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Reports until 12:06, Tuesday 03 September 2024
H1 ISC
sheila.dwyer@LIGO.ORG - posted 12:06, Tuesday 03 September 2024 (79883)
POPAIR B centering

While Oli was relocking I went to ISCT1 and checked the centering on POPAIR B (motivated by the observation that the POP18 is low compared to before the vent, as well as the DC light on this diode 79663).  The beam wasn't well centered on the diode, and I've moved it to be more centered while the IFO was locked at 22W on PRM (this didn't make much difference in the powers at 22W).  This did improve the powers on POP18 after power up by about 15-30%, but it doesn't recover us to the power levels we had in the earlier part of O4b.  It seems that the degradation started around May 15.  We might want to go to the table to check for clipping upstream (today I only touched the mirror in front of POP AIR B), or think about if we need to touch that pico motor.

 

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