Kiwamu, Terra, Lisa

We had a hard time dealing with bounce and roll modes tonight and that slowed us down.

After keeping them under control, we followed directions from Daniel and we engaged the  ISS boost  (gain increase from 5dB to 7dB, boost 1 on -- we believe this is supposed to give us a factor of 2 suppression at 2 kHz, with higher gain at 100 Hz). 

The higher suppression of intensity noise around 100 Hz exposed a suspicious shape in the noise curve, so we decided to triple-check the calibration by making complete calibration measurements (see Kiwamu's entry).

With the new calibration filters, the suspicious shape at 100 Hz disappeared, and we got back a more familiar curve...and some Mpc, SensMon is around 60 Mpc.

The "jitter/intensity/(frequency?)" noise coupling to DARM stabilizes in a bad place after a while at 50W (yellow is O1 reference, all the other colors are curves taken at different times during the lock in low noise), making DARM worse between 500 Hz and 1 kHz, and even more clearly above 3 kHz. So there is more work to do to figure out how to keep the coupling low.


We leave the IFO to Terra for PI tests.


Some details:

- bounce and roll modes are becoming a problem, they required constant attention during lock acquisition;

- we had an error message once complaining that the ISS third loop was not engaged, and we couldn't move on in the locking sequence; Kiwamu bypassed the problem by forcing power increase (we also had some problem closing the ISS second loop from the medm screen (?)) 

- there have been (at least) a couple of ISS instabilities that prevented us from staying locked in DRMI; we "fixed" them by increasing the diffraction power, that happened at least twice today

- we reversed the change to the DARM gain, now it is back to 1400