Displaying reports 141-160 of 88245.Go to page Start 4 5 6 7 8 9 10 11 12 End
Reports until 14:21, Tuesday 23 June 2026
H1 SPI (SEI, SPI, SYS)
jeffrey.kissel@LIGO.ORG - posted 14:21, Tuesday 23 June 2026 (90716)
2026-06-22 SPI Pathfinder -- Installation Complete!
J. Kissel, J. Wright, T. Shaffer, J. Warner, J. Freed
(belated aLOG covering 2026-06-22 activity)

After enjoying a lovely long, Juneteeth Holiday weekend, TJ and I wrapped up the few loose ends that were left after the 2026-06-18 super push to get everything installed (see last update; LHO:90676). 
   - As a fall out of LHO:90667, Jim, Arnaud and I discussed the pros and cons of using the current, D1000907-v7, balance mass "Payload & Suspended Mass Assembly" arrangement in regards to the W9 corner. We concluded that leaving the D1000907-v4 configuration for this corner in place -- i.e. having 11.6 [kg] of mass in small, modular, optional components -- was better that having one "giant" 10 [kg] mass in "the same" location (on the table top, but in the same W9 corner). As such, we left the plates as re-installed on LHO:90713, with the acknowledgement that the final configuration to create a balanced ISI may be different even further than D1000907-v7.

   - Using a beam profiler, we measured the Beam Profile of the beam returning from M_C1 on the HAM23 ISIJ Reflector. This is to, at least roughly, confirm the radii of curvature of the M_C1 mirror. We expected a 2 [mm] diameter beam, and we got a 2 [mm] beam diameter. A more thorough aLOG to come.

   - We did NOT address the stray beam that Jennie mentions in her summary -- yet. I'll also write a separate aLOG on this, but in short -- it's a ~0.2 [mW] beam that's what ~18% reflection there is off of a silicon diode, and it hits the -X/-Z rim of the chamber of the +Y door, and the (splotchy) spot size is ~4-5 [mm] in diameter. The SPI team has been aware of this beam since testing in the optics lab (see mention of it, e.g. in LHO:90455), but hoped that it would land on some part of the SPI Shroud assembly, but it *just* misses it. 


With this last item, we consider the Installation and Integrated Test Plan COMPLETE (T2500024) ... to as good as possible with the HAM3 ISI still locked.

And that ... qualifier is a "just in case" qualifier, as it's a "we'll see what happens" when the ISI gets unlocked, and we've got an excellent amount of remote adjustability to be able to recover the MEAS IFO's alignment if HAM3 moves a lot between 
    - "locked," 
    - "re-balanced and damped" and 
    - "isolated with feedback and DC positioning engaged."
Essentially, we've launched the SPI pathfinder into space, and now its up to out built-in remote controlled actuators and sensors to take us home to achieve our scientific goals (see T2600019).

Super congrats to all, and similarly large thank you. We did a thing!
Images attached to this report
H1 CDS
david.barker@LIGO.ORG - posted 13:40, Tuesday 23 June 2026 - last comment - 13:44, Tuesday 23 June 2026(90711)
DAQ restart for new PWRCS Beckhoff Chiller channels

WP13303 Reimage PWRCS Beckhoff, update Corner HEPI Pump controller INI

Patrick, Erik, Jonathan, Dave:

Patrick created a new H0EPICS_PWRCS INI file. All of the EPICS channel names have changed since the first version of this system, and 40 of the new channels have old-channel equivalents. To preserve recent minute trends, the data acquired so far were transferred to the new names as part of the upgrade.

The sequence followed was:

 - Remove the old names from the edc_green_ioc IOC. 43 disconnects at this point (40 from H0EPICS_PWRCS and 3 from H1EPICS_HEPIPUMPL0)

 - Create the copy scripts to be ran on TW0,TW1 to copy the old files to the new, so that the new channels will "continue from where we left off"

 - Create the new H1EDC.ini and verify its changes.

 - Stop daqd on TW0 and TW1

 - Run the copy scripts on TW0 and TW1

 - Restart the 0-leg, followed quickly by restart of the EDC.

 - Wait till 0-leg was fully operational, including TW0

 - Restart the 1-leg

All went well except for the usual GDS1 needed a second restart, FW1 restarted itself after 5 minutes.

Comments related to this report
david.barker@LIGO.ORG - 13:44, Tuesday 23 June 2026 (90712)

Here is a random new channel which has non-zero data trended back one month to view its data back when it had its original name.

Images attached to this comment
H1 AOS
camilla.compton@LIGO.ORG - posted 12:50, Tuesday 23 June 2026 - last comment - 17:57, Tuesday 23 June 2026(90708)
BS Alignment with SQZ Beam, got MICH fringes with SQZ and IFO beam

Continued from 90691. Betsy, Keita, Sheila, Oli, Eric, Camilla, Ryan S, Jenne

First thing, we went back to alignment we had ITMX SQZ  the "flashes" and "fly-bys" yesterday, put the same size oscillation on the BS, but saw no flashes of fly bys. Betsy took a video of what the two SQZ beams looked like at PR2 at this alignment, they were crossing each other. 

We then rethought the alignments from yesterday, we are leaving:

Once we did this, we had SRY fringes, Betsy and I then adjusted the BS to bring the beams back on top of each other at PR2. This was a change in the BS sliders from (P 1000, Y 1290) to (P 1350, Y 1180).

Keita then wobbled ITMX and found the SQZ beam off ITMX! Aligned ITMX to get MICH flashes at AS_AIR, AS_A/B and ISCT1 REFL. He had to move ITMX from (P -96, Y 104) to (P -280, Y 94). 

He then got the PSL IX and IY reflection in the AS_AIR camera in this alignment. Sliders at this alignment attached

However as we are not sure we trust the ITMY alignment form top mass osems (from 90551), we want this Pitch change to be in ITMY, so ITMX is at it's known DRMI pointing. We could try to walk these, maybe along with SRC which might reduce some of our Pitch differences in SR2 and SRM. This change is so small that we will go ahead with mechanically offloading BS Pitch. The BS YAW will not mechanically changed. 

The OMs are also not currently in their O4 sliders/osems position, attached. We could verify the SQZ beam pointing by putting these back if we thought that was needed.

Images attached to this report
Comments related to this report
keita.kawabe@LIGO.ORG - 17:57, Tuesday 23 June 2026 (90724)

Since IMTX was moved today, I had to move PR3 to compensate in order to regain IMC flashes in the AS camera as well as ISCT1 camera.

H1:SUS-PR3_M1_OPTICALIGN_P_OFFSET is now -247.0 (used to be -140).

H1:SUS-PR3_M1_OPTICALIGN_Y_OFFSET is now -245.0 (used to be -583).

H1 CDS
erik.vonreis@LIGO.ORG - posted 09:58, Tuesday 23 June 2026 (90707)
Workstations updated

Workstations were updated and rebooted.  This was an os packages update.  Conda packages were not updated.

H1 General
ryan.crouch@LIGO.ORG - posted 07:31, Tuesday 23 June 2026 (90704)
OPS Tuesday Day shift start

TITLE: 06/23 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: 3mph Gusts, 1mph 3min avg
    Primary useism: 0.01 μm/s
    Secondary useism: 0.08 μm/s 
QUICK SUMMARY:

H1 SEI
arnaud.pele@LIGO.ORG - posted 19:35, Monday 22 June 2026 - last comment - 16:32, Monday 29 June 2026(90703)
ITMs as-built balance mass pictures

Pictures of as-built balance mass of ITMs taken today to compare with drawings in anticipation of rebalancing both ITMs with the added baffle weight

ITMY:

table: pic1, pic2, pic3
corner 1 side wall: pic4
corner 2 side wall:  pic5
corner 3 side wall: pic6 and pic7

ITMX: 

table: pic8, pic9, pic10
corner 1 side wall: pic11
corner 2 side wall: pic12, pic13
corner 3 side wall: pic14, pic15

 

 

Images attached to this report
Comments related to this report
arnaud.pele@LIGO.ORG - 16:32, Monday 29 June 2026 (90813)

The as built configuration (redline) was uploaded to the dcc: 

BSC1: https://dcc.ligo.org/LIGO-D1001989 

BSC3: https://dcc.ligo.org/LIGO-D1002185

H1 SEI
arnaud.pele@LIGO.ORG - posted 19:05, Monday 22 June 2026 - last comment - 09:45, Tuesday 23 June 2026(90702)
CRS Chamberside testing started

Shohana, Michael, Fil, Jim, Arnaud

wp 13344 

Following up from 90652. The CRS chamber side testing started: 

Images attached to this report
Comments related to this report
michael.ross@LIGO.ORG - 09:45, Tuesday 23 June 2026 (90705)

Adding numbers for the fringe contrasts for each PD:

 HoQI 1 (right): 

  Sin: 85%

  Cos: 80%

  MCos: 84%

 HoQI 2 (left): 

  Sin: 70%

  Cos: 5% (electronics issue)

  MCos: 71%

H1 SUS (SUS)
ibrahim.abouelfettouh@LIGO.ORG - posted 19:02, Monday 22 June 2026 (90701)
BBSS M2 BOSEMs Centered, M3 AOSEMs cabled and centered

Ibrahim, Oli

Today, Oli and I installed and centered the M2 BOSEMs and centered and attached the cables for the M3 AOSEMs. AOSEM and BOSEM cams were also inspected and centered.

A few notes:

Next:

Images attached to this report
H1 SUS
thomas.roocke@LIGO.ORG - posted 18:19, Monday 22 June 2026 (90697)
BBSS Pitch Yaw Coupling Investigation - Coil Driver Chain

[Tom, Ibrahim, Oli]

Summary: The yaw / pitch coupling seen on the BBSS is not due to the the coil driver chain.

As noted in LHO alog 90665, we are seeing strong pitch yaw coupling on the BBS, when actuating via the top stage QOSEM coils. When we try and adjust the optic yaw we see a 1:5 response in pitch and vice versa. This is seen in both the QOSEM readouts, and visually using an IR beamcard on the PSL beam bouncing off the optic. 

To investigate whether the cause was electronic in nature, we went into chamber to ensure that only the F2 and F3 QOSEM coils are being driven when requesting yaw drive. We used a multimeter to measure the voltage drop across the coils, to determine whether theyre being driven or not. As we expected, only the F2 and F3 coils are being driven, with equal and opposite magnitude, when trying to drive yaw. This suggests that this coupling is not coming from the coil electronics chain, or an issue in CDS.

H1 IOO
jennifer.wright@LIGO.ORG - posted 17:54, Monday 22 June 2026 (90700)
Aligned JAC wavefront sensors

I took an opportunity while the BSC team was in the control room and opened the light pipe and aligned the WFS on IOT1 while JAC was unlocked.

This was done at 200mW.

I used the manual adjustment knobs on the picomotor mounts as the IOT1 table is not hooked up to its pciomotor controller currently.

Got both WFS A and B as close as I could using this method. NB: pitch and yaw on QPD A are swapped as the manual pitch adjuster changes the yaw degree of freedom. I need to check this in the physical wiring for the QPDs.

Images attached to this report
H1 SQZ
camilla.compton@LIGO.ORG - posted 17:02, Monday 22 June 2026 (90698)
SQZT7 Beam profiles/alignment, no progress made.

Eric, Ryan S, Camilla

Went onto SQZT7 and checked on the M^2 profiler. It needed their alignment procedure ran but as we're aren't at a set alignment we did not do this yet.

In the control room we used the ASC set up in 88777 and had to adjust the H1:SQZ-ASC_TRIGGER_THRESH_ON/OFF, it worked well when we changed PSAMS but we then realized we needed a ZM4/5 ASC rather than a ZM5/6 ASC for SQZT7 profiles. Tried just changing the output matrix, did not work. 

Strangely, when I used the SQZ IFO ASC screen's "!graceful clear history", we now have outputs in the LOCK OUTPUTs but the beam looks a lot clearer on AS_AIR camera. We are now in a different alignment than we have been, but it's better on AS_AIR so we'll reassess tomorrow...

H1 General
ryan.crouch@LIGO.ORG - posted 16:32, Monday 22 June 2026 (90695)
OPS Monday Day shift summary

TITLE: 06/22 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY: CRS, SPI at HAM3, BS / input alignment work, and a little bit of beam profiling at HAM7 continued today.
LOG:                                                                                                                                         

Start Time System Name Location Lazer_Haz Task Time End
20:18 SAF LVEA IS LASER HAZARD LVEA YES LVEA IS LASER HAZARD 12:18
14:41 FAC Kim LVEA Y Tech Clean 15:50
15:34 VAC Jordan LVEA Y CP1 checks 15:43
15:53 SPI Jennie LVEA Y Unshutter SPI laser 15:56
16:10 FAC Kim LVEA Y Tech clean 17:01
16:22 SUS Jennie LVEA Y Open light pipe, IOT1 work, light pipe closed at 1700 17:00
16:40 SEI Jim, Arnaud LVEA Y BSC2 cabling, 1 person in-chamber 18:29
17:00 SPI Shoshana LVEA Y H2 enclosure to HAM3 parts shuffle 18:09
17:06 PEM Robert EndX N Grounding study 18:20
17:13 SUS Ibrahim, Betsy LVEA Y BS pitch adjustment in-chamber, by HAM3 checks, Betsy out 1830 18:49
17:24 SUS Oli, Camila LVEA Y Help alignment team by HAM3 18:46
17:33 OPS RyanS LVEA Y Bring Dust monitor to BSC2 crew 17:50
17:57 VAC Gerardo LVEA Y Inspect viewports, input/output tube 18:20
18:00 ISC Keita LVEA Y Talk to HAM3 crew 18:42
19:02 SUS Oli LVEA Y Move a chassis 19:10
19:48 PEM Carlos, Shrey Site Y Huddle test at vertex 20:54
19:49 PEM Robert Site N Searching for a seismometer 20:54
20:00 CDS Patrick Ends N Check on Beckhoff computers 20:22
20:13 SPI Jeff, Jim Optics lab, LVEA Y SPI work, optics lab then HAM3 at 21 UTC, Jim in at 2100, Jeff out at 2259 23:22
20:33 PSL Betsy LVEA Y Shutter PSL laser 20:40
20:35 VAC Jordan, Gerardo LVEA Y CP1 RGA scans and checks 22:55
20:40 SPI Jennie LVEA Y Search for a laptop 20:53
20:55 PEM Robert, Carlos, Shrey EndY N Retrieve seismometer 22:49
20:59 SPI TJ LVEA Y Join Jeff at HAM3 for SPI work 22:05
21:00 ISC Betsy LVEA Y Progress checks 21:26
21:05 SUS Oli, Fil LVEA Y Plug in chassis for BS 21:28
21:22 CRS Shoshana, Michael LVEA Y CRS  work by HAM3 Ongoing
22:04 SQZ Camilla, Eric, RyanS+1 LVEA Y Beam profiling at HAM7, RyanS out at 23:10 23:15
22:05 CRS Arnaud LVEA Y Join CRS team Ongoing
22:09 SUS Oli, Ibrahim LVEA Y BS work Ongoing
22:14 SEI RyanC Ends N Reset VFD panels for HEPIs, EY then EX 23:04
22:28 SAF CRS LVEA YES CRS laser ON near HAM3 Ongoing
23:32 IAS Jason LVEA Y FARO auto OFF/ON 23:37
23:34 ISC Betsy, Robert LVEA Y Checks Ongoing
H1 SEI
arnaud.pele@LIGO.ORG - posted 14:45, Monday 22 June 2026 (90696)
BS CPS replugged

Jim, Arnaud

The x12 in-vac BSC2 / BS ISI CPS sensors were replugged to their feedthrough as per D1003079. Jim worked from the platform, verifying the signals were live with a cds laptop while I was plugging them in from the chamber.  Before starting this work we turned on the interface chassis and had to power cycle corner 3 a couple of times before getting the -18V LED from the back panel to turn on.

Images attached to this report
H1 ISC
camilla.compton@LIGO.ORG - posted 12:38, Monday 22 June 2026 - last comment - 14:15, Monday 22 June 2026(90691)
BS alignment, could see SQZ beam off ITMX fly-bys at AS Port
Betsy, Ibrahim, Oli, Keita, Camilla. Follow from 90665 where we left ITMY and SR2 in a strange location. 
Summary: With ITMs back to top mass osems and BS at  (P 1000, Y 1290), we have seen fly-by of SQZ beam of ITMX at AS port. Expect BS is moving to much to get steady beam. SR2 alignment very different than March/O4 (+500urad P, +150urad Y).
 
 
9am. We started by putting ITMs, SRM, SR2, SR3 back to March DRMI time sliders (11:02 PDT 19 March 2026), attached sliders. We did not like that ITM PIT top mass osem sensors were far from the March time (-30urad for ITMX, +220urad ITMY).
We tried adding -170 to the ITMY Pitch slider as per 90551, this still took us very far form the osem sensors. 
 
9:33am We took ITMs, SRM, SR2, SR3 back back to the sensors (top mass osems) in March DRMI time (11:02 PDT 19 March 2026), attached sliders of this.
 
We then misaligned SRM but did not get our SQZ beam back on AS_A,B or AS_AIR camera off ITMY. We then went back to the time Thursday we had the beam on the camera at the current ITMY pitch pointing, moved according to osems for SR2 and oplev for SR3 (as HAM5 moved Thursday late afternoon 90671). Got the SQZ beam from ITMY back on the camera as per last Thursday, but this time we are happy with out ITM pointing.
We started the /ligo/home/sheila.dwyer/SUS/BS/BS_raster.xml but still could not see sign of SQZ beam off ITMX. BS was at (P 1000, Y 1000)
 
10:15am Went into HAM4 and moved BS sliders to get SQZ beams on top of each other:  (P 1000, Y 1290). This is encouraging that even with a different ITMY position, the BS pointing is very similar to last week. Sliders attached. 
 
On AS_A and AS_B we could see intermittent flashes of the SQZ beam off ITMX as it hit the sensors, we could also see it "fly-by" on the AS_AIR camera. We moved BS in a few 100's of counts and ITMX in ~100urad counts to try to improve this, it was intermittent (more flashes when there was more activity in the changer and when BS was not damped) but we did not improve it. Our best fly-bys are attached, typical good flashes also attached,  amplitude of flashes as are expected. We'd later like to go back to this alignment.
 
We tried using SR2 to center ITMY SQZ beam on AS_AIR camera but the beam quality got worse we we reverted. Expect there’s a better SRC alignment could find, currently SR2 slider is ~ 500urad different than March! 
Images attached to this report
Comments related to this report
keita.kawabe@LIGO.ORG - 13:44, Monday 22 June 2026 (90692)

Found the ITMX alignment that sends IMC flashs all the way to AS camera AND the SQZ beam all the way to ISCT1

But, as of now, IMC flashes don't come back to ISCT1 at all, and SQZ beam only comes back to AS camera via ITMY reflection. PRM is misalilgned.

The ITMX alignment is very different from where I started but this is expected as we have moved PR3 by a large amount when we tried to center the IMC flashes on  ITMX.

sqz -> SR chain -> BS-> ITMX -> BS -> PR-chain -> ISCT1

  before/after
H1:SUS-ITMX_M0_OPTICALIGN_P_OFFSET -96/-125
H1:SUS-ITMX_M0_OPTICALIGN_Y_OFFSET 104/-331

In the attached video (PXL_20260622_203143545TS~2.mp4), ITMY is misaligned and only ITMX reflection reaches two cameras. In the ISCT1 REFL camera you can see a big bright beam which is from SQZ, while in the AS camera you can see IMC flashes.

What we should do is to refine ITMX alignment such that we can see ITMX reflection of IMC flashes in ISCT1. After that, if the IMC flashes arestill visible in AS camera, scan BS alignment to find ITMY reflection of IMC flashes in ISCT1. If the flashes are not visible in AS camera, we need to do some math.

 

Images attached to this comment
Non-image files attached to this comment
camilla.compton@LIGO.ORG - 14:15, Monday 22 June 2026 (90694)

Ryan S and I went back to the ITMX and BS alignment of the best ITMX SQZ beam "fly-bys", we did not see them or any flashes again. 

H1 SPI (SEI)
jennifer.wright@LIGO.ORG - posted 18:39, Thursday 18 June 2026 - last comment - 13:47, Tuesday 23 June 2026(90676)
SPI install update - day 6

Jennie W, Jeff K, Josh F, TJ S,

Summary: SPI interferometers aligned, shroud installed successfully. One stray beam and possible clipping on shroud to investigate/deal with but otherwise all problems were solved. Obligatory success photo taken by Josh.

Today we:

 

Images attached to this report
Comments related to this report
thomas.shaffer@LIGO.ORG - 10:08, Monday 22 June 2026 (90690)

More details regarding the baffle installation:

When placing the below table baffle brackets, there was a ballast mass baffle (D1700262) that was blocking the angle bracket for the furthest -Y bracket. The bracket could not slide under the ballast mass baffle (bmb), so we decided to move the bmb in the +Y direction a few inches and I had to loosen the baffle panel within the feet to slide it up a few mm and then reclamp. This allowed the bracket to slide under the baffle just to the side of the feet, but the move partially exposed a corner of the shiny ballast mass stack.

The lower baffle shroud that covers the breadboard needed the fiber spools to be moved. We moved them over one set of bolt holes, but they are quite close to chamber edge, I'd guess around 1/2". Jeff then centered the two aperatures to the SPI beam, and we called it good. We still need to B&K the whole area.

Images attached to this comment
jennifer.wright@LIGO.ORG - 17:46, Monday 22 June 2026 (90699)

Just did an 8 hour trend of the fiber power monitor channels for REF and MEAS channels (left two plots) and the optical lever QPDs (right two plots) to check whether we expect variations on the order of ~2V on the QPDslike we saw on Thursday before and after baffle installation.

From this trend the power appears to drift more than this for two hours after unshuttering the laser (around 15:56 UTC), but once it reaches a steady state both QPDs were only drifting by 1V and the fiber power input monitor PDs by 1V or less.

Conclusion: I think we would have seen a dramatic power drop on Thursday when we installed the shroud, that I would expeact to have been much larger than the trends I saw today.

Images attached to this comment
jeffrey.kissel@LIGO.ORG - 13:47, Tuesday 23 June 2026 (90713)
Note mentioned in the summary of activities in the main entry -- per LHO:90667, we re-installed all the ballast or balance mass discussed during this 2026-06-18 day's session. See attached "after" picture.
Images attached to this comment
H1 SEI (SEI, SPI, SYS)
jeffrey.kissel@LIGO.ORG - posted 13:19, Thursday 18 June 2026 - last comment - 13:48, Tuesday 23 June 2026(90667)
ISI HAM3 Wide Wall Balance Masses vs. SPI
J. Kissel, J. Warner

During SPI install we removed the following side-wall balance mass from the W9 side wall (see first bullet of LHO:90558):
    Plate              Mass [lbs.]   Mass [kg]    QTY    Total Mass [kg]
    D071200 Type 04    7.9           3.583        3      10.750
    D071200 Type 01    1.1           0.499        1       0.499
    D071200 Type 00    0.6           0.272        1       0.272
    D071201            0.1           0.045        3       0.136

    Total Mass                                           11.657

First attachment is a diagram to convey which side wall I'm talking about.

This is inaccurate with the latest version of the ballast / balance mass inventory, D1000907-v7, which states that this side wall has only 1x Type 04 (3.583 [kg]) and a 1x Type 03 (2.041 [kg]), for a total of 5.625 [kg]; much less.

Remember, from LHO:90504 that the total SPI mass is 12.599 [kg]. 
This *excludes* the mass of the lower ISI Shroud baffle (D2400106-v4) and the three upper HAM Table Baffles (D2600007) with all their bracketry and bolts, currently only represented only in e-drawings posted to D2400103-v6.

After talking with Jim, he wants more mass in this -X / +Y corner of the table, because that's where all the new stuff is. So he wants this corner "over" or "heavy" (because the new stuff must be in a fixed position) so that he can adjust the *opposite* corner of ballast mass (which has more open table and side wall access and thus is adjustable).

As such, he says "put all the at 11.657 [kg] back on the corner. 

So we will!

Second attachment is a picture of the wall mass arrangement prior to us removing it taken on 2026-06-09.

Images attached to this report
Comments related to this report
jeffrey.kissel@LIGO.ORG - 13:48, Tuesday 23 June 2026 (90714)SEI, SPI
Masses were re-installed as of 2026-06-18! See LHO:90713.
H1 SEI (SEI)
shoshana.apple@LIGO.ORG - posted 10:26, Friday 12 June 2026 - last comment - 09:55, Tuesday 23 June 2026(90607)
ETMY BRS not damping down

The ETMY BRS seems to be continuously ringing up. I've tried to make the changes to the thresholds which was the previous fix outlined in 87634 for the same BRS, and will check back in on it later to see if just increasing the thresholds helped at all.

 

Changed thresholds:

H1:ISI-GND_BRS_ETMY_LOWTHRESHOLD 800-->2000

H1:ISI-GND_BRS_ETMY_HIGHTHRESHOLD 2000-->4000 Changed

Additonally I changed the ETMX BRS drift control to 6.00V and the ETMY BRS to 2.00V to try and better center them

Images attached to this report
Comments related to this report
shoshana.apple@LIGO.ORG - 15:55, Wednesday 17 June 2026 (90654)

[Shoshana, Jim]

Shut off the damping for ~2 hours hoping it would damp down somewhat but the ringing just got worse

Jim recaptured the ETMY BRS frame to see if that would solve the problem, but it did not.

We went down to the BRS to test if the dampers were wired correctly/making contact. We checked the voltage going through and applied a voltage directly to the dampers to make sure the wires in vacuum were connected to the plates. We found that the 2 pin (+ direction) and 5 pin (- direction) (diagram below) were the pins which applied voltage to the dampers, were applying voltage as expected (maxing out at around 2.9V). It looks like applying a voltage directly made the BRS move as expected (we applied 3V to each pin one at a time in order to ring it up or damp it down), so we don't think there is an issue with the connection, and voltage was making it through the cable. 

After watching the signal and the voltage going through the cable for a while, my best guess is that the + damping doesn't turn off fast enough when the BRS switches directions which causes it to continuously oscillate, but switches off eventually so it doesn't continue ringing up?

Michael Ross (who wrote the Beckhoff code) will be here next week, so we will ask him to take a look at it.

Images attached to this comment
shoshana.apple@LIGO.ORG - 09:55, Tuesday 23 June 2026 (90706)

Michael is in this week and fixed the EMTY BRS by raising the upper threshold (H1:ISI-GND_BRS_ETMY_HIGHTHRESHOLD) from 4000-->8000 for 20 minutes, see 90693

Current Thresholds:

H1:ISI-GND_BRS_ETMY_HIGHTHRESHOLD: 4000

H1:ISI-GND_BRS_ETMY_LOWTHRESHOLD: 2000

 

Looking through ndscope it the same changes were made to the ETMX BRS, raising the thresholds

 

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