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Entry  Thu Sep 4 01:28:32 2014, ericq, Update, LSC, Recycling cavity lengths 
    Reply  Thu Sep 4 10:10:23 2014, Koji, Update, LSC, Recycling cavity lengths 
       Reply  Thu Sep 4 18:16:20 2014, ericq, Update, LSC, Recycling cavity lengths 2014-09-CavityLengths.zip
Message ID: 10451     Entry time: Thu Sep 4 10:10:23 2014     In reply to: 10449     Reply to this: 10453
Author: Koji 
Type: Update 
Category: LSC 
Subject: Recycling cavity lengths 

Com'on. This is just a 60ppm change of the mod frequency from the nominal. How can it change the recycling cav length by more than a cm?

https://wiki-40m.ligo.caltech.edu/IFO_Modeling/RC_lengths

This describes how the desirable recycling cavity lengths are affected by the phase of the sidebands at non-resonant reflection of the arms.

If we believe these numbers, L_PRC = 6.7538 [m] and L_SRC = 5.39915 [m].

Compare them with the measured numbers

  • Lprc = 6.752 m
  • Lsrc  = 5.474 m

You should definitely run MIST to see what is the optimal length of the RCs, and what is the effect of the given length deviations.

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