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AdV-SGD (FDS commissioning)
delaurentis, lartaux, demarco, sorrentino - 22:58 Tuesday 11 June 2024 (64487) Print this report
CC scans for different DCP values

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).

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Comments to this report:
seglararro - 10:35 Thursday 13 June 2024 (64498) Print this report
I checked the validity of the h(t) reconstruction during this intervention, looking into the hrec/hinj values (attached). We observe that the effect of this intervention is mostly catched by the lines around the DCP frequencies, from 200Hz to 400Hz. We can say that hrec remains correct, although a bias (upper shift) of ~2-3% in modulus and ~0.02 rad in phase is observed.

During these tests, we see how the BNS range decreases with the scan to over ~40 Mpc, how the DCP increases up to 305Hz and the optical gain decreases down to 2500*10^6 (~15% of variation).
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