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Reports until 14:42, Monday 28 October 2013
arnaud.pele@LIGO.ORG - posted 14:42, Monday 28 October 2013 (8286)
SRM phase 2b results

Attached are damped and undamped top mass transfer function results taken last friday night for SRM phase 2b (test bench, surrogate glass mounted)

Undamped TF are matching the model, cf the first attachement. Damped TF are slightly different for longitudinal and roll (cf second attachement), which might be due to a discrepancy between the design gain and the medm one. Since the filters will be redesigned soon, there's nothing to worry about for now.

The last attachement shows a comparison between SRM phase 1b (staging building), the last phase 2b measurement, and PRM phase 2b back in february.

The only 2 differences seen are for the pitch DOF (5th page)

1) SRM gain at DC is slightly higher by a factor of ~1.3 compared to PRM

2) Phase 2b shows a slight increase of the longitudinal to pitch cross-coupling at 2.8Hz compared to phase 1b

Other than this results are good.

Travis will be centering the lower stages osems this afternoon in order to check the actuation chain, before closing phase 2b.


Note : SRM has the "side" osem, which drives the "transverse" DOF, on the opposite side as PRM. The gain for the side drive is then different, (+1), cf the picture attached as reference.

The new settings have been saved under the "safe" snapshot.

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