Yesterday, Travis and I worked on finishing the reaction chain cabling now that the ESD connection is back to working. We also fixed the noisy signal on the L2 UL OSEM by swapping the short quadrapus cable D1002524 that connects to all 4 L2 (PenRe) AOSEMs.
D1002524 s/n 904 was removed and 905 was installed. Note, there are no more spares at LHO of this type of cable. Will look into getting spares.
While at it, we swapped 2 AOSEMs which had open light voltages which decayed down to 15k (from 30k).
We then aligned the L2 AOSEMs to the flags on the PUM, in a few iterations.
We made a few more alignment tweaks to both chains and then ran a series of transfer functions to make sure all 8 masses were fully suspended and free from mechanical interference.
Details of this were posted by Travis on the original alog associated with the L2 UL signal, below.
travis.sadecki@LIGO.ORG - 16:23, Tuesday 22 May 2018 (42127)
Betsy and I swapped the quadrapuss cable to the L2 (PUM) AOSEMS. This seems to have fixed the noise issue that had been plaguing the UL OSEM for several years. See attached spectra for comparison.
After swapping the cable, we noticed that the 2 lower AOSEMs at the L2 stage (LL and LR) had low OLV values, so we decided to swap these as well. We also took OLV values for UL and UR that were not replaced, but are dying of natural causes.
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