Sheila, Naoki

Instead of SQZ angle dither servo, we tried the SQZ angle ADF servo. The dither servo seems to work, but the dither makes the squeezing level worse and the SQZ angle the dither servo ended up is not exactly optimal value as reported in 74210. For ADF servo, we made a new guardian state named ADJUST_SQZ_ANG_ADF. This state has the same logic as ADJUST_SQZ_ANG_DITHER which is explained in 74210. We adjusted the ADF demod phase so that the ADF SQZ angle crosses 0 when the SQZ BLRMS4 gets minimum. The attached figure shows that the ADF servo seems to work. When the servo is closed, the ADF SQZ ANG goes to 0, the SQZ BLRMS4 goes to minimum, and the SQZ angle goes to the optimal value at 188 deg. We will leave the ADF servo on and see if it stabilizes the squeezing level next week.