Reports until 20:07, Monday 27 January 2014
H1 SEI
sebastien.biscans@LIGO.ORG - posted 20:07, Monday 27 January 2014 - last comment - 08:50, Tuesday 28 January 2014(9585)
BSC-ITMX 0.5Hz investigation part2

Arnaud, Sebastien

We've kept investigatiing on the 0.5Hz resonance issue that we've been having on ISI-ITMX (see first alog here). Reminder: we see a  peak at 0.5Hz on all the sensors of the ISI when it is controlled.

After more tests, we realized that this peak appears on all the sensors only when the T240s are in the blend (see plot attached).

Plus, by looking at the T240-X signal, you can clearly see this peak at 0.5Hz. It is even more obvious when the noise floor is reduced (ISI controlled).

 

Thus the issue seems to come from the T240s. We'll continue the investigation tomorrow and find which T240 is bad and how to fix it.

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daniel.sigg@LIGO.ORG - 21:46, Monday 27 January 2014 (9587)
Link

The last plot seems to show harmonics at 1Hz, 1.5HZ(?) and 2Hz. Is this 0.5Hz sharp? If so, this could indicate a problem with the DAQ timing.

sebastien.biscans@LIGO.ORG - 23:04, Monday 27 January 2014 (9588)
Link

Good point Daniel. We have to double check how the other sensors behave. We'll check that tomorrow.

keita.kawabe@LIGO.ORG - 08:50, Tuesday 28 January 2014 (9596)
Link 

Exactly 0.5Hz (and its harmonics).
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