Virgo Logbook

AdV-PSL (Laser Bench setup)

turconi, soulard, chaibi, chiummo - 17:18 Friday 16 October 2020 (49676)

Beam dump on the slave laser

Yesterday afternoon we blocked the beam of the slave laser. Two beam dumps were put on the beam path (pointed by the arrows in the picture). The big one blocks the SL beam, the small one blocks the ML beam. Both dumpers are not clamped on the bench. --> Thus the SL is not locked, the signals PSL_ML_DC , PSL_ML_AC and PSL_SL_REFL_PD1_DC are not at their nominal value.

This activity is part of the investigations on fast unlocks. We are now sure that no feedback light from the slave goes into the master. We recall that we are now monitoring the feedback light on the signal PSL_ML_FREQ_Q_MONIT_FS . Since yesterday 13:45 UTC we added an amplifier x10 on this signal.

The IMC and RFC were relocked yesterday afternoon at about 14:00 UTC and no unlocks were observed last night.

Images attached to this report

Comments to this report:

mwas - 15:01 Sunday 18 October 2020 (49683)

Note that there are still times when the noise on the EOM is increased from +/-0.1V to +/-0.5V see figure 1 and 2.

Thes times correspond to a broad band (up to 200kHz or 10kHz) increase in noise on the ML PZT, the frequency monitor and the EOM correction.

Images attached to this comment

49683_1603025748_Screenshot from 2020-10-18 14-45-10.png

49683_1603025754_Screenshot from 2020-10-18 14-45-30.png

49683_1603026013_Screenshot from 2020-10-18 14-59-55.png

direnzo, narnaud - 11:34 Friday 23 October 2020 (49730)

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.