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| 40m Log |
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 Fri Nov 7 10:52:57 2008, steve, Update, PEM, AC is back on 
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 Fri Nov 7 15:58:10 2008, rana, Update, PEM, AC is back on
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Mon Nov 10 19:39:40 2008, steve, Update, PEM, thump noise from particle counter
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Tue Nov 12 23:05:06 2013, rana, Update, PEM, thump noise from particle counter
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Wed Nov 13 11:30:07 2013, Steve, Update, PEM, particle counter MOVED
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Message ID: 1122
Entry time: Fri Nov 7 15:58:10 2008
In reply to: 1121
Reply to this: 1129
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| Author: |
rana |
| Type: |
Update |
| Category: |
PEM |
| Subject: |
AC is back on |
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I'll bet Steve a dollar that it is mechanical. The attached PDF compares all of the accelerometers from right now.
You can see that the RMS in MC2 is way bigger than MC1.
In the second PDF file you can see the time series. I had to play around a lot with DTT to get it to work. The DTT/Foton
combo on Allegra is not stable, so make sure your work early and often.
In the plots shown, I am bandpassing the time series from 600-700 Hz. I found that doing so allowed the burp in MC1 to remain
large and reduce the extraneous fuzz in MC2. As you can see there is no such noise in MC2.
So its a noise around 600-700 Hz that comes on quickly and then shuts off after several seconds. Its also very periodic in that
it comes on around every 20 minutes. Steve also tells me (although he refuses to put in the elog) that it started up around
August 20th (?). I feel like someone in the 40m lab ought to be able to guess what this is at this point.
Please convince Steve to elog his findings about when the noise started.
If one goes out there and stands next to it when the trend predicts its happening it becomes clear what it is. |
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