ITF found in Science mode.

At 6:35 UTC the ITF unlocked; the Autoscience/Autorelock requested to go in LN1 (instead of LN3). The ITF locked in LN1; at this point I disabled the Autoscience/Autorelock  and I requested LN3; then I enabled again the Autoscience/Autorelock . The ITF locked in LN3 and Science mode was automatically set after 180s.

Guard tours (time in UTC)

6:14-6:48; 8:03-8:36; 12:07-12:52

I found ITF in SCIENCE; It remained locked for the whole shift.

Guard tour (UTC):

• 22:30 - 22:59
• 00:13 - 00:43
• 02:13 - 02:43
• 04:14 - 04:45

ITF found during locking acquisition. It was back in Science Mode  and LOW_NOISE_3 from 14:37 UTC.
ITF left locked.

Guard Tour (UTC)
18:16 - 19:07
20:18 - 20:47

There was a test done to study the 120Hz on B8 DC / Hrec yesterday by adding an alignment offset into the soft (minus) mode of the west arm alignment in the vertical direction.

Figure 1 shows the trend of data during that test with WE MIR Y AA the offset in the vertical position of the beam on the mirror. There is an unlock in the middle of that time series.

Figure 2. shows the spectrogram of DARM for that day, and between 18h00 and 18h30 the bump at 120Hz disappears when there is a negative offset on WE Y.

Figure 3 looking at spectra of h(t) the change in the bump is less clearly visible

Figure 4 looking in the B8 DC spectrum both in LN3 and in CARM NULL 1F there are clearly changes in the height of the 120Hz bump. The relation is not very clear with WE Y, but the bump tends to be smaller for negative offsets on WE Y.

To understand better this relation the position on the WE mirror would need to be scanned in CARM NULL 1F over a wider range and also in the horizontal direction.

Today I continued to work on the node:

• the automatic transition to Science has been set after 180 s of LOCKED state; this can be updated and is configurable inside the ITF_STATUS.ini file;
• improved the engagement of AutoScience: if requested, it will be engaged in any state of the interferometer, not only if just LOCKED;
• improved the node management between the two features AutoRelock and AutoScience;
• added a new channel, DQ_META_AUTORELOCK_FAILED, which will be set to 1 when the Failsafe triggers and we stop trying to lock; this should help in setting up flags and alarms on the DMS.

Still missing:

• test of unlock when the feature is activated;
• squeezing management and multiple-crossing of Science-viable states;
• implement a possible reason to trigger an intervention, which is maybe better to set up directly in the DMS: in case we consistently lock, but the locks last a short time, there is no way now to monitor this, as the AutoRelock will be reset at each successful acquisition, while AutoScience has no ways of failing as it is just a flag set once we're locked; maybe some check made on the duration of DQ_META_ITF_Mode being 1 for how long can be implemented in the DMS:
• still in the DMS, make explicit that the AutoScience is enabled.

The feature has been turned on and it will be in operation for the weekend, supervised by the operators to spot any misbehaviour. It can be deactivated by asking the STOP state to ITF_CONDITIONS, in case of Calibration activities and of any manual intervention.

There is a vague (~ 0.1) coherence with one (and only one) of the magnetometers that are near the towers: ENV_WI_MAG. None visible in all others, and none in CEB IPS and UPS sensors.

The noise has period of high and low sidebands level, as well as disappearances, such as the one that occurred today at 10:00 UTC that lasted 4 minutes. .

ITF found in Science mode.

It unlocked at 13:40 UTC; relock in progress.

Here is an update of the analysis presented above. In this new analysis, the ratio between the PSD of Hrec and the PSD of the PSTAB during the time of the injection is used for the projection instead of the transfert function. This is defined as:

PSD(Hrec(High_frequency_injection)) * (PSD(RIN_reference)/PSD(RIN_HIGH_FREQ_INJECTION)),

this ratio is plotted on the figure 1 and compared to the sensitivity curve during the time of the injection. Here we need to found a criteria to define which frequency keep for the projection. We tried two methods for the frequency selection.

Method 1:
Use the ratio between the PSD of the RIN during the injection and during the reference time. This is what is shown on the figure 2. The upper figure shows the PSD during the injection and during the reference time. The ratio of the two curves is plotted in the figure at the middle. For the projection, we keep only the frequency where the ratio is higher than three (the threshold is represented by the horizontal line). Finally, the projection with this method is shown on the bottom subfigure. We observe that several peak of the sensitivity curve are conserved during the projection.     

Method 2:

Use the ratio between the sensitivity curve during the injection and during the reference time. This is what is show on the figure 3. The upper subfigure show the two sensitivity curves, the one during the injection and the on during the reference time. As a criteria for the projection, we use the ratio between those two curves. The ratio is plotted on the middle graph of figure 3. The horizontal line show the position of a threshold equal to 2. Finally, The projection with this method is shown on the bottom subfigure of figure 3. With this methods, the peaks are no longer conserved.

The figure 4 show what the total projection with the second method look like. This projection is done, for the low frequency injection with the method presented in the previous logbook since no problem occur during the projection, and the high frequency projection is done with the method 2 presented in this logbook. We choose to keep the projection done with the method 2 because the peaks of the sensitivity curve are not conserved by the projection. Since the injection of noise keep the sensitivity curve below the peak, it seems reasonable to say that the method should not be able to show if the peaks are due to the PSTAB noise or not.

ITF found in relocking and in PREPARE_SCIENCE mode. 
It unlocked at 22:25 UTC (TBC).
Relocked at 2nd attempt at 23:26 UTC after the usual cross-alignment in ACQUIRE_DRMI (0.6 urad Tx+, 0.5 Ty- for SR and 0.7 urad in Ty- for PR). SCIENCE mode set.

Guard tour (UTC):
22:16 - 22:46
00:11 - 00:41
02:05 - 02:35
04:08  -04:38

Today, I found ITF in SCIENCE. 16:30 UTC scheduled COMMISSIONING activities started:

• Automation tests for automatic Science Mode (D. Bersanetti)
• Sensitivity vs CP tilt (M. Was)

21:06 UTC ITF back in SCIENCE

21:50 UTC ITF unlocked. Relocking in progress.

Guard tours (UTC):

• 18:39 - 19:09
• 20:21 - 20:51

Air Conditioning
I noticed that the EE_Room - ENV_EER_TE flag dropped to 16.85 degrees, so I contacted the HVAC on-call technician, D. Soldani, who asked me to check the EE room. At 18:26 UTC, I observed that the temperature inside the room was normal, and both the splitter and the fan coils were functioning as expected. Additionally, the Euroterm box indicated a room temperature of 19 degrees (see attached picture). Subsequently, V. Dattilo and M. D'Andrea entered the EE room to reassess the situation. They switched off the malfunctioning splitter and left the fan coil on to control the room temperature. The splitter remote control had been placed in the CR.

Putting the CP ghost beams as close as possible to the B1 beam while remaining on the B1/B5 diaphragm on SDB1 following instructions in https://logbook.virgo-gw.eu/virgo/?r=65427

Figure 1. Starting point, only WI CP ghost beam is visible, as the other ghost beam is on the silicium part of the beam dump which scatters much less

16:49 UTC - starting changing NI and WI CP TY tilt
17:08 UTC - finished the changes

Figure 2. End point of the alignment of the two CPs

There is a significant difference between the two pictures in terms of where are bright patches of light on different parts of SDB1. For example the bright patch on the side of the close loop picomotor of MMT_M2 disappears. This is not just a transient, as the starting point picture looks very similar to the end point picture from end of October. So the position of these light patches is stable over long time scale, but changed completely by changes in CP tilt of ~1mrad.

17:44 UTC - starting moving beam on WE mirror using MIR_Y_SET in order to check the 120Hz bump on B8 DC.

The mis-centered states by 3mm in either direction are not stable, with the interferometer progressively getting in a worse state once the transition on the end mirrors is over. At one point it caused an unlock.

During the relock checked in CARM NULL 1F that adding offsets in MIR_Y_SET doesn't seem to be creating issues, and the 120Hz is visible in that state too.

I will post some figures tomorrow, there seem to be an impact of the beam spot position on the arm cavity mirrors on the 120Hz bump on B8 DC and in h(t).

Today I started to implement some modifications to the node, in order to have it also automatically set the Science Mode; this is a follow-up to the AUTORELOCK_FAILSAFE functionality, meaning that the AutoScience mode will force also the Failsafe to be on. For the time being we decided (see issue 100) not to constrain this with the BNS Range, both for methodological and DAQ reasons.

There are two new states and a modified one:

• AUTOSCIENCE_ON (new, idx = 200): this is after AUTORELOCK_FAILSAFE in the same path, so it will be executed after it; it will set an (internal) global flag "autorelock" True, that is used in the other states of the node (the "automatic" LOCKED, NOT_LOCKED and LOCKING states which follow automatically the status of the interferometer; it will also set to 1 a new channel DQ_META_AUTORELOCK_AUTOSCIENCE, which can be used also in the DMS; as it happens for the AUTORELOCK_FAILSAFE state, this new one is executed to turn on things, but then the node will fall back to the appropriate one of the three channels listed above; finally, this state will enable the management of both ITF_LOCK (as the Autorelock did already) and ITF_STATUS;
• AUTOSCIENCE_OFF (new, idx = 175): this is similar to the STOP state, but it will turn off ONLY the AutoScience feature, and it will set free only ITF_STATUS; the Autorelock will be still enabled;
• STOP: already present, now it will turn off both the Autorelock failsafe and the Autoscience;
• LOCKED: in here now we make the check: if the Autoscience is enabled, and if we are in PREPARE_SCIENCE, after a timer the node will request SCIENCE to ITF_STATUS; now the timer is 10 seconds for testing purposes, but we may want to have a larger one, both to make sure that we didn't unlock immediately at the end of the acquisition, and to allow also the injection of the squeezing without going in and out of Science for a few seconds before engaging it;
• LOCKING: no change;
• NOT_LOCKED: when we unlock, ITF_STATUS will go out of SCIENCE automatically; in case AutoScience is on, ITF_CONDITIONS would complain that ITF_STATUS changed request; so here we force ITF_STATUS to go to PREPARE_SCIENCE as it would already do by itself.

Things tested:

• automatic transition to Science;
• engagement/disengagement of the Autoscience feature;
• transition to SCIENCE blocked if ITF_STATUS is not in PREPARE_SCIENCE.

Things not tested:

• correct transition in case of unlock;
• correct management in case of squeezing engagement (i.e. moving from one Science-allowed state to another, with part of the lock acquisition in-between);
• improve node management in case only Autorelock Failsafe is on and not AutoScience;
• extensive testing.

The current manual functionality should have been left alone, as everything happens only when autoscience == True.

In case other debugging channels are needed let me know. The new states layout is attached.

In fact, the noise level in ENV_EXT_MAG_N is much higher also at low frequency (plot1) and at high frequency (plot2).

A new noise appeared in our external magnetometer ENV_EXT_MAG_N on December 6, at 14:00 UTC.

This noise is a couple of wide sidebands around the mains line at 50 Hz, 15 Hz apart from it.

No equivalent noise is visible in Hrec, nor in our internal CEB magnetometers.

ITF found in LOW_NOISE_3 and in Science Mode. It kept the lock for the whole shift.
ITF left locked.

Figure 1 shows the spectra of B8 during the 4 types of SWEB local control injections, and two references, before and after the injections. There are many narrow peak excited, 79.7Hz, 127.3Hz, 135.3Hz, ... but the much wider bump at ~121Hz is not affected at all by the noise injections.

ITF found in LOW_NOISE_3 in SCIENCE mode. 
It unlocked at 00:13 UTC (BS TX loop high gain).
Relocked at 01:09 UTC after the usual cross-alignment in ACQUIRE_DRMI (2.6 urad in Ty- for SR and 0.5 urad in Tx- for PR). SCIENCE mode set.

Guard tour (UTC):
22:14 - 22:44
00:12 - 00:42
02:16 - 02:46
04:12 - 04:42

Are the changes in amplitude of the line in h(t) corresponding to changes in the amplitude of the line in accelerometers? The question is if it is the coupling that is changing over time or the amplitude of the external disturbance.

Bruco shows also similar coherence with NI optical lever signals and with NI TCS environmental sensors (accelerometer, microphone). So the coherence is not pin-pointing a particular location very well.

A possible origin could be a turbo pump, but that is just an educated guess. Turbo pumps have fairly constant frequencies but can drift by a few Hz, and are usually rotating a few hundred Hz.

I ran my noise budget script just for this injection (logfile /virgoData/NoiseInjections/LSC/LSC_injection-1417282698.txt) and the outcome is attached: the injected noise managed to get coherence in a relatively high band, the projection is quite low on DARM, with no particular shape.

Continuing the investigation of the residual spectral noise after the problems of the past weeks, I came across this wandering line at about 260 Hz. This line may have appeared after the July break, as reported in this entry by Irene #64838, and whose coherence with accelerometers in the detection area has been described in this entry #64873.

Figure 1: median-normalized spectrogram of the strain data since August in the frequency range 256-268 Hz. A structure (line plus sidebands at about +/-1 Hz) seems to be present initially at about 262 Hz. This structure is visible in this plot from August. From August 9, it seems to have disappeared, to reappear in mid-September at around 260 Hz. The sideband structure seems to suggest that this is the same structure as the previous month. This line seems then to have made a jump down to 259 Hz on October 20. Some transients at larger frequencies between the end of October and early November, to then increase in intensity since mid-November.

Figures 2 to 4 show various peculiar moments in the evolution of this line until recently.

Looking at the daily results of BruCo in the 260 Hz region on days when this line appears strongest, the coherence with various accelerometers in the detection area seems to be confirmed.

Further analysis of the data would be necessary to confirm these correlations and to understand what caused the jumps, the disappearance or increase of intensity of this line. Furthermore, in situ investigations could shed more light on what the real origin of this is.

ITF found in SCIENCE mode (LOW_NOISE_3).

At 15:25 UTC, I set the ADJUSTING mode to allow access to the EE room. The ITF unlocked at 15:28 UTC.

At 15:35 UTC, horizontal and vertical SIB2 QD2 galvo loops opened. I restored them shortly after.

The ITF returned in SCIENCE mode at 16:34 UTC.

Guard tours (UTC):

- 18:40 - 19:10

- 20:09 - 20:39

ITF found in LOW_NOISE_3 and in Science Mode. It kept the lock for the whole shift.
ITF left locked.

Air Conditioning
During the night the temperature of the EE Room decreased (see attached plot). Due to the ITF being in Science Mode it was not possible to allow access to Soldani to the EE Room to investigate the issue.

I add to Federico's excellent catch on the origin of the glitch and the 48 Hz resonance the pointer to a past entry reporting the same kind of noise: #48619.