ITF found in LOW_NOISE_3 in UPGRADING mode. According with commissioners, at 13:34 UTC, I set COMMISSIONING mode.
ITF and TCS tuning activities carried out by commissioning team, Nardecchia and Was from remote concluded at 18:00 UTC with ITF locked at CARM_NULL_1F and LOW_NOISE_2.
At 19:37 UTC ITF unlockd (TBC). Autorelocked at 1st attempt.
ITF left in LN3 (AUTORELOCK_FAILSAFE ACTIVATED).
Today at 14:33 UTC I re-enabled the DOWN condition for the two Etalon loops, now that we have the main beam back most of the time:
After the WE PCal laser was turned back on yesterday we saw an increase in the noise seen by the two photodiode and the Rx sphere (see this plot).
It appears that this increase in noise is coming from glitches that can be seen in this plot.
Yesterday afternoon I tried turning off the pump diode and turning back on the laser and saw that without the laser control loop we do not see those glitches and that right after truning the pump diode off and back on the glitches did not appear right away but only after a few minutes.
We are not sure what is causing this noise increase at the moment but it is still below the noise requirement. We decided to turn back on the permanent lines around 12h50UTC today on both NE and WE and now the noise seem to have come back to a normal level with the lines (see this plot).
In order to understand the origin of the new noises seen on hrec after recovery, this afternoon at around 14:10 UTC, we unplugged the power PDU of the instrumented Baffle WiFi (see figures).
As agreed during the daily meeting, a new step for the WE RH power was performed in CARM NULL 1F:
STEP 6 – 14:57 UTC (20 minutes after reaching CARM null 1F):
The WE RH power was further decreased to 8.0 W (V = 17.25 V).
(P = 8.2 W (17.5 V) → 8.0 W (17.25 V))
This morning we encountered few unlocks during LN3 due to small glitches in the BS TX optical levers that would cause a saturation of teh B1 photodiode and a consequent loss of control. IN order to overcome this problem we engaged the BS TX in full bandwidth already in LN2, and this time we managed to reach LN3. We automated the engagemenet of the full bandwidth in LN2 again.
The intervention to replace the WE mirror and the replacement of the uncoated payload baffles with the nominal AR-coated baffles has had an improvement on the stray light we can spot with the tower camera.
In the first picture, the situation just before the intervention, with the WE showing some additional brigth spots with respect to the NE.
In the second picture, taken after the recovery of the ITF up to CARM_NULL, the images from the two payload look much more similar to each other (with comparable circulating power situation, see third picture).
A more quantitative analysis could probably be done by adjusting the integration time of the cameras so to avoid saturation, to be possibly scheduled.
It can also be seen that, despite the disappearance of the bright spot on the bottom left of the image of the WE, the markers on the WE payload still look brighter than the equivalent on the NE (and also brighter than before!). It could be useful to swap the cameras to check whether it is related to some differences in the senstivity or it is a true effect of some larger scattering off the NI mirror wrt the WI for instance. To be also re-assessed after the tuning of the ring heaters is complete.
Starting from the status left yesterday evening it was enough to:
After that we could drive everything from the automation and pass succesfully the OMC driving states
ITF found in LOCKED_ARMS_IR and Upgrading mode. The first part of the shift was dedicated to the recovery up to CARM_NULL_1F, with ALS verified by the experts at 13:17 UTC and LOCKED_ARMS_BEAT_DRMI_3F reached at 13:39 UTC after a brief alignment of the PR and SR Mirrors. CARM_NULL_1F reached at the first attempt at 13:44 UTC.
Due to the high power in B1p_DC, at 14:00 UTC under request of the crew I contacted Nardecchia to adjust the power of the Ring Heater.
At 19:27 UTC an attempt to lock the OMC was performed, but ITF_LOCK got stuck in SHUTTER_OPENING. While investigating the problem, Was noticed that there were an issue with the process SDB1_Rot, and the related device connected (see report #66613). I went to the Central Building to disconnect and reconnect the unit, and replace it with a spare one, but it was not possible to restore the standard condition. Further investigation will be performed tomorrow.
ITF left in CARM_NULL_1F.
The slow shutter of the OMC was not opening. There was an error message from the SDB1_Rot process
2025-04-23-19h32m26-UTC>WARNING-error while moving to limit channel 2 axis 1 mode 3
Running the commands by hand did not work either, and after starting the process it didn't not want to restart.
On the computer it is connected to, phasecam1, the device shows on lsusb -v with the following error:
Bus 003 Device 024: ID 104d:3000 Newport Corporation
Couldn't open device, some information will be missing
The other driver connected to the same computer (the other device is used for squeezing), doesn't not show this error.
Disconnecting and reconnecting the USB cable of the Agilis driver (AG-UC8) did not solve the issue. Disconnecting and connecting the USB bridge it is connected to did not solve the issue. Plugging a spare AG-UC8 did not solve the issue. None of the USB cables connected to phasecam1 looked loose when touching.
To be done is to replace the USB bridge by a spare, and try other ways of understanding why the USB communication doesn't work properly. The device does disappear from the lsusb list when disconnected, and reappears after connecting.
Starting from the status left yesterday evening it was enough to:
After that we could drive everything from the automation and pass succesfully the OMC driving states
The tuning of the WE RH mentioned in entry 66610 is detailed below.
Before starting, the B1p value was 0.04 mW.
STEP 1 – 14:16 UTC:
The WE RH power was increased by 200 mW:
P = 7 W (V = 16.1 V) → 7.2 W (V = 16.34 V)
STEP 2 – 14:47 UTC:
The WE RH power was further increased to 8.7 W (V = 18 V).
STEP 3 – 15:30 UTC:
The WE RH power was increased again to 10 W (V = 19.3 V).
After reaching the minimum (about 0.022 mW), B1p started to increase again, returning to the initial value, even surpassing the initial 0.04 mW.
Thus, I performed a final adjustment in the opposite direction.
STEP 5 – 16:58 UTC:
The WE RH power was decreased to 8.2 W (V = 17.5 V)
Following this step, the fringe became darker, reaching 0.03 mW (but the transient is still ongoing).
I left this power for the night.
The behaviour of the main signals during the RH steps is shown in the attached figure.
Starting from Tuesday 22 afternoon, after the valve was open again, we started the recovery of the interferometer.
The first, very long step was to find again the West arm alignment and, then, signals on the B8 photodiodes. We could find rather easily the beam on the WE markers by changing orientation of the BS, so to have a rough alignment, then we used the locked North Arm to get a reasonable orientation of the WI by superposition on the B1p camera. However, after all this we could not find signals on B8 even scanning the WE orientation with the "snail".
We also used the reflection of the ALS beam back on the bench, and the spot on the WI mirror in order to improve such alignment.
This morning we changed strategy and we only aligned the West Arm, in order to see the flashes in reflection on the B4 PD up to a similar level to what only the North Arm aligned could provide.
While doing all of the above, we tried to follow with the SWEB alignment (and the vertical position of WE, this one with no effect), which could lead to marginal but visible improvements.
Later, we tried, after we were sure to have the cavity well aligned by hand, to make a "snail" on the SWEB bench itself; this did not work as expected, but a wide change in its orientation actually helped to find again good signals on the bench, which had a very different working point with respect to before. We've been probably chasing a ghost beam before.
We could then recover the lock of the West Arm, which went quite smooth:
Then we moved on with the lock acquisition, getting up to the lock of the DRMI without any problems. We will have to check later if the working point of the West ALS is the best one, but we could lock easily and keep the lock. Once we locked the DRMI, we checked also the SDB1 alignment and we re-engaged the floating setpoints.
We could go then towards CARM_NULL_1F without the need of any adjustment. Once there, after an initial thermalization, we noticed the B1p_DC fringe signal being twice as usual; therefore we started the tuning of the WE Ring Heater, in order to at least reduce the fringe up to a reasonable level before opening of the SDB1 shutter.
We are currently in the RH transient, we'll monitor the situation for the next hours and decide when to do the next step of the recovery.
This morning the work to find the west arm alignment went on; at around 10:00UTC a 6.2 magnitude earthquake in Turkey prevented to go on with the activity during the lunch time; in the afternoon the west cavity was aligned and locked, the lock recovery will go on in the afternoon.
Sub-system reportsSBE
SIB2, SDB2, SPRB, SNEB and SWEB position controls opened because of the earthquake, controls properly closed.
Figure 1 The beam arrived several times during the snail on the markers of the WI mirror, with spikes of power on the areas of the markers (looking at the video images of the camera it is clear that these are the markers)
Figure 2 Zooms in a few of the peaks. The right areas seems to be for WE TY at around 0, and WE TX at around 150
ITF found in Down State and Upgrading Mode, North Arm Cavity locked.
The shift was dedicated to the recovery of the West Arm cavitiy after the WE intervention, carried out by Casanueva, Bersanetti, De Rossi, Boldrini with the remote support of Was.
After various attempts to realign the cavity, from around 21:15 UTC I started to use the WE Snail to see flashes on B8. I have left it running until 21:15 UTC, but unfortunately I wasn't able to spot any flashes on the photodiode. After stopping the movements, I returned WE MAR TX and TY to its initial starting point for the procedure (TX: 31, TY: -564).
North Arm Cavity left locked.
Figure 1 The beam arrived several times during the snail on the markers of the WI mirror, with spikes of power on the areas of the markers (looking at the video images of the camera it is clear that these are the markers)
Figure 2 Zooms in a few of the peaks. The right areas seems to be for WE TY at around 0, and WE TX at around 150
the W arm was reopened today at about 13h00LT, the pumpdown is progressing regularly. For now an auxiliary turbo pump is still in use, the system will be fully restored next Tuesday.
After the covering of the FCIM optical levers I found SBE and LC loop out of range. I recoverd before the IP position loops
Than I had to close the Optical lever loop one by one
Finally the reflection of FCIM was not reaching anymore SQB1. With the help of ipcam61 I was able to find again the beam back and relock the filtercavity
ITF found in Down State and Upgrading Mode, North Arm Cavity locked.
At 6:00UTC started the planned maintenance with the following activities:
The WE big valve was opened at 10:54UTC
At 12:00UTC started the recovery with the west arm alignment. Recovery in progress
Today around 12:20 UTC I restored the air covers on FCIM optical levers, see pictures
We have observed that the Etalon loop of the west arm was oscillating. So we have decreased by a factor 2 the gain of the filter and we have reloaded the filters. We will monitor the situation.
This morning, I checked the CO₂ actuator powers.
A small adjustment was applied to the WI CH power, from 0.264 W to the nominal value of 0.284 W.
A minor correction was also made to the NI outer ring power, from 0.625 W to 0.613 W (nominal value).
Activity completed at 08:24 UTC.
The SQB1_FI Acl server, used to manage the SQB1 Faraday insulators FI1 and FI2, has been set up on the SQB1_rtpc .This server is running ar 10KHz on the RT_CPU0 .
Expected cabling:
The use of SQB1_rtpc’s RT_CPU processors is now
