Upon reaching the site, I've found the ITF in LOW_NOISE_3_SQZ and Science Mode.
At 14:00 UTC I set the ITF in Commissioning Mode to allow the planned activity for the afternoon (Characterization for EM RH tuning) carried out by Nardecchia, de Rossi, Melo, Gouaty (see report #64205).
At 14:17 UTC the ITF was unlocked by De Rossi and Melo by performing a kick on the end mirrors, followed by a brief period at LOCKED_ARMS_BEATING (from 14:28 UTC to 14:51 UTC).
At 16:06 UTC we reached CARM_NULL_1F, and we waited one hour before performing the OMC Scan (scan done from 16:08 UTC to 16:31 UTC, see report #64206).
After that we reached LOW_NOISE_2 at 16:50 UTC, we waited 90 minutes to take reference data.
ITF back in LOW_NOISE_3_SQZ and Science Mode from 18:31 UTC.

Guard Tour (UTC):
17:06 - 17:36
19:01 - 19:28

The goal of the shift was to characterize the ITF working point with the following RH powers:

The actions performed during the shift are listed below:

13.08 UTC: ITF relocked in LN3

14.18 UTC: ITF manually unlocked to perform input beam mode matching measurement with the free swinging technique and green laser scan (performed by Suzanne, Camilla and Matthieu).

                    See detailes in 64204

15.03 UTC: ITF relocked in CARM NULL 1F

16.08 UTC: OMC scan started (performed by Romain and Andrea)

16.30 UTC: OMC scan ended 

16.52 UTC: ITF relocked in LN2

After 1.5 hr in LN2, at 18.20 UTC, Andrea will proceed with the lock acquisition.

The main ITF signals during this afternoon are shown in figure 1.

Figure 1 shows the scan of the OMC performed from 16h08 utc to 16h30 utc, after waiting for 1 hour in CARM_NULL_1F.

Figure 2 shows a zoom of this scan around a Free Spectral Range.

Assuming a calibration factor of about 4800 for B1_PD3, we have: ~75 mW on the first order mode, ~29 mW on the second order mode, ~200 mW on each of the third and fourth order modes, ~70 mW on each of the 5th and 6th order modes, ...

ITF found in LOW_NOISE_3_SQZ and in Science Mode. It kept the lock for the whole shift.

DAQ
From around 10:39 UTC the process ELE_QGBT was reported as not responding on VPM (Orange State) and as not working on DMS (red flag). At 10:46 UTC I restarted the process via VPM to restore the nominal condition.

ITF found in LOW_NOISE_3_SQZ and in Science Mode. It kept the lock for the whole shift.

Guard Tours (UTC):
5:01 - 5:28 
7:01 - 7:30
9:11 - 9:38
11:01 - 11:30

ITF found in LOW_NOISE_3_SQZ and in Science Mode. The ITF unlocked at 3:41 UTC, and failed the relock twice at LOCKING_CARM_NULL_3F (3:57 UTC) and ACQUIRE_LOW_NOISE_1 (4:34 UTC). 
Relock in progress.

No DMS alerts received during the shift.

Guard Tour (UTC):
21:06 - 21:33
23:00 - 23:30
21:34 - 22:03
03:45 - 04:17

ITF found in LOW_NOISE_3_SQZ and in Science Mode. It kept the lock for the whole shift.

Guard Tour (UTC):
21:01 - 21:29
23:02 - 23:29
01:01 - 01:29
03:01 - 03:29

TCS
At around 4:25 UTC the value of TCS_WI_CO2_PWROUT suddenly decreased (see attached plot). Expert informed via mail of the issue.

ITF found in LOW_NOISE_3_SQZ and in Science Mode.
At 18:30 UTC I set the ITF in CALIBRATION Mode to perform the planned measurements:

• 18:31 UTC - check hrec (CALIBRATED_DF_DAILY);
• From 18:46 UTC to 19:16 UTC - ISC Injections (inject_SSFS.py)

ITF back in Science mode from 19:16 UTC.

Guard Tour (UTC):
14:05 - 14:55 
15:57 - 16:32
19:06 - 19:36

DAQ
The process FCIM_MotSwitch stopped working at around 17:41 UTC. Process restarted via VPM at 17:44 UTC.

ITF found in LOW_NOISE_3_SQZ and in Science Mode. 
From 13:07 UTC to 13:08 UTC I set the ITF in ADJUSTING Mode to allow Nardecchia to turn the WI waveplate (see report #64116).
At around 17:50 UTC I was contacted by the LIGO Livingston Control Room, which reported that both LIGO ITF would postpone the planned calibrations by 24 hours. In agreement with the Commissioning coordinator, the planned Hrec calibration and LSC injections are postponed until tomorrow afternoon. 
ITF left locked.

Guard Tour (UTC)
13:01 - 13:29
15:01 - 15:29
17:50 - 18:20
19:41 - 20:20

Nicola called me because the WI CO2 laser changed its state (see figure 1).
To address the change in the WI outer power, I first rotated the WI outer ring waveplate to recover the nominal  power to be injected into the ITF (11.59 UTC-12.00.26 UTC ) (ITF in ‘adjusting’ mode). Then, I adjusted the WI chiller set point to return the laser to its usual operating point, in particular I decreased it by 0.01 degrees, from 19.02 to 19.01 (12.21.04 UTC). The BCK chiller set point has been changed accordingly. This action did not solve the problem; in fact, the direction turned out to be wrong.
Thus, at 12.41 UTC, I increased the chiller set point from 19.01 to 19.03 degrees.
Finally, the standard situation has been restored (see fig.2). 

ITF found in LOW_NOISE_3_SQZ and in Science Mode, it kept the lock for the whole shift.

Shift in Progress

ITF found in LOW_NOISE_3_SQZ and in Science Mode, it kept the lock for the whole shift.

Guard tour (UTC):
7:02 - 7:29
9:01 - 9:27
11:01 - 11:28

DAQ
During the shift the VPM stopped working three times (9:19 UTC, 9:57 UTC, 10:52 UTC). In all cases, it was possible to restart the VPM following the procedure provided by Pacaud.

Upon reaching the site, I found the ITF locked in LOW_NOISE_3_SQZ and in Science Mode. At 22:12 UTC the Squeezing disengaged, bringing the ITF back in LOW_NOISE_3. ITF back in LOW_NOISE_3_SQZ from 22:14 UTC.
ITF left locked.

Guard Tour (UTC):
21:30 - 22:00
23:30 - 00:00
1:38 - 2:07
3:07 - 3:18

DAQ
The process ELE_QGBT was not working correctly, it was reported as not working on DMS and in Orange state on VPM. At 4:13 UTC I restarted the process to solve the issue.

Upon reaching the site, I found the ITF locked in LOW_NOISE_3 and in Science Mode. It kept the lock for the whole shift.

Guard Tour (UTC):

21:06 - 21:36
22:55 - 23:25
1:33 - 2:02
3:50 - 4:20

DAQ
The process ELE_QGBT was not working correctly, it was reported as not working on DMS and in Orange state on VPM. At 1:05 UTC I restarted the process to solve the issue.

Upon reaching the site I found the ITF relocking. After a brief alignment of the PR/SR Mirrors, LOW_NOISE_3_SQZ was reached at the first attempt at 13:50 UTC, ITF back in Science Mode from 15:32 UTC.
At 15:07 UTC I set the ITF in Commissioning Mode to allow the planned ISC activity, DIFFp set point error signal test, carried out by Mantovani. The work could not be concluded due to an unlock at 15:22 UTC due to an earthquake (M 5.6 - 9 km W of Sulusaray, Turkey, 15:11 UTC). After various attempts we were able to reach LOW_NOISE_3_SQZ at 16:53 UTC, and the second planned activity, ENV Acustic Injection, started (see report #64024).
ENV Activity concluded at 18:11 UTC and ITF back in Science Mode. A quick adjusting period, from 18:16 UTC to 18:17 UTC, was done to allow the switch off the Speaker PDU.
The ITF unlocked at 19:34 UTC, relock in progress.

Guard tour (UTC):
17:06 - 17:44
19:03 - 19:30

Upon reaching the site, I found the ITF in LOW_NOISE_3_SQZ and in Science Mode. The ITF unlocked at 15:03 UTC due to an earthquake (M 6.3 - 17 km WSW of Uwajima, Japan, 14:14 UTC), preventing the lock of the infrared cavities.
From 15:40 UTC the influence of the shaking decreased enough and it was possible to relock.
ITF back in LOW_NOISE_3_SQZ at 16:16 UTC and the planned ISC/INJ activity (see report #64007) started; work concluded at 19:13 UTC.
The ITF unlocked at 19:24 UTC, followed by various unlocks at different steps of the locking acquisition (ACQUIRE_LOW_NOISE_2, LOCKING_CARM_NULL_1F).
Relock in progress.

No DMS alerts received were received during the shift.

Guard tour (UTC)
17:01 - 17:42
19:01 - 19:28

This morning we noticed that the WI main CO2 laser continued to be in an unstable state since last night at around 06.30 UTC, so we decided to act on WI CO2 chiller setpoint, changing it from 19.04 °C to 19.02°C (12.37 UTC, Fig. 1) in order to restore the correct power values. Also the BCK chiller set point has been changed at the same setpoint.

After this change, there have been no significant changes in the powers of the actuators, which have remained stable around their nominal values. The situation will continue to be monitored to determine whether further intervention will be necessary.

Upon reaching the site, I found the ITF relocking, but it kept unlocking during various steps of the locking acqusitition.

At 6:07 UTC I set the ITF in Maintenance Mode, here the list of the activities communicated to the Control Room:

• Cleaning of Central Building, Laser Lab (external firm managed by Gargiulo);
• VAC Refill (Vacuum Team);
• Crane inspections (external firm managed by Bazzi, the approximated timetable is NE: 6:30 UTC, WE: 7:00 UTC, CB: 8:10 UTC, MC: 8:30 UTC);
• SNEB angular setpoints updated (see report #63979);
• At 8:00 UTC, Restart of ASC_pre (Casanueva);
• From 8:30 UTC from 11:10 UTC, PR F0 accelerometer change modulation frequency (see report #63984);
• Operator Periodic Tasks (see section below);

Periodic Tasks carried out by the Operator:

• From 5:57 UTC to 6:10 UTC, Check of IMC Working Point and Position;
• At 6:29 UTC - 5 minutes of OMC Lock in Single Bounce configuration;
• From 6:37 UTC to 6:58 UTC - OMC Scan in Single Bounce configuration;
• At 7:30 UTC - TCS Chiller Refill;
• At 8:00 UTC - TCS Thermal Camera Reference;
• At around 8:30 UTC - TCS Power Checks (see table below for resuts):

To allow the external firm to clean around EIB, the bench was blocked by De Rossi from 8:48 UTC to 9:29 UTC. Due to the ongoing activities (missing laser and PR ID loop open) it was not possible to perform the planned ALS Maintenance.
 After the activity on the PR was concluded we started to relock, but the ITF kept unlocking at various steps of the locking acqusition, possibly due to the worsening of the weather.
Relock in progress.

The ITF was locked for the whole shift in LOW_NOISE_3_SQZ and in Science Mode.

Guard Tour (UTC):
21:02 - 21:31
23:10 - 23:40
00:56 - 1:27
3:15 - 3:45

The first part of the shift was dedicated to the SAT Investigation on PR glitches, carried out by Boschi, Ruggi and Dattilo. At 14:20 UTC the crew left the Central building and, after Boschi recovered the Vertical correction of the PR (from 14:50 UTC to 15:05 UTC) we started to relock.
ITF back in LOW_NOISE_3_SQZ at 16:01 UTC, Boldrini performed the planned DIFFp_TX line adjustment (see report #63885), which was concluded at 16:23 UTC. 
The planned DET activity, SDB1 Y scan, carried out by Gouaty from remote, started soon after. The ITF unlocked at 17:24 UTC due to a PR Trip (see attached plot), after relocking at 18:16 UTC the work proceeded until 20:01 UTC.
At 20:02 UTC I started the daily calibration (CALIBRATED_DF_DAILY), but unlocked at 20:16 UTC at the 10th injection.
Relock in progress.

Guard Tour (UTC)
17:45 - 18:20 
19:40 - 20:13

The goal of this shift is to check the impact of a vertical translation of SDB1 on the sensitivity.

We start from ITF locked in Low Noise 3 with squeezing on.

Initial height of the bench: SDB1_LC_Y = -4808.5 um, which corresponds to F0_Y_SET = 1380

We scan the vertical position of the bench in the negative direction from 16h47m40 utc to 17h20 utc.

Fig.1 shows a comparison between the reference sensitivity curve (purple) taken with the bench at nominal height and the sensitivity measured when the bench height was lowered by ~200 um. The noise floor is pretty much unchanged, but we see a few peaks amplified when the bench is misaligned, in particular in the 200-300 Hz region (see Fig.2 which is zoomed around these frequencies).

Fig.3 shows the whole scan that was performed from Y=-4808 to Y = -5170 um (translation of -362 um). It can be seen that at the same time as we are translating SDB1, the SDB1 drift control changed the angular position of the bench in TX in order to keep the OMC aligned. The TX correction is then getting close to the saturation limit which implies that we cannot move further in this direction. It seems difficult to extract any clear conclusion on the optical gain or on the BNS range from these trends.

ITF unlocked at 17h23 utc due to a PR trip (identified by Mattia).

Low Noise 3 restored at 18h16 utc.

Start rising up the bench from 18h40 to 19h30 utc: the bench height is changed from -4808 to -4390 um (translation of +418 um). On Fig.4 and Fig.5 we compare the sensitivity obtained when the bench was at -4390 um (blue) with the sensitivity obtained with the bench close to its nominal height (actually it was already translated by 50 um): The noise floors are almost very similar. We notice some differences in the height of a few peaks, but not at the same frequencies as for the negative scan.

We then restore the nominal height of the bench from 19h40 to 20h00 utc.

Fig.6 shows the overall trends during the scan of the bench height in the positive direction. There is not any clear correlation between the bench height and the optical gain of the BNS range.

Upon reaching the site, I found the ITF in LOW_NOISE_3_SQZ and in Science Mode. It unlocked at 14:29 UTC, ITF locked again from 15:12 UTC.
At 18:51 UTC I set the ITF in CALIBRATION to perform the planned daily calibrations. Measuremenets successfully concluded at 19:16 UTC, but the ITF unlocked few seconds later.
ITF back in LOW_NOISE_3_SQZ at 19:58 UTC and left locked.

Calibrations:
18:51 UTC - CALIBRATED_DF_DAILY

Guard tour (UTC)
13:45 - 14:38
16:00 - 16:30
17:01 - 17:28
19:01 - 19:28 

The shift was dedicated to the troubleshooting issue that started this night (see operator report #63861). Upon reaching the site I found the ITF in LOW_NOISE_1, further attempts unlocked while at ACQUIRE_LOW_NOISE_2 or ACQUIRE_LOW_NOISE_3. 
During the morning the ISC Team (Casanueva, Spinicelli, Bersanetti, Boldrini, De Rossi), Ruggi, and Gouaty performed various checks to better understand the ongoing issue.
Activity still in progress, ITF left in LOCKED_DC_READOUT.

Guard Tour
5:06 UTC - 5:41 UTC
6:52 UTC - 7:23 UTC
11:32 UTC - 12:06 UTC 

DET
(06-04-2024 08:00 - 06-04-2024 11:00) From remote
Status: Ended
Description: One of the possible causes of the locking issue was connected to an increase of power on B1 after CARM_NULL_1F.
Actions undertaken: The DET Oncall (Gouaty) investigated the issue with the ISC crew, but no clear indication of the problem was identified on SDB1.

ISC
(06-04-2024 01:30 - ) From remote
Status: On-going
Description: ITF kept systematically unlocks at ACQUIRE_LOW_NOISE_2 or ACQUIRE_LOW_NOISE_3.
Actions undertaken: During the shift, the ISC Oncall (Casanueva) with the help of the crew investigated the issue, trying to understand the cause of the problem. A possible cause seems connected to a rising 1.8Hz oscillation during the lock acquisition (see report #63863).

Upon reaching the site, I found the ITF relocking. LOW_NOISE_3_SQZ reached again at 6:16 UTC.
During the shift the ITF unlocked three times (7:13 UTC, 9:39 UTC, 11:18 UTC), only the first one seems to be caused by a PR Trip (see attached plot #1), but a similar event happened during the locking acquisition at 10:29 UTC (see attached plot #2).
At 12:55 UTC I manually unlocked to allow the investigation on the PR Suspension by Boschi and Ruggi. Activity still in progress.

DET
At 9:54 UTC, while in CARM_NULL_1F, I closed the B1p QD1 that was opened during the locking acquisition.

ISC
During the first two locking attempts, the ITF remained stuck at LOCKING_DARM_IR. As a first attempt I manually unlocked the ITF, but the issue reappeared again. At the second attempt, I tried to unstuck the Metatron node which ITF_LOCK was complaining about, ARMS_LOCK, which itself was stuck in LOCKED_DARM_IR_RF and unable to reach the required state (OFFLOADED_TO_MANAGER). After forcing this state the ITF unlocked, but the following attempt was successful. Expert informed of this issue.

SBE
SPRB position loop opened by the guardian at 13:05 UTC due to PR ID Loops open. It was closed again at the end of the activity at 13:35 UTC.

SUSP
At 13:00 UTC, under request of Boschi, I opened all the loops of PR ID to allow the ongoing investigation.

TCS
During the night the value of TCS_WI_CO2_PWROUT decreased multiple times (see attached plot #3). Today, under request of Taranto, I changed the WI Chiller setpoint from 19.0 to 19.02.

Vacuum
After an unlock, at around 7:45 UTC, the VAC Team performed a cryotrap refill, opening the related valve.

Upon reaching the site I found the ITF relocking, LOW_NOISE_3_SQZ reached at 21:28 UTC. It unlocked twice during the shift (22:02 UTC, 23:47 UTC), in both cases due to a PR Trip (see attached plots #1, #2).
LOW_NOISE_3_SQZ reached stably again at 1:04 UTC, ITF left locked and in Science Mode.

Guard Tour
21:34 UTC - 22:03 UTC
23:55 UTC - 0:25 UTC
1:55 UTC - 2:25 UTC
3:50 UTC - 4:32 UTC