Jennie, Jordan, Camilla 

We covered the REFL septum widow with the cover to protect it and then placed the HAM1 periscope on the table. Then removed the septum covers so that now that REFL, PSL and POP/ALS septum windows are uncovered and we can get beams though. Photo attached. 

I was using the RF test input to test the response of the photodetectors in HAM1.

LSC-POP_A, LSC-REFL_A, LSC-REFL_B are working as expected after swapping the cables at the patch panel for Test-Out and RF1.

ASC-REFL_A was working as expected.

ASC-REFL_B showed no response.

ASC_POP_X looks like the RF cables may be switched.

Thu May 01 10:14:06 2025 INFO: Fill completed in 14min 2secs

Jordan confimed a good fill curbside.

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

Dew point measurement at HAM1 , approx. -42C

The turbo on the YBM tripped as a result of the power glitch reported last night see alog 84217, leading to a slight pressure rise in the corner.

I closed the main gate valve at that turbo and restarted the scroll pump/backing turbo and main turbo. Once the turbo reached full speed and the intake pressure was lower than the main volume pressure I verified trip setpoints and re-opened the gate valve..

This was the only turbo station that tripped. Output tube/XBM & HAM6 turbos were all nominal.

Another site power glitch, caught by GC OSB UPS but not CDS MSR UPS. Seen by CS MAINSMON.

My house lights flickered around this time.

UPS email:

Date : 04/30/2025
Time : 21:39:31
Code : 0x0109

Warning - UPS: On battery power in response to an input power problem.

Jonathan, Dave:

I have added the new third framewriter (FW2) to DAQSTAT.

H1:DAQ-FW2_STATUS is now viewable in the DAQ section of the CDS Overview (see attached).

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, 3mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.12 μm/s
QUICK SUMMARY:

Vent work today includes:

• EY wind fence
• HAM1 beam profiling
• PM1 installation
• HEPI upgrade software
• HAM4/5 cable tray work
• Ground checks of LSC/ASC diode boxes now fully cabled

Keita, Elenna, Oli, Rahul, Camilla

Summary: Majority of REFL path optics are aligned. Need to beam profile and finish LSC and ASC REFL diode placement on this path and place/check all beam dumps.

This morning, Keita opened the light pipe, locked the IMC  but couldn't see the beam as nicely as he did on AS_AIR yesterday. Since that time he had restored PR2 and PR3 to a time we were last locked. He reverted those changes as we could see the beam back at AS_AIR. Checked again IM4 trans QPD was the same as yesterday.

• The beam coming out of the spectrum port was not centered on the REFL optics that had been placed as per D1000313-v19. We checked Corey's photos to compare REFL optics position relative to periscope and the D10002313 drawing and convince ourselves the beam in correct just the drawing of it is incorrect.
• Firstly checked the incoming beam was centered on M14 and the reflected beam off this was dumped on the HiPWR beam dump which was moved to it's final position.
• Beam centered on HW1
• Beam centered on M17 and the reflected beam off this was dumped on the HiPWR beam dump
• Beam centered on M1 and headed towards M2
• Beam centered on M7, following the correct beam path off the table and dumped but a temporary dump (before we put in BDV1)
• Beam centered on M2 and headed towards center of RM1.
  • Transmitted M2 beam dumped by BD8
• Rahul got RM1 and RM2 damping loops working so they are now in DAMPED nominally (changed OPS whiteboard) Rahul set sliders to zero.
• Beam centered on RM1 and headed towards center of RM2 (we had to turn RM1 in YAW)
  • BD16 placed behind RM1 but beam can't be seen to align to.
• Placed M5 in roughly correct place
• Beam centered on RM2 and headed towards center of M5 (we had to turn RM2 in YAW)
• Beam centered on M5 and headed towards the SLED
  • There was a fair bit of iteration of M2 and M5 here to get the beam to be aligned and centered on all optics through the SLED, still needed to adjust SLED mirror to get it centered on the final mirror.
• Adjusted the SLED steering mirror (in the position +X -Y) on the SLED to center the beam on the ASC REFL B diode steering mirror.
• Adjusted ASC REFL B diode steering mirror so that picomotors had some range left.
• Beam centered on M6 and headed towards L1/M18
• Beam centered on L1
• Beam centered on M18 and headed towards LSC REFL A and LSC REFL B
  • We stopped here before fully aligning these too diodes
  • LSC REFL A is aligned by eye and 22cm from L1 (+222mm FL)
  • LSC REFL B is 20cm from L1 and will be moved to match LSC REFL A tomorrow.

Additionally M16 was placed roughly in the correct position, all optics are now on HAM1 (apart from PM1) and the class-B pans are empty and packed up.

Left IMC locked.

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: The vent work continues...
LOG:                                                                                                                                                                                                                                                           

RM troubleshooting alog84204

EY wind fence continues

HAM1 alignment continues

Vacuum gauge work by HAM6

Following the work from yesterday post, 2 questions came up immediately. One, how much does the sensing function change with input power? We can plot it as a function of arms circulating power instead. Second, if the detuning is the same, but at different mode mismatches, do we get the same sensing function?

We can see the answer to the first question in this plot. These sensing functions are normalized to 100 Hz value. The ratio between the highest power and the lowest power sensing functions is plotted (dashed line) as well.  

Before answering the second question, let’s look at the following scenario. 

We lock the interferometer, get SRCL.DC to be -90.4643, then we change that detuning while locking. What happens to the PDH signal and the sensing function now?

Here I plotted the error signals as I change SRCL.DC detuning by ± 0.5 deg 

And the DARM sensing at different detuning looks like this 

So, we see that the sensing function significantly changes with detuning at a constant mismatch. 

So, from here, let’s answer the 2nd question. What we will do is to change the mismatch then manually offset the detuning to be the same in both cases. 

For that I look at 2 cases. The first case is the default case where there is a mismatch between SRC and ARM cavities with SRCL.DC = -90.4643 and I plot the sensing function. Now, when I change the radii of curvature of ITMX and ITMY - I get almost a perfect mode matching - SRCL.DC becomes ~ -90.004. Again, the question is, if I add an offset to make SRCL.DC = -90.4643, would I get the same sensing function as the first case, where SRCL.DC is -90.4643 due to the mismatch.

The answer turns out to be not entirely, but also it depends on the power as well. 

So, I looked at 2 cases, the first with input power of 1W, in which both sensing functions are very similar to each other in behaviour (not magnitude). The normalized plot shows that, in addition it shows the ratio between both of them.  This is shown in here

The 2nd case is with an input power of 60W. In this case, they are not as similar to each other anymore, though not so different either. 

This is shown in here

To conclude the 2nd question: the sensing function is almost the same (depending on the power) at the same detuning regardless of the mismatch (in the low mismatch limit < 2%)

Jim, RyanC

We noticed that the oplev damping values seemed pretty large, so we turned off the output for the OLDAMP. The noise increase started the morning of the 1st which makes sense as it's when the vent started.

WP 12505.

Patrick, Gerardo

I tried various restarts of the Beckhoff PLC on h0vaclx, but none of them changed the error on the PT110 gauge. I did notice an additional diagnosis of the error, which is that the status of the EtherCAT ports is abnormal, which I think is an indication that something is not right with the connection of the gauge to the h0vaclx EtherCAT network. Gerardo went out to reseat the cable and look for anything odd about it.

I went through and checked the relay trip point levels for each of the gauges on h0vaclx. I found PT110, PT180 and PT170 set to 1E-5 and changed them to 5E-5. PT132 was already at 5E-5. The other gauges do not have the trip points enabled.

PT110 1E-5 -> 5E-5
PT140 not enabled
PT180 1E-5 -> 5E-5
PT170 1E-5 -> 5E-5
PT132 5E-5
PT193 not enabled
PT192 not enabled
PT191 not enabled

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.

Edgard, Oli.

Follow up to the work summarized in 84012 and 84041.

TL;DR: Oli tested the estimator on Friday and found the ISI state affects the stability of the scheme, plus a gain error in my fits from 84041. The two issues were corrected and the intended estimator drives look normal (promising, even) now. The official test will happen later, depending on HAM1 suspension work.

____

Oli tested the OSEM estimator damping on SR3 on Friday and immediately found two issues to debug:

1) [See first attachment] The ISI state for the first test that Oli ran was DAMPED. Since the estimator was created with the ISI in ISOLATED (and it is intended to be used in that state), the system went unstable. This issue is exacerbated by point 2) below. This means that we need to properly manage the interaction of the estimator with guardian and any watchdogs to ensure the estimator is never engaged if the ISI trips.

2) [See second attachment] There was a miscalibration of the fits I originally imported to the front-end. This resulted in large drives when using the estimator path. In the second figure, there are three conditions for the yaw damping of SR3:
           ( t < -6 min )          OSEM damping with gain of -0.1.
    ( -6 min<  t  < -2 min)   OSEM damping with a gain of -0.5, split between the usual damping path and the estimator path.
     ( -2 min < t < 0 min)     OSEM + Estimator damping.

The top left corner plot shows the observed motion from every path. It can be seen that M1_YAW_DAMP_EST_IN1 (the input to the estimator damping filters) is orders of magnitude larger than M1_DAMP_IN1 (the imput to the regular OSEM damping filters).

The issue was that I fit and exported the transfer functions in SI units, [m/m] for the suspoint to M1, and [m/N] for M1 to M1. I didn't export the calibration factors to convert to [um/nm] and [um/drive_cts], respectively.

____

I fixed this issue on Friday. Updated the files in /sus/trunk/HLTS/Common/FilterDesign/Estimator/  to add a calibration filter module to the two estimator paths (a factor of 0.001 for suspoint to M1, and 1.5404 for M1 to M1). The changes are current as of revision 12288 of the sus svn.

The third attachment shows the intended drives from the estimator and OSEM-only paths. They look similar enough that we believe the miscalibration issue has been resolved. For now we stand by until there is a chance to test the scheme again.