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Reports until 08:10, Thursday 23 January 2014
H1 SEI
jim.warner@LIGO.ORG - posted 08:10, Thursday 23 January 2014 (9463)
Xarm ISI Current States

This is HughR, not Jim.

 

The current running configuration of the ETMX is almost as it was when Hugo logged the operational state  6 Dec.  That was before the ISC etc crew began complaining that the ISI was broke or at least made things worse.  I don't have an explainatioin why that period of poor ISI performance occurred.  Was the HEPI & ISI too tilted?  Things seem to be better since we eased the tilting (~13 Jan) though we weren't happy until now.  The large drives on the ISI required to hold the tilted Optical Table with the Tilted HEPI may cause performance issues.  RyanD of LLO would be seeking relief of our 1000s count drives.

The ISI blends are all 750 mHz except for X & Y dofs on Stage1.  These are set to T100mHz with a 0.44Hz notch.  This is the configuration from early December.  Yesterday Sebastian added another Notch closer 0.5Hz on the X & Y dofs to address a peak on the Oplev pitch and the MO L.

The ITMX which was not commissioned in early December.  The ITM now has the same controls as the ETM.  Sebastian added a number of filters and taylored another notch as well.  Both ETM and ITM are running the level 1 gain bank.

Sebastian also added Feed Forward from the HEPI L4Cs but didn't think it did very much, at least in the current area of interest for the ISC crew.

I'd be sckeptical that this state can be reached with one button push.  Engaging the Trillium blend directly may be tricky and may have to be switched on when things have settled down after turning them on with out the Trilliums.

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