The master laser shows increase in the power high frequency noise these are similar to the increases in the EOM correction noise. To investigate this we have monitored the output power of the laser used in the clean room at LAPP. That laser is similar to the Virgo master laser (maybe even indentical). It is a Mephisto free space laser at 1064nm.

Figure 1 shows the spectrogram over 1 night of the LAPP laser output power normalized by the median spectrum. Between minute 50 and 100 there is a small increase in broadband noise above a few kHz. At a few hundred Hz there many peaks which are moving up and down in height, these are expected to be mechanical resonances of various mounts on the optical bench.

Figure 2 shows the spectrogram over a weekend, with the noise eater switched off. There are many more times when the noise at high frequency increases, and there is also a series of harmonics of ~230Hz moving up and down at the same time.

Figure 3 shows for spectra of:

• Yellow, noise eater enabled, noise low
• Purple, noise eater enabled, noise high
• Blue, noise eater disable, noise low
• Red, noise eater disable, noise high

In all cases there is no external control loops applied to the laser (but there DAC cables attached to the PZT, temperature and current inputs of the laser with active signals sent during various measurements on working days).

Clearly the noise eater is reducing the amplitude noise by a large amount, especially the ~230Hz harmonics, and the broad bump at a few kHz. A plausible explanation is that the master laser has its amplitude noise level fluctuating over time scale of hours, the noise eater has sufficient gain to mostly remove this noise level fluctuation, but not completely. As the noise eater acts on the pumping current, there might be some cross talk to the master laser frequency which is causing the increase EOM corrections to compensate.

The shift was dedicated to the reinstallation of the Squeezer Box ( see entry #49745 ) and Green beam alignment on West arm cavity ( carried out by Tacca and Leroy ). To allow this last activity a lock of the West cavity was required; luckily the alignment was still good after the weekend and we were able to lock it at the first attempt.
The SQZ and ALS activities continued during the afternoon. ALS alignment still in progress.

DET
At 13:45 UTC the ID loops of SDB1 were opened by the Guardian. I tried to close them, but this action seems to excite the Local control of the bench. Thanks to V. Boschi the loops were restored at 15:05 UTC.

SBE
During the weekend the SPRB Vertical correction decreased below the safe threshold. From around 8:40 UTC to 8:55 UTC, using the related motors, I returned the value around zero.

The cabling between DET lab and DET electronic room continued over Thursday and Friday. Now the cabling of AEI squeezer and SQB1 multiSAS are completed. We also added the cables for environmental sensing on ESQB1. Cables for the remaining ESQB1 hardware will be completed after the end of the works on AEI squeezer.

State of Virgo: Unlocked.
ITF Mode: Upgrading.
Quick Summary: IMC locked; SNEB in-air, SDB2 loops open; all suspensions loops closed; SR-BS Valve close; TCS CO2 lasers off; INJ_MAIN in pause, all the other automation nodes OFF.
Activities ongoing since this morning: No activity known so far in the control room.

The AEI squeezer was installed on the ESQB1 table in the afternoon. Set up will continue over the weekend.

Today we switched on again the AEI squeezer laser in the DET Lab, in particular in the new FDS cleanroom inside the DET clean room.

From today remember to wear safety goggles when entering in the clean room

Taking advantage of the accident to PR control, I resetted the thermal correction to the master laser which had been quite high in the past days. INJ was relocked afterward.

Below the list of the today's activities:

- squeezer board re-installation & cabling (in progress);
- green beam alignment on west arm cavity by Matteo, Raffaele and Romain (in progress);

SUSP

at 9:10UTC the PR local control get crazy and the F7 controls opened by the guardian because of one of the two SLED has switched off, probably due to some human activity around the tower base; with the help of Paolo from remote the SLED had been switched on and the control restored.

We started to populate the rack5 and the FDS-Rack2

Rack5 from the top (figure 1 rack on the left)

• DAQ BOX 58 (2U)
• Cable duct (1U)
• Wenzel 500 Mhz (1U)
• 4 DDS Boards (1 each)
• PLL Board (1U)
• 3x Line Drivers/ Line Receivers (1U each)

Missing on rack 5: 2x DCF and DCG (12U total), 1 or 2 cable trays and 2 Line Driver/Receiver Box

Rack FDS2 from the top (figure1 rack on the right):

• DAQ BOX 91 (2U)
• Cable Duct (2U)
• DAQ BOX 90 (2U)
• Cable Duct (2U)
• DAQ BOX 89 (2U)
• Cable Duct (2U)
• 2 Translation Stages and 2 Tip Tilt Driver
• Empty space
• QPD Controller SN 30 (2U)
• QPD Controller SN 23 (2U)
• Rohde & Schwartz Power Supply (3U)
• Rohde & Schwartz Power Supply (3U)

Missing on FDS Rack 2: 2 x 5U Boxes with 6 PI Controller each one

Today we recabled all the RF cables to the DDS1 (g25squeeze1)

• channel 1 PDH @ 128.53 MHz
• channel 2 Int PLL ref frequency @ 7MHz
• channel 3 Homodyne detector demodulation @ 7MHz
• channel 4 Pump Phase demodulation @ 14 MHz

The variable output of the channel 1 is connected to the mDemod channel 3 DAQ BOX 58

We also connected the 80MHz reference for the PLL Ext to the channel 1 of the DDS2 board (g25squeeze2)

Then we reconfigured the two DDS boards and we connected them to the 500MHz OCXO.

Finally we cabled and switched on the PLL Boards (the Beat Note of the PLL Ext is now the cable Spare2 N 56

To control again the PLL we had to restart the SQZ istance of the tango server on the phasecam1 pc. We found it switched off, we switched on it again and then we run again the tango starter with the following commands

DataBaseds 2 -ORBendPoint giop:tcp::20000 &

export TANGO_HOST=olserver129:10000

Starter phasecam1 &

When the two PLL boards were reacheble we set the same laser temperature used for the O3 run:

• Ext PLL OUT SLOW: 38110
• Int PLL OUT SLOW: 37720

For the data between Oct 13 and 14, looking at INJ_EOM_CORR is not a good witness channel. The input mode cleaner was unlocked (on purpose) and there was no correction sent to the EOM. For that night a good channel to look at instead is PSL_PMC_REFL_I_FS_rms.
 

This morning, by taking advantage of the cabling activities between DET lab and DER, I was able to mount and test two single axis episensor on the east (photo 1) and north (photo 2) flange of the DET tower. I used the channels already available for the episensor installed on the SQZ bench (currently disconnected), so the sensor on the east flange is ENV_SQZ_SEIS_x while the sensor on the north flange is ENV_SQZ_SEIZ_Y.

The two probes work fine: a little adjustment of the offset has to be done. Since on the east flange we already have a PZT accelerometer (ENV_DT_ACC_Z) and there is another PZT at the end of the pipe located on the north flange (ENV_SQZ_PIPE_ACC_Y), it is also possible th have a comparison (fig 1).

Since the second episensor is on the flange, measuring along Z, while the second PZT accelerometer is on the pipe, measuring along Z, the coherence between these probes is limited (also the spectra are clearly different...).

After the test the signal of the two episensors were disconnected, so no signal is available now.

Triggered by Nicolas, I've run NonNA-corre to estimate the Pearson cross-correlation coefficient between a target channel, in this case the max or the rms of INJ_EOM_CORR from the trend frame, and a set of (330+) channels from trend: [ENV_*,PSL_*,INJ_*], either *_rms or *_max. The results are then ranked on the base of (the absolute value of) this coefficient, and listed in at the links below:

• trend rms;
• trend max.

Mind also the log files, with an extended list of most correlated channels.

Of course most/some correlations are trivial and expected (like the one with INJ_IMC_REFL, which however I didn't exclude from the analysis as a check) but hopefully something could be of interest. Also, feel free to post comments/requests or to suggest me other similar analyses.

Triggered by Nicolas, I've run NonNA-corre to estimate the Pearson cross-correlation coefficient between a target channel, in this case the max or the rms of INJ_EOM_CORR from the trend frame, and a set of (330+) channels from trend: [ENV_*,PSL_*,INJ_*], either *_rms or *_max. The results are then ranked on the base of (the absolute value of) this coefficient, and listed in at the links below:

• trend rms;
• trend max.

Mind also the log files, with an extended list of most correlated channels.

Of course most/some correlations are trivial and expected (like the one with INJ_IMC_REFL, which however I didn't exclude from the analysis as a check) but hopefully something could be of interest. Also, feel free to post comments/requests or to suggest me other similar analyses.

Here below the instructions for the cavities locking

Preliminary steps

• Open a terminal
• go in the folder wich contains the two scripts by typing: "cd /olusers/virgorun/ISC/LSC"
• start ipython

Run of the locking scripts

• for the North Arm type "run narm _lock.py"
• for the West Arm type "run warm_lock.py"

Then you acces to the following functions:

• {N or W}ARMlock() to lock the arm
• {N or W}ARMunlock() to unlock the arm
• {N or W}ARMdrift_ctrl(1) to switch on the drift control
• {N or W}ARMdrift_ctrl(0) to switch off the drift control
• {N or W}ARMhandoffB4() to pass from the lock in transmission to the lock in reflection

To lock the cavity in transmission:

1. {N or W}ARMlock()
2. {N or W}ARMdrift_ctrl(1)

To pass from the lock in trasmission to the lock in reflection

1. {N or W}ARMhandoffB4() with the cavity locked in trnsmission

To unlock the cavity (either from the lock in transmission or reflection)

1. {N or W}ARMunlock()

Note that: to simplify the things today I renamed the functions in order to be coherent between the two arms. I tested only the script of the North arm, I could not test the script for the west arm because there was an ALS acrivity

Below the list of the activities communicated in control room:

- SQZ cabling inside the detection lab (in progress);

 - ALS alignment by Matteo, Raffaele and Romain (in progress);

- mechanical works around SQZ area by LAPP team (in progress);

Today, I covered the WI CH CO2 bench with a pellicle layer as a temporary solution to protect the optics from the dust.

The final plexiglass cover will be installed in a few weeks.