TITLE: 05/01 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: GV6 was closed as part of the CP1 regen effort today, along with some beam profiling in the PCal lab and small tests on the QOSEM electronics.
LOG:

Fri May 01 10:08:36 2026 INFO: Fill completed in 8min 33secs

Gerardo, Jordan, Dave;

In the event of a REGEN pump cart failure we expect PT100A to show a large and rapid change in pressure. I have added PT100A to VACSTAT and set the trigger limits quite high to start with to prevent false positives. Note that currently the PT100A VACSTAT channels are not in the DAQ.

TITLE: 05/01 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
OUTGOING OPERATOR: None
CURRENT ENVIRONMENT:
    SEI_ENV state: MAINTENANCE
    Wind: 4mph Gusts, 2mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.11 μm/s 
QUICK SUMMARY: Work continues to prep for the BBSS; likely a quieter day today.

PT100A has been added to the VAC Overview MEDM. Overnight pressure trend also shown.

[Tom Roocke, Oli]

Summary: The 6 QOSEMs and their signal chain for the BBSS are operational with the final sat amp, CER wiring, CDS mapping, in vac DB25 extension cables. All that remains to test before SUS installation is the duopus cables, which are in C&B currently.

In continuation from yesterday, we are testing out the QOSEM signal chain prior to installation of the BBSS. Yesterday we verified the sat amp was still functional and the readouts were showing up in CDS appropriately. See LHO:90072. Today we checked both the DB25 to DB25 extension cables, and the QOSEMs. To come is testing of the duopus cables, which are still in C&B.

DB25 Extension Testing:
Using a known functional Duopus cable (S2600215), and inair DB25, we tested the three DB25 extension cables by reading for the QOSEM coil resistance and diode drops at the in air DB25, where it connects to the sat amp. See the signal continuity test section in T2600170 for more information on this. All 3 cables are functional.

S2001548: DB25 working
S2100358: DB25 working
S2100410: DB25 working

QOSEM CDS Readout Testing:

Using a known functional Duopus Cable (S2600215), DB25 Extension (S2100410) and in air DB25, we checked for the open sum voltage in the CDS readout. This is the voltage seen on the sum channel of the QPD with no lens installed. Seeing a nonzero voltage here indicates that the QOSEM LED, QPD and signal chain are functional, but will be far lower than the operational sum level when the lens flag is appropriately focusing light onto the QPD. We tested the open sum voltage for all 6 QOSEMs designated for the BBSS. All QOSEMs and there signal chain are functional.

S2600008: working with open sum of 13910
S2600009: working with open sum of 14755
S2600010: working with open sum of 15550
S2600011: working with open sum of 15470
S2600012: working with open sum of 15348
S2600013: working with Open Sum of 14380

Summary: Since I had trouble seeing a noticeable improvement in jitter by looking at the IMC WFS in this alog #89988 where the PSL output power was 2W, I looked at times when we were at 10W PSL output power to see if we were limited by shot noise. The measurements at 10W show that we might have decreased jitter but I checked the QPD sum values for the measurements after JAC was installed vs. before and we are near the edge of the QPDs.

I took reference times, when our input power was 10W to see if this gave a better measurement of jitter

Time 1: 2025/11/17 16:13:17 UTC during initial alignment. Without JAC.

Time 2:2026/03/19 15:31:23 UTC during commissioning when HAM1 was at vacuum.

Image one shows the yaw measurement, there is again a difference in the value at DC of the QPD ASDs. It looks like the peaks seen between 40 and 1000 Hz are slightly better with JAC than without JAC but it is only obvious on WFS A and B QPDs (top left plot comparing green and purple lines for WFS A and red and yellow lines for WFS B).

Image two shows the pitch measurement, there is again a difference in the value at DC of the QPD ASDs. It looks like the peaks between 40 and 1000 Hz are slightly better with JAC than without JAC but it is only obvious on WFS A QPD (top left plot comparing green and purple lines).

I also checked that the QPD sum values changed between my reference times during O4 and after JAC installation. See these four images.

1. 2W reference time during run. A and B QPD SUMs were arpund 0.03 counts.

2. 2W reference time after JAC installation. A and B QPD SUMs were arpund 0.002 counts. Maybe we are now nearer the edge of the diode?

3. 10W reference time during run. A and B QPD SUMs were around 0.16 and 0.13 respectively.

4. 10W reference time after JAC installation. A and B QPD SUMs were around 0.009 and 0.008 respectively. Maybe we are now nearer the edge of the diode?

Gerardo, Jordan, Richard, Patrick, Fil, Jonathan, Dave

A temporary vacuum gauge was connected to the h1vacly beckhoff terminal to monitor the CP1 regen over the coming weeks. In lui of adding this to the production h1vacly code, we chose instead to read the raw voltage from Beckhoff and serve this data on a temporary IOC.

I wrote pt100a_ioc.py which reads the raw voltage from the Beckhoff channel H0:VAC-LY_TERM_M14_CHAN2_IN_VOLTS. It reposts this value and then converts it to torr. These channels exported are:

H1:VAC-LY_Y5_PT100A_VOLTS

H1:VAC-LY_Y5_PT100A_PRESS_TORR

Jonathan setup a containerized IOC on the VMs to run this IOC.

We created H1EPICS_VACLY.ini to add these channels to the EDC. The DAQ+EDC was restarted at 16:21.

This work is in support of the CP1 regen work permit.

The conversion from Volts to Torr is:

P = 0.75(10**((V-6.143)/1.286)))

To check for any rubbing or other issues that the BSFM might be encountering on the test stand, I took some transfer functions today after Betsy plugged the top mass in yesterday (90063). The measurements have really poor coherence because the BSFM isn't covered, but it's decent enough to at least verify that TFs are looking good and we aren't near touching anywhere.

Data
$(sustrunk)/BSFM/H1/BS/SAGM1/Data/2026-04-30_1615_H1SUSBS_M1_WhiteNoise_{L,T,V,R,P,Y}_0p02to50Hz.xml

TITLE: 04/30 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: Transfer functions were run on the BS, water lines on the TCSX table were replaced, a galled HEPI spring at BSC2 was removed, and a feedthru on HAM3 was swapped out.
LOG:

Camilla C, Madi S., TJ S

We finsihed swapping out all of the flex lines on the TCSX table, and have tested the lines at full flow. We will leave the chiller off over the weekend.

We left off last week (alog89976) with the 1/2"OD lines that were spec'd on the BOM not fitting in the Kentek beam dump. I looked it up and the push fittings on the beam dump actually take 10mm OD lines. Ordered those, and we finally were able to install them today. We first plugged in the table lines to the rest of the systme lines but with the chiller off, to get a bit of water on the table, and immediately noticed a leak at one of the beam dump fittings. We tried cutting and reseating the line, but it still had a drip. We replaced the dump with a spare and that seemed to do the trick.

In an effort to put water back in all of the table lines in a lower pressure manner, we hooked one end of the table lines to a wet vac and dipped one in a bucket of lab water. This pulled enough water through the lines and then we capped both lines and let it sit over lunch. There were no drips or evidence of drips when we returned, so we connected the table lines back into the system lines. Madi and I were on the phone while I turned the chiller on with the back 3way valve turned to recirculate (down). I then very slowly moved it up and Madi observed water starting to flow through the system. We kept slowly increasing the flow and watching for leaks until we were at our full 4.0gpm as read from the chiller. 

We decided to keep the chiller off over the weekend, but will turn it back on Monday and will keep a close eye on it since I'm a bit paranoid.

I updated and restarted the frame writer on h1daqfw2 yesterday at 1:37pm and today at 3:04pm localtime.

The D6 feedthru on HAM3 was swapped from the 3-port version with 3x Dual DB25 feedthrus to the single piece 12x DB25 connector feedthru.  We re-attached both the in-vac and in-air cables that were originally in that port so that the SUSes can be controlled.

J. Kissel, S. Koehlenbeck

Executive Summary: as an initial guess -- we chose DEMOD parameters as follows:
    . SIG Bank = NO pre-demodulation filtering (just frequency-independent calibration)
    . I & Q Banks = a comb of notch filters at 4096 Hz (the 1f DEMOD frequency), and 8192 Hz (the 2f DEMOD frequency) and a super simple single-pole 200 Hz low-pass.
as the DEMOD filters for the demodulation of signals from the SPI pathfinder's IFO PDs.

I now have a user interface (LHO:90006) to the SPI pathfinder front-end model infrastructure (LHO:89777), so we're now thinking about filling in that infrastructure with real science (or at least real digital signal processing). 

SIG filters
One of the core principles of the SPI pathfinder's longitudinal degree of freedom is demodulating the 4096 Hz between note between the MEAS and REF beam. We only expect to use the SPI up to ~10-50 Hz, as the demodulated interferometer PDs noise floor begin to be limited by ADC noise ~5 Hz -- see LHO:83412 and detailed noise budget in Figure 1bii.1 in T2400145. Of course, it remains to be seen how much displacement signal we see above this noise floor.

Traditionally when demodulating nowadays, we're looking for the amplitude and phase of the excitation line we inject among surrounding noise that we don't want (think ADS lines, calibration lines, violin mode and PI damping, etc). In that case it makes sense to band-pass the raw signal pre-demodulation -- this is why you see narrow band-passes in many SIG banks. However, in the case of the SPI IFOs and other heterodyne IFOs, we're actually quite interested in the "noise" -- the "excitation line" is instead the carrier frequency, and the "noise" is the phase signal that we then interpret as differential displacement. As such, the design of the SIG, I and Q filters has an entirely different mentality:
    - in the "find the amplitude and phase" mentality, you want a tight band pass on the excitation frequency in the SIG bank, and then as low-a-frequency low-pass filter that you're patience allows.
    - in the "measure the sideband noise out to 100 Hz or so" mentality, you want as little filtering magnitude / phase distortion as possible from any filtering while sill removing any noise above the band of interest from the signal, post demodulation -- which is typically down-conversion from the 2f signal.

So -- we want *no* filtering in the SIG bank prior to demodulation, and a low-pass that has minimal in-band magnitude ripple and minimal in-band phase loss.

Attached is a trade study of filters that show the magnitude, phase, and step response for several options. All these options are installed in the MEAS A and B and REF A and B I and Q filters, but we've turned only the comb and single pole.

Since we removed the cartridge from BSC2, I took the opportunity to try to remove a spring that had galled when we first installed the BS & ISI stack for Advanced LIGO. I initially tried coaxing the preload nut on the end of the spring free with alcohol and a couple of long wrenches, but eventually that wasn't enough. With Randy's help, we pulled the two cap pieces off the end of the HEPI house spring tube and lifted the cap, load cell and spring out. This spring was taken to the high bay where Randy used a porta-band to cut the galled nut off, allowing us to retrieve the other hardware off the spring. Was suprised to hear Randy say the kind of dull looking blade on the portaband had no difficulty with steel cap on the spring.

A spare spring from LLO has been installed in it's place, torqued to the crossbeam foot, the old load cell and hardware have been added above.

I didn't get any photos of the work really, but here's a shot of the de-galling method we used. 

[Tom Roocke, Oli]

Summary: QOSEM Sat Amp installed, run into ADCs and Coil drivers, injected signals into sat amp appearing where the should in CDS.

Yesterday the QOSEM Sat Amp was installed into the SUS-R2 rack (D2300383, LHO:90004), along with the in air DB37 wiring into the ADC. We checked that the signal routing into CDS was good, by injecting a current into the QPD inputs on the front panel. We used the portable calibrator found in the EE shop, to generate a 3.5mA DC current, which is about the expected level of photocurrent during nominal operation of the QOSEM. The negative output of the calibrator is connected to the cathode input for the QPD (pins 16 and 21 on the DB25 QOSEM inputs on the sat amp, see D2500300), and the positive output is connected to the anode inputs (pins 25, 12, 24, 11 and 20, 7, 19, 6). 

We injected current into the anodes for all 6 channels in the sat amp, and all showed up in CDS on the expected channels. Next to check is the QOSEM Duopus cables, which we are waiting on from C&B. After which that should be the full signal chain tested.

Camille (CIT), Austin , Rahul

This morning we went to HAM7 chamber and changed the preload on ZM4 (P-SAMS) suspension as per the document E2300463_V1. This changed the RoC of ZM4 mirror without the PZT actuation. Given below are the details of our work - Camille will add pictures later on.

- After setting ZM4 into SAFE state we locked all three stages of the suspension. We had already taken healthy TF measurements before starting our work.

- The bottom mass cable was disconnected and carefully re-routed so that it stays away from the fixture plate.

- four add-on masses (basically 1/4-20 screws with washers) attached to the bottom mass was then removed.

- bottom mass Fixture plate (D2100121) was attached to the structure using six 8-32 screws.

- The bottom mass (already locked using EQ stops) was then further clamped using four 1/4-20 screws through the fixture plate. We had to adjust the height of the bottom mass to the align the threads with the holes on the fixture plate.

- Once the bottom mass was securely clamped, we removed the three set screws on the preloader.

- Using a torque wrench we increased the preload on the bottom mass by ~29 in.lb. (Total preload from torque after increase was 75 in.lb).

- We then followed all the above steps backwards (i.e set screws, add on mass put back, fixture plate removed, cable re-connected and the suspension set free).

- Once all done, we started damping the suspension and checked for any BOSEM flag changes - looked all fine.

- We took the transfer function measurements and ZM4 looked healthy.

Hence we took all the tools out and put the curtains back on HAM7 chamber.

Next, we will go into laser hazard with SQZ team and check for any changes in beam alignment and make adjustments as required.