Sheila, Jennie W

Today Sheila changed the guardian to use the camera offsets that we determined via beam walking yesterday. Since we improved the camera offset that sets the spot on the BS (CAM YAW1) we decided to optimise the YAW to Length gains for the ITMs to improve on this change.

Sheila and tuned the Y2L drive align gains to see if it increased or decreased our coupling to DHARD and CHARD.

We used templates at each step to check the transfer function and coherence from H1:ASC_{CHARD,DHARD}_Y_SM to DARM by injecting broadband noise.

The nominal Y2L gains are 2.1 for ITMX and -1.9 for ITMY.

We found a minimum in the coupling with both a common and differential step (that brought us back to our nominal gain for ITMX) but changed the gain on ITMY DRIVEALIGN to -2.5. The yellow trace in both plots shows the transfer function and coherence for this configuration between dhard and darm and chard and darm where nominal is in dark blue.

Templates are saved in /ligo/home/sheila.dwyer/Alignment/DHARD/DHARD_A2L_tuning.xml and
/ligo/home/sheila.dwyer/Alignment/CHARD/CHARD_A2L_tuning.xml

I updated the gains in SDF and Sheila has also put them in the guardian.