Vibration Sensors To Gauge Health Of HVAC Fans Site Wide

FAMIS 39862 Vibration Sensors To Gauge Health Of HVAC Fans Site Wide
 

looking at SRC gouy phase measurements

I had a look at the three SRC gouy phase measurements listed in 88155, this is related to commissoning modeling git issue 33

To do this, Evan Hall helped get me started using the current version of finesse (3.13.13) in the control room.  Anyone can use this conda environment by using conda activate finesse.  

In the first plot, the upper left subplot shows the cold gouy phase measurement, which is reasonably close to the finesse prediction using nominal parameters from the LHO_O4.yml.  I've added traces to show what happens when the SR3 ROC and SR2 ROC are changed by the rss error given by Garilyn, +/-6mm for SR3 and +/-3.7mm for SR2, and varied the distance between SR2 and SR3 around the value in the finesse yml.  The gray band shows the measurement result, indicating that the gouy phase measurement could be explained by the nominal ROCs if the SR3-2 distance is longer than the value used in finesse by 3mm, or if the distnace is nominal the SR3 ROC could be shorter by 6mm to explain the measurement.  

The next two panels show the two measurements made in October 2019, before the ITM replacement (52638 and 52658).  The ring heaters were on for both of these measurement, decreasing the expected gouy phase, and central heating was also on which should increase the gouy phase.  Using the TCS actuation strengths from 90004 we cannot easily explain these measurements as compatible with the cold state measurement.  

The last panel shows the impact of each indivdual TCS actuator on the gouy phase measurement.  The fact that all these lines are fairly close to parallel suggests that a series of measurements where we change only one actuator at a time could be a useful check of the actuation strengths.  

In the second attached plot, I plotted the difference in gouy phase between having the heater on and off, which we can get from the comparison of the two 2019 measurements, with various parameter changes.  I was wondering if we could use this difference to get information about the SR3-SR2 distance if we trust the HWS measurement of the SR3 heater strength.  The 1.8 degree systematic uncertainty on the gouy phase measurements is large enough to make this seem not very promising.  

The script used to make these plots is in the commissoning modeling repo here commit 8635b914

DUST LVEA3 channels added to DAQ

WP13209 Add DUST LVEA3 to EDC for trending

Ryan C, Jonathan, Dave:

The EDC+DAQ were restarted to add DUST LVEA3 channels. A new H1EPICS_DUST.ini was created with a modified create_edcu_dust_ini_file.py script.

Before the full DAQ restart Jonathan took the opportunity to install new code on FW2.

There were no issues with the DAQ restart.

(temporary) model changes for h1susbs and h1suslo12 (aka BSFM and BBSS)

Dave, Jeff, Oli

Model-wise, BSFM is good to damp for IAS work and the QOSEMs are ready to test using the BBSS overview screen found on the sitemap under BS / ITM -> BBSS (temp). Channel names for the old beamsplitter (BSFM) are the same, and channel names for the BBSS are 'SUS-BBSS'. This is temporary - once the BBSS is installed, its model will overwrite the current BSFM model.

Yesterday Betsy, Jeff, Tom, and I came up with a plan for how we want to test out the BBSS, QOSEMs, and build up the BBSS infrastructure while keeping the BSFM (currently on the test stand) damped for now. The plan can be found at T2600169.

The first part of the plan required figuring out how to split up the BSFM electronics with the BBSS in a way that allowed us to keep damping the BSFM while also having sufficient electronics for testing the QOSEMs. I built up a temporary BBSS model called h1susbbss.mdl and compared it to the h1susbs.mdl, as well as using the 2026 google slides in G2301306 to compare the ADC and DAC lineup for the BSFM vs BBSS.

Model needs
BSFM
M1: Damping aka ADC and DAC
M2: Not needed
M3/OPLEV: Oplev not needed

BBSS
M1: Readbacks for QOSEMs aka ADC
M2: Not fully necessary
M3/OPLEV: Not fully necessary

M1
Since we needed to have damping available for the BSFM, we needed to keep the ADC to BSFM M1 as well as the BSFM M1 to DAC how it's been. Luckily, the BBSS M1 QOSEMs use different ADC channels, so we can still have readbacks for the QOSEMs. The readouts are supposed to go to the same DAC channels as the BSFM M1 readouts, so I've terminated these outputs, but that's okay since we won't be wanting to drive the coils for a bit. After BSFM work is done, we will be putting the BBSS on the test stand and taking transfer functions with BOSEMs first, so this setup also means that we'll be able to use the BSFM model (WITH DIFFERENT OSEM2EUL MATRIX VALUES) to take those measurements before needing to swap to driving those CDs/DACs with the QOSEMs instead. The QOSEM connections were done according to the proper order of F1 F2 F3 SD LF RT (D080273). The BOSEM connections in the BSFM model were NOT changed, and so are currently F1 F2 F3 LF RT SD.
M2
Regarding M2 for each suspension, we don't need M2 on the BSFM anymore, so I've taken those ADC and DAC connections away. I've connected them to the BBSS model though. We obviously don't need them now but they will be good to have already ready.
M3 / OPLEV
Similar to M2, on the BSFM I've disconnected the ADC -> OPLEV connections since we don't need them anymore. For the BBSS, I connected up M3 OSEMs, but I did not connect the ADC -> OPLEV since the channels that the OPLEV uses with the BBSS are the same as the first four channels of ADC -> BSFM M1, which we still want.

To make sure the BBSS model channels would be named correctly, I renamed the BBSS block from BS to BBSS. I also removed any IPC channels in the BBSS model that will be needed in the future, and also removed these IPC channels from the BSFM model to be safe, even though it probably would've been fine.

Updating h1susbs model
h1susbs was updated with the changes listed above (r35127), built, and installed. before vs now

Turning "h1suslo12" into "h1suslo12 but actually it's for the BBSS/QOSEMs"
h1susb2h34 has a model running called h1suslo12, meant to be for LO1 and LO2. Since neither of these suspensions are currently needed, Dave decided it would be easiest to install the BBSS model as an updated h1suslo12 model instead of removing h1suslo12 and replacing it with h1susbbss. To do this all we needed to do was change the dcuid in h1susbbss to h1suslo12's dcuid of 188, and then copy h1susbbss over to overwrite h1suslo12. h1suslo12 was built and installed with these changes (r35136). before vs now

Dave documented installing these models in 90043.

 

Guardian notes (tagging GRD and OPS):

The SUS BS guardian has been STOPPED to keep it from doing anything weird. Please leave it stopped. There is no SUS BBSS guardian, and we don't want there to be. We will be controling both suspensions manually.

Wed CP1 Fill

Wed Apr 29 10:08:08 2026 INFO: Fill completed in 8min 4secs

 

Ops Day Shift Start

TITLE: 04/29 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: 0.02 μm/s
    Secondary useism: 0.14 μm/s 
QUICK SUMMARY: Work continues today with the old BS on the test stand and in the vented corner chambers.

WP 12469 updated the experimental framewriter

I updated and restarted the experimental framewriter on h1daqfw2 today around 2:20pm localtime today.  This was to verify some new code still produced identical frames.

h1suslo12 model now temporarily running as the BBSS model alongside the original (but slightly modified) BSFM h1susbs model

WP13213 Jeff, Tom, Oli, Dave:

h1susbs (the original BSFM model) was changed slightly to no longer drive the 2nd LIGO-DAC chans 08-11. This frees these up for use by the BBSS model. At the same time 4 IPC senders and 11 IPC receivers were removed.

Instead of replacing h1suslo12 with a brand new h1susbbss model, with all the associated RGC/DAQ/puppet changes, we chose to keep the h1suslo12 model essentially in name only, but change its function to drive the BBSS and test QOSEMS.

To do this, Oli changed the h1susbbss.mdl file to:

 - use h1suslo12's dcuid=188

 - remove all IPC senders

 - reduce the number of DAC channels, only using those freed up by the h1susbs changes

This approach means the H1.ipc and testpoint.par files are unchanged. The H1SUSLO12.txt filterfile and safe.snap files are substantially changed, but these had not been commissioned. The H1SUSLO12.ini file was also essentially rewritten for BBSS with the exception of some FEC channels.

There were no issues with rebuilding and installing the new h1susbs and h1suslo12 models. The old versions were stopped before the new ones were started because we are swapping DAC drives between these models.

DAQ Restart

The DAQ was restarted for the model changes. There were no issues found.

CDS Overview

The h1suslo12 entry on the CDS Overview has a new color/label to denote its current usage as the BBSS model. Also note the removal of some IPC senders from h1susbs means we have continuous IPC receive errors on the h1susmc2 and h1seiproc models.

Maintenance Tuesday Report

TITLE: 04/28 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:

Test T634314 @ 16:00:30 UTC

Firepump1 is on 16:30:23
FirePump2 on 16:31:20 UTC
Eric confirms that Firepumps are done being used at 16:35 UTC

Vacuum Alarm for PT120B pressure torr started alarming @ 16:42 UTC, likely due to Fil pulling cables.

Dust monitors for LVEA 10 (Which I beleive is the dust mon in the BSC2 area.)
 

Test Frame Writer2 was restarted without incident. 

HEPI Pump pressure diag main. Jim says he'd like this to become a Diag Main flag that gets raised when the following channels are more that 5% off from each other.:  
H1:HPI-PUMP_L0_PS1_PRESS1
H1:HPI-PUMP_L0_PS2_PRESS1
H1:HPI-PUMP_L0_PS3_PRESS1
H1:HPI-PUMP_L0_PS4_PRESS1

MC2 and PR2 were taken to safe while betsy and Travis work in HAM3.

DC0 & FW restarts for new SPI front end models  at 22:13 UTC.

LOG:

 

Start Time	System	Name	Location	Lazer_Haz	Task	Time End
14:40	FAC	Kim	LVEA	N	Technical Cleaning & Supplies.	15:56
14:54	FAC	Tyler & Betsy	LVEA	N	talking with Kim	14:59
15:19	SUS	Rahul	HAM3	LVEA	Installing baffles.	19:29
15:20	FAC	Randy	LVEA	N	Helping Betsy	15:39
15:31	FAC	Chris	LVEA HAM7	N	Checking traps.	15:55
15:38	SUS	Mitchell	LVEA HAM3	N	Helping Rahul with Baffles	19:25
15:41	PEM	Ryan	LVEA	N	HAM3 Dust monitor	15:48
15:42	Safety	Richard & Gerardo	LVEA	N	Talking to Betsy, Gerardo still in.	16:24
15:53	FAC	Chris	MY,EY,MX,EX,FCES	N	Famis checks.	16:42
16:04	EE	Fil	LVEA	N	Pulling cables to the Test stand	19:19
16:10	Tour	Jeff & Adrian	LVEA	n	Touring the LVEA	16:51
16:24	Cheta	Camilla	Optics Lab	N	Checking for parts	16:48
16:25	VAC	Gerardo	LVEA	N	Moving the bang Blocks.	17:38
16:26	FAC	Randy	LVEA	N	Chatting with Betsy	17:16
16:27	FAC	Tyler	LVEA Highbay	N	Moving the MeatLocker.	19:12
16:32	FAC	Kim	LVEA	N	Techincal cleaning & Re-Suppling	17:26
16:46	VAC	Travis	LVEA	N	Checking on HAM3 Feed throughs.	17:30
16:48	VAC	Jordan	LVEA	N	Checking CP1 RGA tree	17:18
17:30	VAC	Travis	MX	N	Measurements on Cryopump	17:54
18:08	EPO	Cassidy & Youth Tour	Over pass	N	Leading a tour for the Youth.	19:08
18:09	Controls	Jeff, Tom, Oli	LVEA	n	Looking for Fil	18:49
18:14	Bets	Betsy	LVEA	N	Counting Cereal numbers.	19:20
18:21	SEI	Jim	LVEA IY	N	Reconnecting a cable that was accidentally disconnected.	19:02
18:42	EPO	Maggie	Over pass	N	Leading a Youth tour.	19:27
18:52	SPI	Jeff	LVEA HAM6	n	5 minute scavenger hunt for parts.	18:54
19:01	IAS	Jason & Ryan	LVEA	N	Faroing	19:01
19:44	SEI	Jim	Mech Mezz	N	Recovering the HEPI Pumps.	20:15
20:09	SEI	Jim	LVEA	N	Revalving BSC2 HEPI	21:34
20:18	IAS	Jason & Ryan C	LVEA	N	Faro Surveying	23:48
20:22	BHSS	Keita & Elenna	Optics Lab	n	working on Manta ray.	22:09
20:23	FAC	Randy	LVEA mega Cleanroom	N	adding unistrut!	21:24
20:59	VAC	Travis & Betsy	LVEA HAM3	N	feedThrough work in HAM3	22:59
21:11	EE	Marc	CER	N	Installing SUS chassis	21:20
21:28	IAS	Sheila & Adrian	LVEA	n	Faro Surveying	22:30
23:06	VAC	Gerado	LVEA West bay	N	Poking the "Super Sucker 500"	23:26
23:21	VAC	Jordan	LVEA WestBay	N	to help Gerardo with uh.... device mentioned	23:26

HAM3 D3 feedthru swapped

The D3 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 the in-vac cables that were originally in that port and Betsy re-attached the in-air cables so that the SUSes can be controlled overnight. 

Cables were unplugged on both the vac and air sides, so keeping track was a bit tedious.  I have started an AS-BUILT cheatsheet which tracks the serial numbers as we go on the main LHO HAM3 Flange Layout DCC page https://dcc.ligo.org/D1002874-v10, see the google doc.  Attached is a snapshot of the sheet with the D3 work logged so far.  
TBC...

OMC QPD sense pin problem: Solved

Summary:

The problem of "Sense" pin of OMCA QPD1 short-circuited to the BHDS structure (alog 90029 from yesterday) was tracked down to the free "sense" wire inside the QPD enclosure touching the aluminum part inside the enclosure. We solved the problem by trimming the wire short.

Merely opening the QPD enclosure broke the short circuit temporarily:

We lifted the OMCA QPD1 from the BHDS while QPD2 is still attached to the BHDS and confirmed that the sense pin for the QPD1 is conductive to the QPD1 enclosure but not to the BHDS. As soon as we opened the back of the QPD1 enclosure, the short-circuit to the enclosure was broken. 

It seemed that the free part of the sense wire was a bit too long and bowed in the enclosure, allowing the tip of that wire to touch the inside wall of the enclosure itself (see Elenna's first image in her comments).

Cutting the sense wire short broke the short circuit permanently:

I cut the wire short such that it cannot touch the enclosure (Elenna's second picture), reassembled the enclosure and confirmed that there's no short circuit between the sense pin and anything else. 

Repeating the tests:

We put the QPD1 back on the BHDS and connected the cable to the transimpedance amplifier. On the oscilloscope, it was immediately apparent that the terrible 60Hz noise (which was 6.5V p-p) was gone (Elenna's 3rd picture).

We repeated the flashlight test, all segments responded with O(1)mV negative voltage (i.e. positive output minus negative output from the TIA amplifier was negative few mV maximum) while the dark offset was O(0.1mV).

We also measured the dark noise. It seems that all measurements for both QPD1 and QPD2 were limited by the noise of the TIA. Low frequency noise especially 60Hz and its harmonics varied from channel to channel, but in all cases it seemed that there's very little difference between the noise measured with QPD connected VS the noise without QPD. As such, I'll just show here a few examples. First attachment is the QPD1 segment 1 noise with the QPD attached, the second is the same thing but without QPD connected to the front panel of the TIA. They look identical. The third one is the QPD1 segment 4 (with QPD attached, not much different without QPD). The fourth one is the QPD2 segment 3 (with QPD attached, not much different without QPD).

There's no reason to suspect that QPD1 for OMCA is broken (nor QPD2).

1 of 4 HEPI Corner station pumps have been off since Dec 14 2025 power outage, remaining 3 pumpstations were running at ~95% to cover since

Last week I tripped the HEPI pump controller valving out the BSC2 actuators, it took me until today to try to recover it. In the process of investigating this I found that one of the 4 corner station HEPI pump carts has been more or less off since a power outage in December. The remaining pump stations have been running at about 95% drive to cover for the lost cart. I am working on some revisions to the famis and asking to Tony to add a verbal notification if there is a mismatch in the manifold pressures for the 4 corner pump stations.

Nice to know that we have overhead to lose one pump station and still supply the corner HEPI with pressure. Drive is much lower now that all 4 are running again.

Attached image shows how long we have been running with only 3 pumps. Crosshair in the upper left plot shows approximate time of the power outage. Bottom right shows we have been running at ~1900 cts drive out of 2048 total available since then. We are back around 1100 cts drive now.

HAM3 chamber vent work - SLiC, BAFFLE ASSY attached to both PR2 and MC2

Mitchell, Rahul

This morning we entered HAM3 chamber and attached the baffles (for stray light control) to both PR2 (HSTS) and MC2 (HSTS) suspensions. The baffle assembly design is shown D1700257_V5. These baffles were attached (directly mounted on the HSTS structure) on both the sides of the optic, i.e  HR and AR side.

Before attaching the baffles I inspected both the optics and they looked nice and clean, hence didn't needed any First Contact cleaning. 

I am attaching pictures below for reference.

We found that both PR2 and MC2 had two missing 1/4-20 threads on the HR side for attaching the mounting rail (D1700249_v1) of the baffle (Mitchell will attach a picture showing the same). Typically, these rail need four holes on the structure for securing them. However, we used the lower two threaded holes for attaching these mounting rail and they were rigidly secured. On the DCC I found that both PR2 and MC2 have D020023_V3 of the HSTS_Structural Weldment Assembly, latest D020023_V7 has more holes on the frame.

We also noted that one of the Siskiyou mount is very close to the MC2 baffle (AR side) as shown in the picture here. However, I can confirm that they are not touching and there is a decent amount of clearance between them. 

I still need to perform health checks on both the suspensions to rule out any rubbing and will post the results as a comment over here.

Note - counts on dust monitor were in single digit before and after entering/exiting the chamber (Thanks to Ryan C for arranging this). 

BSC2 Cartridge de-install prep

Today, with the BS SUS set to SAFE and the SEI chassis turned off at the rack, Tony, Ibrahim and I started unplugging and logging all of the cables in the chamber at the feedthrus.  I have a master log going which will be posted as an As-Built to the D1003079 BSC2 Flange Feedthru Layout Drawing for future re-plug-in activities.  Pictures of 2 feedthrus prior to unplugging are attached for samples of what I'm talking about.

As well, we dropped the ITMX Elliptical Baffle and Down Tube Sub assemblies from Stage 2 and have a good start on the ITMY one but didn't finish since it has mismatched hardware and we need a different tool.  (In the event we need to put them back up, we left them off to the sides of the chamber to deal with later - the ITMX one is the one closest into the ITMX chamber.)

Also also, we locked the BS SUS, tightened all of the nuts, removed all of the Vibration Absorber Cubes, and put the sock on the full SUS.

Tomorrow we need to:

Add the BS Face cover
Remove a Stay or 4
Finish stowing all of the dangling cables
Finish removing the ITMY Elliptical Baffle
Get on with the Support Tube and SEI work

Here is a snapshot of the LHO BSC2 AS-BUILT cheatsheet of cable serial numbers, also posted as a google doc on https://dcc.ligo.org/LIGO-D1003079.

Comparison with IMC WFS before and after JAC installation

Jennie W, Jeff Kissel,

 

Summary: Can we see a difference in jitter with JAC in the IMC ASC sensors? Short answer, yes.

The IMC has less angular motion with JAC installed at some frequencies - jitter is being suppressed by the JAC so less input beam motion relative to the cavity axis. The QPD readouts are noisier with JAC but there is one new suspension between JAC and the IMC so maybe the beam pointing to MC1 is noisier? MC2 TRANS QPD looks pretty similar with and without JAC, but this makes sense as cavity axis is still well aligned to this QPD. I need some other figure of merit to look at jitter as it only limits the IFO above 20 Hz, see alog #86555 by Sheila.

Since there was no time for a full IFO lock betwen the HAM1 vent and the current vent of the corner volume, we cannot directly check whether the jitter coupling to DARM is better with the JAC cavity.

We have lots of data of the JAC and IMC locked after the installation of JAC, however.

So I compared two times when we had roughly 2W input from the PSL to HAM1. In both cases H1 and the corner were at vacuum to rule out confounding effects from purge air and other sound noise seen when HAM1 was at air.

In both these cases the IMC was locked.

The two times I used were:

2025/11/17 15:38:54 UTC no JAC, during O4c

2026/03/20 00:26:01 UTC JAC installed, HAM1 at vacuum

Here is the ASD measurements for five sensors in the pitch degree of freedom:

IMC REFL WFS A  Roughly the same above 10Hz with and without JAC. Better with JAC between 0.3 and 7Hz.

IMC REFL WFS B Roughly the same above 10Hz with and without JAC. Better with JAC below 7Hz.

IMC REFL QPD A has lower noise now below 5Hz than before JAC installation and much higher noise at frequencies above 10Hz.

IMC REFL QPD B has lower noise now below 3Hz than before JAC installation and much higher noise at frequencies above 10Hz.

MC2 TRANS QPD roughly the same with and without JAC.

Jitter noise is more of a problem in the 20-800 Hz region, which these plots don't tell us much about.

I also need the check YAW