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AdV-COM (1/√f noise)
vardaro, irace - 23:36 Tuesday 20 August 2024 (64977) Print this report
Attempt of data acquisition with SR aligned

The aim of the today shift was to acquire some data with the SR aligned (without SQZ). 

Unfortunatelly we had many unlock during the shift and the activity should be repeated. 

Here the timing of the shift:

  • We reached LN3 at 14:42 UTC and we waited 10 minutes
  • At 14:54:45 we opened the SQZ fast shutter to check the level of the 4MHz magnitude on B1 (max 1.96mV min 0.64mV)
  • I firstly changed the SR_TY_SET to 305 Hz with a 180s ramp
  • At 15:04 UTC the ITF unlocked. Probably the SR TY ramp was too fast
  • We reached again LN3 at 16:48 UTC
  • I immediatly sent the ramp to move the SR TY SET at 305Hz this time 1200s (16:49:15 UTC)
  • After about 30 minutes the SR TY arrived at the set point of 305 Hz
  • Then I run the command to completely realign the SR: run the script /virgoDev/AEI_SQZ/changeDCP.py after that run the command LN2error_signal() 
  •  After 10 minutes the SR was aligned 
  • I opened the shutter of SQZ in order to align SQB1 with the SR aligned. I moved SQB1_LC_TY_set from 330 to 100 with a ramp of 200s. 
  • Once the bench arrived the ITF unlocked again 17:25 UTC
  • LN3 reached again at 18:20 UTC
  • I immediately set SR_TY_SET at 305 Hz with a 20 minutes ramp
  • At 18:44 UTC the SR_TY_SET reached the set point
  • I run the command LN2error_signal()
  • The SR was aligned at 19:53 UTC
  • I opened again the SQZ fast shutter to check the alignment of the SQZ and the ITF unlocked immediately
  • The ITF reloched at 20:30 UTC and we decided to stop the activity

Procedure to do the activity without unlocks:

  • ASC.SR_TY_SET.AcConstChSet(305,1200)
  • Wait 25-30 min
  • run /virgoDev/AEI_SQZ/changeDCP.py
  • LN2error_signal() 
  • wait 10 minutes
  • SQB1_LC.LC_TX_set.AcConstChSet(100,300)
  • Not open SQZ fast shutter and acquire the data

I did not test the procedure for coming back at the end of the shift

I did not understand why the ITF unlocked opening SQZ shutter we need to check

Comments to this report:
mwas - 15:17 Wednesday 21 August 2024 (64985) Print this report

Figure 1. During the SR realignment MICH input was running away to -25, with the error signal (PSTAB coupling) still fall from zero and actually moving slowly away from zero. This might the cause of the unlock (and not the squeezing shutter opening). It would be good if someone could check what was happening with MICH input in the previous SR alignment tests done for studying squeezing vs SR alignment.

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vardaro - 14:24 Friday 23 August 2024 (65002) Print this report

Fig 1 the plot of the 18th June shif in wich we performed SQZ injection with the SR aligned.

Also here the MICH input was far from zero, but the ITF was already locked since a couple of hour before the beginning of the shift, then we moved the DCP at 305 Hz and then we did the final step to align the ITF.
When the DCP was at 300 before performing the last step the MICH input was zero. On the 20th August the MICH Input was higher Fig 2. I don't know if wait more time is the solution.

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