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V. Dattilo, A. Gennai, D. Huet, E. Majorana, F. Paoletti, D. Passuello, P. Ruggi

Latest week activitiesLatest week activities

• LC power supplies

• x-damping status

• Vertical damping

• DSP software

LC Power supplies (1/2)LC Power supplies (1/2)Before WI off NI off BS off

Fastest solution : move away LC power supplies

LC Power supplies (LC Power supplies (22/2)/2)

• WI, NI and BS LC power supplies moved closed to the ID rack

• WI, NI and BS light halogen bulbs replaced• It would be better to do it also on NE, WE,

and PR (even if no effect on the ITF was observed, expectedly the magnets are properly orientated)

x-damping status (1/2)x-damping status (1/2)

LCoils: previous tests (30/01/07) were not conclusive because of the poor quality of the x position signal, hence:ErrSignal: calibration of a cleaner signal (as already done for BS in fall 2006)

Same test performed on NE (12/03/07) with improved x position signal

Goal : to have a more direct and efficient way to damp x oscillation: using lateral coils and a cleaner signal

x-damping status (2/2)x-damping status (2/2)

TowerImproved x

positionLateral coils

testStatus

NE OK Done Not functioning, likely due to magnets

WE OK To redo ?

NI To do To redo ?

WI To do To redo ?

BS OK To do 1 coil broken

PR To do To confirm Likely OK

Vertical dampingVertical damping

Problem : frequent aperture of vertical damping on WE and PR, by the guardians, due to the saturation of vertical accelerometers (see entry 15701 for details)

Actions : performed last Friday on WE• removal the DC offset on accelerometersnote: systematic monitoring and readjustment campaign of of the offsets should be performed ?

• amplification reduction by a factor 3

Some days of observations to check the benefits before applying these modifications to vertical accelerometers of PR

DSP SoftwareDSP Software

• Tests of the new DSP SW were performed but there are still some spikes that confirm the previously seen problems

note: however, the new DSP SW is currently in use for compiling ID cards in order to avoid numerical noise.

• Diego is preparing a new version with reduced numerical noise, protection against corrupted data, but DOL readout as before.

GIPC !!GIPC !!• Paolo has implemented in-line the GIPC, tested again, successfully (entry 15713).

• Next actions: check of other components coupled to the seism (short tower ID optimization suggested)

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