to touch up POP90 &18 at this state with SRM, as long as PRC2 is on to follow. I've also been turning on the RF violin mode damping whenever we sit in this state to help reduce teh high violins that we currently have.
LOG:

J. Freed,

Spur Problem

As discussed in part 1, the Double Mixer has good phase noise around the carrier frequency to about a 100Hz out where SPI operates, however, it also has signals every 4096Hz away from the carrier.  I had assumed that it was an issue relating to phase and amplitude mismatch on the phase delayer, but after adding attinuators to correct the missmatch, it helped, excepecially the 80Mhz + 4096Hz signal saw a ~15dB improvement. DM_Att.pdf. However, the double mixer still has large signals and the largest did not change with the addition of the attinuators.

I realize now that the problem lies with the mixers themselves as by the nature of a mixer they create spurs on the output. 

DM_Mixer.pdf Shows the output of a single mixer. Along with the expected 80MHz - 4096 Hz and 80MHz + 4096 Hz there is extra peaks which i believe is caused by the Spurs of the mixer. The largest spur is at 80Mhz + 12,288Hz. This spur is actually in phase with the main signal and is thus construtivly interfered at the power combiner. 

I do not know how to get rid of this spur as it is so close to the main carrier signal. For fun, I used a combination of Marki LC filter Design Tool and LTspice to simulate adding a filter to the end of the system to reduce the 80Mhz + 12,288Hz spur, but even an 8th order elliptical filter would only reduce the spur by ~0.04dB due to how close it is to the main signal. For fun I went to 20th order elliptic and it only reduced it by ~0.1dB. In addition, with nonstandard parts for a 20th order elliptic it got reduced by ~4dB. I am unsure of any other method to reduce the spur.

Double Mixer is a Single Sideband Mixer

I realize now that the basic design of the double mixer actually exists and is fairly common, it is called a Single Sideband Mixer (SSB mixer). Thanks to Brian, who gave me one of these mixers to test, I have something to compair the results  

DMvsIRM.pdf Shows a plot of the double mixer vs a SSB mixer. The SSB mixer is tuned to 80MHz+4096Hz as apposed to the Double Mixers 80MHz -4096Hz but comparisons can still be made. For starters, the double mixers 80Mhz+4096Hz sideband equivalent is much better in the double mixer vs the SSB. However this comes at the cost of the 80Mhz+12,288Hz sideband equivalent which is much better in the SSB. In summary, just based on this single graph, the double mixer is more likely to be better for SPI for 2 reasons. One, we have already found out that SPI would be senstive to the 80MHz+4096Hz sideband equivalent. And two, if there is a way to attinuate these spurs by filtering, the spur further away from the carrier could be more easily attinuated.

High order modes filtering

Ive already discussed that adding fliters does not help the area around 80MHz. However, it does help with higher order modes

DM_Filter.pdf Shows a plot of adding a MC80-10-4AA bandpass filter from Lark engenering that has a bandwidth of 10MHz and a center of 80MHz at different positions in the Double Mixer. The best place to put one seems to be just before the amplifier, not entirly sure if adding one is nessisary to SPI but it should be good for reduceing a possible noise source.

Thu May 29 10:13:45 2025 INFO: Fill completed in 13min 41secs

Gerardo confirmed a good fill curbside.

TITLE: 05/29 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 5mph Gusts, 3mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.10 μm/s
QUICK SUMMARY: Still locked at PREP_ASC_FOR_FULL_IFO. HAM1 is in DAMPED, everything else looks OK.

Plan for the day is to get the ASC working.

(Travis S., Jordan V., Gerardo M.)

First, the good news, we managed to helium leak check all of the conflats that were added or "touched" related to HAM1 volume, and no leak was detected above the background of 1.9x10^-10 torr*l/sec of He.  All electrical feedthroughs, all five way crosses, new gauge tree, and a new turbo flange were leak tested. 

Now for the puzzling part, after all items were leak checked, we valved in the ion pump to HAM1, as soon as that was done, since we still had the leak detector backing the turbo pump the background went up to 2.5x10^-09 torr*l/sec of He, a little sick ion pump??

HAM1 annulus system is lagging behind, its ion pump controller is railed at 10 mA.  HAM1 and HAM2 share the same annulus volume, both systems are currently being pumped down with two different aux carts, both of the ion pump controllers were turned on today, HAM2 system is currently sitting at 7 mA, but HAM1 still railed as stated above.  If the performance does not improve we'll need to break out the big wrenches to revisit the doors.

The squeezer path from HAM7 to HAM8 is open now, all closed valves were opened today, RV1, FCV1, FCV2, FCV3, FCV4, FCV5.

Main Turbo pumps were shut down today, output manifold turbo, Y-Beam manifold turbo, and the X-Beam manifold turbo.  HAM6 turbo pump was also turned off, but the cart still powered on.

Rogers Machinery was in the mechanical room today, see work in progress on the photo below, new compressor and new dryer skid, rough location, rough position.

TITLE: 05/29 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: This evening was mostly focused on trying to gradually engage full IFO ASC. We've been able to consistently get relocked up to PREP_ASC_FOR_FULL_IFO as long as (mostly) PRM alignment is touched up every so often, but work is still ongoing to close ASC loops once there. See primarily alog84646 and comments for details.

For the night, we're leaving H1 locked at PREP_ASC_FOR_FULL_IFO with a few ASC loops closed, but 'DOWN' is requested so that it won't try to relock if it drops out. [Tagging OpsInfo] In the morning, if H1 is still locked here, hang tight until more commissioning of the ASC loops can happen. If unlocked, run an initial alignment skipping PRC steps (as we have been this week).

LOG:

Ryan S, Sheila, Syracuse Squad

After Sheila and Ryan turned up the BS oplev laser current more (and no one is climbing on HAM1), we seem to be requiring more successfully.

We got through DRMI_to_POP. To check it was safe, Sheila loaded the LSC POP_A input matrices into the unused XARM filter, and we checked the transfer function from PRCL, MICH, SRCL to the XARM for each input matrix. The PRCL TF looked flat and had 0 phase: good! The other DOFs had a bit of slope and phase but were close enough to 1 that we powered through, and DRMI_to_POP didn't cause any locklosses. It's on our to do list to check the LSC open loop transfer functions.

Then we sat at PREP_ASC_FOR_FULL_IFO and tried checking the phase of the ASC REFL diodes. Sheila++ plugged the LSC AO 2 into the refl servo so we could drive a line in frequency noise, which we want to tune the phasing so it shows up in the I quadrature for each QPD quadrant. I found some handy templates in /opt/rtcds/userapps/release/asc/h1/templates/phasing, complete with excitation. I turned the excitation down to 0.1 and that seemed good. The line was predominatnly in I for each quadrant in REFL_A_RF9 and REFL_B_RF9 EXCEPT Q3 of REFL_B. I imagined I would just tune the phase and see the line go down in Q, but this wasn't the case. It bounced around a bit and was hard to tell if I made progress. Attached screenshot (#1) is with the new phasing.

I accepted the changed phase in SDF, screenshot attached (#2) in case this was a bad move that needs to be reverted.

It seems like we have a 15 minute death (lockloss) timer while we sit at PREP_ASC_FOR_FULL_IFO right now, which is making it hard to get the ASC working, but we'll keep trying...

M. Todd, S. Dwyer

Following the same routine layed out in alog 64204, we had the SR785 already plugged in for a CARM OLG measurement using the gpib from the control room.

I adjusted the carm olg template a tiny bit as it didn't have the right gpib number.

Then I ran

Results:

I measured a 11kHz UGF with a 41 degree phase margin; while this is quite different from previous measurements (2022-07-29) which had something around 27 kHz, I think this is because of the different power states.

TITLE: 05/28 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY:
Epochs of locking:
When I first got in to the control room I ran a full Auto initial alignment.
This lead us to no flashes on DRMI & PRMI.
We then manual initial alignment through a few PRX steps.
Which gave us flashes, but after that we had some noise on the beam splitter oplevs.

Then a REFLAIR phase issue was overcame.
Mean while the SQZrs are turning on the laser and did some aligning on the SQZ tables.
Then unknown 70hz feature was later found out to be ISI in HAM1.

The VAC team checked HAM1 for leeks, and didn't find any.


LOG:

TITLE: 05/28 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: Tony
CURRENT ENVIRONMENT:
    SEI_ENV state: CALM
    Wind: 14mph Gusts, 3mph 3min avg
    Primary useism: 0.02 μm/s
    Secondary useism: 0.11 μm/s
QUICK SUMMARY: H1 locking continues this evening; currently have made it up to CARM_TO_ANALOG and have paused to measure CARM OLG. More SQZ table work also going on.

J. Kissel, J. Warner, S. Dwyer, O. Patane, E. Capote, T. Sanchez

After finally making progress past Beam Splitter optical lever glitching (LHO:84631), a poorly phase REFLAIR sensor set for PRMI (LHO:84630), and adding loop gain to the REFL DC centering loops (LHO:84623), we were just about to see some success and made it ISC_LOCK's RESONANCE state.

Alas, Jim started commissioning/debugging the HAM1 ISI loops (in a different room), trying to carve out some time to deal with a ~70 Hz feature in some DOFs of the plant. In doing so he made sure to turn off the DOFs he thought were problematic (RX / RY). LHO:84638

We (including Jim) now know that even only having the X, Y, Z, and RZ loops closed, the ISI HAM1 X loop slowing goes into oscillation slowly, on the order of 5 to 10 minutes after the ISI is isolated.

This manifested in IFO commissioning in very confusing ways mostly because of the timing of events (and the "front row" didn't know that Jim had started commissioning the ISI). The first attachment "shows" this story.
    - The first re-acquisition after an unrelated lock loss started with the ALS COMM's out-of-loop sensor (H1:LSC-TR_X_NORM_INMON) oscillating at 70 Hz, i.e. "looking fuzzy" on the wall "DRMI buildups" screen.
        (See bottom, 5th panel.)
    - It started to dissipate in the middle of this acquisition (we now know because Jim was independently cycling the ISI Isolation loops)
        (See 4th panel)
    - But by the time that DRMI was locked, the "fuzziness" oscillations started to reappear.
        (again, see 5th panel)
    - All the while we notice that MC2's M2 stage -- feedback for the IMC -- is saturating. This in itself is confusing because our impression is that the IMC F / IMC L cross-over is at ~15 Hz, so "there shouldn't be any drive from the IMC common mode board to MC2 up there, especially not offloaded to the M2 stage."
        (see 2nd and 3rd panels)
    - But also, "why is the IMC seeing any HAM1 motion?"

I also attach an ASD of IMC F, the middle stage of MC2's DAC drive, and the HAM1 and HAM2 ISI motion. These clearly show the 70 Hz feature, and show nothing in HAM2.
I call out the "nothing in HAM2" to dispel the suspicions that vacuum equipment that's still vibrating and moving the HAM1 / HAM2 chambers is causing this noise. It's not. It's the oscillation in the ISI HAM1 loops.

Here's why "the IMC is seeing HAM1 motion:" at this point in the lock acquisition, ALS COMM is inserted as an additive offset to the IMC's Common Mode board, which drives MC2 length and the PSL frequency (see e.g. the difference between pg 12 and 13 of G1400519). This is why the MC2 M2 DAC request is peanuts when the IMC is locked alone, but then is gigantic once the ALS COMM signal is ramped in to push the laser frequency around to find the X arm resonance in IR. The ALS beam is "caught" in HAM1 with a periscope and steered around the table before being sent on to ISCT1. So the unstable 70 Hz motion in the new HAM1 ISI is imprinted there on the beam, which is then used to inform ALS COMM, which is then fed to the IMC.

For now, we're going to leave the HAM1 ISI loops off and carry on with ISI commissioning, and give Jim some dedicated time to figure out the issues with the ISI.

J. Freed

Contiuning the work from 84198 this alog is about characterizing the other components of the Double Mixer. D2400315

D2400296 PCB Board transimpedance amp

According to oscilloscope, the signals coming from PCB board are from J2 being cos and J3 being sin. The Vpp are 1.199V on J2 and 1.195V on J3. As before the phase measures are hard to get a read on as the phase measuremnt on the osciloscope says 90deg when I put J3 in the channel 1 position and 91deg when I put J2 in the channel 1 position. Instead I put a 4096 Hz signal generator on Channel 2 then put the of the sin and cos signals on channel 1.

ZLW-1BR Mixer

The mixer data was collected at a range of values incase LO input power needed to be changed, however I would not recomened going below 4dBm LO as the isolation of all the ports falls gets worse the lower the power. The indivitual signals were colected on the Agilent 4396B with a BW of 10 Hz (best one the spectrum analizer allowed without giving an overload notification). While the Total power was given on the E4418A power meter. SRS SG382 was used for the LO power.

ZMSC-2-1BR Combiner

The combiner values were colected by using the Agilent 4396B to apply a sweep of values around 80 MHz. All values were the same in about a 10kHz span that was measured

ZMDC-10-1+ Couplier

The couplier was characterized by applying a -1dBm from a SRS SG382 signal generator signal at 80MHz on the input port and reading off from the E4418A power meter. The other port not being measured was terminated. We do not care about relative phase so it was not collected

J. Freed

The reason we picked the ZFL-500HLN amp for SPI's Double Mixer was that it was an amp that met requirements from minicircuts

-frequency range contains 80MHz (our operating frequency)

-Operates at voltage supplied by Low Noise Power(15V, 17V, 24V etc.)

-Has a P1dB well above our output power of 10dBm (to remove non-linearity)

-No heat sinks (to fit in a 1U chassis.) (This requirement actually doesnt matter, the ones discussed here are still the best even compaired to amps with heat sinks)

-sma connections

-Low noise

-Low gain (we only need ~8dB of amplification)

The ZFL-500HLN was chosen because it fit all those requirements, with the cavieat of having to attuniate before amplification (adding noise). Though if I am correct and the Low noise power board 5V Vcc port is capable of supporting a 63mA load, another option would be the ZX60-P105LN+ instead due to the lower gain and lower noise. This would remove the need for an attinuator before amplification but its low input return loss means alot of power is reflected back towards our mixers (Also causeing noise). So it becomes a pick your poison of adding noise by attinuating before amplification vs by reflections back into our mixers. In practice, I believe both would operate about the same. Will add a comment if something changes

Double-MixerAmpComparison.png shows a quick comparison of the 2 amps

Calibration is currently regenerating the O4b uncertainty budgets.

Due to a missed change to the ETMX UIM suspension filters, which was found in LHO alog 82804, and then fixed only on Feb 27, 2025 (see LHO alog 83088), we need to add a correction TF to be included in the uncertainty budgets.

I attach a graph of that correction TF (corrected model / original model) and the text file needed for that correction.

We will be using correction TF in all our uncertainty budgets for O4b, and up to Feb 27, 2025 around 20:00 UTC, or GPS 1424721618 for O4c.