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Reports until 13:39, Monday 09 September 2024
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sheila.dwyer@LIGO.ORG - posted 13:39, Monday 09 September 2024 - last comment - 18:38, Monday 09 September 2024(79985)
offset and OFI temperature checks this morning

TJ, Vicky, Naoki, Sheila

Since the vent we haven't fully checked some of the usual offsets and settings that we might need to adjust, I started with some of them this morning. 

I started with stepping the BS camera pitch offset, which I'd started in 79663 but wasn't able to finish at that time because of a lockloss.  We gained a little more than 1 kW of circulating power in the arms by adjusting the offset from 233 to 230, see first attachment, this has been added and loaded in lscparams.  The improvement on POP A + B may be because of an alignment shift, we are probably clipping on both of those.

Went to no squeezing and ran OMC alingment offset scan: went to no squeezing and copied Jennie's dtt template from 78616.  This scan saturated the OMC pitch actuator, so I reduced the OMC ANG Y amplitude from 3 to 1 and restarted the scan at 15:53:07-16:16:29 UTC.  TJ and I noticed that the strange flashing behavoir of the OMC camera was coming and going while this scan was happening. 

Following up on 79719 I used the template sheila.dwyer/OMC/OMC_fringe_wrapping.xml and reduced the amplitude to 600 as Naoki did to adjust the OFI temperature. We found that the fringe wrapping shelf amplitude was reduced by increasing the temperature, we went up to 37.5C and the amplitude of the shelf dropped by a factor 3 (second screenshot attached).  We didn't go hotter than this because we weren't sure how hot we would want to operate.   This change in OFI temperature doesn't seem to have changed the optical gain, shown in the 3rd attachment.  (template in sheila.dwyer/OMC/OMC_fringe_wrapping_after_OFI_repair.xml, ref 38 25C, ref 39 28.5C, 40 29.5C, ref 41 30.5, ref 42 31.5C, ref 42 31.5C, ref 43 32.5C, ref 45 34.5C, ref 46 35.5C, ref 47 36.5C, ref 48 37.5C. )

Vicky, Naoki and I started some alignment scans for 4 squeezer DOF (ZM5+6 P+Y) with different frequencies (similar to the OMC offsets), at 17:10 UTC- 17:34:20 UTC. (We continued OFI temperature adjustments while this was happening). 

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victoriaa.xu@LIGO.ORG - 18:38, Monday 09 September 2024 (80004)

Analyzing the OMC alignment offset scan, adapting Gabriele's and Jennie W's codes from lho78616.

Script here lives in /opt/rtcds/userapps/release/omc/h1/scripts/OMC_alignment_dither_check_qpd_offsets.*     Saved as both a script and as a jupyter notebook.

If running as a script, then the gps start & stop times around turning on/off the dithers can be input manually (lines 44-45), or on the command line, for example:

  • python OMC_alignment_dither_check_qpd_offsets.py 1409932335 1409933965
  • gps0 = start time of data pull, e.g. just before dither lines turn on
  • gps1 = end time of data pull, e.g. just after dither lines turn off

There are three main plot outputs:

  • Time series of dithers + darm + dcpd_sum
  • DCPD BLRMS vs. QPD offsets. Purple = kappaC.  Green = DCPDs @ PCAL line. These should and do track, which makes sense.
  • DARM BLRMS vs. QPD offsets. Purple = kappaC.
  • Dashed black line = original QPD offsets.  Solid red line = potentially better offsets (chosen by hand after looking at plots).

 

Current offsets are all 0. Based on today's dithers, could try the following offsets:

  • A_PIT = -0.15
  • A_YAW = +0.15
  • B_PIT = -0.15        (this plateau'd and didn't go through an optimum)
  • B_YAW = -0.08      (this plateau'd and didn't go through an optimum)
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