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Message ID: 209     Entry time: Wed Nov 23 08:55:41 2016
Author: Gabriele 
Type: General 
Category: Noise hunting 
Subject: "Advanced" vibration isolation 

In normal conditions the RMS of the QPD signals is dominated by the 58 Hz line generated by the roughing pump. Also, when the modes are excited, they exhibit large sidebands at +- 58 Hz that are an annoyance for the analysis.

I improved a bit the level of the 58 Hz in the QPD signals by putting the roughing pump on top of a "Very Useful Box":

Despite the fact that this advanced vibration isolation is already a little bit effective, it might be good to try to build some better suspension and maybe add an acoustic isolation around the pump.

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