Goal of the shift: perform multiple scans of the coherent control CC phase in the ITF, for different DCP values, to reach a tradeoff between SQZ efficiency and SR misalignment (issue 47).
Outcome of the shift: three CC scans were made for DCP=255 Hz, 285 Hz, 305 Hz.
Starting time: 14:00 UTC
We started at DCP=255 Hz, since previous measurements were already taken at 195 Hz and 225 Hz (entry #64146).
- 14:14 DCP value set to 255 Hz (ramp time of 1800 s)
- 15:18:44 fast shutter open
- 15:19:34 CC loop gain set to 75000
- 15:20:04 AA loop engaged
- 15:23 CC scan started DCP = 255 Hz
At 15:30:32 PumpPhase_Lock_Status goes to 10 (unlock and then relock after 4 seconds), see Fig. 1. This automatically closed the fast shutter. We restarted the scan afterwards:
- 16:11 CC scan started DCP = 255 Hz (Fig. 2-3)
- 16:48:55 ITF in SQZ (phi0 = 0.95 rad)
- 16:50:21 EQB1 fast shutter open
- 16:51:21 CC loop engaged: SQZ mode now effective
- 16:58:16 ITF in ASQZ (phi0 = 2.5 rad)
- 17:06:27 shutter closed
- 17:06 DCP set to 285 Hz
- 17:38 CC scan started DCP = 285 Hz (Fig. 4-5)
- 18:06:22 EQB1 fast shutter open
- 18:06:55 CC loop engaged: ITF in ASQZ (phi0 = 2.55 rad)
- 18:14:31 ITF in SQZ (phi0 = 0.95 rad)
- 18:20:28 shutter closed
- 18:20 DCP set to 305 Hz
- 19:06 CC scan started DCP = 305 Hz (Fig. 6-7)
- 19:36:48 EQB1 fast shutter open
- 19:39:06 CC loop engaged: ITF in ASQZ (phi0 = 2.55 rad)
- 19:49:19 ITF in SQZ (phi0 = 0.9 rad)
- 20:00:08 shutter closed
- 20:01 DCP set to 335 Hz
We were not able to perform the CC scan with DCP=335 Hz, due to the long time needed for the loop to stabilize (Fig. 8).
At 20:24 we decided to go back to the nominal DCP value (195 Hz).