This alog summarizes the measurements done with an ISC whitening chassis that implements ISC whitening boards D1001530-v7 using a 9V battery at the input.

Several issues were found:

1. Due to a BOM error resistors R15 and R21 were stuffed with 3kΩ thick film resistors instead of metal film. Plot 1 shows the output referred noise measure at test point TP1. The blue curve was measured with a grounded input, whereas the red curve was measured with a 9V battery at the input. The later clearly shows the flicker noise of a carbon film resistor at roughly 600nV/√ f.
2. The power supply input of the whitening board eomploys 10µH series inductors. Together with the bypass capacitors this forms a resonant circuit near 10kHz which shows up as a noise peak in the plots. Plot 2 shows the output noise with no whitening engaged for the original board (blue curve), the board with fixed 3kΩ resistors (green), and with the power supply indcutors shorted out (red).
3. The gain stages will generate excess noise when over driven. The whitening board employs 4 switchable gain stages with 24, 12, 6, and 3dB of gain, respectively. With 9V input both the 24 and 12dB stage are over driven with their ouput voltage limited by the power supply rails. This will in turn lead to a large differential input voltage at the inputs of the OpAmp which then triggers the protection diodes. The current is limited by the 300Ω resistors (R11) in series with the + input. Even so, it is safe to operate like this, it can generate execss noise as seen in Plot 3. The blue curve shows the output noise with the input grounded, whereas the red curve uses a 9V battery at the input. The green curve shows the noise of the SR785 and the battery alone.

Plot 4 shows the 9V input noise using the optional whitening stages. A whitening stage consist of a 1Hz zero and a 10Hz pole.
Plot 5 shows the same plot but with the 300Ω resistors removed, the 3kΩ resistors replaced with metal films, and the inductors at the power supply shorted out.
Plot 6 is an overlay of Plots 4 and 5.

Jennie W, Sheila, Elenna

In order to get data for mode-matching and for Elenna to get data to calibrate sideband heights we ran some mode scans after the SR3 heater was turned on last night.

16:55:24 UTC Carried out single bounce OMC scan at 10W PSL input with sensor correction on HAM6 on, high voltage on for PZT driver in HAM6, sidebands off , SRM mis-aligned, ITMY mis-aligned, DC 3 and 4 on, OMC ASC on.

Excitation freq changed to 0.005 Hz as the top peak of the TM00 mode looked squint so could have been saturating. Lowering this frequency prevented this.

Ref 15-17 corresponds to dcpd data, pzt exc signal, pzt2 dc monitor.

Then mis-aligned ITMX and aligned ITMY (Sheila had to re-align SR2 to centre on ASC-AS_C).

Measurement starts at 17:08:18 UTC.

Ref 18-20 corresponds to dcpd data, pzt exc signal, pzt2 dc monitor.

Traces saved in 20250516_OMC_scan.xml. The top left plot is the first scan bouncing beam off ITMX, the second scan is the bottom right bouncing off ITMY.

The top right is the two plots of the PZT2 DC voltage monitor. That is, the current voltage applied to the PZT. The bottom left is the plot of the voltage ramp applied to the PZT2 on the OMC for this measurement.

The ndscope attached shows the power in mA transmitted through the OMC on the top, then the PZT used for the scan DC voltage underneath, then the input PZT voltage underneath that, then the reflected power from the OMC in mW, then at the bottom the SR3 heater element temperature in degrees.

Elenna did two more scans in single bounce with sidebands back on and different modulations depths in each.

Fri May 16 10:06:36 2025 INFO: Fill completed in 6min 33secs

Jordan confirmed a good fill curbside.

Closes FAMIS#37205, last checked 83981
 
HEPI pump trends looking as expected (ndscope).

Dry air skid checks, water pump, kobelco, drying towers all nominal.

Dew point measurement at HAM1 -42.1 °C.

TITLE: 05/16 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: 6mph Gusts, 3mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.09 μm/s
QUICK SUMMARY:

Most of the work for today involves final checks for HAM1

(Jordan V., Travis S., Gerardo M.)
Today we installed a new gauge on the 16.5" conflat on top of HAM1, installed on the top central port, D1.  A single gauge replaces a gauge pair combo, pirani and cold cathode, this gauge will be used for the high voltage interlock system for HAM1.  The gauge still needs the installation a couple of cables for it to work.

The turbo pump was the second item that was replaced on HAM1, an outdated and noisy turbo pump was removed and replaced with a new turbo pump.  No issues were encountered during the removal or installation of the new pump.

All of the affected conflats will need to be checked for leaks.

Shoshana, Michael, Jeff, Tony

We spun the NCal as a life check while we were on site. At first the NCal wouldn't turn on and threw a 'NCal power' error. Power-cycling the motor power by replugging the AC cable running to the Beckhoff motor controller (black cable coming from the left in attached picture) fixed the error. We spun the rotor up to 10 Hz for a few minutes before spinning it down.

NCal Settings:

Motor Frequency Request: 1040 ct

Motor Ramp Gain: 0.01

Motor Low Pass Time Constant: 5

TITLE: 05/15 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

Vac Folks are still in the LVEA working on the Top VAC Flange Guage.

The TCS SLEDs were swapped.

The Ground checks were done on HAM1

The Ring Heater for SR3 is being left on all night.

BRS team has been pumping down the BRS, seems like perhaps they are mostly done and may go back to EY clean up some wiring.

HAM1 Suspentions seem to be saturating a lot today , but there was a lot of activities on ther ISI and ontop of the HAM1 chamber.

There was some Wind fence work done today at EX, where another Bee hive was spotted on a tumble weed. So please Bee aware, of the TumbleBees.

LOG:

Camilla C, TJ S

The two corner station HWS SLEDs were last swapped back in October 2023 (alog73371), going a bit long than our usual ~1 year before swapping. Today we swapped them with fresh SLEDs following the T1500193 procedure, calibrated their power channels, and started the code back up with fresh references.

TJ, Camilla, Sheila

TJ and Camilla got the HWSs working, and now we turned on the SR3 heater at 15:54 UTC, 2W requested power.  This is to do a check of the SR3 heater calibration and range similar to 27262

Fil, Rahul

This morning we finished ground loop checks on HAM1 chamber, since Jim was done with final cabling work. The only grounding issues we found were in RM1 and PM1, hence we removed pin1 from the in-air cable (connecting Satamps).

Now that ISC is done with their alignment, I have been working on testing the ISI. Last night TJ and I unlocked and balanced the ISI, I did some quick tests to make sure the actuators were pushing where I expected them and found the horizontal and vertical actuator for each corner was swapped, so I switched the cables at the chamber. This morning I did some tests like range of motion and CPS linearity and some quick spectra to check that all of the sensors looked more or less the same and a quick set of tfs to look for rubbing. Now starting my long overnight tfs, so hopefully there are no big eqs overnight. If those go well, I hope to have everything for the testing report by the afternoon tomorrow.

Attached images are some of the tests I did today. First image is CPS linearity, which looks kind of ratty because I think the purge was too high, but otherwise looks okay. Second image shows unlocked asds for the CPS, GS13s and L4Cs. No glaring issues, but the kind of noisy V2 GS13 and CPS made me think some rubbing or high purge was happening. Last image is a set of tfs I used for chamber closeout comparing the measurements on HAM8 from last year to HAM1 today. Looks okay for a quick measurement.

[Shoshana, Michael]

We've started preparing to install the BRS mass adjuster to the End-Y BRS. The plan is to follow the same procedure/same parts as the End-X install outlined in LIGO-T2400043 and SEI log 1886 (https://alog.ligo-la.caltech.edu/SEI/index.php?callRep=1886).
 We've taken apart the BRS and discovered that doesn't match the designs on the DCC. How the parts are arranged blocks access to where the pico-motor mount should attach, but we think we have a work around that should work.
The electronics/wiring of the BRS is as expected and we've finished all the wiring for the pico-motor so that it should attach to the feed through.
Assuming all goes well we plan on installing the mass adjuster parts and begin testin.

Oli, Keita, Elenna, Jennie, Sheila, Ryan S, Rahul, Betsy, Camilla

Day 1: 84193, Day 2: 84228, Day 3: 84230 and 84239, Day 4: 84274, Day 5: 84292

• To work on REFL beam: need PRM aligned and ITMX or ITMY misaligned 
• To work on POP flashes: need PRM aligned and ITMX aligned
• To work on POP single bounce (low power ~30uW into HAM1 POP path for 20W from PSL): need PRM and ITMY misaligned 

In the morning Keita and Jennie aligned the POP flashes on the periscope mirrors and M10 dichroic. The height of this beam is 3.75" on these mirrors to account for the ALS green beam being 13mm above the POP beam. Keita was a little concerned about the height of the top periscope mirror so we'll need to check the green ALS beam carefully on this and if it 's near clipping we may need some in-vac pico-ing.

Rahul then moved PM1 to it's final position. Elenna and Rahul checked that the signed of the PIT and YAW sliders were correct. 

Shiela, Rahul and I then worked on centering the beam on PM1 and L2 without the 90/10 M12 in place, so that we could later have enough power to beam profile the POP single bounce beam. To get the beam height back up to 4" at PM1, Rahul needed to pitch PM1 mechanically. 

Oli then increased PSL input power to 20W, we aligned to POP single bounce and Sheila and I took beam profile measurements before PM1 and after L2, details in 84307.

Elenna, Rahul and I then replaced the 90/10 M12 and recentered the beam on PM1 and L2. We started aligning the POP air path but aren't happy with it, dumped the beam and will continue to work on. 

Betsy let in the PSL ALS beam into HAM1 by opening the light pipe and I dumped it straight away. See 84312.

Today we plan to: align the POP, REFL and PSL ALS beams out of the chamber, open the X-arm check the green ALS beam alignment on the shared optics and off the table, including rolling up ISCT1 and adding the VP simulator. The POP LSC/ASC diodes and all beam dumps still need to be aligned and checked. 

I took two single bounce OMC scans today with the help of TJ and Tony. Here are some notes to future me and others to reference if we want to do single bounce scans:

• align one ITM. We chose ITMY today because of work happening with the oplev that required ITMY to be aligned
• for this scan, I increased the input power to 10 W
• first check if the fast shutter is OPEN (silly mistake, spent a few minutes wondering where the beam was)
• take the OMC guardian to DOWN. After the fast shutter mistake, TJ and I were fighting to scan and realized that the guardian was set to "OFF_RESONANCE" and overriding us as we scanned
• I turned on the AS centering loops by hand, DC3 and DC4 P/Y (this aligns OM1 and 2 onto the AS WFS)
• To ensure alignment to AS_C was good, TJ and I ran SR2_ALIGN in the ALIGN_IFO guardian (after this I had to reengage the DC centering loops because the ALIGN_IFO guardian turned them off going to DOWN)
• I saw an off-centered beam on the OMC QPDs, so I engaged the OMC ASC master gain which centered the QPDs
• There was a moment where I thought the PZT2 offset mattered, so I changed it. I see now that it probably didn't matter, and only effects where the scan starts
• I used an OMC scan template in [userapps] omc/h1/templates/OMC_scan_single_bounce.xml
• run some scans! Today, I ran a scan with nominal settings, and another scan with the RF9 modulation down by 3 dBm and the RF45 modulation down by 6 dBm, which are the settings in full lock
• my scans are saved in [userapps] omc/h1/templates/OMC_scan_single_bounce_RF_cal.xml

Edit to add: unfortunately the scan results from today look pretty bad. In short, the peaks look "lopsided" somehow, and so I'm not sure the results are usable. Looking back at Jennie W's previous scans, it looks like she had to slow them down to 200 second scans. I only did a 100 second scan with amplitude 105 so maybe I scanned too fast. I'm not sure what the correct resolution of this is, because the scans I did in 2022 were 100 second scans and the results were fine. Adding this note here for reference in the future to think about the appropriate scan length and amplitude.