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Entry  Fri Jan 27 06:07:47 2012, kiwamu, Update, LSC, glitch hunting 
    Reply  Fri Jan 27 17:16:05 2012, kiwamu, Update, LSC, hypothetical glitch scenario 
    Reply  Thu Feb 16 03:47:16 2012, kiwamu, Update, LSC, glitch table 
       Reply  Wed Feb 22 01:53:57 2012, kiwamu, Update, LSC, update on glitch table 
Message ID: 6235     Entry time: Fri Jan 27 17:16:05 2012     In reply to: 6231
Author: kiwamu 
Type: Update 
Category: LSC 
Subject: hypothetical glitch scenario 

Here is a hypothetical scenario which could make the glitches in the LSC error signals. It can be considered as a 4 step phenomenon.

        (1) up conversion noise due to a large motion at 3 Hz

   => (2) rms level exceeds the line width (a.k.a. linear range) in some LSC sensors

   => (3) unlocks some of the DOFs  in a moment

   => (4) glitches due to the short unlock.

- - plan  - -

 In order to check this hypothesis the low finesse PRMI must serve as a good test configuration.

What I will do is to gradually decrease the offset in MICH such that the finesse of PRMI becomes higher.

And at each different finesse I will check the spectra, glitch rate, and etc.

Quote from #6231

        Low finesse PRMI      

In this configuration NO glitches ( a high speed signal with an amplitude of more than 4 or 5 sigma) were found when it was locked.

Is it because I didn't use AS55 ?? or because the finesse is low ??

Also, as we have already known, the up conversion noise (#6212) showed up -- the level of the high frequency noise are sensitive to the 3 Hz motion.

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