DRAFT - SHIFT IN PROGRESS

Upon arrival, I found the ITF in LOW_NOISE_3_SQZ and PREPARE_SCIENCE mode, with a low BNS range (35-38 Mpc).

At 06:44 UTC, the squeezing disengaged. The situation returned stable soon after, and the ITF again reached LOW_NOISE_3_SQZ at 06:48 UTC. This occurred again at 07:39 UTC and 07:44 UTC. After the latter disengagement, I put the ITF in LOW_NOISE_3 and contacted the on-call expert. The issue has been addressed due to a malfunction in the humidity loop (see #65584). Checks are currently ongoing.

To follow up on this night's on-call intervention (see #65582) and to investigate the red DMS flags for Cal_NEMIR_ZCORR_VOUT, the suspension expert has been contacted.

I have been called by CR due to frequent unlocks of the SQZ system. They are due to a loss of MZI control, which in turn depends on the large ongoing transient in DET lab humidity. I leave the MZI lock threshold unchanged for the time being, to look at the evolution of humidity in the next few hours. Davide Soldani is aware of the problem.

missing figure

The following report has been submitted to the On-call interface.

On-call events -> Interferometer Sensing & Control

Title: Locking troubles

Author(s): mantovani

Details:

I ve been called since the ITF was unlocking at CARM null.
The reason was that frequent "kicks" were visible on the powers, see figure 1, making the fringe to exceed the allowed value and unlocking the system. No loop oscillations (no margin to cure it with ISC).
We manage to make the ITF to survive CARM null by misaligning the SR ty (in the direction toward the LN3 wp) of 1urad.
To be noticed that the violins were still quite high
We made few trials but we failed during the lock of OMC.
Fabio has continued to try and after a while he managed to lock but a huge noise is still present in the region 20Hz -200Hz. To be understood, may be related to suspensions.

* Note that any files attached to this report are available in the On-call interface.

The sea activity decreased over the night but the lock was not working; once reached CARM_NULL_1F some slow fluctuation arose, not a real oscillation but something like kicks visible on all the powers, I called Maddalena trying to understand the problem without finding any clear explanation, we tried to lock mis-aligning the SR at CARM null, in this configuration the ITF was less sensitive to these events but going on with the lock it failed while locking the OMC, at this point we gave it up with the investigation; for the rest of the night I tried to lock with the SR trick, at some point I succeeded to lock up to LOW_NOISE_3_SQZ (3:08UTC) but the sensitivity is not good with the BNS range around 35-37 Mpc.

ISC
(20-11-2024 23:45 - 21-11-2024 01:15) From remote
Status: Ended
Description: locking trouble

ITF found in DOWN and in BAD_WEATHER mode. 

The microseism due to the sea activity is still high (pict1) and it prevens the lock.
After several attempts and the usual cross-alignments in ACQUIRE_DRMI, the ITF reached CARM_NULL_1F but not further. The lock acquisition is very low and very noisy (in particular ARMS_IR and CITF).

Guard Tour (UTC):
18:00 - 18:32
20:00 - 20:40

DET
During a relock, at 17:40, 19:56 UTC, SIB2_SBE loop opened. Properly closed via VPM.
- At 21:29 UTC, at CARM_NULL_1F, both B1p_QD1 and B1p_QD2 galvos remained open. Properly closed via VPM.

SUSP
Sc_NE_MIR_PSDI_PWR_50Hz out of range (red flag on DMS) since tuesday morning during the intervention on NSN NCal.
Experts informed

After the last maintenance, we swapped back the EAB_EOM_TRA_audio cable on its original photodiode and added a new one spefically for the new RFC_TRA photodiode (see fig. 1).

The cable, named 12 LL-EER has been connected to the dbox in eeroom "EER_DBOX3_ADC0" #40 (SN30) in place of the unused (and commented till today) channel INJ_SIB1_PELTIER.

The correspondent dbox configuration has been restarted today at 14h52m57 UTC, and the new channel INJ_RFC_TRA_AUDIO is now available.

ITF status: BAD WEATHER. Strong wind activity is preventing the lock. 

Other
ALS : A. Masserot performed ALS_CEB : BPC tuning

The attached plot show the trend, from the 14/11 to th 20/11, of the BEAT _DC and BEAT_15xMHz_mag signals for the North and West ARMs

• the green line referred to the NARM and WARM CEB BPC adjustments performed the 2024-11-15-14h40-UTC
• Starting from the 2024-11-19, one can see a decrease of the WARM_BEAT_154MHz_mag on the West Arm (red rectangle)
• this morning,2024-11-20-08h34m-UTC with the ITF in LOCKED_ARM_IR_ALS state, a BPC adjustments were performed on the ARMs
  • it allowed to recover  the previous value for the WARM_BEAT_154MHz_mag (purple rectangle)

Figure 1. The NE MIR optical lever power has dropped suddenly a few days ago and the power continue to slowly decreasing. This needs to be checked urgently.

There are also many other optical levers that are repored in yellow (low power) state in DMS that should be checked.

The ELE_WAB server is working fine: the orange color in VPM shows us that the server is in Error state: in effect the Yocto Net 1500_W (IP:192.168.101.100) device, interrogate by this server, does not answer to the ping command. The expert was informed by email.

ITF found locking to CARM_NULL_1F and in PREPARE_SCIENCE mode. 
Ruggi, from remote, investigating on violin modes and damped enough to try to restart lock acquisition but unfortunately it unlocked every time at different steps.
In additions to the violin mode issue, the bad weather doesn't help us (pict1). At 20:13 UTC I set BAD_WEATHER mode.

Planned activities not performed.

Guard tour (UTC):
18:40 - 19:09
20:19 - 20:49

DET
SIB2_B2_QD2_GALVO loop remained open few times. Properly closed via VPM.

ISYS
BPC - Beam not centered (pict 4,5). Expert informed. Check foreseen for tomorrow.

SQZ
17:40 UTC - SQB2_SBE vertical position restored via stepping motors.

The amplitude of the violin modes has been further reduced: now at CARM NULL they stay well below the DARM line at 491 Hz (fig 1). Given that yesterday CARM NULL has been reached with the violins 100 times larger, I would conclude that now they should not prevent the lock acquisition up to CARM NULL and the current difficulty to ramp the carm offset is more likely due to bad weather.

In DC readout the situation could be more critical: the violins are the largest component at high frequency (fig 2). Looking at the time domain (fig 3), it seems that this component does not determine the saturation of the photodiode: the reason of the unlock is not clear to me. Anyway, I would like to damp the violins a bit more. Unfortunately the largest peak (447.3 Hz) does not react anymore to any action: now the only effect is to excite the other peaks. I will try something different tonight or tomorrow, if we manage to stay at CARM NULL.

This morning during maintenance I made some maintenance on FDS hardware:

- around 10:15 UTC, to debug SQB2 suspension, I reset the power switches of the motor crate. Right afterwards, I could restart the SQB2_MotSwitch server without problems;

 - around 10:20 UTC I switched off the noise eater on SC laser source, to check if this has any impact on the stability of SC PLL; I left the noise eater off for the time being;

- around 10:50 UTC I checked the alignment of MZI in the squeezer box; I got a marginal improvement of contrast;

- around 11:05 UTC I checked the OPA alignment in the squeezer box; I got a marginal improvement of peak transmission;

- I measured the power of SC beam to be 19 mW.

A damper for NE violin modes has been prepared and used effectively. At LN2, MIR CORR and B1 Audio were still high but not saturated: the unlock could be due to something else. Anyway, I will try to damp a bit more next time at CARM NULL.

On November 15, we completed the 19th height monitoring campaign of the North Tunnel - North End Building reference points.

Tab.1 summarizes the result of the survey and Fig.1 shows the longitudinal profile, that reports graphically the trend of the subsidence over time.

Upon arrival, I found the ITF in CARM_NULL_1F and TROUBLESHOOTING mode.

At 07:00 UTC I set the MAINTENANCE mode as planned and manually unlocked the ITF. 

Here is a list of the actions communicated to the Control Room:

- cleaning of NAB and WAB (external firm managed by Ciardelli);

- TCS chillers refill (Ciardelli);

- upgrades on virtual infrastructure, see #65561 (Kraja, Cortese);

- SQZ maintenance (Sorrentino);

- SIB1 mechanical measurements (Gosselin);

- recentering of the beam on the ITMs, see #65567 (De Rossi, Gosselin, Mantovani);

- INJ activities in Laser Lab (De Rossi, Melo);

- work on SIB1 suspensions (Ruggi);

- work on PCal channels, see #65565 (Masserot, Rolland);

- NCal LED replacement, see #65566 (Mours).

I performed these periodic tasks:

- OMC lock (07:19 UTC - 07:24 UTC) and scan (07:27 UTC - 07:48 UTC) in SINGLE_BOUNCE_NI;

- at 07:59 UTC thermal camera reference acquisition;

- at 08:38 UTC TCS power checks (see table below);

- at 11:06 UTC IMC working point and position check.

During the maintenance activities, the SWEB_SBE vertical position loop and the SNEB_SBE horizontal position loop opened. I restored them at 08:31 UTC and 08:42 UTC respectively.

I set the PREPARE_SCIENCE mode and started the lock acquisition at 11:48 UTC.

I left the ITF in LOCKING_ARMS_BEAT_DRMI_1F.

This morning we recentered the beam on the ITMs by moving the PR F7_Y and F0_X (see attached plot).

On November 18th accelerometer DSP boards (serial #31015, #41065) have been replaced with an LVDT and a DIFF board (serial #43170, #45275). The relative distribution box has to be replaced as well with a v2. For each sensor, demodulation phases has been set, transfer functions measured and controllers re-designed. Code has been changed in order to allow automatic TF measurements. DSPServer configuration files has to be updated due to the hardware changes. New gains for horizontal and vertical inertial damping has been estimated as well. During the night both IP loops has been kept closed and no glitches have been reported.

This morning, during the maintenance time, the LED used to measure the NSN NCal rotation was replaced, in order to address the issue reported in the logbook entry 65532. The thresholds to detect the rotor have been also adjusted on NEN, NNF, NNN and NSF . (PS for NCal people: two additional spares LED are stored in the IPHC office, bottom of the closet)

For debugging purposes, the PCAL_NE_PD{1,2}_DC_NS channels acquired at 200KHz are now stored  in the RAW_FULL stream as PCAL_NE_PD{1,2}_DC_NS_FS

Operations completed at  2024-11-19-10h17m06-UTC

The attached plot show the SSFS loop UGF and phase according the ITF state and the SSFS GAIN from the 2024-11-07-00h00m-UTC up to 2024-11-19-06h00-UTC :

• with the SSFS gain at 670,
  • the UGF remains above 9.5kHz until the 2024-11-15-16h07m-UTC
  • after the 2024-11-15-16h20-UTC, the SSFS UGF is below 8.5KHz (zoom)

The operations performed on the IMC working point (green rectangle 2024-11-15-17h42m-UTC - 2024-11-15-19h07m-UTC) did not allows to recover the standard UGF 

This morning, 2024-11-19 around  04h15m-UTC, with the ITF in CARM_NULL_1F as trial the SSFS_GAIN has been increased from 670 to 770  (green rectangle). It allowed to increase the SSFS UGF from 7470Hz to 8630Hz with a stable phase (plot)