DRAFT - SHIFT IN PROGRESS

ITF in SCIENCE

ITF found in Science mode; it kept Science mode for all the shift.

ITF found in LOW_NOISE_3 in SCIENCE mode. 

At 01:19 UTC ITF unlocked due to end TM (MIR or MAR) correction saturation. Relocked at first attempt. SCIENCE mode set at 02:10 UTC.
At 03:05 UTC ITF unlocked due to end TM (MIR or MAR) correction saturation. Relocked at first attempt. SCIENCE mode set at 03:50 UTC.
At 04:55 UTC ITF unlocked due to end TM (MIR or MAR) correction saturation. Relocked at first attempt. SCIENCE mode set at 05:42 UTC.

Guard tour (UTC):
22:55 - 23:30
00:50 - 01:25
04:00 - 04:35

The goal of the shift is to measure the beam jitter coupling to the sensitivity in LN2 and LN3, because the measurement we have are too old. This will be useful to give an upper limit for phase II.

DSP card damping-adv BPCCD
page 4 wnoise 1
bpnoise bpnoise.flt 0.01 ( 2 zeros with Q=0 @0Hz, 1 pole with Q=0.5 @30Hz antd 1 pole with Q=0.5 @300Hz)
bp noise noise 1

amplitude set ont the dofs txcorr, tycorr, xcorr, ycorr

%%%  LN3  %%%

%%%  LN2 %%%

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

looking at the injection of yesterday we could fine tune the gain of the loop by increasing it of about a factor 1.2 in order to have the right UGF and the right gain at LF. 

Below the detail for a 1s frame  , expressed in MB/s,  for the RAW stream and the RAW_FUL stream  the GPS1423958000_2025-02-18-23h53m02-UTC

Under the directory, /virgoData/DAQ/DataFlow],

• one can find a script called TreatFrameSize.sh
• this command coud be launched  with the following syntatx ./TreatFrameSize.sh -gps <gpstime of a frame file>  -ffl "raw full" -full where
  • -ffl "raw full":  means to analyse the frame files contents for the raw frame and the raw_full frame
  • -full : means to analyse all the defined sub-systems , to display the ordered channel size  and to store the result in a file called /virgoData/DAQ/DataFlow/GPS-<gps>

ITF in LOW_NOISE_3 and in SCIENCE mode for the whole shift. BNS Range ~54 Mpc.

Guard tour (UTC):
22:55 - 23:20
01:40 - 02:05
04:10 - 04:45

ITF relocked at the first attempt and science mode started at 14:41UTC, ITF unlocked again at 16:31UTC so I started with the scheduled calibrations and noise injection, science mode restarted at 19:34UTC.

- guard tours (UTC):
18:55 --> 19:25
20:50 --> 21:30

Calibration
- 16:37UTC: Measurement of the TF between CAL and Sc channels (CALIBRATED_DELAY);
- 16:54UTC: Measurement of actuators response for PR and BS mirrors (CALIBRATED_PRWI);
- 18:19UTC: Measurement of actuators response for NI,WI mirrors (CALIBRATED_DF_INtoEND_LN);

ISC
- 19:13UTC: LSC injections (inject_lsc.py);

the engagement went fine.

fig.1: time domain response comparison of older filter VS new filter.

fig.2: spectra comparison. As expected, the filter gains more at the region of 2 and 3 Hz. In that region, also the phase margin has been a little been improved. There is a predicted worsening in some LF region, but the overall accuracy has not been touched.

we leave this control on line by default. we will evaluate the response also in better weather conditions, with less wind and sea activity.

I found ITF in SCIENCE; at 14:55 UTC, ITF was unlocked. ITF is currently in the process of relocking.

Today, around 13:12 UTC, I have definitely stopped the process HrecN which was providing h(t) computed using FFTs of 4s instead of 8s.
This process provided, since the start of O4b, an h(t) with a BNS range approximately 1 Mpc lower than the BNS range of the h(t) provided by Hrec.
In addition, it provided several channels V1:HrecN* which were redundant with V1:Hrec* channels.

I took this occasion to investigate what we would gain in the raw data buffer if we removed the HrecN channels from the raw data frames:
the answer is 9 TB for one year.
According to Nicolas's presentation at today's commissioning meeting, this action would give about 3 additional days to the raw data buffer.

There could be more days to gain if we would excise more useless channels from the raw data storage, if we review the raw data content
and find a list of channels that could be excised. Up to concerned responsibles to decide if such a (big) work would be valuable.
As a first information, I did a non-exhaustive list of the channel families stored in the raw data , with their data flow:

V1:Sc_*                               : 8.47 MB/s --> 255 TB/year
V1:ENV_*                            : 3.38 MB/s --> 102 TB/year
V1:SW* V1:SN* V1:SUSP* : 2.91 MB/s --> 87 TB/year
V1:*CAL* V1:*PCAL*          : 1.42 MB/s --> 42 TB/year
V1:LSC_*                            : 1.22 MB/s --> 37 TB/year
V1:ASC*                             : 0.91 MB/s --> 29 TB/year
V1:Sa_*                              : 0.57 MB/s --> 17 TB/year
V1:Hrec_*                           : 0.53 MB/s --> 16 TB/year
V1:HrecN_*                        : 0.33 MB/s --> 9 TB/year
V1:DAQ*                             : 0.3 MB/s  --> 8 TB/year
V1:NCal*                             : 0.3 MB/s  --> 8 TB/year

Could there be some redundancy to track in the Susp, Env or Cal channels
(which represent about 500 TB per year over the total of 1323 TB of raw data per year) ?

Of course, this list being non-exhaustive, there are other families of channels where we could track redundancy or usefulness.
This is a big work that Alain Masserot already did successfully before the start of O4b and that could be continued if we decide it is useful to go further.

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

Guard Tour (UTC)
23:10 - 23:45
01:45 - 02:25
04:00 - 04:35 

ITF found in LOW_NOISE_3 in SCIENCE mode. 

15:00 UTC - started the planned activity "on BS AA using B1s" (Bersanetti). COMMISSIONING mode set.

ITF back in SCIENCE mode at 21:36 UTC.

Guard tour (UTC):
18:58 - 19:35
20:50 - 21:24

Today I carried on the tests for the BS_TX loop using EDB_B1s_QD1_50MHz_Y_I that started a while back (entry 66104).

Giving a quick look at the spectra of the in-loop signal and the new one, back when the last test was done and today, no big difference can be spotted (Figures 1 and 2 respectively).

I first used the line at 3.1 Hz to verify the last measurement: line amplitude 2e-3 since 15:53:00 UTC onwards, while in LOW_NOISE_3. After finding the weight (with ASC_BS_TX_INPUT, not ASC_BS_TX otherwise the loop gain will cause a miscalibration) I attempted the handoff, failing twice (LOW_NOISE_3 and _2 respectively). The measurement is also not obvious given that the DIFFp_TX line nearby (3.3 Hz) muddles the reading.

A good attempt was done injecting the line (amplitude 5e-3) from 17:42:12 UTC to 17:56:40 UTC, while in LOW_NOISE_2; I found a ratio between the weighted in-loop ASC_BS_TX_INPUT and B1s_QD1_50MHz_Y_I equal to 0.015 (Figure 3).

At 18:01:33 UTC I made a successful handoff, while in LOW_NOISE_2, from the blending B1p_QD1_50MHz_V_I_LP/B4_QD1_6MHz_V_HP to B1s_QD1_50MHz_Y_I. Clean data from 18:01:40 UTC to 18:13:15 UTC.

At 18:13:17 UTC I injected again the same line, with the same amplitude; the line was turned off at 18:23:30 UTC, clean data afterwards.

In Figure 4 the in-loop signals with the usual one (in purple) and the B1s one (in blue).

At 19:01:53 UTC I moved on towards LOW_NOISE_3 with this configuration; clean data in LOW_NOISE_3 starting from 19:11:59 UTC.

I leave the interferometer in this configuration, which is not macroscopically detrimental to the sensitivity (Figure 5); at the next unlock the lock acquisition will bring back the usual loop configuration.

Today we had an unlock, at 12:52:13 UTC, as SRCL oscillated at ~2.25 Hz (Figure) causing then the saturation of B1 and, eventually, the unlock.

During the afternoon shift we put online a new filter, SRCL_ctrl5c, which should address this problem by removing some unnecessary structures and gaining more at low frequency. This is intended to be used instead of SRCL_ctrl5b in LOW_NOISE_3.

We haven't tested it yet not to mix things up with the ongoing shift, but it will be tested soon.

Figure 1. I have reduced the integration time of the camera from 15000us to 5000us, so that it is the same as the WI camera. Both are still larger than the NE/WE cameras, that have an integration time of 1800us.

This morning during the maintenance Camilla and myself did a power budget of the fibre boxes, located in the Atrium, that bring light to the squeezer in Detlab. The results are summarised in the following table (nomenclature in fig.1).
 

In general it seems that the insertion losses of the pigtailed AOM and fibre splitters are greater than expected. A systematic and dedicated investigation will probably be necessary.

The second activity consisted of verifying the status of EQB1's FI cabling for the implementation of TGG temperature control. As can be seen from the attached picture two sets of cables come out of FI. The first is wrapped in a white Teflon sheath and is probably the line carrying the correction signal to the Peltiers. The second consists of a pair of thin copper wires that are probably connected to the temperature sensor. Both sets of cables are not terminated, they are floating on the EQB1 bench. In other words, in order to test the FI temperature control system, the wiring from the EQB1 to the Det-E-room must first  be made and/or installed.

A third task was to move the frequency offset of the SC PLL from 50 MHz to 1.206 GHz. To do this, in addition to reshuffle the cables, the setting point of the SC laser's Peltier was moved from 33622 to 31966.

Since the image on the NI_Cam appeared out of focus again, I went back this morning.

I thought that the camera had somehow moved, but the image was the same as last Tuesday. Michal suggested that, with natural light, the camera sees through the HR face of the mirror and therefore I had mistakenly tuned its focus on the AR face.

I went back at 16:00 LT to re-tune the focus with the ITF locked. I managed to do so without causing an unlock.

The beam is now clearly visible on the mirror (Fig.1)

The shift was dedicated to maintenance started at 7:00UTC, here a list of the activity reported to the control room:

- standard vacuum refill from 7:00UTC to 11:00UTC (VAC Team);
- cleaning of central building (Ciardelli with external firm: from 7:00UTC to 11:00UTC);
- PAY: adjust NI camera (Boldrini from 8:30UTC to 9:00UTC);
- INJ: check of IMC working point and position from 7:55UTC to 8:50UTC;
        check of EOM correction (Gosselin, Melo, Spinicelli from 10:30UTC to 11:25UTC);
- ALS: check WE amplifier (Derossi, Montanari from 10:20UTC to 11:20UTC);
- QNR: work on injection area and detection electronic room (Zendri from 8:30UTC to 11:00UTC);
- DET: OMC Lock in single bounce configuration from 7:16UTC to 7:22UTC;
          OMC scan in single bounce configuration from 7:25UTC to 7:47UTC;
- TCS: chiller check and refill (Ciardelli 7:10UTC);
          thermal camera reference from 8:55UTC;
          power checks (Cifaldi from 10:00UTC to 10:15UTC);

maintenance activity completed at around 11:25UTC, ITF relocked at the first attempt and science mode started at 12:36UTC, this first lock lasted about 15 minutes, relocked again at the first attempt, science started at 13:41UTC.

Beatrice had checked the cables of the SOA and prepared them with shorter screws but they gave the same problem as before, so we left in place the original connector (eventhough we cannot properly close the electronic box and the box with soa driver and crystal oven).

I also checked the connections between the fibers and cleaned them, without any improvement. The power is completely dependent on the position of the input fiber, but we did not manage to obtain more than 1.2 mW on PSTAB cali photodiode, so we did not close the loop (2mW in input from the arm, 100.4mA of the SOA and -0.2dBm seeding the 2W amplifier).

Next Tuesday we will check the connectors of the fiber in the DAQ room in the CEB.

In the shift of last week we did not manage to run the automatic alignment on EIB since we forgot to push the "release" button (to remind that it keeps memory of the last value of tension on the piezo). The instructions are available here.

Alain made a modification in the VPM and we are now able to manually choose an offset to apply to the piezo (set X/Y memory).

We ran the usual "snail" (fig. 1). It could be worth to do it on a weekly basis during the maintenance.

This morming at  09h45,40-UTC, there is a jump in the Timing 100MHz clock distribution for the

• SQB2_DBOX_Up and SQN2_DBOX_Down
• SQB2_DBOX_LC and SQB2_DBOX_SBE
• EQB2_DBOX_03

The related DBOXes have been reconfigured at 11h30-UTC and the LC loops successfully closed

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