Kiwamu, Sudarshan, Jenne, Darkhan

Overview

EPICS records that are used for calculating DARM time-dependent parameters ("kappas"), were updated using corrected DARM model (with the correct sign of the ETMY_L3_DRIVEALIGN_L2L gain). These EPICS values result in reasonable kappa values (see details).

"512 Hz DAQ downsampling" filter was installed into CAL-CS synched oscillator that replicates 35.9 Hz cal. line (ESD).

Investigations showed that the synched oscillators for 35.9 Hz cal. line were running at 180 degrees out of phase w.r.t. each other. They got synched to the same phase after I played some with the oscillator settings in CAL-CS model.

Jenne noticed that today f_C was oscillating between 320 and 360 Hz at the time-scale of ~20s. This issue was resolved by turning on low-pass filters in the CAL-CS model.

Details

Sudarshan confirmed that kappas calculated from SLM tool data using these EPICS values are within reasonable ranges. After updating EPICS records one of the issues was that κ_TST calculated in the front-end was around -1.0. Further investigations showed that the synched oscillators for 35.9 Hz cal. line in SUS-ETMY and CAL-CS models were running at 180 degrees out of phase w.r.t. each other. We could get rid of the discrepancy by setting the phase of the CAL-CS oscillator to 180 degrees (see attached plot).

After changing settings on the synchronized oscillators their phases somehow got synchronized. So, I removed 180 degrees of an additional phase in the CAL-CS oscillator. It is still not clear what was the cause for the phase of two synched oscillators being exactly 180 degrees off. Now the oscillator outputs (after the 512 Hz DAQ downsampling) are pretty much the same (TF measurement at 35.9 Hz is attached).

New EPICS values and corresponding logs were commited to calibration SVN. The values were accepted in SDF_OVERVIEW.