TITLE: 01/28 Day Shift: 1530-0030 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Planned Engineering
INCOMING OPERATOR: None
SHIFT SUMMARY:
IFO is in IDLE for PLANNED MAINTENANCE
Good progress on activities today.
Other:
LOG:
| Start Time | System | Name | Location | Lazer_Haz | Task | Time End |
|---|---|---|---|---|---|---|
| 22:49 | SAF | LVEA IS LASER HAZARD | LVEA | YES | LVEA IS LASER HAZARD \u0d26\u0d4d\u0d26\u0d3f(\u239a_\u239a) | 16:49 |
| 15:44 | FAC | Nellie | LVEA | Y | Technical Cleaning | 17:06 |
| 15:51 | SUS | Betsy | LVEA | Y | BSC2 Inspection | 17:51 |
| 15:51 | FAC | Randy | LVEA | Y | BSC2 Inspection | 16:22 |
| 16:01 | FAC | Kim | LVEA | Y | Technical Cleaning | 17:06 |
| 16:33 | FAC | Richard | LVEA | Y | BSC2 Inspection | 17:07 |
| 16:33 | FAC | Randy | LVEA | Y | BSC2 Inspection | 23:04 |
| 16:42 | PCAL | Tony, Dripta | PCAL Lab | N | PCAL Meas. | 17:13 |
| 17:10 | FAC | Eric, Chris | EX, EY, MX, MY | N (YES EX) | Air Handler and HVAC Maintenance | 18:28 |
| 17:14 | PCAL | Tony, Dripta | EX | Y | PCAL Measurement | 19:17 |
| 17:16 | EE | Fil | LVEA | Y | Moving electronics by HAM6 | 20:21 |
| 17:33 | ISC | Jennie | LVEA | Y | Turning on light pipe | 17:35 |
| 18:06 | FAC | Kim, Nellie | LVEA | Y | Technical Cleaning | 18:44 |
| 18:08 | SUS | Rahul | LVEA | Y | HAM7 OPO | 18:31 |
| 18:14 | TCS | Matt, Sophie | JOAT/Vac-Prep Lab | N | CHETA | 15:14 |
| 19:05 | EE | Marc | HAM1 | Y | EOM Electronics | 20:11 |
| 19:06 | EE | Daniel | LVEA | Y | HAM6 Electronics | 20:11 |
| 19:07 | OPS | Oli | LVEA | Y | Reminding Daniel about a meeting | 20:21 |
| 19:07 | COC | Masayuki, Jennie | LVEA | Y | HAM1 EOM | 20:45 |
| 19:08 | SUS | JAson | LVEA | Y | HAM1 EOM | 20:46 |
| 21:08 | EE | Fil | LVEA | Y | HAM6 Electronics | 23:06 |
| 21:11 | PCAL | Tony, Dripta | EX | Y | PCAL Meas. | 01:11 |
| 21:37 | SUS | Sheila, Rahul | LVEA | Y | HAM7 | 22:48 |
| 21:45 | COC | Elenna, Keita | Optics Lab | N | EOM | 00:34 |
| 22:05 | SUS-FAC | Travis, Jim, Betsy, Gerardo, Tyler, Randy | LVEA | Y | BSC2 Inspection | 23:04 |
| 22:10 | COC | Masayuki, Jason | LVEA | Y | HAM1 JAC | 00:07 |
| 22:13 | TCS | Marc, Jennie | Vac-Prep/JOAT Lab | N | CHETA Lable Table Cable | 23:59 |
| 00:41 | EE | Marc | LVEA | Y | EOM Reconnection | 01:41 |
J. Kissel Took a set of TFs after Rahul and Sheila re-dressed the cables surrounding the H1SUSOPO (LHO:88920). The TFs -- especially Y to Y look a *lot* better with the higher frequency modes re-aligning with historical measurements and the model. There's still some mode splitting in the lowest mode, that I suspect is the transverse/vertical/yaw system not quite yet as soft as it used to was. Rahul mentions they did *not* address the cables that were zip-tied to the H3/V3 spring post so that could be it. We'll discuss and game plan more with the crew tomorrow. Data templates saved here: /ligo/svncommon/SusSVN/sus/trunk/OPOS/H1/OPO/SAGM1/Data 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_L_0p02to50Hz.xml 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_P_0p02to50Hz.xml 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_R_0p02to50Hz.xml 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_T_0p02to50Hz.xml 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_V_0p02to50Hz.xml 2026-01-27_2316UTC_H1SUSOPO_M1_WhiteNoise_Y_0p02to50Hz.xml Again ran in the configuration where only the DOF being driven was undamped.
WP 12991
WP 12994
D1200196 ISC-R5 Layout
D2400300 - ISC-R6 Layout
D1900511 - ISC/SQZ Wiring Diagram
In preparation for the installation of BHD, the following work was done to the HAM6 field racks:
1. ISC-R3 is now on its own set of power supplies for ±18V
2. ISC-R5 and ISC-R6 share a set of power supplies for ±18V
3. ISC-R3, ISC-R5, and ISC-R6 share a set of power supplies for ±24V
4. ISC-R5 was updated to D1200196-v15
5. ISC-R6 was updated to D2400300-v1
Racks are not complete. Missing electronics will be installed when available.
F. Clara, D. Sigg
Test stand log book entries that document the setup and testing prior to production
Physical layout
The following components are racked together in rack 12.
Basic setup
When I updated the ipmi address in the bios I also did the install of the proxmox nodes. I follow the basic routine in reworking the proxmox setup for pve-node0.
Repeat this for pve-node1 & 2, incrementing the ip addresses.
Cluster network configuration creation
Configured the niccluster0 interface on each node
Did the same on each node, and a ping test.
Cluster creation
On pve-node0 go to the datacenter / cluster and click on create cluster
Then on the other nodes to to datacenter / cluster and click join cluster
Support subscription activation and updates
Now that the basic pieces are in place and will not need a reinstall, it is time to enable the subscription on each node.
Go to each node to the subscription section and upload the subscription key.
Now run updates against the enterprise repo and reboot each machine.
Configure the ceph network
Repeat for all nodes
Install Ceph
Go to datacenter / ceph page. When prompted, select install ceph
Clean up disks
We had used these machines for other testing in the test stand, we will go through and clean up the disks prior to use.
This was done on /dev/sdc and /dev/sdd on the systems
Create the Ceph OSD (Object Storage Deamon)
On each machine go to ceph/OSD
Repeat for /dev/sdd.
After a minute they should show up on the ui.
Add more Ceph monitors
Add pve-node1 and pve-node2 as ceph monitors and managers.
Add a Ceph pool
pve-node0 /ceph / pool
Setting up the VM data links, a bonded bridged network
Go to network / Create / Linux Bond
Create a data bridge, network / Create / Linux Bridge
Do this on each of the nodes.
Notes
When creating VMs we want to connect the network to vmbr1 and specify the vlan tag that should be used as this setup gives us access to more than one vlan.
Jeff, Sheila, Rahul
Details about OPO health check issues (Yaw dof. - frequencies are off and unnecessary peak observed) is currently being analyzed - see Jeff's alog 88913.
This morning we discussed about possible cable interferences in OPO.
I went into the chamber and took fresh pictures of the OPO from several angles, focusing on cable routing, cable resting on the OPO etc - please find them attached below. I will compare them with the pictures posted in LHO alog 61643 (by Sheila in 2022) and look for possible culprits (a few of them already).
Moving cables could cause some misalignment, hence we will start doing so once Sheila gives us a green light.
This afternoon Sheila and I went into the chamber and nudged some of the cables away from the OPO - Jeff will re-check the TF measurements to look for any improvements.
There is a cable connector sitting on the OPO (which is a new addition to the OPO). I lifted that cable connector and then Sheila looked for alignment shifts - which she confirmed. For now we left the cable connector at the same spot on the OPO. We will think of moving it away after Jeff's results.
Sheila also found some changes in the beam alignment since last week - not sure if this is due to our work (AOSEM re-centered LHO alog 88910) from yesterday - although centering aosem-flag should not change the mechanical alignment.
J. Kissel, R. Kumar, B. Weaver, S. Dywer
Context
After the SQZ team felt done with OPOS suspension the re-install of the OPO (with an upgraded translation stage) we're following up on
- Ryan's first look of the suspension's health (LHO:88851)
- After restoring the OPOS to normal control system configuration (LHO:88872)
- After recentering the AOSEMs (LHO:88910)
Measurement
I gathered more standard health check TFs. In doing so, I spruced up the excitation frequency response and data gathering templates to ensure good coherence. I also ran the TFs with all the damping loops besides the excitation degree of freedom ON to reduce incoherent motion from cross-coupling. The refreshed templates are
/ligo/svncommon/SusSVN/sus/trunk/OPOS/H1/OPO/SAGM1/Data
2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_L_0p02to50Hz.xml
2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_P_0p02to50Hz.xml
2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_R_0p02to50Hz.xml
2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_T_0p02to50Hz.xml
2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_V_0p02to50Hz.xml
2026-01-26_2054UTC_H1SUSOPO_M1_WhiteNoise_Y_0p02to50Hz.xml
Results
Attached is comparison of
- the opos dynamical model (Equations of Motion matrices: ssmake_voposus.m rev 12322; parameter set: oposopt_h1susopo_fit rev 12322)
- the most recent, best at-vacuum, measurement of L1's OPOS
- the last, best, at-vacuum measurement of H1's OPO prior to moving from HAM6 to HAM7
- the last, bext, at-vacuum measurement of H1's OPO after moving to HAM7 (with a payload almost identical to what's installed now)
- yesterday's measurement described above.
Focusing on page 6 first, one can clearly see that YAW to YAW transfer function is wildly different, implying a significant change to the dynamics of the suspension.
There's more supporting (but less signficant) evidence in
- pages 1 and 2 which shows and increase in the primary L / T resonance from 1.25 Hz to a split 1.32 Hz / 1.39 Hz
- pages 1 thru 6 (all diagonal elements of the TF matrix) and pages 7 thru 20 (most off-diagonal elements) all showing a huge (tho incoherent) resonance in yaw at 4.98 Hz that was not there before
- Nominally an oversight in the design, the expected large V to Y coupling looks quite impeded.
Discussion
After conversing with Sheila about what might have changed, or what might be impacting the dynamics, she reviews the changes:
- The OPO cavity assembly (D1500296) has only a few changes -- the translation stage within is new, and there are now thin remote-control cables coming out of the assembly that weren't present before.
- Those new remote control cables have been bundled into a pre-existing bundle, potentially making the system stiffer. We guess that this is the likely culprit of our problems.
- Further the re-placement of the OPO assembly on the OPOS was not precise. It's plausible that the physical location of the cavity is now *slightly* different position, *potentially* changing the balance and mass ratio of how much moving mass is in which translational DOF. Maybe the source of L / T resonance shifts, but I doubt it.
Also, conversing with Betsy and Rahul about the state of cables they found while centering the OSEMs:
- They see a collection of cables (OSEM and SQZ) on the "far" (+Y) H3/V3 side of the OPOS that are resting on the platform without a good, dressed, soft connection between the platform and where the cable stress is relieved on the base.
Conclusion
We need to address / free-up the dynamics of this suspension before closing up the chamber.
Jennie W, Jason O, Sheila D, Masayuki N,
Following Jim bringing HAM3 HEPI online (alog #88909) and isolating HAM3 ISI.
Jason and I restored the MC1, 2 and 3 sliders to their position on December 3rd during a lock when the mode-cleaner was locked with 2W input, HAM2 and 3 ISO Gain was , HAM2 and 3 ISI Guardian was set to 'isolated' and 2 and 3 HEPI guardian was set to 'RoBUST ISOLATED'.
This lock state for the IMC Guardian is 100.
Before any adjustments today, we had 45 dB whitening gain on MC2 trans, and 91% of the power was in the 00 mode. This gave us 46 counts on MC2 trans nsum.
After HEPI, ISI, and suspensions are restored, we have mostly 10 mode, with 17.9 counts on MC2 trans sum, still 45 dB whitening gain.
I lowered the whitening gain to 30 dB to restore us to the normal whitening gain.
If we restore the alignment so that 90% of the power is in the 00 mode again, we should have 8.2 counts MC2 trans nsum
All fan bearings at Corner, Mids and Ends were greased this morning.
Tue Jan 27 10:06:26 2026 INFO: Fill completed in 6min 22secs
Karmeng, Betsy, Jeff, Rahul
Following the recommendation given in LHO alog 88872, yesterday (01/26/2026, Monday) we went into HAM7 chamber and re-centered the three horizontal AOSEMs (H1, H2 and H3) as best as we could. All three AOSEM counts (raw inmons) are now between 11-15k.
Next, Jeff will re-take the transfer function measurements and confirm if OPO is healthy.
Also, Sheila et al will re-confirm if the beam is well aligned with other suspension in HAM7 chamber.
OPO is currently unlocked and suspended.
Because there was some confusion about the mechanical states in the corner station, I'm posting a summary of things as they stand today. The only HEPIs that are locked are HAM1,2 and BSC2, and HEPI Isolation are still bypassed. The white board in the control room says HAM1-4 are locked, this is not true. I have re-enabled the isolation loops for HAM3 HEPI (set H1:HPI-HAM3_ISO_GAIN to 1) and set HAM3 SEI back to ISOLATED. HAM1&2 HEPI are still bypassed. HAM1 & 7 ISI are also still locked.
HAM1,2, BSC2 HEPI - LOCKED, BYPASSED
HAM1,7 ISI - LOCKED
Everything else should be able to be run as normal.
WP12997 Jonathan, Erik, Dave:
The cdswiki server, which actually is now just our CDS Apache web server after the wiki moved to GC, was physically moved from MSR-RACK12 [U17,18] over the MSR-RACK11.
We decided to put it where the unpowered netmonitor machine was in U16,17. The netmonitor machine was removed and is now in H2 storage.
cdswiki has only a 10.20 ethernet cable connection, I used a shorter 6-footer (E5B-006-0001) which was dangling in the rack.
TITLE: 01/27 Day Shift: 1530-0030 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: 0.03 μm/s
Secondary useism: 0.33 μm/s
QUICK SUMMARY:
IFO is in IDLE due to PLANNED MAINTENANCE
Work continues on in-chamber JAC alignment and EOM work is continuing (RTP installation planned for today). Work is being done to close out HAM7.
Fire pump alarms bypassed for next 4 hours while churn testing is ongoing.
VACSTAT detected a gas release at EY originating at the EY BT Ion Pump and rapidly propagating to EY. Cell phone alarms were sent to team-VAC.
Gerardo determined that the Y2-8 ion pump turned off for 1 min 41 seconds and then recovered.
vacstat_ioc.service was restarted at 07:57 to reset this alarm.
Nothing wrong with our previous reflection dip measurements with alumina.
We (MichaelL, StephenA, MattH, Gabriele, Elenna and myself) had a meeting in the morning.
Looking at the "with the alumina" reflection screen shots, Michael didn't see any serious problem so we decided that the electrode-crystal-face plate capacitance is OK. We won't worry about that, we'll just make sure that there's no visible gap.
Third mounting method ("in-between") was proposed and tested.
Stephen proposed an in-between method where we use washers between the input side plate and the front plate (bottom of three_methods.png cartoon). After the washer contacts the face plate AND the input side plate, screws are gently tightened in a balanced manner like in Appert method. (In a retrospect this is not that different from Laxen method except the way screws are tightened and that the input side plate contacts with the face plate at two points.)
We first tried to use a presicion thickness shim washer for 1/4-20 screws but I didn't like that they're too big. We ended up using smaller stamped washers that is 0.039" or 0.99mm thick (according to the caliper). That's not flat but seems OK to me.
This in-between method worked in that it was doable and gave us a reasonable reflection dips.
Mechanical stability test of Appert method and in-between method. The latter is better, we'll use that for the real RTP.
My original concern for the original Appert method (middle of three_methods.png cartoon) was that somehow the screw gets loose during transport or after a large change in the in-chamber temperature and the tuning will be off. Upon hearing this, Stephen proposed a test to loosen one screw and see if the tuning changes. We performed this test for both Stephen method and the in-between method. (Spoiler: yes.) We measured all four dip frequencies right after the alumina piece was mounted but only tracked the frequency change of 118MHz peak.
Loosening one screw changes the frequency, but the frequency change for the in-between method is an order of magnitude smaller (10 to 30kHz) than the original Appert method (300kHz) when the FWHM (or rather the width between the points where reflection is 6dB larger than the bottom of the dip) is about 70kHz or so. This is just one trial but I'm convinced that in-between method (or maybe Laxen method too though we haven't tried) is better, so that's what we'll do for the real crystal.
We only loosened the screws on the output side for both mounting methods.
| Initial four frequencies | Shaking? | Loosen 1st screw | Loosen 2nd screw | |
| In-between method |
9.142, 24.110, 45.972, somewhat smaller than 118.214kHz |
changed to 118.214kHz, unclear why. (Something like 10k or 20kHz change, couldn't cause another change by gentle tapping.) |
118.214 -> 118.240 (+26kHz) |
118.240 -> 118.251 (+11kHz) |
| Original Appert method | 9.14685, 24.107, 46.066, 118.322 |
118.322 -> 118.592, caused by gentle tapping. (+270kHz) |
118.592 -> 118.876 (+284kHz) |
118.876 -> noman's land (>1MHz) |
Shake and it will shift, we need to measure it again in chamber?
It's good to know that the in-between method can somewhat withstand the loosening of the second screw (because the tighter screws still support the face plate). However, it's disappointing to find that the assembly is susceptible to shaking.
In the in-between method, we couldn't record the initial 118MHz dip because it jumped up by 10kHz or so in front of our eyes when we were moving around the table. Not sure what happened but I assumed that it was some kind of shaking. However, I gently tapped the front and side plates and couldn't cause another shift.
In the original Appert method, since we knew something could happen, I tapped the front and side plates and there was a huge jump. See the difference between initial_118.jpg and taptap_118.jpg.
Even though we'll use in-between mounting method, it's plausible that the frequency shifts during transport or when the EOM lands on the ISI surface. I'm thinking we'll have to measure it in situ after everything is tuned in the lab.
What's to come tomorrow.
We'll install RTP and tune. Before doing that, though, I'll discuss inserting indium foil between the crystal and the front plate with Masayuki. Michael suggested that (and even between the crystal and the electrode, though that would be tricky) today, Masayuki and I talked about the possibility briefly last week, it just sounds like a good thing as a buffer to absorb gaps here and there.
Other things.
In the previous alog (88886) in one of the pictures (gap.jpg), there was a time when it looked as if the circuit board was slightly bowed. We took a picture of the electrode today (electrode_contactpoint.jpg) and it looks as if the electrode is more abraded close to the outside edge of the crystal, so maybe the board bowing is real.
Why (change in) the gap might matter.
Gabrilele asked me why a tiny gap matters so I made a quick calculation.
Suppose that we can ignore the edge effect at the edge of the electrode for convenience, we can replace the 4x4x40mm crystal with an infinitely wide and long crystal that is 4mm thick, and replace the capacitance with the capacitance per area.
In the attached, the electrode, the crystal and the face plate are all inifnitely larger in a plane orthogonal to the surface of my log book. Thickness of the crystal is d (4mm). There's a gap of delta between the electrode and the crystal, and there's no gap between the crystal and the face plate (but it's not important where exactly the gap is).
Under such a configuration, if you do the math, the capacitance per area is equal to the no-gap capacitance per area multiplied by 1/(1+epsilon*delta/epsilon_0/d) where epsilon and epsilon_0 are the permittivity of the alumina and vacuum, respectively, and the former is 10 times the latter.
In the end, the capacitance with the gap is a factor of
1/(1+10*delta/4mm)
smaller than without the gap.
The capacitance with a 0.1mm gap is 80% of that without the gap, 0.2mm and it's 67%, 0.3mm (12 thou) and it's 57%. If the gap doesn't change, maybe that's OK. If the gap changes it will change the tuning via capacitance change. There are other effects (like coil winding) but the capacitance change via the gap change cannot be ignored/dismissed.
S Muusse, M. Todd
New QCL unit (0920) has been put in place of original unit (0923) which is malfunctioning (cause unknown). Initial profiling has taken place and L1 focal length is 10% larger than spec.
QCL unit failure summary:
All day on 2026-01-21 we were running the laser at 900mA doing beam profiles and alignment work. No malfunctioning was witnessed and the laser unit was operating as expected, similar to the laser unit we had run in December for a week. Before lasing we set the following limits on the LD and TEC, per the datasheet.
On 2026-01-22 we turned the laser on to do some more beam profiling with the same limit settings as yesterday, but setting the LD current to 1A (forward voltage was around 12.2V) as was done when we originally profiled this laser in September. We were in the middle of setting up for a new beam profiling measurement (alignment showed the beam was fine, as usual) and we blocked the beam with a high power beam dump at the laser head while installing the profiler. Upon removing the beam dump, we noticed no power was coming out of the laser, and then noticed the forward voltage had dropped to around 800mV. We noticed no sounds or smells or any other signs that something had stopped, only sudden lack of light coming from the unit. All other settings were fine, meaning the controller had not faulted and was still outputing 1A LD current and the TEC was maintaining 20C.
We ran the following checks to see if we could remedy the problem, without success.
QCL 0920 profiling summary:
Replaced broken unit with 0920 and confirms it lases as spec'd. We built telescope as modelled but beam profile was 75% of expected beam width at L2. We subsequently profiled the laser output and confirmed QCL output q measured previously by Matt was still correct. We became suspicious of the true focal length of L1. Then we profiled multiple places after L1 and fit a q parameter using a non-linear fit. A plot of this fit is attached. Using these 2 q parameters the focal length of L1 was estimated to be 220mm instead of 200mm as spec. We think this is mostly because L1 focal length stated by manufactorer is for 588nm where the refractive index is almost 3% larger than at 4.6um. Focal length in the model was modified to reflect our estimated f1 which predicted a beam size closer that measured earlier.
Side note: the scanning slit beam profiler reflects significant amount of 4.6um light which is observable on a thermal beam card.
This morning we continued profiling to characterize the true L2 focal length and install the modeled telescope and characterize it.
We replaced L1 with L2 in the telescope and made several measurements to fit for a q-parameter after L2, because we think we know the q going into it quite well. Then with the q parameters, you can estimate the focal length using ABCD matrix for a thin lens (our estimates yield relatively low complex angles, less than 1 deg, making confident estimates).
| Parameter | x [m] | y [m] |
| Input q (coming from the laser) | 0.411 + 0.067i | 0.376 + 0.056i |
| Output q (fit from profiles) | 1.496 + 1.289i | 1.221 + 0.632j |
| Focal Length (-q1/(q1/q2 - 1) | 0.503 | 0.511 |
Average focal length of L2 = 0.507 m. Which is around 1.5% different from the spec'd value. To reiterate Sophie's log above, the focal length of L1 is estimated to be 0.217 m. Which is almost 9% different than the spec'd value. With these values in hand (as well as the updated value for CaF2 refractive index at 4.6um), we can make a more accurate model and see if measurements of the outgoing q-parameter from the telescope match that model.
We installed a telescope as set up in a model and measured several proviles to fit for the q-parameter after L2. The modeled waist size in both the horizontal and vertical are within the fit uncertainty; however the waist position of the modeled beam is roughly 20cm off in both directions. I think this is because of the Gouy phase regime that we are sampling gives better estimates of the waist size and since we did not sample near the waist we do not have a good idea of where it is.
This afternoon we will try and re-build the telescope as optimized in our models with these measurements to see if we can get a q-parameter that will be 53mm at the "ITM" (propagated 35m from L2).
J. Kissel, O. Patane, D. Barker, F. Clara, M. Pirello
Our big SUSB123 and SUSH34 to SUSB13 and SUSB2H34 upgrade last week wasn't the full upgrade for O5.
SUSB13 is fully upgraded to its O5 configuration, but for SUSB2H34, we can't fully upgrade to the final O5 build yet because we still need full control of the BSFM for the February commissioning period, whereas O5 will have the BSFM replaced with the BBSS (with QOSEMs instead of BOSEMs), requiring different electronics. The final O5 build will also include the electronics for the new suspensions LO1 and LO2. Going from the current configuration, which we call the "No QOSEMs/BBSS" configuration, to our final O5 build will require eight new chassis and two new ADC cards.
Since we will be needing to add/change things on the racks, that future upgrade will also come with user model additions/changes.
Table showing comparison diagrams
| Current “No QOSEMs/BBSS” Config | Final O5 Config | |
| Rack overviews | slide31 | slide33 |
| DACs | slide10 (excluding BS BOT/LO1/LO2 and AI in U13) | slide10 (everything) |
| ADCs | slide15 | slide16 |
| BIOs | slide21 (excluding BS BOT chans) | slide21 (everything) |
| AUX ADCs | slide26 (excluding pink) | slide26 (everything) |
I've also attached the slides above in pdf form here. The full slides outlining all the changes O4 -> now -> O5 can be found here.
Changes needed to go from current configuration to final O5 configuration:
SUS-C1
U33:: Remove cable inputs for (BSFM) BS M1 OSEM sensors, re-arrange cable inputs for BS M3 Oplev to make room for (BBSS) BS M3 OSEM sensors, and bring in PR3 M3 Oplev because we can
U14:: Add (BBSS) BS M3 input for Binary Output
U13:: Add (BBSS) BS M3 input for Binary Input
U5 :: New D090006 TACQ Driver for (BBSS) BS M3
SUS-C2
U22:: Add (BBSS) BS M3 Noisemon and (BBSS) BS M3 SFVmon inputs
U20:: New D0902783 AA Chassis for LO1 M1 and LO2 M1 HAM-A Coil Driver Volt Monitors
U16:: New D1300282 AA Chassis for (BBSS) BS M1 QOSEM sensors and LO1 M1 and LO2 M1 OSEM sensors
U14:: Add (BBSS) BS M3 input to AI chassis
U13:: New D2500353 AI Chassis for LO1 and LO2 Coil Actuation
U9 :: New D1100687-v1 (100 Ohm Output Impedance) HAMA Coil Driver for LO1 M1 F1F2F3SD
U8 :: New D1100687-v1 (100 Ohm Output Impedance) HAMA Coil Driver for LO1 M1 LFRTxxxx
U6 :: New D1100687-v1 (100 Ohm Output Impedance) HAMA Coil Driver for LO2 M1 F1F2F3SD
U5 :: New D1100687-v1 (100 Ohm Output Impedance) HAMA Coil Driver for LO1 M1 LFRTxxxx
susb2h34 IO Chassis
Needs an additional ADC Card (and adapter card and internal SCSI cable)
susauxb2h34 IO Chassis
Needs an additional ADC Card (and adapter card and internal SCSI Cable)
To clarify a bit on the status of SUSB13 and SUSB2H34, "as of these Jan 2026 changes, the SUSB13 racks and IO chassis are 'fully upgraded,’ as only the ITM QUADs are left in this system and there are no changes to the QUAD control system electronics for O5, and we’ve now upgraded the whole chassis to use 28-bit 32CH LIGO DACs. For the SUSB2H34 racks and IO chassis, while we’ve imported the existing BSFM beam splitter control system electronics, that’s all we can do at this point and we need the BS under control as it was for the Feb 2026 commissioning period. After that’s done, and as the suspensions get installed, we’ll add electronics to upgrade the BSFM BS to become a BBSS BS (with M1 QOSEMs replacing the M1 BOSEMs, and new M3 OSEMs for sensing and control there), and we install the LO1 and LO2 HRTS electronics for BHD as needed. So, it may be a while before the wiring diagrams match reality again".
(Thanks to Jeff for the clearer wording!)