Displaying reports 61-80 of 88882.Go to page 1 2 3 4 5 6 7 8 9 10 End
Reports until 18:11, Monday 10 August 2026
H1 CDS
jonathan.hanks@LIGO.ORG - posted 18:11, Monday 10 August 2026 (91469)
WP 13504 investigating higher rate of transport issues

As per WP 13504 we made some changes on h1daqdc0 to see if they would impact the error rate*.  We turned on the irqbalance daemon to see if that would help with IO load.  We are going to let this run a day or two and evaluate what things look like.  We are looking at other ideas (timing changes, network config changes, possible code changes to lock cores and network interrupts together better) but are going to hold off until the control room is ready.

* In the daqd, the CRC errors are a misnomer.  It really means late data, not corrupt data.

H1 SEI
jim.warner@LIGO.ORG - posted 17:58, Monday 10 August 2026 (91468)
Testing high voltage CPS on HAM8 ISI overnight

While Huyen is here, we've dug out the high voltage CPS that we got several years ago to try testing them on HAM8 again. We have a little preliminary data, that doesn't look good so far, but we will try to see if we can get any improvements over the next couple of days, while HAM8 is still isolated from the rest of the detector.

H1 SPI
jim.warner@LIGO.ORG - posted 17:48, Monday 10 August 2026 - last comment - 09:56, Tuesday 11 August 2026(91467)
No power on power mon pd in SPI laser chassis

Jennie and I were looking at the SPI with Sina during a call today and Sina pointed out there was no power on the first PDs on the SPI breadboard. She said there was a witness pd in there SPI laser chassis that could be checked with a multimeter next to the chamber, so I went and checked that this afternoon. I'm not totally sure what all of the labels meant, but I think there is no laser light on the pd in the interface chassis. The SPI_LP_M1_PD was at 0v, the other two, SPI_LPMON_M2_RFMEAS and SPI_LPMON_M3_RFREF were at ~.8v regardless of the state of the CDS control of the SPI pick off shutter, which I had Ryan toggling remotely. We've talked to Ryan and Jason about going into the PSL tomorrow to check the function of the SPI pick off shutter, I think we will also try to check the output of the fiber at the chassis with a laser card at least. Not sure how hard it would be to look with a power meter.

Images attached to this report
Comments related to this report
filiberto.clara@LIGO.ORG - 09:56, Tuesday 11 August 2026 (91478)

Cable at shutter controller on IOT1L was not connected. DB9 was connected to ouput CH2.

LHO General
corey.gray@LIGO.ORG - posted 16:33, Monday 10 August 2026 (91458)
Mon Day Ops Summary

TITLE: 08/10 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: Ryan S

SHIFT SUMMARY:

Input Align & ZM4 work continued today with LVEA being transitioned to HAZARD toward the end of the shift for checks at ISCT1.

Apollo on-site to begin work addressing a beam tube enclosure section which is failing by installing framework inside the beam tube enclosure (this section in question is part of X1 on the Xarm [near the bridge]).

VAC team has been preparing for the quick X-arm opening peek tomorrow.

 LOG:

H1 SUS (SUS)
timothy.ohanlon@LIGO.ORG - posted 15:29, Monday 10 August 2026 (91466)
QOSEM to BOSEM Performance Comparison

+ Valera

Now that we have the full 6x12 QOSEM to Euler matrix implemented at LLO, I have made a bunch of comparison plots looking at ITM BOSEMs and BBSS QOSEMS. Per sensor, we see about 2 to 3 times improvement but expected more like 10x. I made the comparison for L1 and H1. I also directly compared L1 v H1 BBSS QOSEM performance and compared the L1 6x6 v L1 6x12 OSEM to Euler Matrix.

L1 BS QOSEM vs L1 ITM BOSEM
H1 BS QOSEM vs L1 ITM BOSEM
L1 vs H1 QOSEM
L1 6x6 vs L1 6x12 OSEM to Euler Matrix 

Some things to note for the comparison plots

Non-image files attached to this report
H1 IOO (ISC)
louis.dartez@LIGO.ORG - posted 14:00, Monday 10 August 2026 - last comment - 15:18, Monday 10 August 2026(91463)
Morning input alignment work: better IR alignment to POP_X and LSC-POP
L.Dartez, S. Dwyer, M. Nakano

Continuing from alog 91450, I started using awg to raster the im4 alignment to find the IR beam on the ISCT1 REFL camera on Friday. This effort was paused at the end of the day without finding the beam. This morning, Masayuki and Sheila noticed that the AS AIR camera had a beam but it was off-center. They walked it back using PR2 and IM4 and adjusted PR3 and the BS to compensate. 

When I got in to the control room I adjusted IM4 further to center the beam on ASC-POP_A. ASC-POP_B is still off center but we're choosing to prefer that POP_A stays centered for now.

Later this morning, Masayuki and I decided to see if we could find a PR2 + PR3 + PM1 alignment that 1.) maximizes LSC-POP, 2.) maintains the beam centered on ASC-POP_X, and 3.) maintains the beam center on the ISCT1 REFL camera. Starting from the nominal position (e.g. the position it was already in before we started) we moved PR2 in each direction. Each trial move's procedure was as follows: 1.) move PR2, 2.) compensate with PR3 to recenter ISCT1 REFL camera, 3.) adjust PM1 to center onto POP_X, 4.) observe/record the LSC POP counts.

We currently have roughly 3.4 counts on ASC-POP_X NSUM and 2.7 counts on LSC POP with POP_X centered within about 0.15 and 0.1 counts for PIT and YAW, respectively.

The slider values for PM1 are in PM1_sliders.png and the sliders for PR2,PR3, and IM4 are in IFO_sliders.png.

This new alignment configuration should better position us for the arm peak taking place this week, since we can confirm that we have red beam down to the ISCT1 table and on POP_X. The next intermediate step here will be to lock PRMI...
Images attached to this report
Comments related to this report
louis.dartez@LIGO.ORG - 14:21, Monday 10 August 2026 (91464)
Masayuki and I aligned PRM. We aren't able to lock PRMI yet since there is no light on LSC POPAIR 18 right now.

Sliders for PRM are in PRM_sliders.png.
Images attached to this comment
louis.dartez@LIGO.ORG - 15:18, Monday 10 August 2026 (91465)
I briefly misaligned the PRM and BS to check the actuation range of the RMs with the DC centering loops engaged to make sure that we aren't at risk of railing them. All looks good.
H1 AOS (SEI)
wandaelisabeth.vossius@LIGO.ORG - posted 11:28, Monday 10 August 2026 (91462)
DAS Interrogators settings
Wanda V., Reinhardt R. 

On Friday (08/07) we connected both fibres which measure the arms to the Febus interrogator, with the X arm on Ch1 and the Y arm on Ch2. This frees up the Sintela interrogator for Reinhardts experiments. 

The Febus interrogator is now measuring at 2500 Hz with a downsample factor of 10 before saving, coming to a recorded sampling rate of 250 Hz. The gauge length was 6m. In case there is a crash or the measurement needs to be restarted, the pipleline to load is LIGO_20260807_DS_SR_Writer_both250hz_v2. Filesize is ca 50 MB/min/channel

Monday August 10th: 
We measured at 10 m gaugelength over the weekend and it was changed to 6m at 11:00 am (PST) on Monday. 

The filesize is roughly 100 MB/min for the 6m gaugelength (so 200 MB/min for both channels) and roughly 60 MB/min per channel for 10m GL. If this measurement should be restarted, the pipeline is LIGO_20260807_DS_SR_Writer_both250hz_v3. 

In principle, the interrogator can now run "as is" through IR1, but we are still free to change any of the settings. 

LHO General
tyler.guidry@LIGO.ORG - posted 08:29, Monday 10 August 2026 (91459)
Well Pump Failure
On the morning of Monday, 8/3 I noticed that the well tank was quite low. Given the sporadic re-routing of well water supply to CEBEX this was not immediately concerning. Because the well tank can call for the pump to run, it sometimes calls but never satisfies because of the possible configuration of valves at MY. This confuses the FMCS logic, and will cause it to no longer function as designed. That said, when I attempted to manually command the well pump remotely, it alarmed out. At that point, Eric, Bubba and Richard did some lite electrical troubleshooting. The most obvious issue at the time was that the IR contactor refused to pull in despite the cabinet being in hand and being told to run.

At this point, I called Ohmco to see if they were able to shift their schedule around to put eyes on the well cabinet ASAP. They arrived within ~2 hours and began their troubleshooting. After hours of poking around, their assessment was that the soft start motor control was likely faulty. Unfortunately, despite the soft start readout being largely shielded from the sun, it was not operable so no apparent faults could be documented.

A soft start (P/N ATS480D88Y) was ordered on Monday and arrived Friday. Ohmco arrived that day, swapped the motor control's, set the appropriate parameters according to our pump HP and we verified rotation. This fixed the issue and operation of the wellhead returned to normal.

A second, identical soft start motor control has been ordered and is expected to arrive today. This will serve as a backup in the event this issue arises again. It will be clearly labeled and stored in the carpenter shop.

B. Gateley E. Otterman R. McCarthy T. Guidry 
Images attached to this report
LHO General
corey.gray@LIGO.ORG - posted 07:37, Monday 10 August 2026 - last comment - 10:45, Monday 10 August 2026(91456)
Mon Day Ops Transition

TITLE: 08/10 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: EARTHQUAKE
    Wind: 7mph Gusts, 4mph 3min avg
    Primary useism: 0.58 μm/s
    Secondary useism: 0.09 μm/s 
QUICK SUMMARY:

NOTE:  Both Ops work stations had troubles logging in  (I could enter my username, but then the computer would freeze...for both computers).  So I'm back here at cdsws27.  It worked, but it was a little slow.

We had a M7.4 earthquake in Bogota (sort of in between Cali/Medellin/Bogota) that rolled in here about 2hrs ago.  Looks like this has mainly tripped mostly LVEA HAMs.  Picket Fence is lighting up in yellow also.

Oh and Rattlesnake Mountain finally returns (after missing quite a bit last week due to a smoky week).  AQI for Richland (closest sensor on AirNow) is at a YELLOW 71.  Only active fire in Benton Franklin counties is far away up near Kahlotus (Nunamaker Road Fire with 20k+ acres.

Also, the GWANW (Gravitational Wave Astronomy North West) meeting will be hosted here at LHO today and tomorrow.

Post NOTE:  Looks like BOTH ops workstations have now moved to the password for the login, so I will try to move back there.

Comments related to this report
corey.gray@LIGO.ORG - 07:47, Monday 10 August 2026 (91457)SEI

Untripped HAMs 1-5+8 After the Colombia EQ tripped them at 1245utc (545amPDT).

corey.gray@LIGO.ORG - 10:45, Monday 10 August 2026 (91461)

Whoops...apparently I did NOT un-trip HAM8 ISI.  But that's ok since SEI group is working on CPS for HAM8 this morning.

H1 General
anthony.sanchez@LIGO.ORG - posted 16:29, Friday 07 August 2026 (91452)
Friday Ops shift report.

TITLE: 08/07 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:
Dust levels for H1:PEM-CS_DUST_LAB1_300NM_PCF is climbing up to 70,000 counts today. I imagine that the Dust level is goign to continues to rise with the wind this weekend. 

Input Alignment team has a PLAN, which is a simple matter of just walking the mirrors.  

Output  Arm team has been looking for MAXIMUM_POWER through their straws in HAM7, Note: Removed yellow View Port cover and left a guillotine in place on HAM6  & Misaliging SR2 & SR3.  

VAC team reports:  "Cryo Traps are open to the Beam Tubes." &  "The Corner station is still isolated from the Beam tubes." 

End Station Y had it's PCAL Integrating sphere returned today after it was stolen for some lab measurements last night. 

LOG:

Start Time System Name Location Lazer_Haz Task Time End
14:53 FAC Kim LVEA n Technical cleaning. 15:35
15:30 VAC Jordan LVEA n Taking pics of GV6 status 16:00
17:12 SQZ Sheila & Ryan S LVEA YES Power measurements In HAM7 19:42
18:29 VAC Jordan & Mitchel LVEA y/n opening ION pumps in the LVEA 19:14
19:49 PCAL Tony, Cory PCalLab, EY YES Taking Ey's PCAL Sphere back to EY's Laser Enclosure. 21:05
20:01 FAC Tyler +1 EY - Wellhead work 22:01
20:24 CDS Marc, Caroline CER - Swapping ISC power supply 21:04
20:26 PEM Carlos, Shrey, Miranda Overpass - Seismometer tests 22:26
20:37 VAC Jordan LVEA - Opening/closing GVs 22:25
21:08 SQZ Sheila & Ryan LVEA HAM7 YES Power Budget measurments & Beam Profiling 23:08
22:09 CDS Dave CER N Looking at the accelerometer.... Specifically Not Touching it 22:25
22:35 CDS Dave Miranda CER N Checking on more accelerometer chassis cabling 23:15
22:43 VAC Jordan LVEA HAM6 yes Isolating turbo pumps, and turning on the ION pump in HAM6 22:54
H1 CAL
anthony.sanchez@LIGO.ORG - posted 16:21, Friday 07 August 2026 (91453)
PCAL Receiver Spheres Romoved from End Stations!

Both End Stations had their  PCAL Reciever modules pillaged for Integrating spheres. They were taken to the lab and measured against PS4 on the lab bench for the first time in..... at least 4 years. 
Preliminary Results found here: PSEYRX
And Here: PSEXRX.


Set up notes:
python pcalRRSO4_measure.py \
    -DN1 PSEXRX \   <-Power Sensor  from EX's Receiver side.
    -DV1 8018023 \  <- This KVM is getting the signal that we usually get a temperature signal from.
    -DN2 PS4 \ <---- this is nominal 
    -DV2 8002111 \ < - nominal
    -DT2 1421891 \ <-nominal 
    -a yes \
    -x \
    -log 'PSEXRX_PS4 PSEXRX front track PS4 on the rear track' \

These measurements were ran without a temperature measurement as they do not have an AD590 to read from. But rather the script just assumes the temperatures for both spheres are the same and just used PS4 temperature sensor.
I used the PS5 Kit to set them up (Satelite box, cable, & accessories.) plugged in exactly the way I'd set up PS5.
Read the Voltage off of what would normally be the temperature KVM as it is nominally plugged in. The reason for this is because I was surprised to see that the KVM that we would normally get temperature signals from PS5 with would change voltage readings when the Sphere was exposed to Laser light....  I Also noted that this Temperature KVM had a Higher voltage reading that the normal KVM we would use to read the voltage from PS5 . Infact the normal Voltage KVM is half of the voltage read by the Temperature KVM. So I chose that one for a better signal to noise ratio. Is this the correct value. I'm not sure yet. but we will find out.

I ran this over night running multiple measurments. 


Another  Note: The PCAL Laser Chassis at End X has been showing a Red LED that is not normally red and Labeled "I limit" or "l limit" either way. The First time I saw it was right after a power outage so i thought it was just a weird one off sort of situation. I just powered the laser Off and back on again and the LED went away.
But I saw it had happened again yesterday, and power cycling the Chassis did NOT resolve it. I checked the MEDM screen and saw that  H1:CAL-PCALX_LASERDIODECURRENT was jumping around 9.7-10.0 Amps. So I simply changed the voltage a little and brought the voltage back up and it resolved the issue. l limit was no longer lit. Checking on it today and it seems to still be functioning normally now.

All spheres are now back in their Nominal configuartion.... bolted to the IFO.

Images attached to this report
H1 SQZ
sheila.dwyer@LIGO.ORG - posted 16:12, Friday 07 August 2026 - last comment - 15:30, Saturday 08 August 2026(91444)
HAM7 power budget repeat

Ryan S, Sheila

In summary, after removal of the A:L2 apperture stop we still see about 4% extra losses in HAM7.  We searched for the rejected beam from SFI1 in both directions with lights out, IR card, and viewer.  To explain a few % loss we should expect to have 10-20urad in this beam, which should be visible with lights out an a viewer.  We also noticed that the beam is off in yaw at the location where we had an iris after ZM1.  

Since Ryan and Camilla aligned the beam onto the SQZT7 PD yesterday, we are noting the power on that PD here after each measurement so we can use that to account for fluctuations in power out of the OPO.  

From the control room, we dithered ZM2 + ZM3 and tried to reduce the fluctuations in the SQZT7 IR PD, we were able to recover a 4% of power this way, with fairly small adjustments (+9urad ZM2 P, +19 urad ZM2 yaw, 5 urad ZM3 yaw).  

One more round of power measurements: 

 

Images attached to this report
Comments related to this report
ryan.short@LIGO.ORG - 17:19, Friday 07 August 2026 (91454)SQZ

After all of this power budgeting, OPOS rebalancing, ZM4 PSAM preloading adjustments, and alignment, this afternoon I took another (possibly the last?) ZM4/5 PSAM M^2 grid on SQZT7. Data files attached. I used different strain gauge values for ZM4 than in the past since they've shifted with the preloading change, but this still covers pretty much the whole PZT range.

This was a 26-point grid using the following PSAM strain gauge settings:

ZM4 PSAMS = [-2.6, -1.0, 1.0, 4.0]

ZM5 PSAMS = [-8.0, -6.75, -5.5, -4.5, -3.3, -1.0]

Non-image files attached to this comment
sheila.dwyer@LIGO.ORG - 15:30, Saturday 08 August 2026 (91455)

The attached plot shows the qs measured on SQZT7 propagated to SRM, with three different ZM4 preloads. Camilla has summarized the history of our ZM4 + ZM5 preloading in 91404

 

Clickable Image

The blue points here are with 75 in lbs on ZM4, as adjusted in 75677.  The teal points were after an attempt to lower the pre-load to 65 in lbs, which Rahul and Camilla later rechecked with the torque wrench and thought that it went to something between 40-60 in lbs. ( 91416)

On Wensday, Rahul and Camilla believed that they applied more torque to the psams (91416), but somehow the beam profiles that Ryan took show that the preload was reduced instead.  

We did not repeat the OMC scans at this preload.  The M^2 range is similar to previous measurements, but the astigmatism is a little better here.  

Images attached to this comment
H1 IOO
louis.dartez@LIGO.ORG - posted 15:27, Friday 07 August 2026 (91447)
New input alignment settings for IM1, IM2, and IM3
K. Kawabe, E. Capote, L. Dartez

This log covers work that started yesterday. We set out to scan the IM1 pointing to see if we could find evidence of clipping and to potentially identify a preferred input pointing configuration. We applied a dither to the IM1 and IM3 suspensions to use IM4_trans and the ISS second loop QPDs as sensors. This test was laborious because each new IM1 pointing mis-centered the beam on both QPDs. Keita pointed out that we can use IM2 and IM3 to center the beam on the IM4_trans and ISS second loop QPDs, respectively. Moreover, by centering the beam on IM4_trans and the ISS second loop QPDs, we get the beam for free on the POP QPDs (even though it is not centered there). To support the argument that we can arrive on a pointing now that will be relevant once we open the arms, we note that the QPD NSUM levels for the IM4_trans, ISS second loop, REFL WFS A and B QPDs are all consistent with what we had in O4 at 2W. The NSUM levels of the POP QPDs is consistent with what we had in O4 at 2W straight shot (PRC misaligned) as well. During this test we paid particular attention to avoid moving the input alignment to a spot that would have the RMs near their actuation range to keep the beam centered on the REFL QPDs.


For each IM1 pointing trial we did the following: 

1. Move IM1 alignment to new trial position
2. Walk the alignment of IM2 and IM3 to center the beam onto IM4_trans QPD and the ISS Second Loop QPD (within about 0.04 in PIT and YAW). I used IM2 to center the beam onto IM4_trans and IM3 to center it onto the ISS Second Loop QPD.
3. Check that the beam hasn't fallen off of the REFL PDs or the POP PDs and that the NSUM, PIT, and YAW signal values are at roughly the same values as they were before the IM1 adjustment.
4. Run the DC centering loops to center the beam on the REFL PDs and ensure that the RMs are not close to their actuation range. 
5. Measure the transfer function from the IM1 and IM3 DAMP banks to the IM4_trans and ISS second loop QPD SUM channels while injecting an 8Hz excitation into the IM1 and IM3 SUS TEST banks. 

The IM1 trials we tried are as follows:

Nominal position (the IM1 position when we began): 524.2 / -386.6 (P/Y)

Trial 1 (pink): (+30 uRad Yaw): 524.2 / -356.6 (P/Y)
Trial 2 (brown): (-50 uRad Yaw): 524.2 / -436.6 (P/Y)
Trial 3 (green): (-10 uRad Yaw): 524.2 / -396.6 (P/Y)
Trial 4 (blue): (+40 uRad PIT): 564.2 / -386.6 (P/Y)
Trial 5 (red): (-40 uRad  PIT): 484.2 / -386.6 (P/Y)

The five trials for this test were split across two days. And the excitation amplitude was not necessarily constant across all 5 measurements. This made it difficult to compare today's measurements against yesterday's. In any case, we think that the position at Trial 4 is the best one so far in that it shows the lowest coherence between the dither at IM1/IM3 and the IM4 trans QPD. We do not know or think it is unilaterally the best position, but we think it is better than it was before we started this. We won't know more until we have the arms. 

The new slider values for IM1, IM2, and IM3 are in IM_alignment_sliders.png. A screenshot of the TFs we took is at blueisgood.png. The colors of the traces correspond to the color next to each trial listed above. The blue trace has the best coherence for most of the measured transfer functions (and for all of the IM4_trans measurements). The DTT template we used can be found at ~keita.kawabe/IM1_moves_IM4_trans_ISS_QPD.xml.
Images attached to this report
LHO VE (VE)
jordan.vanosky@LIGO.ORG - posted 17:10, Wednesday 29 July 2026 - last comment - 10:50, Monday 10 August 2026(91314)
Seal Replacement on GV6 Air Cylinder

Travis, Gerardo, Jordan

During the closing of GV6 back in May, we noticed that there was some blow-by in the pneumatic system when trying to hard close the valve, see alog 90093

We were able to hard close the valve eventually but as preventative maintenance we wanted to replace the air cylinder seals, similar to GV7.

Prior to disassembly we measured the locations of the reed switches from the top surface of the bottom plate to the bottom surface of the reed switches:

Bottom Switch: 1 1/8"

Top Switch: 49 1/4"

We then disassembled the air cylinder and replaced the seals following procedure/notes collected during the GV7 repair. During cleaning of the old grease on the piston head, we noticed there were two burrs on the top of the piston, we did not notice any damage to the inside of the cylinder, but as a precaution we used a small flat file to remove the burrs. We also chased the threads on the four threaded rods with a die to aid with reinstallation. After cleaning and inspection of the cylinder tube, we found no issues or damage so we decided to continue to use that cylinder and keep the new one as a spare.

No other issues encountered, we removed the old seals, cleaned the grooves, added copious amounts of the supplied grease to the o-rings, seals and the inside of the air cylinder, and then re-assembled the cylinder tube. Pictures posted below and a final procedure is in progress and will be posted to the DCC.

We did not get a chance to cycle the valve after the seal replacement, so we will continue tomorrow with cycling the valve.

 

Images attached to this report
Comments related to this report
jordan.vanosky@LIGO.ORG - 16:04, Thursday 30 July 2026 (91333)

We were unable to fully open GV6 today after the cylinder repair. We heard the clunk of the gate camming over at 45 psi, but it did not start to raise until 55 psi, at which point we could hear air blow-by at the solenoid manifold, and up at the cylinder itself.

So we stopped trying to open the valve any further and slowly reduced the regulator output in order to bleed out the accumulated pressure on the bottom side of the piston. This lowered the gate back down and we heard the gate touch down indicating it is soft closed.

We will have to disassemble to air cylinder again and see what may be the issue. We still have 4 sets of replacement seals and one brand new air cylinder on hand if needed.

The valve remains soft closed until we are able to troubleshoot and repair the cylinder.

jordan.vanosky@LIGO.ORG - 17:45, Monday 03 August 2026 (91378)

8/3/2026

Travis, Gerardo, Jordan

Today we again disassembled the GV6 air cylinder with the valve soft closed to try and see what may have been causing the air blow-by which prevented us from fully opening the valve last week.

We did not find anything immediately obvious such as a seal that had jumped out of the groove, so we measured the ID of the original air cylinder, which was re-used, and found that it was ~0.01" larger than the ID of the spare cylinder (original ID ~8.015", spare ID ~8.005"). We then elected to use the spare cylinder instead to make sure there is good sealing contact with the cylinder wall, so we re-distributed the grease on the new cylinder and attempted to install over the piston, but the tube seemed to be slightly out of round and would not fit over the piston. So we flipped the tube 180 degrees and measured that side of the tube and found it was better. We again added grease to that side of the cylinder and installed it over the piston, ensuring the seals and wear band stayed in place, Then we re-installed the threaded rods, torqued the nuts, installed the reed switches and installed the air lines.

To verify all the new joints/connections were ok, we put ~10 psi to the top of the cylinder and then to the bottom to see if there were any leaks. There were none so we started to open the valve by increasing air pressure at the regulator, once we got to ~25 psi we could hear and feel air coming out of the bottom plate/adapter flange below the cylinder assembly, see picture below the area where air is coming out of is circled in red, at which point we stopped trying to open the valve and closed the quarter turn isolation valve to the air line.

We spoke with a GNB rep who advised we try to to open at a higher pressure and see if the bottom seals, so we then tried to open the valve again. This time we started at 20 psi and followed our normal opening procedure with the exception of increasing by 5 psi instead of 10 and waiting 3 minutes between increases. At ~35 psi, air stopped leaking out of the bottom flange, there was no air blow-by in the cylinder and we could hear the carriage starting to move. The gate fully opened at ~48 psi and Gerardo was able to take a video where you can hear the piston incrementally move up the cylinder. We increased the holding pressure to 58 psi and verified the MEDM screen showed the valve status as green.

Images attached to this comment
jordan.vanosky@LIGO.ORG - 17:10, Thursday 06 August 2026 (91437)

8/6/2026

This morning we wanted to soft close GV6 to see if the scraping/squeaking sound continued, or if grease just need to be distributed in the cylinder. Following our normal soft close procedure,we still heard the same noise as the piston moved down. 

We decide to swap the cylinder one last time to the spare cylinder which removed from GV7 back in May. This cylinder had an ID of 8.004" on both ends. 

During the removal of the "sticky" cylinder, we saw there were some small metal shavings on top of the piston, so we decided to remove the seals and install new ones to make sure there is no damage or debris that could cause sealing issues. We added grease to the new seals/o-rings, and the inside of the cylinder, then re-assembled the cylinder/threaded rods/nuts. 

An updated cylinder repair procedure in the works at E2600176.

Once we were done with the cylinder assembly we opened the gate valve to test functionality, and see if there were any leaks in the cylinder. We again heard air coming out of the bottom flange, same as the entry above, but once we got to 35-40 psi the leak stopped and we could hear the carriage moving up. This time there was no excess noise or dragging, and the valve fully opened at 48 psi. After of ~10 minutes with the valve open, and we confirmed there were no leaks in any of the newly assembled joints, we soft closed the valve, again there was no excess noise or dragging of the piston. This is what we typically see/hear when actuating the pneumatic valves.

GV6 remains soft closed for now, closing WP 13471

melina.fuentes-garcia@LIGO.ORG - 10:50, Monday 10 August 2026 (91460)

Videos related to alog 91378 above (original .mov files compressed to be able to upload in alog)

Non-image files attached to this comment
Displaying reports 61-80 of 88882.Go to page 1 2 3 4 5 6 7 8 9 10 End